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‫ﺑﺴﻢ اﷲ اﻟﺮﺣﻤﻦ اﻟﺮﺣﻴﻢ‬
MASTITIS, IN DAIRY COWS AND IT’S
ECONOMIC IMPLICATIONS IN THE RIVER
NILE STATE ( SUDAN)
By
ISAM MAHMOUD MOHAMED ADAM
( B.V.Sc., University of Baghdad, Iraq, 1986)
(M.V.Sc., University of Khartoum, Sudan, 1997)
A Thesis submitted to fulfill the requirements of the Ph.D. in
veterinary science.
Department of preventive medicine and public health
University of Khartoum
Faculty of veterinary medicine
February 2007
Preface
This work was undertaken at Atbara Livestock Research Station
from 2003 till 2005 and part of this work has been done at Atbara
Regional Veterinary Laboratory.
I
DIDICATION
To the soul of my mother, great
brothers, sisters and uncles.
II
father,
patient wife, dear
Acknowledgements
Initially I would like to express my sincerest and deepest gratitude
to my academic advisor, Professor Abdel Aziz ElTayeb for diligent
guidance, valuable advices and continued encouragement during the
course of this study. My gratitude and appreciation are extended to Dr.
Ahmed ElGhali, the director of Atbara regional veterinary research
laboratory, for the valuable contribution and permission of conducting my
work in the laboratory. I would like to extend my dear thanks to Dr.
Kamal Abdel Wahab, the director of Atbara dairy research station, and
Dr. Ahmed Gamal, general director of ministry of agriculture and animal
resources, River Nile State, for their valuable help and financial support.
Also my gratitude is extended to Dr. Mohamed Tag El-Dien, Dr. Yassir
Ahmed Hassan, Dr. Khalid Mohamed Taha, Dr. Mohamed Osman
Hussein, Mr. Mohamed El-Hassan Burhan and to the staff members of
Atbara dairy research station and laboratory for their great help and
support.
Many thanks to all of those who submitted an advice and gave a
hand to accelerate the practical work in this study.
III
Abstract
This study was conducted in River Nile State to investigate, the
prevalence of mastitis in dairy cows and the economical implication of
bovine mastitis, through the reduction in milk yield, milk dumped
after antibiotic treatment and the cost of drugs and other costs inferred
with mastitis.
California mastitis test was performed in dairy farms to identify the
infected quarters. The result revealed that about 87.5% of herd
individuals were mastitic. The bacteria isolated from milk samples
were staphylococci, streptococci, micrococci; coliform bacteria
together with mycotic infection.
The economical implication of mastitis was evaluated through the
calculation of milk yield reduction. Reduction, which represented
67.2% from the total loss, had been assessed through the direct and
indirect estimation of somatic cell count. It represented more than
12% of milk yield for one infected quarter. Also the reduction
percentage had been assessed through comparison between infected
and healthy quarter for the same cow. The reduction percentage of one
infected quarters was about 12.5% . The reduction as average was
14.2% (234kg /cow/season). The milk reduction cost was 27325
Sudanese Dinars. The discarded milk due to treatment with antibiotic
was 14.5% of the total loss, with total cost 5670 S.D. Drug cost was
estimated as 5167 SD(13.2%.). Veterinary services cost 2000Sudanese
Dinnars. Represented 5.1 % of total financial loss. The total financial
loss was estimated as 30252 SD per cow/year.
Cows were investigated to confirm the effect of mastitis on milk
yield. The average of total and daily milk yield had been adopted. The
IV
results showed irregularity in average of total and daily milk yield for
the mastitic cows compared to healthy ones.
The effect of mastitis on milk yield was confirmed statistically and.
The milk yield curve verified the differences in milk yield between
mastitic and healthy cows.
V
‫اﻟﺨﻼﺻﺔ‬
‫ﺗﻤﺖ هﺬﻩ اﻟﺪراﺳ ﺔ ﺑﻮﻻﻳ ﺔ ﻧﻬ ﺮ اﻟﻨﻴ ﻞ ﻟﺘﻘ ﺼﻲ ﻣ ﺪي اﻧﺘ ﺸﺎر ﻣ ﺮض اﻟﺘﻬ ﺎب اﻟ ﻀﺮع واﻷﺛ ﺮ‬
‫اﻻﻗﺘﺼﺎدي اﻟﻨﺎﺟﻢ ﻋﻦ اﻟﻤﺮض ﻓﻲ اﻷﺑﻘﺎر‪ ،‬واﻟﻤﺘﻤﺜﻞ ﻓﻲ ﻧﻘﺺ إﻧﺘﺎج رﺑﻊ اﻟﻀﺮع ﺟﺮاء اﻟﻤ ﺮض‪،‬‬
‫اﻷﻟﺒ ﺎن اﻟﺘ ﻲ ﻳ ﺘﻢ إﻋ ﺪاﻣﻬﺎ ﺟ ﺮاء ﻣﺰﺟﻬ ﺎ ﺑﺎﻟﻤ ﻀﺎدات اﻟﺤﻴﻮﻳ ﺔ أﺛﻨ ﺎء اﻟﻌ ﻼج‪ .‬وآ ﺬﻟﻚ ﺗﻜﻠﻔ ﺔ اﻷدوﻳ ﺔ‬
‫اﻟﻤ ﺴﺘﺨﺪﻣﺔ ﻓ ﻲ اﻟﻌ ﻼج و أﻳ ﺔ ﺗﻜ ﺎﻟﻴﻒ إﺿ ﺎﻓﻴﺔ أﺧ ﺮى ﺗ ﺪﺧﻞ ﺿ ﻤﻦ داﺋ ﺮة اﻷﺛ ﺮ اﻻﻗﺘ ﺼﺎدي ﻟﻬ ﺬا‬
‫اﻟﻤﺮض‪.‬‬
‫ﺗﻢ اﻋﺘﻤﺎد ﻓﺤﺺ آﺎﻟﻴﻔﻮرﻧﻴﺎ ﻟﻤﻌﺮﻓﺔ اﻷﺑﻘﺎر اﻟﻤﺮﺿﻴﺔ ﺑﻤ ﺰارع اﻷﻟﺒ ﺎن‪ ،‬ﺣﻴ ﺚ وﺟ ﺪت ﻧ ﺴﺒﺔ‬
‫اﻹﺻﺎﺑﺔ ﺑﻤﻌﺪل ‪ %87.5‬ﻣﻦ ﺟﻤﻠﺔ اﻟﻘﻄﻴﻊ وان اﻟﺒﺎآﺘﺮﻳﺎ اﻟﺘ ﻲ ﺗ ﻢ اﻟﺘﻌ ﺮف ﻋﻠﻴﻬ ﺎ آﻤ ﺴﺒﺒﺎت ﻣﺮﺿ ﻴﺔ‬
‫آﺎﻧ ﺖ ﻣ ﻦ ﻧ ﻮع اﻟﻤﻜ ﻮرات اﻟﻌﻨﻘﻮدﻳ ﺔ واﻟ ﺴﺒﺤﻴﺔ ‪،‬واﻟﻌ ﺼﻴّﺎت اﻟﻘﻮﻟﻮﻧﻴ ﺔ ‪ ،‬وآﺎﻧ ﺖ هﻨ ﺎك إﺻ ﺎﺑﺎت‬
‫ﻓﻄﺮﻳﺔ‪.‬‬
‫ﻋﻠ ﻰ أﺛ ﺮ إﺛﺒ ﺎت اﻹﺻ ﺎﺑﺔ‪ ،‬ﺗ ﻢ ﺗﻘ ﺪﻳﺮ اﻟﻔﺎﻗ ﺪ ﻓ ﻲ اﻹﻧﺘ ﺎج ﻋ ﻦ ﻃﺮﻳ ﻖ ﺣ ﺴﺎب ﻋ ﺪد اﻟﺨﻼﻳ ﺎ‬
‫اﻟﺠﺴﻤﻴﺔ‪ ،‬واﻟﺬي أﺷﺎر إﻟﻰ أآﺜﺮ ﻣﻦ ‪ %ٍٍ12‬ﻟﺮﺑﻊ اﻟﻀﺮع اﻟﻤﺼﺎب‪ .‬آﻤ ﺎ ﺗ ﻢ أﻳ ﻀًﺎ ﺗﻘ ﺪﻳﺮ اﻟﻔﺎﻗ ﺪ ﻓ ﻲ‬
‫إﻧﺘﺎج رﺑﻊ اﻟﻀﺮع ﻋﻦ ﻃﺮﻳﻖ اﻟﻤﻘﺎرﻧﺔ ﺑ ﻴﻦ اﻟﺤﻠﻤ ﺎت اﻟﻤ ﺼﺎﺑﺔ واﻟ ﺴﻠﻴﻤﺔ‪ٍ .‬أﻇﻬ ﺮت اﻟﻨﺘ ﺎﺋﺞ أن اﻟﻔﺎﻗ ﺪ‬
‫ﻓ ﻲ إﻧﺘ ﺎج رﺑ ﻊ اﻟ ﻀﺮع ﺟ ﺮاء اﻹﺻ ﺎﺑﺔ ﺑﻤ ﺮض اﻟﺘﻬ ﺎب اﻟ ﻀﺮع ﺗﺤ ﺖ اﻟ ﺴﺮﻳﺮي ﺑ ـ ‪ ،%12.5‬ﺗ ﻢ‬
‫اﻋﺘﻤ ﺎد اﻟﻤﻌ ﺪل ﺑ ﻴﻦ اﻟﻄ ﺮق اﻟﻤ ﺴﺘﺨﺪﻣﺔ ﻓ ﻲ ﺗﻘ ﺪﻳﺮ ﻧﻘ ﺼﺎن اﻹﻧﺘ ﺎج ﺑ ـ ‪ %14.2‬ﺧ ﻼل اﻟﻤﻮﺳ ﻢ‬
‫)‪234‬آﺠﻢ( واﻟﺘﻲ ﻗﺪرت ﺑﻤﺒﻠﻎ وﻗﺪرﻩ ‪ 27325‬دﻳﻨﺎر ﺳﻮداﻧﻲ وهﺬا ﻳﺸﻜﻞ ً اﻟﺠﺰء اﻷآﺒﺮ ﻣ ﻦ اﻟﻔﺎﻗ ﺪ‬
‫اﻻﻗﺘ ﺼﺎدي ﺑﻤﻌ ﺪل ‪ ، % 67.2‬ﺛ ﻢ ﺗﻘ ﺪﻳﺮ اﻷﻟﺒ ﺎن اﻟﻤﺒﻌ ﺪة ﺟ ﺮاء ﻣﺰﺟﻬ ﺎ ﺑﺎﻟﻤ ﻀﺎدات اﻟﺤﻴﻮﻳ ﺔ ﺑ ـ‬
‫‪ %14.2‬ﺑﻤﺎ ﻗﻴﻤﺘﻪ ‪ 5670‬دﻳﻨﺎر ﺳ ﻮداﻧﻲ‪ ،‬أﻣ ﺎ ﺗﻜ ﺎﻟﻴﻒ اﻷدوﻳ ﺔ اﻟﻤ ﺴﺘﺨﺪﻣﺔ ﻓ ﻲ اﻟﻌ ﻼج )‪(%13.2‬‬
‫ﻗ ﺪرت ﺑ ـ ‪ 5167‬دﻳﻨ ﺎر ﺳ ﻮداﻧﻲ ﻓ ﻲ ﺣ ﻴﻦ آﻠﻔ ﺖ اﻟﺨ ﺪﻣﺎت اﻟﺒﻴﻄﺮﻳ ﺔ ﺑ ـ ‪ % 5.1‬ﻣ ﻦ ﺟﻤﻠ ﺔ اﻟﻔﺎﻗ ﺪ‬
‫اﻻﻗﺘ ﺼﺎدي وﺑﻤﺒﻠ ﻎ ﻗ ﺪرﻩ ‪ 2000‬دﻳﻨ ﺎر ﺳ ﻮداﻧﻲ ﻟﺘ ﺼﺒﺢ ﺟﻤﻠ ﺔ اﻟﻔﺎﻗ ﺪ اﻻﻗﺘ ﺼﺎدي ﺟ ﺮاء اﻹﺻ ﺎﺑﺔ‬
‫ﺑﺎﻟﺘﻬﺎب اﻟﻀﺮع ﺗﺤﺖ اﻟﺴﺮﻳﺮي ﻟﻸﺑﻘﺎر ﻣﺒﻠﻎ ﻗﺪرﻩ ‪ 30252‬دﻳﻨﺎر ﺳﻮداﻧﻲ ﻟﻠﺒﻘﺮة ‪ /‬ﻓﻲ اﻟﺴﻨﺔ‪.‬‬
‫ﺗﻢ اﻋﺘﻤﺎد ﻣﻌﺎﻳﻴﺮ أﺧﺮى ﻟﺘﺜﺒﻴﺖ أﺛﺮ ﻣﺮض اﻟﺘﻬﺎب اﻟﻀﺮع ﻋﻠﻰ اﻹﻧﺘﺎج ﻋﻦ ﻃﺮﻳ ﻖ ﻣﺘﺎﺑﻌ ﺔ‬
‫اﻹﻧﺘﺎج اﻟﻴﻮﻣﻲ آﻤﻌ ﺪل ﻟﻤ ﺪة ﺳ ﺒﻌﺔ ﺷ ﻬﻮر وﻣﻘﺎرﻧﺘﻬ ﺎ ﻓ ﻲ ﻇ ﻞ وﺟ ﻮد اﻹﺻ ﺎﺑﺔ واﻟﺘ ﻲ أﻇﻬ ﺮت ﻋ ﺪم‬
‫اﻧﺘﻈﺎم ﻣﻌﺪل اﻹﻧﺘﺎج اﻟﻴﻮﻣﻲ وﻓﻖ ﺣﺎﻟﺔ اﻹﺻﺎﺑﺔ ‪.‬‬
‫ﺗﻢ اﻋﺘﻤﺎد اﻟﺘﺤﻠﻴﻞ اﻹﺣﺼﺎﺋﻲ ﻟﺪراﺳﺔ اُﺛﺮ ﻣﺮض اﻟﺘﻬﺎب اﻟﻀﺮع ﻋﻠﻰ اﻹﻧﺘﺎج ﻣﻊ ﺟﻤﻠﺔ ﻣ ﻦ‬
‫اﻟﻌﻮاﻣﻞ اﻷﺧﺮى واﻟﺘﻲ أﻇﻬﺮت ﻧﺘﺎﺋﺞ ذات ﻣﻌﻨﻰ ﻋﻨﺪ ﺗﺪاﺧﻞ اﻟﻌﻮاﻣﻞ ﻣﻊ ﺑﻌﻀﻬﺎ ﻣﺜ ﺎل رﻗ ﻢ اﻟ ﻮﻻدة‬
‫واﻟﻤﻮﺳﻢ ﻣﻊ ﻓﺘﺮة اﻟﺠﻔﺎف وﻃﻮل ﻓﺘﺮة اﻟﺤﻠﻴﺐ وأﺛﺮهﻢ ﻋﻠ ﻰ اﻹﻧﺘ ﺎج اﻟﻴ ﻮﻣﻲ وﺟﻤﻠ ﺔ اﻹﻧﺘ ﺎج‪ ،‬اﻷﻣ ﺮ‬
‫اﻟﺬي ﻳﺆآﺪ ارﺗﺒﺎط ﻋﺎﻣﻞ ﻣﺮض اﻟﺘﻬﺎب اﻟﻀﺮع ﻣﻊ رﻗﻢ اﻟﻮﻻدة واﻟﻤﻮﺳﻢ ﻓﻲ اﻟﺘﺄﺛﻴﺮ ﻋﻠﻰ اﻹﻧﺘﺎج‪.‬‬
‫‪VI‬‬
‫أﺧﻴ ﺮًا ﺗ ﻢ اﻋﺘﻤ ﺎد رﺳ ﻢ اﻟﻤﻨﺤﻨ ﻰ وﻣﻼﺣﻈ ﺔ اﻟﻔ ﻮارق ﺑ ﻴﻦ إﻧﺘ ﺎج اﻷﺑﻘ ﺎر اﻟ ﺴﻠﻴﻤﺔ واﻟﻤ ﺼﺎﺑﺔ‬
‫ﻳﻮﻣﻴًﺎ آﻤﻌﺪل واﻹﻧﺘﺎج اﻟﺴﻨﻮي‪ ،‬واﻟﺬي أﺑﺮز ﺑﻮﺿﻮح ﻗﻠﺔ ﻓ ﻲ اﻹﻧﺘ ﺎج ﻋﻨ ﺪ اﻷﺑﻘ ﺎر اﻟﻤ ﺼﺎﺑﺔ ﻣﻘﺎرﻧ ًﺔ‬
‫ﺑﺎﻷﺑﻘﺎر اﻟﺴﻠﻴﻤﺔ‪.‬‬
‫‪VII‬‬
Table of content
Preface
Dedication
Acknowledgement
Abstract
Arabic Abstract
Table of content
List of tables
List of Figures
Introduction
1. Literature Review
1.1. Mastitis
1.2. Classification of mastitis
1.3. Signs of mastitis
1.4. A etiology of mastitis
1.4.1. Etiology of clinical mastitis
1.4.2. Etiology of subclinical mastitis
1.5. Pathogenesis of mastitis
1.6. Factors affecting susceptibility to mastitis
1.6.1. The per partum period
1.6.2. Deficiencies of vitamins and minerals
1.7. Mastitis caused by different organisms
1.7.1. Staphylococcal mastitis
1.7.2. Streptococcal mastitis
1.7.3. Coliform mastitis
1.8. Diagnosis of mastitis
1.8.1. Clinical mastitis
1.8.2. Subclinical mastitis
1.9. Somatic cell count
1.9.1. Advantage of CMT
1.9.2. Factors affecting milk somatic cell count
1.10. Economic importance of mastitis
1.10.1. Somatic cell count and milk reduction
1.11. The milk yield curve and mastitis
1.12. Factors affecting production traits
1.12.1Morphology of the mammary gland
1.12.2.Milk yield
1.12.3. Lactation length
1.12.4. Dry period
2. Materials and Methods
2.1 Location of the study
2.2 Herd Management
VIII
I
II
III
IV
VI
VIII
XI
XII
1
4
4
5
6
7
9
10
10
11
11
11
12
12
13
13
13
14
14
15
16
19
22
23
23
23
24
25
27
27
27
2.3 Data collection and manipulation
28
2.4 Milk tests and sampling
29
2.4.1 California mastitis test. (C.M.T)
29
2.4.2. The direct microscopic somatic cell count 30
2.4.3. pH test
31
2.5. Sampling procedure
31
2.6. Laboratory examination of milk
31
2.6.1. Sterilization methods
31
2.6.2. Preparation of culture media
31
2.6.2.1. Blood agar media
32
2.6.2.2. Edward's medium
32
2.6.2.3. Mac Conkey's agar medium
32
2.6.2.4. Chapman stone medium
32
2.6.3. Media for biochemical test
33
2.6.3.1. 40% bile agar
33
2.6.3.2. Hugh and Leifson's (O.F) medium
33
2.6.3.3. Motility medium
33
2.6.3.4. Aesculin broth.
33
2.6.3.5. Arginine broth
33
2.6.3.6. Mac Conkey's broth purple
34
2.6.3.7. Bromothmol blue
34
2.6.4. Reagents
34
2.6.4.1. Hydrogen peroxide 3 %( Volume10)
34
2.6.4.2. Oxidase test reagent
34
2.6.4.3. Nessler's reagent
34
2.6.5. Culture methods
34
2.6.5.1. Primary isolation
34
2.6.5.2. Examination of inoculated culture media 34
2.6.5.3. Purification
35
2.6.6. Primary identification
35
2.6.7. Identification of bacterial genera
35
2.7 Statistical analysis
37
3. Results
38
3.1. Recorded number of cases with subclinical mastitis and dead
quarters in dairy farms examined
38
3.2. The number of cows with positive quarters examined by
