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فصل پنجم عوامل موثربرتوليد و تركيب شير خصوصيات يك گاو شيرده پرتوليد چيست؟ 365 day lactation Milk 57,460 lb Fat 4.0% (2,318 lb) Protein 3.5% (2,020 lb) Ruann Royalty Cora 1994 Beecher Arlinda Ellen 1975 70 Milk Maintenance NEL intake, Mcal/d 60 50 40 83% 30 75% 75% 20 66% &5% 75% 10 0 Av. US cow 27 kg Cora 72 kg Holstein 45 kg Jersey 24 kg 70 Milk Maintenance NEL intake, Mcal/d 60 50 40 83% 30 75% 20 66% &5% 75% 10 0 Av. US cow 27 kg Cora 72 kg Holstein 45 kg Jersey 24 kg 70 Milk Maintenance NEL intake, Mcal/d 60 50 40 83% 30 75% 20 66% 85% 10 0 Av. US cow 27 kg Cora 72 kg Holstein 45 kg Jersey 24 kg عوامل موثر بر توليد و تركيب شير عوامل موثر بر توليد وتركيب شير Daily yield and composition of milk are affected by : 1-Physiological 2- Environmental عوامل موثر بر توليد وتركيب شير Physiological factors are divided into two parts: 1- Inheritance 2- Nonhereditary factors such as age, No. of previous lactations and pregnancy نوسان روز تا روز Both milk yield and percentage composition of milk vary considerably from day to day. Daily variation in milk yield is related to the completeness of evacuation of milk from the udder. Variation caused by disease, undernutrition, cows being off-feed, and related factors are usually of longer duration than those caused by udder evacuation, incomplete milking, estrus, or excitement. منحني نورمال شيردهي The relationship between milk yield to the milk fat and protein percentage is negative (Fig 1). Phase 4 Peak Milk Phase 5 Peak DMI Phase 6 Tail End Phase 1 Phase 3 Dry Matter Intake Cl Fa ose rO Up ff Phase 2 Fresh Milk Production Body Weight 0 1 2 3 4 5 6 7 Month 8 9 10 11 12 Period of Negative Energy Balance ht g i e W y Bod Dry M atte r Intak e M il k Pr odu ctio n Lactation DMI and Milk Production During Early Lactation 60 50 kg/d 40 30 20 Milk yield 10 Dry matter i ntake 0 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10 11 12 13 Week of Lactation McGuire, unpublished Energy Balance of 29 ID Cows During Early Lactation 15 10 5 0 -5 -10 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10 Week of Lactation Energy Balance versus Body Condition Score 15 10 BCS 3.5 5 3 0 BCS EB 2.5 -5 -10 2 Energy balance (Mcal/d) 4 -15 12 11 10 9 8 7 6 5 4 3 2 1 -1 -2 -3 -4 Week of lactation McGuire, unpublished ? Which Cow is Thin BCS = 1.0 3.5 Which Cow is in Negative Energy Balance ? 5.0 Stage of Lactation & Parity (Milk Yield – lbs./day) Parity > 1 100 Parity = 1 80 60 40 20 0 1 2 3 4 5 6 7 Months post-partum 8 9 10 Peak Milk 40 to 70 days postpartum Second month on DHI test Peak times 200 equals lactation total potential Example: 45 kg X 200 = 9000 kg Heifers (1st Lactation) equal 75% of older cow peaks (2nd + Lactation) Example: 66 kg / 85 kg = 77.6% :اوج توليد بستگي به عوامل زير دارد Body condition Inherited potential Freedom from metabolic and infectious diseases Feeding regime Persistency: Is the rate of decline in yield after calving تداوم در شيردهي :نرخ يا ميزان كاهش در توليد بعد از زايمان آغوز The first milk after parturition is colostrum, which has a marked difference from that of normal milk (Table 1). عوامل محيطي رطوبت ودرجه حرارت Temperatures between 4-24 o C have no effect on the milk production of most dairy cows. In this range known as the comfort zone, no body processes are directly involved inn maintaining body temperature (Fig 5). Temperature & Humidity (Percentage of max.) -17 -7 4 15 Temperature, C 27 38 48 Lower Critical Temperature Maintenance Cold Thermal Comfort Zone Kilocalories Gain Upper Critical Temperature Effective Temperature Intake Heat 22 0 20 Relative Humidity, % 60 40 80 Degrees, C NO 27 STRESS 32 MILD STRESS HEAT STRESS 38 43 49 SEVERE STRESS DEAD COWS 100 Gestation The exact reason for the decrease in milk production at the end of the pregnancy is not known. One hypothesis is an increase in the nutrient required for fetal development. A more reasonable explanation is a hormonal changes that occur at this time. Pregnancy Status (Milk Yield – lbs./day) 100 Open 80 60 Conception 40 Pregnant 20 0 1 2 3 4 5 6 7 Months post-partum 8 9 10 A. Pezeshki,* J. Mehrzad,† G. R. Ghorbani,‡ H. R. Rahmani,‡ R. J. Collier,§ and C. Burvenich*1 J. Dairy Sci. 90:5531–5541 Journal of Dairy Science Vol. 90 No. 12, 2007 Previous Days Dry (Lactation Yield as a Percentage of max.) 105 100 95 90 85 80 75 0 20 40 60 80 Previous Days Dry 100 120 Previous Days Open (Lactation Yield as a Percentage of max.) 20 40 60 80 100 120 Previous Days Open 140 Month of Calving (Percentage of max.) D B E F O K T M S M A A Month of Calving Current Days Open (Lactation Yield as a Percentage of max.) 20 40 60 80 100 120 140 160 Current Days Open Body Weight General relationship exist between the BW of the cows and the amount of milk produced. Larger cows have more udder secretory tissue and larger digestive systems. Photoperiod Cows subjected to 16 h of light and 8 h of darkness produced 7-10% more milk than those exposed to 9-12 h of light per day. Factors Affecting Milk Yield and Composition Disease Mastitis Metabolic disease Locomotive disease Displaced abomasum Calving problems (dystocia) Bovine somatotropin (bST) Oxytocin