Download Determination of Energy-Protein Ratio (EPR) in broilers` diet

Determination of Energy-Protein Ratio (EPR) in
broilers’ diet in southern climate environment
L.BAGHOYAN
The faculty of Animal Husbandry and Veterinary, Armenian Agrarian State University, 74
Teryan st., Yerevan 375009, Republic of Armenia
An experimental study aimed to determine the effective EPR in broiler’s diet, was carried
out in southern region of Armenia (air temperature in broiler house varied 25,50C to 36,30C ).
The experiments were carried out over 180 day-old Cobb broiler chicks, which were equally
divided into control and 4 experimental groups (36 broilers per group). The broilers were fed up
to slaughtering (at 42 day of age). Each group was fed on 3 types of diets (with corresponding
durations 1-21 days; 22-35 days; 36-42 days). The control group was fed on commercial diets
used in any season, experimental groups were fed on diets with high protein and energy content.
In the first period the control and experimental groups’ diets contained the same amount of
EPR-135; second period 150; 135; 132; 131 and 128, respectively, and in the third period 160;
160; 150; 156 and 160, respectively. During the first period of feeding (diets with the same EPR
and 23% protein content) there were no statistically significant differences observed in live
weights of broilers (700-710g) and daily food consumption between control and experimental
groups (P<0.05). In the second period of broilers fattening (22-35 days) the higher results in live
body weight were received in Ist experimental group (with 135 EPR) than the control group (with
150 EPR), protein content 23 and 21%, respectively. In hot southern condition, the effectiveness
of using diets with high protein and energy content is approved by the results obtained for IV,
III and especially II experimental groups (with 25% of protein), their live body weight
significantly differed (P<0.001) as compared to the control group. The results of II experimental
group (with 25% of protein and 132 EPR) is overrating (2300g live weight). Therefore the
economical benefits of protein usage is evident. The results in the final feeding period of II
experimental groups (ration with 23% protein; 150 EPR) obviously exceeded (by 3.9-15.5%) the
other groups. Thus, the definitive variant for hot summer condition should be considered the II,
III and IV experimental groups rations with high protein and energy content, but low feed
consumption - 1.77; 1.84 and 1.91 kg feed per kg live weight gain, respectively.
Keywords: broiler; feed consumption; energy/protein ratio; hot climate
Introduction
The poultry industry has gone trough a tremendous development and expansion during the last
couple of decades. The body weight gain has markedly increased and the utilization of feed strongly
improved. The progresses in breeding and nutrition resulted in broiler chickens having higher
performances today then ever before (Bogdanov G.A., 1990).
It is experimentally found out that the poultry performance is conditioned on 40-50% of dietary
energy and on 20-25 % of protein. In this case the supreme meaning has the edible degree of diet, on
which primarily acts the energy content of diet. The edibility of the ration is the most important factor,
which guarantees the high or low poultry production.
If there is a lack of energy in the diet, then dietry protein transforms not only into body protein,
but also into carbohydrates and lipids. And the rest little amount of protein is used to bring eggs or
muscular tissue. In that case the usage of dietary protein is neither productive nor to the purpose.
1
Taking into consideration the fact that protein compared with the other nutrients is the most expensive
and deficit, so the diet should be balanced with optimum amount of metabolizable energy, so as
determining the best energy-protein ratio /EPR/. This concept is also known as energy-protein balance,
which is expressed by achieved per 1% of protein in 1kg of feed
The diet EPR should vary depend on strain, production trend, age and climatic conditions. In
every case is necessary that the certain protein level corresponds with the essential amount of energy
in diet. This enables to determine such EPR, which contributes to use the diet nutrients and increase
poultry performance (Okolelova T.M., 1990).
The higher production performance and feed conversion efficiency make today’s chickens more
susceptible to heat stress than ever before. The increasing proportion of poultry production in tropic
and subtropical regions makes it necessary to reconsider the selection strategy of today’s commercial
breeding programme in the long run. Nutritional strategies aimed to alleviate the disadvantage effect
of heat stress by maintaining feed intake, electrolytic and water balance or by supplementing
micronutrients to satisfy the special need during heat stress. To enhance the thermotolerance by early
heat conditioning or feed restriction seems to be one of the most promising management methods in
enhancing the heat resistance of broiler chickens in the short run. (Lin H. at al., 2006)
Because fast-growing broilers produce more heat and have a higher heat load, the effect of heat
stress is more pronounced in commercial broiler stocks and broilers with high growth potential
compared to the slower-growing chickens. (Cahaner and Leenstra, 1992; Cahaner et al., 1995). This is
mainly because birds are growing faster than ever before and are thus heaver than previously at any
given age, but also because broiler production is being introduced as a farming system in
environments that are unsuitable for such production. It is not economic for most producers to modify
the environment within the broiler house to account for these problems and so it would be useful to
know of nutritional strategies that could be used to reduce the effect of heat on broilers (Gous and
Morris, 2005). Stresses caused by environmental factors have a negative impact on the development
and immunity of the chick (Vieira and Moran, 1999a).