California mastitis test
38
3.3. The number of CMT performed in farm N0.1 and the number of
infected quarters
38
3.4. The allocation of infected quarters
39
3.5. The grading of infected quarter
39
3.6. The relationship between CMT result and microbial isolation
39
IX
3.7.
3.8.
The microbial isolated from milk samples
39
Somatic cell counts as they relate to estimated milk losses
39
3.9. The reduction percentage in milk yield
40
3.10. The percentage of infected cows in relation to the milk yield
40
3.11. The Evaluation of the average daily milk yield 40
3.12. Comparison of the milk yield of mastitic and non-mastitic cows
41
3.13. The effect of mastitis on milk yield
41
3.14. The cost of treatment and discarded milk
41
3.15. The assessment of reduction in milk yield in relation to the
methods usage
42
3.16. The evaluation of economical loss
43
4. Discussion
61
Recommendations
68
References
69
X
List of tables
1234567891011121314151617181920212223-
24-
The estimated costs of the factors related to the occurrence of
mastitis.
17
Milk loss related to CMT, WMT and somatic cell counts
20
21
The reduction in milk yield in relation to SCC/ml .
Reduction of milk yield in relation to various factors
21
Subclinical mastitis and dead quarters in the dairy farms
42
Results of the California Mastitis test
.
42
The result of California mastitis tests in farm No (1).
43
Allocation of infected quarters.
43
The grading of infected quarters positive to the CMT.
44
Relationship between C.M.T result and microbial isolation
44
Identification of bacteria isolated.
45
Somatic cell counts as they relate to estimate milk losses
46
Reduction percentage in milk yield.
47
The percentage of infected cows in relation to the milk yield
47
Evaluation of the average daily milk yield
48
Comparison between Mastitic and non- mastitic cows milk yield in
both summer and winter (A) Non mastitic cows (B) mastitic 49
The mean effect of mastitis and season on total milk yield
50
Analysis of variance for total milk yield
50
The mean effect of mastitis and season on daily milk yield
51
The analysis of variance for daily milk yield
51
The discarded milk and treatment costs due to the mastitis
treatment .
52
Reduction in milk yield as calculated by different methods
54
The economical loss evaluation /cow/season.
55
The expected cost of treatment and discarded milk (prospective) 56
XI
List of figures
1- Average daily milk yield (mastitic and non- mastitic) (winter
season).
57
2- Average daily milk yield (mastitic and non- mastitic) (summer
season).
58
3- Mastitic and non-mastitic total milk yield/cow (summer season)
59
4- Mastitic and non-mastitic total milk yield/cow (winter season) 60
XII
Introduction
Milk Production System:The production of milk by dairy farmers is not only a business
but also a way of life. Many of the decisions taken on the farm are
consequently dictated by both financial constraints and job
satisfaction. Nevertheless during recent decades there has been a
continuing squeeze on profits in the milk production industry as
increase in prices which have taken place in systems of milk
production are mainly a response to reduced profit per cow. This has
given the dairy farmer an increasing awareness of the need to
produce milk more efficiently. (Leaver, 1982).
River Nile State lies approximately between 22-35 longitude east
and 16-22 latitude north, and extend from Elsabuloga falls on River
Nile south toward Bayoda desert to the Egyptian boarder north. The
River Nile passes through the state from south to north and Atbara
river passes obliquely through the State from east to west where it
meets the River Nile at Atbara town (Mohamed et. al, 1996).
Livestock production system in Africa is classified into intensive,
semi- intensive and extensive system according to husbandry
practice and distribution of pasture that varies with the rainfall,
season or cultivated crop (Pyne 1986). In Sudan 92% percent of
livestock population is possessed by nomads that follow extensive
system of husbandry in eastern, western and southern part of the
Sudan (Kamal, 1983). In Nahr EL-Nil State, the system of husbandry
adopted is a semi-intensive one.
Among the Sudanese breeds of cattle, two breeds namely Kenana
and Butana are known to show high potentiality for milk production
(Alim, 1960; Osman, 1970; Osman and EL Amin, 1971). In the area
1
Introduction
of the present study, cattle represent the second most important
source of milk production. Butana cattle is the dominant breed.
Friesian and Butana and Friesian crosses have been recently
introduced in the State in order to improve milk productivity to meet
the increasing demand for milk as high quality food. In the area
where the study was conducted, milk production is so scanty and it is
almost always sold by producers in unprocessed form. Little
information is available on diseases of cattle in Nahr EL-Nil State.
How ever, mastitis, pneumonia and tropical theleriosis represent the
major diseases of cattle in the State (Elghali and ELHussien, 1995).
Bovine Mastitis
Bovine mastitis can be defined as inflammation of the udder
resulting from infection or trauma. It is caused by a variety of well
known microorganisms, such as Staphylococcus aureus and
Streptococcus agalactia.
The economical implication of Mastitis
Mastitis is known as the disease that causes heavy economic
losses to milk producers. The average production loss per lactation
for one infected quarter is about 1.600 pounds "weight" (Schroeder,
1997). Other
losses are due to discarded abnormal milk and milk
withheld from cows treated with antibiotics, costs of early
replacement of affected cows, reduced sale value of culled cows,
costs of drugs and veterinary services and increased labour costs.
Objectives of the Study
The present investigation was conducted in Aedammer
Province to study:
1.
The prevalence of mastitis in dairy cows.
2.
The economical implications of bovine mastitis through:• Reduction in milk yield.
2
Introduction
• Milk dumped after antibiotic treatment.
• Other expenses incurred as a result of mastitis.
3
1- Literature Review
1-1 Mastitis:
During the last two decades milk production has grown into
a specialized business. Economic pressures make it vital for farmers
to increase the profitability of their dairy herds; a goal only to be
achieved by the intelligent application such as good husbandry based
on the scientific principles involved in breeding, management and
feeding of cow (Leaver,1982).
It is well established that bovine mastitis is of great
economic
importance
to
the
dairy
industry
(Blosser,1979;
Meyer,1980; Miller,et. al,1984).The infection of the udder with
microorganisms capable of causing mastitis.
Hurley and Morin (1996) define mastitis as intramammary
infection, primarily bacterial infection, but also mycoplasmal,
mycotic, or algal infection. Whereas Jones and Bailey (1998)
consider mastitis when the udder becomes inflamed because
leukocytes are released into the mammary gland in response to
invasion of the teat canal usually by bacteria. These bacteria multiply
and produce toxins that cause injury to milk secreting tissues and
various ducts throughout the mammary gland.
Elevated leukocytes, or somatic cells cause a reduction in milk
production and alter milk composition (Jones, and Bailey,1998).
Mastitis is also defined by Cole (1962) as inflammation of the
mammary gland caused by microbial infection or undue stress or
both. Some investigators believe that the mere presence of pathogens
in milk is not indicative of mastitis. The increase in somatic cell
count and the finding of pathogens in milk samples give positive
diagnosis (McDonald, 1977). The two criteria, somatic cell count
4
Literature Review
and isolation of pathogens are necessary to differentiate actual cases
of mastitis from mere contamination (McDonald, 1977). According
to National Mastitis Council’s (1996): mastitis is an inflammation of
the mammary gland in response to injury for the purpose of
destroying or neutralizing the infectious agents and to prepare the
way for healing and return to normal function. Inflammation can be
caused by many types of injury irritants. In the dairy cow, mastitis is
nearly always caused by microorganisms, usually bacteria that
invade the udder, multiply in the milk producing tissues and produce
toxins that are immediate cause of injury.
1.2 Classification of mastitis:Craplet (1963) classified the disease on the following
criteria:
A- By symptoms differentiates between :Acute mastitis that develops rapidly with severe congestion and
rapidly but is of infrequent occurrence, easily diagnosed and of
reduced economic importance and chronic mastitis, the development
of which is more or less obvious clinically with a high frequency in
occurrence.
B- By clinical characteristics which consider the mastitis
condition as gangrenous, catarrhal, parenchymatous or suppurative.
C- By stage of lactation :Beginning of lactation, drying off and dry period .
D-By the causal organism :Contagious or chronic mastitis caused by Streptococcus agalactia
and
common
mastitis
caused
by
streptococcus
groups,
staphylococcus groups, Corynebacterium pyogenes, Escherichia.coli
Pseudomonas, Proteus, yeast and bacteria species.
5
Literature Review
Radostitis, Blood and Gay (1994) classified mastitis into two
forms, clinical and sub clinical mastitis. Clinical mastitis is
characterized by apparent changes of both milk and mammary gland
and subclinical mastitis in which there are no apparent changes.
clinical mastitis are classified in to:
a- Peracute mastitis:
In this type there is marked abnormality of milk and udder with
severe systemic reaction.
b- Acute mastitis:
Characterized by severe inflammation of the udder without
marked systemic reaction.
c- Sub acute mastitis:
There is mild inflammation of the mammary gland and
abnormal milk secretion.
d- Chronic mastitis:
Most changes are detected in the milk with recurrent attacks
of inflammation.
In subclinical mastitis there are no visible abnormalities of
milk or udder. Were subclinical mastitis is characterized by an
increase in somatic cell and/ or leukocyte count (Radostitis, Blood
and Gay, 1994). It is a problem of the herd rather than individual
animals.
1-3. Signs of mastitis:
Michel (2000) described the signs of mastitis according to
the mastitis form. In clinical mastitis, the infected quarter often
becomes swollen, some times painful to touch and the milk is visibly
altered by the presence of clots, flakes or discolored serum and some
times blood.
6
Literature Review
In severe cases (acute mastitis), the cow shows signs of
generalized reaction: fever, rapid pulse, loss of appetite and sharp
decline in milk production.
In contrast, subclinical mastitis is subtle and more difficult to
detect. The cow appears healthy, the udder does not show any signs
of
inflammation
and
the
milk
seems
normal.
However,
microorganisms and white blood cells (somatic cells) that fight
infections are found in elevated numbers in the milk.
Schroeder(1997) characterized subclinical mastitis by lack of
consistent, visible and elevation of somatic cells count of the milk.
Bacteriological culturing of milk will detect bacteria in milk and this
form causes the greatest loss in dairy farms through lowered milk
production.
1-4.A etiology of mastitis:
Of the several causes of mastitis, only microbial infection is
important. Although fungi, yeasts and possibly virus can cause udder
infection.
1-4-1. Etiology of clinical mastitis:
Microbial causes of clinical mastitis include Staphylococcus
aureus (Bryson, 1973), Streptococcus agalactiae (Gonzales et. al,
1988), Escherchia coli (Schukken et. al, 1989), Pseudomonas
aeruginosa (Howel, 1972) Klebsiella pneumoniae and Proteus spp
( Park, 1979), Streptococcus dysagalactiae (Schaufuss et. al, 1968),
Streptococcus ubris, Streptococcus faecalis, (Schaufuss et. al, 1968),
Streptococcus faecium, Streptococcus bovis (Boutrel and Runiewiez,
1984), Micrococcus spp. (Jha et al, 1994), Coagulase negative
Staphylococci (Gonzalez et. al, 1988), Pasteurella multocida
(Pasco, 1960, and O’sullivan et. al, 1971),Corynebacterium spp.
(Costa et al, 1987) Mycobacterium spp .(Oudar et. al, 1966),
7
Literature Review
Bacillus cereus (Nielsen, 1972), Yersinia pseudotubercullosis
(Messerli, 1972), Serratia marcensce (Kim and Kim, 1979), and
Mycoplama spp. (Blood and Henderson, 1989). However the
predominant bacterium incriminated in acute bovine mastitis is
Staphylococcus aureus (Bryson,1973; Pearson and Macki, 1979;
Innes and Lynch, 1990) followed by Streptococcus agalactiae
(Gonzalez et. al,1988; Innes and Lynch,1990) or Escherichia coli
(Jha et. al, 1994).
In the Sudan, Staphylococcus auerus was considered as the
major bacteria isolated from bovine clinical mastitis ( Mamoun and
Bakheit, 1992) followed by Streptococcus agalactiae. Other
organisms isolated include Bacillus cereus (Adlan et. al, 1980),
Escherichia
coli (Haghour and Ibrahim, 1980) ,Klebsiella
pneumoniae (Bagadi, 1972) and Staphylococcus epidermidis .
1-4-2. Etiology of subclinical mastitis:
As in the case of clinical mastitis, many organisms have
been isolated from cases of subclinical mastitis. These include
Streptococcus lactis, and Enterococcus faecalis (Keskintepe et. al,
1992)
Staphylococcus
Streptococcus
aureus,
agalactiae,
Staphylococcus
Streptococcus
epidermidis,
dysagalactiae,
Streptococcus uberis, Escherichia coli, Pseudomonas aeruginosa,
(Bozkir, 1986 and Aydin et. al, 1995), Coryne-bacterium spp.,
Micrococcus spp. (Costa et. al, 1987).
In the Sudan several bacteria have been isolated from cases
of subclinical mastitis. These include Staphylococcus aureus,
Staphylococcus epidermidis, Corynebacterium spp., Pseudomonas
spp. Streptococcus agalctia, Streptococcus dysagalactia and
Micrococcus spp.,(Shalallai et. al, 1992). High incidence of
subclinical mastitis has been reported in Khartoum and the
8
Literature Review
commonest species of bacteria isolated were Enterococcus faecalis,
Enterococcus faecium, Streptococcus bovis, Streptococcus equi,
Streptococcus lactis and Streptococcus pyogenes (Hashim et. al,
1991).
1-5. Pathogenesis of mastitis:
Infections begin when microorganisms penetrate the teat
canal and multiply in the mammary gland. Irritation of the teat most
often occurs during milking. Organisms present in the milk or at the
teat end are propelled into the teat canal. After milking, the teat canal
remains dilated for one to two hours. Organisms from the
environment (Manure, bedding, etc.) or those found on injured skin
at the tip of the teat may easily invade an open or partially open
canal. Some bacteria may proceed into the udder by attaching and
colonizing new tissues; others my move around via milk current
produced. Bacteria first damages the tissues lining the large milk
collecting ducts. The bacteria may encounter leukocytes (white
blood cells) present naturally in small numbers in milk. These cells
are the cow’s second line of defense because they can engulf and
destroy bacteria. If bacteria are not entirely destroyed, they continue
to multiply and begin to invade smaller ducts and alveolar areas.
Milk secreting cells are damaged by toxins and other released
irritants substances (chemotaxes factors) that lead to increased
permeability of blood vessels. Additional leukocytes move to the site
of infection . they enter the alveolar tissue in great numbers by
squeezing between the damaged milk secreting cells . Fluid, minerals
and clotting factors also leak into the affected area. Clotted milk may
close milk ducts. Sometimes the microorganisms are eliminated
rapidly and the infection is cleared. In this case , the clogged ducts
are opened and milk composition and production return to normal in
9
Literature Review
several days. However as the infection persists and ducts remain
clogged , the entrapped milk causes the secretory cells to revert to
arresting (non-producing ) state and the alveoli begin to shrink
.Substances released by leukocytes lead to the complete destruction
of alveolar structures, which are replaced by connective and scar
tissues. Thus as the disease progresses the number of somatic cells in
the milk becomes elevated and this are associated with a permanent
reduction in milk yield (Michel,2000, Hurley and Morin,1996).
1-6. Factors affecting susceptibility to mastitis:
Hurley and Morin (1996) discussed the factors which lead
to susceptibility of mammary gland to infection. Whether or not
intramammary infection occurs depends on the interaction of host,
agent and environmental factors. Host factors include, the presence
or absence of natural resistance to mastitis, the state of defense
mechanisms, the stage of lactation. Whereas agent factors include
the number of organisms in the gland, the pathogencity of the
organisms and the presence of other virulence factors. In addition the
environmental factors include, the milking environment, the milking
practices hygiene, the type of housing, bedding and the weather.
1-6-1. The Peripartum period:In the peripartum period, several defense mechanisms are
compromised just prior to and after parturition which predispose the
gland to mastitis. Fluid volume in the gland increases resulting in
increased intramammary pressure and dilatation of the teat canal and
sometimes leakage of colostrums.
Citrate concentration rises and lactoferrin is low.
Phagocytic cells are not efficient in engulfing and killing bacteria
in colostrum contained in the gland at this time.
10
Literature Review
High immunoglobulin concentration in the gland at this time is
not effective in preventing new intramammary infection. IgG1, the
major immunoglobulin isotype in cow colostrum, is not normally an
effective opsonin in the mammary gland.
Antibiotic concentration from dry cow antibiotic therapy is too
low to combat infection and teat dipping during this period is not
particularly effective in mastitis prevention.
1-6-2.Deficiencies of vitamins and minerals:
Deficiencies shown to be related to increased incidence of clinical
or subclinical mastitis increased severity of infection , or elevated
somatic cell counts, include Selenium, Vitamin E, Vitamin A, Zinc,
Cobalt and some others deficiencies.(Hurley and Morin,1996).
1-7. Mastitis caused by different organisms:1-7-1. Staphylococcal mastitis:Staphylococci are widely distributed in nature where they
make up the normal bacterial flora of the mucous membranes and the
skin (Zingeser et. al, 1991).
Staphylococci are gram positive, catalase positive and ferment
glucose. They are classified according to the coagulation of human
or rabbit plasma in to coagulase postive staphylococci represented by
Staphylococcus aureus and coagulase negative Staphylococci such as
Staphylococcus epidermidis (Baird and Parker,1962). Staphylococci
were found to be the most frequent causative agents of mastitis
among cattle (Cargil and Bootas, 1970; Kapur and Singh, 1978).
Staphylococcus aureus is known to cause peracute, sub acute
and chronic mastitis, in addition to gangerinous mastitis (Radostitis
and Gay, 1994). It also acts as contaminant of milk (VanDijk and
Swanberge, 1963; Zingeser et. al, 1991; Lafont and Lafont, 1985).
On the other hand coagulase negative Staphylococci were identified
11
Literature Review
as primary caustive agent of cattle mastitis during first lactation
(Timms and Schultz, 1987; Derieze and Keyser, 1980).
1-7-2. Streptococcal mastitis:Streptococci are most common upon skin, mucous
membranes and intestine of man and animals (Garge and Mital,
1990). They are classified according to precipitation reaction of
specific carbohydrate antigens into 12 groups (Merchant and Packer,
1967).
Streptococci are the second most common pathogens
isolated from cows' milk (Sharma and Pasker, 1970; Ahmed et. al,
1991).
Streptococcus agalactiae represents the major streptococcus
species that cause mastitis in cattle (Costa et. al, 1991). However
that is known as environmental mastitis. Enterococci that include
Enterococcus faecalis, Enterococcus faecium and Streptococcus
bovis gain entry into milk and milk products through water supply,
equipments and insanitary and unhygienic conditions of production
and handling (Hashim et. al, 1991), They have been incriminated as
direct or indirect causes of the disease ( Garge and Mital, 1991).
1-7-3. Coliform mastitis:Coliform mastitis is an udder infection of cows caused by
Escherichia coli, klebsiela pneumoniae and Enterobacter aerogenes
(Odongo and Ambani, 1989) . They are gram – negative bacilli, that
inhabit water and soil and transmitted by flies , contaminated water
and feed (Merchant and Packer, 1967).
Escherichia coli was defined as the most common Gram
-negative bacilli associated with clinical and subclinical mastitis (Jha
12
Literature Review
et. al,1994; Elliot et al,1976) and causes sudden sharp drop in
production of milk (Mustafa et al ,1977) .
Escherichia coli was also isolated from udders of cattle at calving
and during dry period (Timms and Schultz, 1987) . Escherich coli
may cause acute and peracute form of clinical mastitis (Radostitis
and gay, 1994). It has been isolated from milk, teat canal and teat
wall puncture milk samples as contaminants (Preeze, 1988;
Mammoun ,1981).
Klebsiella is the second most common Gram-negative bacillus
isolated from cattle milk infected with mastitis (McDonald et al
1970; Howel et al, 1972).
Enterobacter spp. were found to cause bovine mastitis (Park,
1979; Haghour and Ibrahim ,1980).
1-8. Diagnosis of mastitis:1-8-1. Clinical mastitis:Diagnosis of clinical mastitis can be achieved by visual
examination of both milk and mammary gland where the
abnormality could be detected easily (Blood and Henderson , 1989)
.Confirmation of diagnosis is usually done by the isolation of
causative agent (Emanuelson et al,1986).
1-8-2. Subclinical mastitis:Diagnosis of subclinical mastitis presents a problem due to
unapparent signs, however several screening tests have been
developed beside culturing methods. Culturing method is not
suitable for large scale monitoring of udder health (Emanuelson et.
al, 1986). Screening tests commonly used include various
inflammatory mediators such has somatic cell, cerum proteins,
emzymes such as NAGas(N-acetyl-B-D-Glucosaminidase), sodium
13
Literature Review
and chloride concentration were conductivity test, directly and
indirectly used for somatic cell count.( Kitchen et. al, 1978;
Sandholm, 1983 and Mancini et. al, 1995).
1-9. Somatic cell count:Somatic cells are defined as epithelial cells or neutrophils
derived from the blood (Schalm and lasmanis ,1968).Normally milk
contains somatic cells and the number of these cells in normal
quarter milk is less than 10.000 cells / ml/,however , counts as great
as 250.000 cell/ml .are found in normal milk samples (Blood and
Henderson, 1989). The preferable method used for indirect
counting of somatic cell is the California Mastitis Test (C.M.T.)
(Brook banks, 1966). California Mastitis Test was developed by
Schalm and Noorlander (1957).It contains Aikayl aryl sulphonate
that breaks down the DNA of the cells and precipitate them, and
bromo cresol purple that impart shade to the tested milk and reveals
the alkalinity or acidity of milk. The test is simple and good
diagnostic tool for detection of subclinical mastitis.
1-9-1. Advantage of C.M.T:a. The C.M.T .is fairly accurate in measuring somatic cell
concentration in milk, correlating well with other tests.
b- It is sensitive, primarily developed for sampling quarters; it can
also be used on bucket and bulk tank milk samples.
c. Foreign material such as hair or other matter does not interfere
with the reaction.
d. It is inexpensive.
e. The test is simple, and little equipments is needed.
f. Environmental temperature changes have little effect on the
C.M.T. as long as the milk has been refrigerated and is not over two
days old(Duane, 1997).
14
Literature Review
1-9-2.Factors affecting milk somatic cell count (SCC):The determination of milk SCC is widely used to monitor udder
health and thus milk quality. SCC is readily available to most udder
health and thus milk quality. SCC is readily available to most
bacteriological culture results, the factors of greatest importance can
be determined include the presence of natural resistance to maistits,
the state of defense mechanisms, the stage of lactation the number of
organisms and the pathogencity. When SCC is elevated , they consist
primarily of leukocytes or white blood cells which include
macrophages ,lymphocytes and polymorph nuclear neutrophil
(PMN) .During the inflammation , the major increase in SCC is due
to the influx of PMN into milk .At this time over 90% of the cells
may be PMN (Jones and Bailey ,1998).
Milk from uninfected quarters displays little change in SCC. As
number of lactation or days in milk increase. SCC of milk from
uninfected quarters rises from 83,000 at 35 day post- partum to
160,000/ml of milk by day 285. SCC of milk from quarters infected
with Staphylococcus aureus was found to rise from 234,000/ml to 1
million over the same period. SCC in uninfected quarters should be
less than 300,000/ml by 5 days post partum (Jones and Bailey,
1995).
The interpretation of SCC records is particularly applicable to
herds
experiencing
infection
from
contagious
pathogens
(Staphylococcus aureas, Streptococcus agalactiae. As infections by
these pathogens tend to be of long duration. New infections in a herd
may lead to increased prevalence of infection and are reflected by
elevated SCC for bulk tank or herds average SCC scores. Well –
managed herds that have controlled mastitis due to contagious
pathogens and have higher average milk production can experience
15
Literature Review
problems with increased cases of clinical mastitis caused by
environmental pathogens, yet maintain herd average SCC below
300,000/ml. Data collected on 50,085 Finnish heifers from 1983
through 1991 revealed that, on average a greater percentage of
heifers were treated in 1991 than in 1983 (27% vs. 18%).
Intramammary infection by environmental pathogens tends to be
shorter than those caused by contagious pathogens (Myllys and
Rautala, 1995).
1-10. Economic importance of mastitis:Mastitis in developed countries is considered as the most
important and main disease of dairy cows (kaneen and Bandhard,
1990). It is of great economic importance due to reduction in milk
yield, change in milk quality ,the possibility of permanent damage of
a quarter or even the entire udder and death of the cow (ElTayeb and
Habiballa,1978). The loss of milk yield due to clinical mastitis may
reach 40% whereas in subclinical mastitis it may reach 60%
(Dijkhuizen and Stelwagen , 1981). In Sudan, clinical and sub
clinical mastitis are lead to substantial (20%) drop in milk (Musstafa
et al, 1977).
Schroeder (1997) estimated the economic loss from mastitis in
the United States is estimated to be approximately $ 185/cow
annually. If the loss assumed, the same milk price and this value is
multiplied by the total number of milking cows (9.5 million head),
the total annual cost of mastitis would be about $ 1.8 billion .This is
approximately 10% of the total value of farm milk sales,and about
two – thirds of this loss is due to reduced milk production in sub
clinically infected cows.
Morin et al, 1993 and Stephen ,1999. found that ,the overall
financial loss calculated , including cases of mastitis amounting
16
Literature Review
$160- $344, also it has been found that the annual costs of mastitis
infection were around $ 200-$300in the USA and France (Seegers et
al, 1977) and 120pound in England (Fourichon et al, 1977).
The National Mastitis Council estimated the annual losses due to
mastitis, that the average production loss per lactation for one
infected quarter is about 1,600 pounds. "weight" Other losses are due
to discarded milk and milk withheld from cows treated with
antibiotic , costs of early replacement of affected cows , reduced sale
value of culled cows, costs of drugs and veterinary services and
increased labor costs .( Schroeder ,1997) .
Table No. (1): The estimated costs of the Items related to the occurrence
of mastitis
Loss per milk
cow$
Total %
1- Reduced production
121.00
66%
2- Discarded milk
10.45
5.7%
3- Replacement cost
41.73
22.6%
4- Extra labor
1.41
0.1%
5- Treatment
7.36
4.1%
6- Veterinary services
2.77
1.5%
Items involved
Source: current concepts in Bovine Mastitis. (National Mastitis
Council, 1996).
These estimates do not include additional costs arising from
mastitis associated problems related to antibiotic residues in human
foods, milk quality control, dairy manufacturing, and nutritional
quality of milk, degrading of milk supplies due to high bacteria or
somatic cell counts, and interference with genetic improvement of
17
Literature Review
dairy animals (Schroeder, 1997). Jones and Bailey (1998) found that
mastitis cost the U.S. dairy industry about $1.7-2 billions annually or
11% of total U.S. milk production. Much of this cost was attributed
to reduced milk production, discarded milk and replacements which
are estimated at $ 102, $24 and $33 per cow per year respectively.
The obvious costs for treatment labor, and veterinary services were
low, can not be eliminated from a herd. However, the total cost of
mastitis in the average herd enrolled in DHIA (Dairy herd
improvement association) was approximately $171 per cow, which
amounted to $18.6 million to the Virginia dairy industry annually
(Jones and Bailey, 1998).
In the Sudan Ibtisam et. al, 1995. investigated the fate of the
cows suffering from the mastitis and found that, (63.6%) dried of the
cows were cured, (23.3%) dried off spontaneously, and (7.1%) by
management (7.1%) . The study showed that the amount of milk
discarded during one year (July 1991 to June, 1992), was 54, 543
liters and this at market price of 19.67 Sudanese pounds/liter, that
amount to a little more than one million Sudanese pounds. Moreover
a total of 118,894 860 Sudanese pounds were spent on drugs to treat
mastitis. Other losses which were not expressed in term of money
included extra time spent with individual diseased cows for milking
and treating (labor/hr, veterinarian/ hr), loss of genetic potential due
to early culling and reduction in milk production due to subclinical
mastitis.
Many workers established the disease effects in the form of
reduced milk production in subclinical mastitis.
In subclinical mastitis, decreased milk production results in the
greatest loss, representing about 75% of the total loss (Fetrow,
1980). Production loss from udder quarters with subclinical mastitis
18
Literature Review
has been assessed for several different causative organisms and
ranged from 10% to 26% of quarter yield. Fat content was reduced
by between 3% and 12%, while non- fat solids content declined by
2% to 11% (De Graves and Fetrow, 1993) . Assume a decrease in
milk production of 10-26% for an affected quarter together with
above changes in the quality of the milk produced (Wood and
Booth, 1983).
As with sub clinical disease, the greatest economic loss in
clinical mastitis is reduced milk production .Clinical mastitis has
been reported as causing an overall decrease in production (covering
all stages of lactation) of between 5.9% and 6.4% whereas an 11%
reduction was seen if mastitis occurred before peak milk production
(wood and Booth, 1983; Lucey and Rowlands , 1984). Mastitis may
also decrease the length of lactation. Wood and Booth, 1983, used
mild cases of mastitis five days milk loss (in addition to the sub
clinical loss ) was assumed and for acute cases 5.9 –11% reduction
in production was assumed.
An approximate culling rate due to mastitis of 3% was found
each year during a three years study by Whilesmith et al,1986.
1-10-1. Somatic cell count and milk reduction:Milk reduction represented the major impact of sub clinical
mastitis.
An inflammatory response is initiated when bacteria enter
the mammary gland which is the body’s second line of defense.
These bacteria multiply and produce toxins, enzymes and cell-wall
compound which stimulate the production of numerous mediators of
inflammation by inflammatory cells. The magnitude of the
inflammatory response may be influenced by the causative agent,
stage of lactation, age, immune status of the cow, genetics and
19
Literature Review
nutritional status (Harmon, 1994). Polymorph-nuclear-leuckocyte.
(PMN), and phagocytes move from bone marrow towards the
invading bacteria and are attracted in large number by chemical
messengers or chemotactic agent from damaged tissues. Masses of
PMN may pass between milk producing cells into the lumen of the
alveolus, thus increasing the somatic cell count as well as damaging
secretory cells (Jones and Bailey (1998).
The Dairy Herd Improvement Association (DHIA) has adopted
an SCC scoring system that divides the SCC of compositive milk
into 10 categories from 0 to 9 known as linear scores. The DHIA
programs determine the SCC on each milk cow each month and
report either the SCC or the linear score. Linear scores can be used
to estimate production losses, but the average linear score for the
lactation most accurately reflects reduced milk yield.
Table (2): Milk loss related to CMT,WMT and somatic cell count
Lactation Average
linear SCC score
CMT Score
WMT(mm)
2
-ve
--
50,000
---
3
-ve
2
100,000
3
4
Trace
5
200,000
6
Trace
8
300,000
7
Trace
10
400,000
8
Trace
12
500,000
9
+1
14-21
600,000-1,000,000
10
<2
24
1,200,000
>12
29
1,600,000
5
6
Somatic cell
count cells/ml
Milk
loss%
CMT= California Mastitis Test
WMT= Wisconsin Mastitis Test
Source: Dairy Herd improvement Association and Philpot (1984).
20
Literature Review
According to . Tolle (1970) , the mean reduction in the milk yield
in infected animals is as high as 17% . However a cell count of less
than 500,000 per ml may be is regarded as acceptable for the average
herd, even though it represents loss in yield of approximately 4%.
Table (3): Reduction in milk yield in relation to SCC/ml
SCC/ ml
Reduction in milk yield %
less than 250,000
-
250,000-500,000
3.9%
500,000-750,000
6.8%
750,000-1,000,000
15.4%
More than 1,000,000
18%
Source: Federal institute for Dairying , Kiel west Germany (1970).
Jones and Bailey (1998) explained the relationship between somatic
cell counts, milk production and intramammary infections as shown
in table (4).
Reduction of milk yield in relation to various factors
Foremilk SCC
Major pathogens
Below 100,000
12,500
25,000
50,000
100,000
100-200,000
200-300,000
300-400,000
400-500,000
500-800,000
Over 800,000
5.9
First lactation 1b
milk/day
Older lactations
1b milk /day
50.8
50.4
49.7
49.3
48.6
48.2
48.0
47.5
47.1
43.8
64.2
62.9
61.6
60.3
59.2
58.3
57.6
57.2
55.6
51.8
11.7
17.3
18.8
23.5
25.2
19.5
Reichmuth et al , 1970 ; Philpot , 1967 and .King (1978) reported,
the reduction in milk production in infected quarters in comparison
21
Literature Review
to healthy quarter where indicated to the loss in milk yield in
infected quarter from 8.8% -45% with increase in SCC as 10x1000
Anderson (1982) revealed the mean SCC over 10x1000 cell/ml
related with loss in milk yield as 259 liter /cow/season.
1.11 The milk yield curve:Many workers was established the effect of mastitis in milk yield,
on the other hand, other workers had been proved the milk yield and
factors affected on it such as lactation length, dry period, lactation
number and season.
Wood defined the lactation curve is known to be the graphical
representation of the relationship between milk yield and lactation
length and also assumed to represent the total milk yield of a single
lactation. On the other hand persistency is defined as the slope of the
decreasing phase of the curve or it is extent to which peak yield is
maintained (Wood, 1967). There fore , peak yield and persistency
are the only variables of the lactation curves which are influenced by
many factors , although the general shape of the curve remains
substantially un changed El- Amin and Osman (1971). Also reported
that month of calving did not influence persistency of Northern
Sudan zebu cattle . Moon et. al, (1992) reported that winter calving
cows had higher and later peak yield and lower persistency than
cows calving in other seasons . Mudgal et al (1986) found
significantly defferent peak yield between farms and among periods,
genetic groups and parities.
The importance of the curve lies in predicting the lactation yield
by using both completed or part lactation length.
Musa (2001) revealed that, the overall mean of milk yield per
lactation was 1662.57±108.96 kg with coefficient of variation of
37.22% .The result also showed the effect of parity number on the
22
Literature Review
milk yield that showed an increasing yield with advancing parity.
The maximum milk yield per lactation was reached after the fifth
parity. The milk yield after the fifth parity was significantly
(P<.0.05) higher than the yield after the first, second and the third
parities while it was similar to the yield in the fourth lactation .Also
for the daily milk yield, the maximum was reached in the fifth
parities and the daily milk yield of the first lactation was
significantly (P<0.05) lower than the other parties for Butana and
cross breed, (Musa,2001, Yousif et al, 1998, Sid Ahmed, 1996 and
Ali, etal 1988).
1-12. Factors Affecting production traits:
1-12-1.Morphology of the mammary gland:
The mammary glands together form a voluminous mass Known
as the udder. This weighs between 12-30 kg-and may hold up to
20kg. Of milk, although fused externally the mammae are
independent and comprise four glands or quarters the right and left
anterior, the right and left posterior. The two posterior quarters are
more fully developed than the two anterior, the former secreting 120150% as compared with the latter (C.Craplet,1963).
1-12-2. Milk yield:The milk yield reflects the genetic potential of the herd and is
greatly affected by climatic conditions, stage of lactation number,
management and feeding. In Sudan khalifa and Shafei (1965) in their
study on the milk yield of Sudanese cattle as affected by the age of
the cow, reported that no definite trend could be detect for the
influence of age at first calving on milk production in the successive
lactation. However, they interesting by noted that there was
a negative trend for the average life –time production with increase
in age at first calving. However , El Amin (1969) mentioned, that
23
Literature Review
the yield tended to increase as the age at first calving increased , but
the effect of age at first calving on first lactation milk yield was
found to be not statistically significant. He also concluded that the
month of calving effect was not significant . Ishag(2000) found that
the period of calving as well as the parity number had a significant
effect on milk yield per lactation .The performance of Butana and
kenana cattle was investigated by many researchers, Alim (1962),
Fangaly (1980), Abdalla et al, (1990) and El-Habeeb (1991) in the
studies on Butana and Kenana cattle at Atbara and Umbenein
Research Station calculated the average total lactation milk yield for
Butana cows. It was 1419± 8.1kg, 1527.06± 928kg, 1807±562kg and
1599.73±502.9 kg and for kenana cattle was 1511±18.7 kg 1358.91±
819.30kg 2136±168kg and 1423.58±551.7kg for the first four
lactation period.
Milk yield of the indigenous dairy cattle in tropical countries
was studied by many authors. In India for first lactation records of
580 Sahiwal cows studied by Bhatnagar et al, (1983) an estimate of
2083± 33kg for 305-day milk yield was obtain. Taneja and
Bhatnagar (1985) reported that the first lactation milk yield for 322
days among Friesian cross–bred cows showed different traits
according to the foreign blood percentage and the average was
between 4136-5733 (1bs) (Ali et al, 1988) . Tharparkar records were
2289.9kg. In Pakistan, Ahmed and Sivarajasingam (1998) computed
the first parity average milk yielded as 1613kg for 909 Sahiwal
cows.
1-12-3. Lactation length:Lactation duration is defined as the period between two
consecutive calving during which cows are capable of producing
24
Literature Review
milk. The length of lactation is one of the lactation curve
components.
Many researchers have concluded that lactation length is
positively correlated with milk yield (El-Amin, 1969; Rao and
Dommerholt , 1981; and Bhatnagar et al. (1983) .
The common unit of measurement of milk yield in days is a
period of 305-days. Mahaderan (1958) showed that the advantage of
the 305-days over other measurement is that the former is more
closely related to the reproductive cycle of the cow calving once a
year.
Lactation length for Sudanese indigenous breeds such as
kenana and Butana was investigated by several researchers, and it
can be concluded that it falls well below the standard period of 305days. For Butana cattle at Atbara Research Station and kenana cattle
at Umbenein Experimental station Abdalla et al. (1990) reported
lactation length average of 283.2±57 and 283±43 days respectively.
Where the Friesian cross-bred cows showed the positive correlation
between lactation length and daily milk yield for 50% and was not
significant for 62.5% (Ali et al, 1988).
1-12-4. Dry period:
The term refers to the period of milking which is necessary
for replenishing the body with nutrients that were depleted during
lactation, repairing and regenerating the alveolar epithelium and
gaining new stimulation for lactation as a result of parturition
following gestation. Thus an optimum dry period is essential for
maximum production of milk in the subsequent lactation. The
standard measurement of dry period in days is a period of 60 days.
25
Literature Review
Dry period influences the total lactation yield through its effect
on the lactation period. Folley et al. (1972) stated that the cows
which were given a longer dry period usually produced 62-75% as
much milk in the subsequent lactation as their twins given a rest of
bodies between lactation.
In Sudan many researchers reported that the Sudanese
indigenous dairy cattle have a dry period that exceeds the 60 days
recommended in the literature. Alim, 1960, khallafalla, 1977
calculated the mean dry period for the kenana herd at Gezira
Research station, Umbenein was 164 ± 94,174±5.1 days respectively
.For Butana cattle At Atbara research station Fengaly (1980)
reported that the mean dry period was 119.56±102.57 which is an
estimate of limited value because of the rather large standard error.
Dry period was investigated by many authers in tropical countries
.In India Bhatnagar et al (1983) gave an estimate of 139.7 days for
mean dry period in first lactation records of 580 Sahiwal cows
.Ahmed and Sivarajasingam (1998)in Pakistan stated that the dry
period for 909 first parity Sahiwal cows averaged 190.4 days . 1 shag
(2000) working on Sudanese data from crossbred cows (Friesian x
kenana) concluded that the average dry period for first and overall
calving were 90.02±89.18 and 96.31±70.16 days respectively.
26
2- Materials and Methods
2,1 Location of the study:
This investigation was carried out at Atbara Livestock Research
Station. The station is situated in the River Nile State to the north of
Atbara town in Northern Sudan. It is located at 17/42° N Latitude
and 33/58° E Longitude at an altitude of approximately 345 meter
above sea level.
At Atbara there are three seasons: winter (November –February)
dry summer (March-June) and wet summer (July-October)
(Hewiston,1945). The atmospheric temperature in this area varies
from a maximum
of 47.7°C recorded in April, to the lowest
minimum of 4.5°C was registered in January .However .Atbara falls
in atypical semi-desert ecological zone with an average annual
precipitation of 70m.m. These are subtype of Northern Sudan zebu.
This breed is named after it is home land , the Butana plains of
central Sudan (between the River Nil ,Atbara River and the Blue
Nile).
2,2. Herd Management:Cows in five farms were fed on irrigated forage crops and
grasses together with locally available concentrate feeds .In Atbara
dairy Farm animals are allowed to graze sorghum grass and legumes
twice daily for five hours whereas in the other farms animals were
fed the same grasses in yard. The milking cows are fed a concentrate
mixture composed of 34.5% cotton seed cakes or peanut oil meal,
34.5% wheat bran and 30% sorghum grains where in Atbara dairy
farm milking cows are fed 50% Molasses , 30% wheat bran, 10%
sorghum grains ,5% peanut oil meal, 3% urea and 2% salt and
vitamins. Cows depending on their milk yield and the condition of
the cows. Some changes to the general pattern of feeding policy
27
Materials and Methods
outlined have taken place over the years either as deliberate policy or
due to circumstances prevailing at particular occasion . Only natural
mating was practiced. Bulls run freely with the appropriate herd
groups .However, breeding bulls were selected from the offspring of
highest yielding dams in the herd.
Calves in Atbara dairy farm are bucket fed on colostrum and
fresh milk to an age of one month after which the amount is reduced
gradually as the calf advances in age and substitution amount of
grass and concentrates are given in small amounts. In the private
sectors calves are reared by lactating the dam beside feeding the calf.
All cows are milked is done by hand twice daily. Animals are
vaccinated against the major infectious livestock disease in Sudan.
2,3. Data collection and manipulation:A) Retrospective study :
The data used in this study were extracted from the station
records, which have been collected from 1972 until 1993 . The
number of cows studied was five hundred and their records extended
from first to twelfth lactation. The parameters used in the study were
the followings:
(1)
Milk yield per lactation
(2)
Daily milk yield
(3)
Lactation length
(4)
Lactation number
(5)
Cow birth date
(6)
Calving date
(7)
Dry period
(8)
Season
(9)
Mastitis test
(10)
Milk curve
28
Materials and Methods
(11) Discarded milk and the cost
(12) Treatment cost
B) Prospective studies :
1-
Milk yield per lactation .
2-
Daily milk yield.
3-
Lactation length.
4-
Dry period.
5-
Season.
6-
Mastitis test.
2,4. Milk tests and sampling
A total of 136 cows were tested for mastitis using California
Mastitis Test from apparently healthy local and cross bred (Local X
Friesian). The tested cows belonged to five herds kept in dairy farm
around Atbara town. They were at different lactation seasons .
2,4,1. California Mastitis Test. (C.M.T.):
C.M.T. was performed on milk samples collected from
individual udder quarters to detect subclinical mastitis. Before
collection of milk sample for bacteriological examination, 2ml of
foremilk were squeezed from each quarter into the cup of the paddle
where equal volume of California mastitis test reagent (Alvetera
rapid mastitis test kit-Alvetera Gmbh-Germany) was added. The
milk and reagent were mixed together and the reaction between them
was interpreted according to Schalm and Noorlander (1957) as
follows:
Negative (-ve):- The mixture remained liquid, homogenous with
no evidence of thickening.
Trace (T):- There was a slight thickening that was seen best by
tipping the paddle back and forth and observing the mixture as it
29
Materials and Methods
flows over the bottom of the cup. Trace reactions tended to disappear
with continued rotation of the paddle.
Weak positive (+1):- A distinct thickening of the liquid formed,
but there was no tendency toward a gel formation.
Distinct positive (+2):- The mixture thickened immediately, and
a gel formation was suggested.
Strong positive (+3):- A gel was formed, which caused the
surface of the mixture to become elevated like a partially fried egg.
(Duane, 1997).
The C.M.T. reaction scores.
C.M.T. score
Average somatic count ( cells/ml)
Negative
100,000
Trace
300,000
+1
900,000
+2
2,700,000
+3
8,100,000
2,4,2. The Direct Microscopic somatic cell count (Breed and Prescott
test):From the milk 0.01 ml was spread on a fixed area of slide and
stained by methylene blue (dissolved in tetra chloroethan and
ethanol.) WBC which stained by the blue colour cells were
counted under oil immersion lens.
2,4,3. pH test:Of Bromcresol purple was prepared by adding 0.9 g to Bromcresol–purle powder to 100ml distilled water. Of this 1.0 ml was
added to 6.o ml of suspected milk. In mastitic milk the colour
changed to purple. Bromcresol purple has a pH range of 5.2 to 6.8
30
Materials and Methods
changing from yellow to purple. When the solution is added to
normal milk the colour remains yellow and when added to mastitis
milk the colour change to purple color. (Hall, 1981).
2,5. Sampling procedure:Before collection of milk samples from the tested cows, the teats
were thoroughly cleaned using pieces of cotton soaked in 70%
alcohol .The first streams were discarded and 5 ml of milk were then
drawn into sterile bottles. The collected samples were then
transferred in ice to Atbara veterinary Research laboratory where
they were tested.
2,6. Laboratory examination of milk:2,6,1. Sterilization methods:Glassware used (bottles , petridishes , cotton–plugged test
tubes , flasks and Pasteur’s pipettes )were sterilized at 170°C for one
hour using hot air oven (Merchant and Packer,1967).
Different laboratory media ,solutions, plastic –stoppers test tubes
and screw capped bottles were sterilized by autoclaving at 115120°C (15Ib- in²) for 10-20 minutes (Cowan, 1985).
2,6,2. Preparation of culture media:Different culture media were prepared according to
instructions of the manufacturer or as recommended by Cowan and
steel (1985). The pH of different media prepared was adjusted using
10% NaoH and 1N-Hcl. Every step of media preparation was
conducted under aseptic condition (either under flame or using
sterile utensils). All prepared culture media were incubated overnight
at 37°C to check their sterility. Unless otherwise stated all inoculated
cultured media were incubated at 37°C.
31
Materials and Methods
2,6,2,1. Blood agar media :Twenty three grams of lab-lemco agar (Oxoid, CM.17) were
suspended in one litre of distilled water .It was heated to dissolve
completely using electric boiler and then sterilized . The media was
then cooled to 50°C in a water bath and 5% of sterile defibrinated
sheep blood was added and mixed well .The mixture was distributed
into sterile petri dishes and left to solidify.
2,6,2,2. Edward’s medium:
Forty one grams of Edward’s medium (Oxoid ,CM.27)
were added to one liter of distilled water. The medium was then
heated to dissolve , sterilized in the autoclave and left to cool to
50°C in a waterbath, 7% of sterile defibrinated sheep blood was
added to the medium, mixed well, distributed in sterile petridishes
and left to solidify .
2,6,2,3. MacConkey;s agar medium:
Fifty grams of MacConkey agar (Merk,5465) were added
to one liter of distilled water . It was then dissolved by heating ,
sterilized , distributed in to sterile petridishes and left to solidify .
2,6,2,4. Chapman stone medium:
Of chapman medium (DIFCO, 00313:01) 20.2g were
suspended in 100ml. of cold distilled water. It was then heated to
dissolve, sterilized, dispensed in sterile petridishes and left to
solidify.
2,6,3. Media for biochemical tests:2,6,3,1. 40% bile agar:
Forty g of bile salt were added to 1 liter of melted nutrient
agar .They were mixed , sterilized and cooled to 55°C .Fifty ml. of
sterile equine serum was then added ,mixed well and distributed in
sterile petridishes .
32
Materials and Methods
2,6,3,2. Hugh and Leif son's (O, F) medium:
Two g of peptone, 5 g of sodium chloride, 0.03 g K2Hpo4
and 3 g of agar were mixed in one liter of distilled water. The
medium was dissolved by heating, adjusted to pH7.1 and filtered.
1.5ml of bromo thymol blue was added and sterilized. One percent
of appropriate carbohydrate was added, mixed and distributed in
sterile tubes. These tubes were then steamed in the autoclave for 30
min.
2,6,3,3. Motility medium:Eighty g of gelatin were soaked in one liter of distilled water
for half –an – hour. The 10g of peptone, 3g beef extract, 5g sodium
chloride and 4 g of agar were added to the soaked gelatin. It was
heated to dissolve, distributed in tubes and sterilized.
2,6,3,4. Aesculin broth:0.5 g of ferric citrate and 5g of aesculin were mixed with
1 litre of peptone water, distributed into Bijuo bottles and sterilized.
2,6,3,5. Arginine broth:Five g of peptone, 5g yeast extract, 2g k2Hpo4 , 0.5 g glucose
and 3 g of arginine monohydrochloride were suspended in 1 liter of
distilled water. They were then heated to dissolve adjusted to pH 7.0
and filtered. The medium was distributed in Bijuo bottles and
sterilized
2,6,3,6. MacConkey’s broth purple:One tablet of MacConkey broth purple (Oxoid,CM.ba) was
added to 10 ml of distilled water in a tube containing inverted
Durham’s tubes and sterilized.
2,6,3,7. Bromo thymo1 blue:
0.2 g of Bromo thymo1 blue was dissolved in 100ml. Of
distilled water.
33
Materials and Methods
2,6,4. Reagents :
2,6,4,1. Hydrogen peroxide 3% (volume 10):
This was obtained from local pharmacies.
2,6,4,2. Oxidase test reagent:
One gram of tetraethyl p-phenylene diamine dihydrochloride
was dissolved in 100ml. of distilled water.
2,6,4,3. Nessler’s reagent:
(Philps and Haris –Cat.No.5 59035/0). This was kindly
donated by Microbiology Department (Central veterinary Research
Laboratory) of soba/ Khartoum.
2,6,5. Culture methods :
2,6,5,1. Primary isolation:
Blood agar and Edward’s media were inoculated by
transferring a loop full of milk sample onto the surface of each plate
and streaked to obtain discrete colonies. Inoculated plates were then
incubated under aerobic condition for 3 days
2,6,5,2. Examination of inoculated culture media :
Culture media were examined for the growth of the
organism's, colony morphology, haemolysis, change in colour and
consistency.
2,6,5,3. Purification:
Recovered bacteria were purified by picking a single
colony that was then streaked onto blood agar plates.
2,6,6. Primary identification :
A drop of distilled water was placed on a clean slide . A
single colony was taken, emulsified in the drop of water and then
spread. The smear was dried, fixed by heating and stained by Gram’s
or Ziehl – Nelsen stains (Cowan, 1985).
34
Materials and Methods
2,6,7. Identification of bacterial genera:The genera of the recovered bacteria were identified after
Cowan (1985) through primary tests that include:
a. Gram’s stain
b. Acid-fastness
c. Aerobic growth
d. Motility
Motility media was inoculated by staping the isolated
bacteria with straight wire loop. The media was then incubated for
up to 3days together with uninoculated media as a control. The
growth of non- motile organism was confined to the stab, while the
motile one was distributed out the stab.
e. Catalase activity:
On a clean slide a drop of 3% H2O2 was placed. A
single colony from the suspected bacteria on nutrient agar was
emulsified and added to the drop of H2O2. Positive reaction was
indicated by evolution of gas.
f. Oxidase test:
A colony of the tested organism was smeared with
glass rod across a filter paper saturated with 1% Tetramethyl-pphenylene diamine dihydrochloride. A positive result was shown by
the development of dark purple color .
g. Oxidation fermentation (O.F) test:
Two tubes of O.F. medium were stabbed by the organism
under test with straight loop. To one of the tubes, a layer of paraffin
oil was added. The two tubes were incubated for 48hrs, with un
inoculated tubes as a control. Development of yellowish color in the
2 inoculated tubes indicated fermentation. Whereas oxidation
35
Materials and Methods
reaction was indicated by the development of yellow colour in the
open tube only.
2,6,8. Identification of bacteria species:
2,6,8,1.Arginine hydrolysis:
Arginine broth medium was inoculated with the tested
organism and incubated over night with an un inoculated arginine
medium as a control. Apositive reaction was indicated by change of
colour to brown after addition of 0.25 ml of Nessler’s reagent.
2,6,8,2. Aesculin hydrolysis:
Aesculin broth was inoculated with the test organism,
incubated with an un inoculated aesculin broth as a control and
observed for 7 days for blackening of the medium.
2,6,8,3. Eijkhman test:
MacConkey's broth purple medium was inoculated
with the tested organism and incubated at 44°C in waterbath
for 48 hrs. With an un inoculated medium as a control.
Development of a yellow colour in the medium and
presence of gas in the inverted Durham’s tube indicated
a positive result.
2-7. Statistical analysis:Data obtained were subjected to statistical analysis using Analysis
of Variance (ANOVA).
36
3- Results
3,1. Recorded number of cases with subclinical mastitis and dead
quarters in dairy farms :The total number of cows in five dairy farms investigated was 408 of
which 175 (42.9%) were adult producing cows. Of the adult productive
cows 39(22.3%) were dry and 136 (77.7%) were milking. The number f
cows with dead quarter are shown in table (5). Ten 10 (7.4%) out of 136
milking cows had one dead quarter. The percentage of cows with one
dead quarter varied from 0% (farm No.5) to 40% (farm No.1). One
hundred nineteen 119 (87.5) out of 136 were positive
reactors for
California Mastitis Test (C.M.T) . The percentage of positive reactors
varied from 9.2% (farm No.5) to 34.5% (farm No.1).
3,2. The number of cows with positive quarters examined by
California Mastitis Test:Table (6) showed the number of quarters examined by C.M.T.
Cows that had one positive quarter represented the highest percentage
42.9%.Those with three quarters represented the least percentage
(10.9%).
3,3. The number of CMT performed in farm No .1 and the number of
infected quarters:On farm No.1, lactating cows had been tested nine times and the
positive cases varied from 90.9% as the highest percentage to 23.5 % as
the least one. Table (7) shows the percentage of infected quarters within
the positive cases 65% was the highest and 25% was the least percentage.
3,4. The allocation of infected quarters:The right posterior quarter represented the highest percentage
(27.1%) within the infected quarters where the right anterior quarter
represented the least percentage of infected quarter's table (8).
37
Results
3,5. The grading of infected quarters:Based on the CMT , strong positive result (+3) represented the
highest percentage (50%) followed by the weak positive (+1) (27.6%)
whereas the distinct positive (+2) result represented the least percentage
(22.4%)(table9).
3,6. The relationship between CMT result and Microbial isolation:Table (10) show all samples with positive CMT were been positive
for bacterial isolation.
3,7. The microorganisms isolated from milk samples:The bacteria isolated from milk samples included Gram-positive
cocci, Gram-negative rods and Gram-positive poleomorphic bacilli. The
bacteria
isolated
were
staphylococci,
stryptococci,
micrococci
enterobacteria. Fungi were also isolated from the samples (Table 11).
3,8. Somatic cell counts as they relate to estimated milk losses:Indirect estimation of somatic cell counts by CMT is shown in
table (12) indirect SCCs varied between 100,000 to 1,200,000 cells.
Whereas the direct SCCs varied between 10,000 to 1,980,000 cells/ml of
milk. The estimation of milk reduction according to the indirect and
direct SCCs ranged from 3% to more
Resultsthan 12%. The results also showed
that the reduction percentage according the number of infected quarters
varied from 10% for one infected quarter to 48% for the four infected
quarters (Table12).
3,9. The reduction percentage in milk yield (comparison between
infected and healthy quarter yield):In Atbara dairy farm where the artificial rearing is adopted, the titre of
milk yield for infected and healthy quarters were monitored for several
days and be consistent many times and compared with them. In the other
farms, the titre of milk yield was monitored at the same time of testing of
38
Results
mastitis. The result revealed the average percentage of milk reduction was
12.5% (Table 13)
3,10. The percentage of infected cows in relation to the milk yield
Table (14) showed the percentage of infected cows in Atbara dairy
farm where the testing for mastitis was repeated many times. A high
percentage of infected cows appeared in cows in lactation No.9,10
(85.7%) and lactation No. 11,12 (77.8%) whereas the least percentage
was lactation No.8.The average milk yield/cow in relation to lactation
number appeared high in lactation No.1 followed by lactation No.6,
however, the least yield was in lactation No.10,11,12 followed by
lactation No.3. The average milk yield /cow/day was highest No.1 is
followed by lactation No.6 where the lactation No. (10, 11, 12.) gave the
least average day milk yield.
3,11. The evaluation of the average daily milk yield:A total of 12 milking cows had been studied for their daily yield
from calving to seven months. The average milk yield per month had
been adopted .The result appeared irregularity in the average milk yield
from the first to the seventh month (table 15).
3,12. Comparison of the milk yield of mastitic and non mastitic
cows:The table (16, A,B) represented the mean reduction in milk yield
per cow. Comparison between the mastitic and non mastitic cows is
made. Taking into consideration the lactation number, total milk yield, of
cows in one lactation number in both summer and winter season.
3,13. The effect of mastitis in milk yield:The mean effect of mastitis on total milk yield demonstrated that,
there was no significant effect (presented in table 17). While the mean of
effect of season showed that there was significant effect of season in
winter than the summer.
39
Results
Analysis of variance showed that, interplay between season and
mastitis; mastitis, parity and season had significant effect (P<0.03),
(P<0.05) respectively on total milk yield. Where the mastitis and season
alone had no significant effect (P> 0.05). On the other hand, the parity
had highly significant effect (P< 0.002) on total milk yield (table 18).
The mean effect of mastitis on daily milk yield is presented in table
(19). The mean showed that there was no significant effect of mastitis
while the mean effect of season revealed that there was significant effect
in winter.
The analysis of variance for daily milk yield demonstrated that
there was no significant effect of mastitis alone or as interaction with
other factors (table20).
3,14. The cost of Treatment and discarded milk :
From the records, 54 mastitis cows had been chosen to calculate
the treatment cost and the milk dumped after antibiotic usage with the
treatment period.
The result revealed, the average period of treatment was 10 days
and the period variability extended from 2days to 42 days . The average
yield of the milk dumped after antibiotic usage was 50.4kg and the cost of
discarded milk as average with updating the prices cost was 5670
SD/cow. Where the treatment cost denoted as average per cow to 5167
SD (table No.21).
3,15. The assessment of reduction in milk yield in relation to the
methods usage:
Table (22) showed the different methods used in the assessment of
the reduction percentage in milk yield of infected quarter. The average
reduction in the milk yield was 14.2% of the total milk yield per
cow/season.
40
Results
3,16. The evaluation of economical loss :
The economical losses were assessed according to the cost of
reduction in milk yield in case of subclinical mastitic (one infected
quarter ) that had been evaluated by 27325 SD represented as percentage
by 67.2% followed by discarded milk (5670SD)(14.5%), treatment
5167(13.2%) and veterinary service 2000 (5.1%). The other costs (table
24) included the clinical cases and the consequence of the disease that
had been probabilities between the kind of infection (peracute, acute and
subacute or chronic form), the milk reduced due to the infection, the sort
of treatment according to the infection, the dead quarter and finally, the
culling, pre mature culling and mortality.
3,17. Milk yield carve:
Fig(1)(2) showed the comparison between the non – mastitic curve
of the average milk yield per cow and the curve of mastitic cow in
summer and winter season .Also Fig (3)(4) showed the different shape of
curve for non- mastitic and mastitic cows for average daily milk yield in
summer and winter season.
41
Table (5) Subclinical mastitis and dead quarters in the dairy farms
Farm
No.
Herd
number
1
2
3
4
5
Total
90
150
120
25
23
408
Number
of cows
Dry
cows
44
14
55
18
41
7
17
4
18
3
175
46
(43.9%) (26.3%)
Lactating
cows
Number of
cows with
dead quarters
30
37
41
13
15
136
(77.7%)
4(40%)
3(30%)
2(20%)
1(10%)
-(0%)
10
(7.4%)
Number of
cases with
subclinical
mastitis
41(34.5%)
28(23.5%)
26(21%)
13(10.9%)
11(9.2%)
119
(87.5%)
Table (6) Results of the California Mastitis test
Number of
cows tested
Negative
test
44
37
41
13
15
150
Total
3
9
15
4
31
(20.7%)
Number of cows with positive quarters
One
Tow
Three
Four
quarter
quarters
quarters
quarters
19
13
6
3
12
6
3
7
10
7
3
6
5
6
2
5
3
1
2
51
35
13
20
(42.9%)
(29.4%)
(10.9%)
(16.8%)
42
Table (7) Results of California mastitis test in farm no. (1)
Test No.
Test No.1
Test No.2
Test No.3
Test No.4
Test No.5
Test No.6
Test No.7
Test No.8
Test No.9
Number of the
tested cows
30
17
18
24
22
20
22
12
15
Number of
negative cases
15
13
7
10
2
5
11
5
6
Number of
positive cases
15(50%)
4(23.5%)
11(61.1%)
14(58.3%)
20(90.9%)
15(75%)
11(50%)
7(58.3%)
9(60%)
Number of
infected quarter
27(45%)
4(25%)
22(50%)
25(44.6%)
46(57.5%)
39(65%)
27(61.4%)
13(46.4%)
19(52.8%)
Table (8) Allocation of infected quarters
Farm No.
1
2
3
4
5
T
Right
anterior
quarter
19
25.8%
11
18.3%
11
20%
8
32%
4
18.2%
53
22.5%
Left anterior
quarter
18
24.3%
13
21.7%
17
30.9%
3
12%
6
27.2%
57
24.1%
43
Right
Posterior
quarter
18
24.3%
16
26.7
13
23.6%
9
36%
8
36.4%
64
27.1%
Left
posterior
quarter
19
25.8%
20
33.3
14
25.5%
5
20%
4
18.2%
62
26.3%
Table (9) The grading of infected quarters positive to the CMT.
Farm No.
1
2
3
4
5
Total
+1
45
9
8
2
64
(27.6%)
+2
9
14
11
12
6
52
(22.4%)
+3
16
37
36
13
14
116
(50%)
Table (10) Relationship between C.M.T result and microbial isolation
Farm
Number of
lactating
cows
Number of
sample
Number
positive
for C.M.T
result
1
2
3
4
5
44
37
35
13
15
10
13
10
5
11
10
13
10
5
11
44
Number
positive
for
Bacterial
isolation
6
7
4
5
7
Number
positive
for
Fungal
isolation
4
6
6
0
4
Table (11) Identification of bacteria isolated
Test
Farm(1)
Number of
samples
Growth on
blood agar
Growth on
MacConkey
agar
Growth on
Edward
mdium
Catalase test
Bromocresol
purple
Shape of
bacteria
10
13
10
5
Farm(5)]
11
+ve
+ve
+ve
+ve
+ve
4+ve
6+ve
3+ve
3+ve
6+ve
4+ve
4+ve
3+ve
2+ve
6+ve
6+ve
+ve
7+ve
+ve
7+ve
+ve
2+ve
+ve
5+ve
+ve
G+ve cocci
and
pleomormphic
bacilli
+ve
G+ve
cocci
and Gve rods
+ve
G+ve
cocci
-ve
-ve
3+ve
-ve
-ve
F.O
3+ve
-ve
-ve
F.O
3+ve
-ve
-ve
F.O
1+ve
-ve
-ve
F.O
2+ve
3+ve
3+ve
3+ve
1+ve
2+ve
4+ve
3+ve
4+ve
3+ve
3+ve
3+ve
3+ve
1+ve
6+ve
-ve
-ve
4+ve
2+ve
4+ve
-ve
3+ve
1+ve
3+ve
6+ve.
Growth
aerobically
Oxidase test
Motility test
O.F test
Growth on
Chapman
media
Arginine
hydrolysis
Aesculin test
Growth on
10% NaCl
Eijkhman test
Growth on
40% bile agar
F.O
Farm(2) Farm(3) Farm(4)
45
+ve
G+ve
G+ve cocci
cocci
and G+ve
and G- pleomorphic
ve rods
+ve
+ve
Table No (12) Somatic cell counts as they relate to estimated milk losses
Cow
DCMT
ISCe
Red%
DISCC
Red %
3/2
7/2
20/2
21/2
30/2
5/5
6/5
7/5
8/2
32/2
31/2
12/5
14/5
15/5
29/2
1/5
11/5
2/2
26/2
33/2
3/5
12/2
17/2
34/2
4/5
1 q+2
1 q +2
1 q +2
1 q +2
2 q +2
1 q +2
1 q +2
2 q +2
1 q +3
1 q +3
1 q +3
1 q +3
1 q +3
1 q +3
2 q +3
2 q +3
2 q +3
3 q +3
3 q +3
3 q +3
3 q +3
4 q +3
4 q +3
4 q +3
4 q +3
12 х104
12 х104
12 х104
12 х104
24 х104
12 х104
12 х104
24 х104
16 х104
16 х104
16 х104
16 х104
16 х104
16 х104
32 х104
32 х104
32 х104
48 х104
48 х104
48 х104
48 х104
64 х104
64 х104
64 х104
64 х104
12
12
12
12
24
12
12
24
12
12
12
12
12
12
24
24
24
36
36
36
36
48
48
48
48
22х104
85 х104
72 х104
35 х104
21 х104
103 х104
98 х104
113 х104
36 х104
28 х104
26 х104
198 х104
141 х104
117 х104
43 х104
87 х104
135 х104
76 х104
82 х104
50 х104
107 х104
31 х104
10 х104
145 х104
94 х104
6
11
10
7
11
11
6
12
7
6
6
>12
12
12
8
11
12
10
11
9
12
8
3
12
11
DCMT= Degree of the California mastitis test
DISCC= Direct somatic cell count
Red %= Reduction percentage
ISCC= Indirect somatic cell estimate
q = quarter
46
Table (13) Reduction percentage in milk yield (comparison between
infected and healthy quarters)
Allocation of inf.
quarters
27
1(ra)
7
2(la)
11
3(rp)
7
3(rp)
5
4(lp)
6
1-2(ra,la)
6
1-2(ra,la)
6
3-4(rp,lp)
7
3-4(rp,lp)
7
3-4(rp,lp)
The total average reduction / quarter =
Cow Numb.
The C.M.T
score
+2
+1
+2
+3
+1
+1-+3
+3
+2
+3
+3-+2
% of milk
Reduction
15.8%
17.55%
18.9%
17.9%
5.3%
35.8%
12.05%
40.2%
2.175%
8.1%
12.5%
1= right anterior
2= left anterior
3= right posterior
4= left posterior
Table (14) The percentage of infected cows in relation to the milk yield
L.N
T.M.Y
1
2
3
4
5
6
7
8
9
10,11,12
46098.9
39123.4
16810.3
13299.1
10916
12248.3
19231.1
11703
10793.5
11382
N.of
cow
22
24
13
10
7
6
10
8
7
9
116
Av.per
Av.LL Av.D.M Inf.cows
%
cow
(54.5)
12
7.1
297
2095.4
(45.8)
11
5.8
283
1630.1
(61.5)
8
5.2
247
1293.1
(50)
5
5.6
237
1329.9
(28.5)
2
5.1
306
1559.4
(66.6)
4
6.5
316
2041.4
(70)
7
5.5
352
1923.1
(25)
2
5.3
275
1462.9
(85.7)
6
5.5
278
1541.9
(77.8)
7
4.2
296
1264.7
16141.9
The average percentage of infected cows= 56.54%
The average percentage of total milk yield
Per cow/ season
= 1614.19 kg
TMY = Total milk yield
LN = Lactation number
Av. LL = Average of lactation length
Av. DM = Average daily milk yield
47
Cow No
13
15
17
19
21
22
30
35
36
45
46
61
Table (15 ) Evaluation of the average daily milk yield
MTR
1st
2nd
CD
L. N
MTD
Month Month
20.01.04
9
13.4.04
4 q +3
4.2
4.6
10.7.04
4 q +3
26.11.03
9
22.1.04 (AL,PL)+3
7.2
6.5
13.4.04
4 q +3
28.12.03
7
13.4.04
Pr+3
7.9
7.6
11.02.04
5
13.4.04
Ar+3
6.9
7.6
26.04.04
5
13.4.04
Pl+1
10.4
11.4
06.04.04
6
13.4.04
Ar+3
6.7
6.8
19.02.04
2
13.4.04
Al+3
7
6.9
10.04.04
3
13.4.04
3 q +2
4.8
5.4
22.11.03
3
13.4.04
3q
4.8
3.7
+1,+2+3
09.03.04
3
13.4.04
2 q +2
5.3
8.1
29.11.04
3
13.4.04
4 q +1
6.9
7.3
21.2.04
2
13.4
3 q +2
7.7
6.4
3rd
month
5.4
4th
month
6.2
5th
month
6
6th
month
5.3
7th
month
3.6
5
5.7
4.9
2.6
2.4
8.1
6.7
9.4
7.2
6.7
4.8
3.4
8.3
5.9
7.9
9.2
6.8
4.5
3.8
8.3
7.5
8
6.2
6.5
4.4
4
8.2
5.9
8.7
5.9
5.7
4.3
4.4
7.3
6.3
7
5.4
5.8
3.3
4.1
5.7
7
7
6.4
6.9
7
6.2
6.1
6.4
6.2
6.2
6.5
5.8
6
6.8
CD=calving date
LN=lactation number
MTR = mastitis test result
MTD= mastitis test date
q = quarter
48
Table (16) Comparison between Mastitic and non- mastitic cows milk yield in both summer and winter .
(A) (Non mastitic cows)
Lact .no
1
2
3
4
5
6
7
8
Summer season
Cow
9
6
2
3
4
1
3
3
number
T.M.y
15057.7
6813.2
2832
2974.7
6132.2
2809.5
4714.6
4158.1
Winter season
Cow
1
7
3
2
1
1
3
number
T.M.y
1053
12279.7
3370.2
3338.6
2150.3
3855
4455
Table (16) B Comparison between Mastitic and non- mastitic cows in milk yield in both summer and
winter(Mastitic cows)
Lact .no
1
2
3
4
5
6
7
8
Summer season
Cow
11
6
3
4
2
1
3
1
number
T.M.y
1254.5
8711.6
4224.7
5673.4
2633.5
1320
7082.9
1790.3
Winter season
Cow
1
5
5
1
3
4
1
number
T.M.y
540
4791.3
5943.1
1312.1
4263.8
7451.6
1299.6
AV./M.Y.d =The average of milk yield per day
AV./D.P
= The average of dry period
49
9
3
5151.7
9
6
7695.8
7
9328
Table (17):
The mean effect of mastitis and season on total milk yield.
Source
1- mastitis
Mean
Standard error
(+ve)
(-ve)
2- Season
Summer
Winter
1167.4(A)
1252.7(A)
52.5
53.5
1212.5
1209.3(A)
49.4
57.1
Means with same letter are not significantly deferent (P>0.05)
Table (18):
Analysis of variance for total milk yield.
Source
Season
Mastitis
Parity
Season &mastitis
Season & Parity
Mastitis & Parity & Season
Mastitis & Parity
Error
Total
Df
1
1
11
1
10
11
9
423
498
** = significant at P <0.01.
* = significant at P< 0.05.
N.S. = Not significant.
Df= degree of freedom
MS= Mean square
F = value of significance
50
MS
135976.8
1129008.1
1011210.2
1614855.9
615880.6
659621.7
546596.4
365861.8
F
0.73 N.S.
3.09 N.S.
2.76 **
4.41 *
1.68 N.S
1.80 *
1.49 N.S.
Table (19):
The mean effect of mastitis and season on daily milk yield:
Source
1- Mastitis
(+ve)
(-ve)
2- season
Summer
Winter
Mean
Standard error
4.3 (a)
4.4 (a)
0.15
0.15
4.5
4.2 (a)
0.14
0.17
Means with same letter are not significantly different P>0.05.
Table (20):
The analysis of variance for daily milk yield:
Source
Season
Mastitis
Parity
Season & mastitis
Season & Parity
Mastitis, Parity & season
Mastitis & Parity
Error
Total
df
1
1
11
1
10
11
9
452
497
MS
8.46
2.11
8.24
6.25
3.59
4.42
3.54
3.09
** = significant at P <0.01.
N.S. = Not significant
Df= degree of freedom
MS= Mean square
F = value of significance
51
F
2.74
0.68
2.76
2.02
1.16
1.43
1.15
N.S.
N.S.
**
N.S.
N.S.
N.S.
N.S.
Table (21) The discarded milk and treatment cost due to the mastitis
treatment
No of
cows
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Treatment period
Discard
milk/kg
112
90
66
92
27
18
90
38
19
44
36
74
14
30
14
30
29
38
33
17.6
29
46
50
120
135
39
125
85
42
18 day
21
10
9
3
13
12
4
2
20
5
10
2
4
2
4
15
16
8
4
7
5
8
12
42
7
30
15
6
52
Cost of
treatment /SD
50366
3490
2920
3430
1590
2380
4750
1120
510
1840
6000
1328
560
1000
1920
500
2150
2360
3960
2060
4760
140
1500
4240
15750
3900
4080
13000
6640
Continuous
Cont. table (21) The discarded milk and treatment cost due to the mastitis
treatment
No of
cows
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
AV.
Discard
milk/kg
60
79
3
4
6
104
21
17
84
57
120
9
60
140
25
30
40
13
31
40
52
14
42
18
80
50.4kg
Treatment period
9
27
2
3
4
15
3
3
11
6
15
2
13
30
4
7
8
2
9
7
14
3
13
16
20
10days
53
Cost of
treatment /SD
6430
7390
360
560
2140
2530
3705
1590
8800
5000
11350
1000
2300
16850
840
3370
2500
1000
13500
16140
6000
1250
2500
4840
8640
5167
Table No.(22)
Reduction in milk yield as calculated by different methods used.
Methods
Reduction %
1- Through the somatic cell count
a- Per infected one quarter
12%
b-Per infected two quarters
24%
c- Per infected three quarters
36%
d- Per infected four quarters
48%
e- Through Tolle (1970) procedure
18%
2- Through the comparison between infected and
healthy quarter.
a-The average of reduction in case of one infected quarter
12.5%
b-The average of reduction in case of two infected
25%
quarters
c-The average of reduction in case of three infected
quarters
d-The average of reduction in case of four infected
quarters
The average of reduction percentage in average of total
milk yield /cow/season
54
37.5%
50%
14.2
234 kg
Table (23) the economical loss evaluation /cow/season
Source of loss
quantity
1-Reduction in milk yield/cow for
one infected quarter
14.2%=234kg
2-Discaded milk
= 50.4kg
3- Treatment cost
= 5167.25SD
4- Other costs had been included as
a- Veterinary services
b- Culling and death cost
(i) culling with replacement
(ii) culling with out replacement
(iii) death
c- dead quarter (RA,LA,RP,LP)
(i) In case of Anterior quarter
=18.75
(ii) In case of posterior quarter
= 31.25
55
cost
27325 SD
5670 SD
5167.25 SD
2000 SD
50.000 SD
111.596 SD
181594 SD
34049 SD
56749 SD
Table No( 24)
The expected cost of treatment and discarded milk (prospective)
parity
Average
of milk
yield
No
Sort of case
1
a
b
c
d
Subclinicl case
One infected anterior quarter
2 infected ant.quarter
one infected posterior quarter
2infected posterior qoarter
6.10
2
a
b
c
d
clinical case
one infected anterior quarter
2 infecred ant. quarters
one infected posterior quarter
2 infected post. quarters
6.10
Discarded
milk
Discarded
milk cost
1.14kg
2.28kg
2kg
4kg
128.25
256.5
225
450
1800SD
3600SD
1800SD
3600SD
128.25
256.5
225
450
acute
4450
7450
4450
7450
1.14kg
2.28kg
2kg
4kg
56
Treat ment cost
chronnic
1800
3600
1800
3600
Figure (1)
Mastatic & non- mastatic- Average daily milk yeild ( winter season)
8
7.4
7
6.5
6.3
6.1
6
5.7
5.3
Av. D. M.Y.
5
5.1
4.9
4.8
4.4
4.3
4
4.1
4
3.9
3
2.6
2
1
0
9
8
7
6
5
4
Parity
57
3
2
1
Non- mastatic
Mastatic
Figure (2)
Average daily Milk Yeild
(Mastatic &non-mastatic) Summer season
7.6
8
5.5
5.3
4.9
5.7
5.8
5.2
4.4
4
4.1
4
5.3
4.2
3.8
3
2
1
0
Parity
Av. D. M.y.
5
5.3
6
5.8
6.3
6
5.8
7
Parity
58
mastatic
non mastatic
Figure (3)
(Mastatic &non-mastatic) Total milk yeild/ cow
( Summer season)
2809.5
3000
2500
2361
991.6
1673.1
1451.9
958.3
1500
1140.5
1000
500
9
9
8
8
7
7
6
6
5
5
4
4
Parity
59
3
3
2
2
1
1
0
M.Y/cow
1418.3
1316.7
1135.5
1320
1416
1571.5
1386
1282.6
1533
1717.2
2000
1790.3
Series1
Series2
Series3
Figure (4)
(mastatic & non mastatic) Total milk yeild /cow ( Winter season)
4500
4000
3855
3500
Milk yeald
3000
2500
non mastatic
mastatic
2150.3
2000
1862.9
1754.2
1669.3
1500
1485
1299.6
1332.6
1421.3
1312.1
1188.6
1123.4
1000
958.3
540
500
10.53
0
9
8
7
6
5
4
Parity
60
3
2
1
4-Discussion
Bovine mastitis can be defined as the inflammation of the udder resulting
from infection and is generally thought to be the most economically important
disease in dairy cows. Losses in the U.S.A dairy industry alone amount to well
over $2 billion/year. Prevalence of the disease in cows approaches or exceeds
25% of quarters at any time (Hurely and morine, 1996). Mastitis results in
reduced quantity and quality of milk and milk products. Costs can be divided into
those where, there is a decrease in revenue and those where there is an increase in
outlay. Decreased milk production, discarded milk and lost value of cull cows are
components of the former. While increased costs of replacement due to early
culling, increased drug usage and increased veterinary and labour costs are
examples of the later (Melnerney and Turner, 1989).
In this investigation, the California mastitis test had been conducted as
the main tool to verify the mastitis problem and its economical implication.
Confirmatory tests such as bacterial isolation, somatic cell count and bromocresol
purple had been performed .The study showed that, 10(7.4) out of 136 milkers
had one dead quarter. These finding are inline with those reported by Zingeser et
al. (1991) about health condition of udders. The dead quarter may be due to a
consequence of tick infestation on the udder (Idris et al., 1991) or as the result of
persistence of mastitis (El Tayeb and Habiballa, 1978). The apparently healthy
cow can harbor subclinical mastitis, which creates tremendous loss in milk
production. The present infection creates an elevation of somatic cell count in
milk. The unseen infections are detected by several methods, including the direct
microscopic somatic cell count (DMSCC), the Wisconsin Mastitis test (WMT),
and the California Mastitis test (CMT). The DMSCC and WMT are laboratory
tests however the CMT is a valuable tool yielding rapid results (Daune, 2000).
Several studies had been published proofing positive correlation between CMT
and somatic cell count of milk (Rao and Rao, 1986) and between CMT and the
61
Discussion
presence of pathogen in both individual udder quarter and composite milk sample
(Edmondson and Marshal, 1962; Ansley and Boul, 1965; and Brook Banks,
1966).
In the present study, the number of cases with subclinical mastitis were
represented by 119 (87.5%) out of lactating cows, while from data collected from
health records of dairy, they were represented by (43.3%) Michel, (2000)
reported, that the subclinical form are the vast majority of mastitis cases. How
ever, for every one clinical mastitis, there were 20 to 40 subclinical cases.
Subclinical mastitis in study involving one infected quarter represented the
highest percentage followed by infection in two quarters. Infection of three
quarters was least. infection of the posterior quarters was more frequent (27.1%,
26.3%) than that of the anterior quarters (22.5%, 24.1%). Similar result were
obtained by Herms (2001) who reported that the two posterior quarters were most
frequently infected than the two anterior ones. Carplet (1963) reported that the
two posterior glands were more fully developed than the anterior ones and that
the former glands secreted 120-150% milk as compared with latter.
In this investigation, the microorganisms isolated from infected quarters
were staphylococcus, streptococcus coliform, micrococcus and fungi. Many
workers had reported that the staphylococci were found to be the most frequent
causative agent of mastitis among cattle (Cargil and Bootas, 1970, Kapur and
Singh, 1978, Shalalli et al, 1992 Aydin etal., 1995). The commonest bacteria
isolated from subclinical mastitis were streptococus species (Hashim et al., 1991
keskintepe et al., 1992) and micrococcus spp. (Shalalli, et al., 1982 and Costa, et
al., 1987). Coliforms causing mastitis included Escherichia coli, klebsiella
pneumoniae and Enterobacter aerogenes. These bacteria are inhabitant of water
and soil and are transmitted by flies contaminated water and feed (Merchant and
Packer, 1967). Escherichia coli was considered as the most common Gram
negative bacillus associated with clinical and subclinical mastitis (Elliot etal.,
62
Discussion
1971 Jha et al.,1994) .Also Candida albicans was established as a causative agent
of subclinical mastitis (Nizaml et al., 1989 Ognean et al., 1992).
Somatic cell counts is one of the confirmatory methods to monitor udder
health and thus milk quality. In the present study, somatic cells were counted
directly microscopically or indirectly by CMT. The results showed the direct
SCC ranged from 10x104 to 19.8x105. This reflects an elevation in SCC above the
normal level confirming the evidence of mastitis. This finding is in accord with
Jones and Bailey (2000) who reported, that many of the cows with SCC over
20x104 cells/ml had subclinical mastitis. Schroeder (1997) stated that normal milk
should have less than 200,000 cells/ml. On the other hand, the estimation of
somatic cell counts had been made using grads of CMT. (Dairy Herd
Improvement Association) (DHIA)( 1984) and National Mastitis council (1996).
This procedure had been adopted in this investigation. The results showed that,
the somatic cell counts ranged from 60x104 and over 10x105 cells/ml of milk.
Reduction in milk yield had been estimated through several methods.
Based and SCC. Dairy Herd Improvement Association (DHIA 1984), National
Mastitis Council (1996) and Schroeder (1997) estimated of reduction 10% and >
12% from the total milk yield/cow, the somatic cell counts was between 60x104
and 1.2x105 cell/ml. The Federal Institute for Dairying (Tolle 1970) estimated
the reduction percentage in the total milk yield as 3.9% to 18% when SCC, was
25x104 and more than 10x105 cells/ml. In this investigation direct SCCs ranged
from 10x104 to 19.8x105 and the reduction in milk yield ranged from 3% to 12%
of milk yield for one infected quarter. Whereas indirectly (CMT), the estimated
SCCs ranged from 10x104 to10x105 and the reduction in milk yield ranged from
10% to >12% of milk yield for one infected quarter. Comparison of milk yield of
infected and healthy quarters showed a reduction of 12.5 % of milk yield for one
infected quarter. This represented 67.2% of the total financial loss due to mastitis.
Estimated financial loss due to reduction in milk yield was found to be
about 27,325 Sudanese Dinnars.
63
Discussion
Many workers collaborated in assessment of reduction percentage due to
mastitis. Fustes, et al. (1986) reported that total loss for one infected quarter was
about 10.36%. Wagner and Stull (1978) concluded that, mastitis had reduced the
milk yield. This reduction amounted to per quarter 13.2% in mastitic cow when
compared with a healthy parallel quarter. More over, Fetrow (1986) reported that
the greatest loss of milk production was attributed to subclinical mastitis and
represented by 75% of the total loss. Whereas Ahlner (2003) found it to cause
70% of the losses in milk production .De Graves and Fet row, (1993) found that
the production loss from udder quarters with subclinical mastitis was from 1026%. This was also confirmed by Oleary and Leavitt (1983) who studied the
effect of infusion of E.coli in quarters. The reduction in milk yield was 14.5%.
While Meyer (1980) found that, milk yield from udder quarters with subclinical
mastitis was 20.8% lower than from parallel healthy quarters. Moreover, he could
estimated a total reduction in milk yield of about 13.2% in mastitic cows.
The other financial losses found in this investigation were due to treatment
cost and veterinary services. The percentage of milk dumped after treatment
represented 14.5%, of total cost followed by treatment cost (13.2%) and
veterinary service (5.1%). Many workers had obtained similar result with some
simple variables, which may be due to the status of cow productivity. Fustes et al
(1986) estimated the discarded milk to be 6.8% of the total financial loss. Where
the drug cost was 1.93%, the heifer replacement 1.52% and veterinary service
0.36% to. Where National Mastitis council (1996) by Shroeder (1997) reported
that the discarded milk percentage about 5.7%, replacement cost 22.6%, extra
labor 1.14%, Drug cost 4.1% and veterinary services about 1.5%. Blosser (1979)
reported about 70% of the loss was due to reduced milk yield, 11% to nonutilizable milk and the cost arising from treatment amounted to 1.7%. The simple
variabilities between the results may be due to the status of the cow,
mistreatment, drug cost variability. In the present study, the amount of reduced
milk as averaged about 234 kg./one infected quarter/ season. Miller et al. (1983)
64
Discussion
estimated the milk losses throughout lactation as 180 and 129 kg for Swedish Friesian and Swedish -Red cows respectively. Where Heeschen (1984) revealed
that the losses in milk yield due to mastitis were 386kg/cow/year. Also Schroeder
(1997) reported that the average production loss per lactation for one infected
quarter was about 1600 pound "weight". Further more, Raubertas and Shook
(1982) reported that, the yield loss for each increase in log cell count, was
associated with a decrease of 135kg.
This variability in amount of milk loss may be attributed to the stage of
lactation. Ibtisam (1995) found there was significant effect of the week of
lactation on which infection had occurred on milk yield ( p<0.05). Also, Lucey
and Rowlands (1984) observed a reduction between peak of production and 10
weeks after peak.
In the present study loss the reduced milk yield for one quarter infected
with subclinical mastitis as an averaged of 14.2% (234kg) which cost 27325
Sudanese Diners. Whereas the average of discarded milk due to the antibiotic
usage was 14.5% of the total loss which cost 5670SD. Treatment was (13.2%)
cost 5167SD of the total and the veterinary service (5.1%) by 2000SD. The
average total loss value of mastitis impact about 30252 SD for one infected
quarter/ season. This was in agreement with the finding of Schroeder (1997) who
estimated the annul loss due to mastitis were U.S.$184.00 . Also Dijkuizen and
Stelwagen (1982) found the losses due to mastitis were Franc 125/cow. Websid
(1989) found mastitis in about 40% of cows with at least two quarters affected
causing loss of about U.S.$182.00/cow /year . While Jones and Baily (2000)
explained that, the total cost of mastitis in average herd enrolled in DHIA was
approximately U.S.$171 per cow.
To verify effect of mastitis on milk yield, the study adopted the average
daily milk yield for the mastitic cows for seven months. Also the average of total
milk yield for mastitic and healthy cows with the same parity and season. The
result demonstrated an irregulatory of average daily milk yield .and average of
65
Discussion
total milk yield /cow. This may be due to many factors. The dominant of them
may be the mastitis factor .Many workers had evaluated the milk yield per cow
and reported that, an increasing milk yield related with advancing of parity
number. Also revealed that, the maximum milk yield per lactation was reached
after the fifth parity. Moreover, the milk yield after the fifth season was
significantly (p<0.05) higher than the yield after the first, second and third
parities, while it was similar to the yield in the fourth lactation. For the daily milk
yield, also the maximum yield was reached in the fifth parities and the daily milk
yield of the first lactation was significantly (p<0.05) lower than the other parities.
This was in agreement with Sid Ahmed,(1986); Ali et al.,(1988),Yousif et
al.,(1998) and Musa, (2001). Figure (1), (2), (3) and (4), illustrates of average
daily milk yield and average of total milk yield. Regarding the productive traits,
the mean effect of mastitis on total milk yield had no significant effect, while the
season had significant effect in winter.
The analysis of variance for total milk yield revealed that, there was no
significant effect of mastitis alone. This may be due to the fact the effect of
mastitis had cleared. In addition the allocation and kind of infection may be play
a role in the effect of mastitis on total milk yield. Moreover, the other factors such
as parity, dry period and lactation length had more significance. While the
analysis of variance revealed that, there was significant effect of mastitis and
season; mastitis, parity and season as display. This in line with Miller et al.
(1983) who estimated the milk losses throughout lactation based on single test /
day. Also Bauman, (1994) reported that, there are several factors predispose the
dairy cow to mastitis such as season, parity, herd, stage of lactation and
environment. They reported that, there is a positive relation between milk yield
and incidence of mastitis.
Musa, (2000); Yousif et al. (1998) and Ali, et al.,(1988) reported that, there
is a significant effect of parity number and period on milk yield. The analysis of
variance for the daily milk yield revealed that, there was no significant effect of
66
Discussion
mastitis alone or as interaction with other factors. While parity had highly
significant effect on daily milk yield. This may be due, to the fact that the daily
milk yield was obtained from the total milk yield with lactation period as average.
67
Recommendations
Veterinarian must be adopt this recommendation to protect the owner from
mastitis infection through.
1- Milking parlour must be constructed for any dairy farm and this is must be
supported by low and conductor.
2- Dairy farmers must be aware of three major factors that lead to mastitis the
microorganisms as the causative agent of the disease, the cow as the host
and the environment which can influence both the cow and the
microorganisms.
3- Mastitis consequence must be understood by the owners who must
recognize with the economical loss.
4- Mastitis management programs must be adopted in any dairy farm such as
• Keep the cow's environment clean and stress –free.
• Isolate the mastitic cows at milking time.
• Monitor Somatic cell count in bulk tank, causative agent and sensitivity
test.
5- Use proper milking procedure as:• Wash only teats and lower udder surface using water and disinfectant.
• Dry each teat thoroughly with individual paper towels
• Check quarters for abnormalities each milking by stripping.
• Dip or spray teats, especially post. Milking with an effective teat dip.
6- Evaluate dry cow management practice as
• Dry-off procedures
• Dry cow therapy
• Dry cow nutrition
7- Transition period feeding and management
8- Develop acomplete herd health program
9- Chronically –infected cows must be culled
68
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