A hot environment is one of the important stressors in poultry production. The resultant heat stress
comes from the interactions among air temperature, humidity, radiant heat and air speed, were the air
temperature plays the major role. The optimum temperature for performance is likely to be 19 to 220C
for laying hens and 18 to 220C for growing broilers (reviewed by Charles, 2002). The heat stress
results in high mortality, decreased feed consumption, poor body weight gain and meat quality in
broiler chickens (reviewed by Howlider and Rose, 1987; Marsden and Morris, 1987; Shane, 1988;
Yahav, 2000a). Numerous authors have shown that the reduction in performance of chicks observed in
high temperature is due, in part, to a limit on food intake imposed by the bird’s restricted ability to
dissipate heat (Howlider and Rose, 1987 and Daghir, 1995 for reviews).
The mechanisms by which feed consumption decreases at high temperature are largely unknown.
Some authors recommend a reduction of dietary protein as a means of limiting further increases in
heat production (Waldroup et al., 1976; Teeter 1994). McLeod (1992) found that the lower heat
increment observed in stressed broilers fed high-fat diets did not translate into higher feed intakes and
the heat production of birds kept at 320C was not influenced by dietary protein. Moreover, various
reports suggest that high protein diets do not suppress feed intake under heat stress (Cheng at al.,
1997; Alleman and LeClercq, 1997; Temim at al., 1999, 2000). Cahaner at al.(1995) actually found
higher feed intakes on birds offered high protein diets versus those fed low protein concentrations.
Any increase in dietary crude protein may compensate for the reduced feed intake observed in
stressed birds and a number of authors have found beneficial effects when feeding such diets (Kubena
at al., 1972; Olomu and Offiong, 1980; Cahaner at al., 1995; Alleman and Leclercq, 1997; Temim at
al., 1999, 2000). Likewise, Marks and Pesti (1984) suggested that low protein diets tend to reduce
water intake under heat stress which may further compromise the performance of broilers.
Although protein has a high heat increment, decreasing dietary protein level would enhance the
harmful effect of high temperature. The lower level of dietary crude protein level results in poor feed
efficiency and body weight gain (Alleman and Leclercq,1997). Chickens fed with low-protein diet
tend to eat more to meet their protein requirement, as compared to the isoenergetic high protein diet,
and resulting in high heat production and more fat deposition (Buyse et al., 1992).
The adverse effects of high temperature on broiler performance should be alleviated by dietary
manipulation.
2
The purpose of the present investigation was to determine the optimum EPR, so as the effective
protein and energy content in broiler’s diet in summer hot climate of south /on example of Armenia/
depends on the above mentioned parameters.
Materials and methods
In the investigation of the determination the optimum EPR in broiler’s diet, studied in summer hot
climate of south, 180 one-day-old commercial broiler chicks of the Cobb cross were used, they were
chosen at random.
The experiment was carried out at June of 2005 in ,,Araks” Poultry Farm. The experimental
groups were kept in the same poultry house (with the total head of farm poultry). They were equally
divided into five groups, each comprising 36 broilers. The broilers were managed in cages – 12
broilers in every cage. The first broiler group was the control group: the broilers in this group received
commercial diets used in any season. The other four groups were experimental groups: the broilers in
this groups received diets with high protein and energy content.
The one-day old chicks were weighed at the beginning of the trial, and the average value of body
mass was 40g in each group.
The broilers received feed and drinking water immediately upon entering the trial. All the broilers
in trial were fed with the feed mix for broilers fattening. Each group was fed on 3 types of diets (with
corresponding durations 1-21 days; 22-35 days; 36-42 days). The quantity of feed consumption was
measured daily. At the end of the trial, the total consumed feed quantity was calculated for each
investigated broiler group. They received feed mix three times a day: water consumption – ad libitum.
The broilers were fed up to slaughtering (at 42 day of age). In this study animals were healthy and
no animal died during the investigation, except 1 chick from II experimental group at the 3 day-old
age.
Over the 42 days duration of the trial eighteen broilers (50 % of the group) were taken at random
from each study group every week. All the isolated broilers were weighed individually.
The control group was fed on commercial diets; experimental groups were fed on diets with high
protein and energy content, so as EPR.
The air temperature in broiler house was measured three times a day and varied from 25,50C to
36,30C, which is above of their comfort condition.
Results and discussion
From the results presented in Table 1 and Table 2 it is apparent that the highest live weight, weight
gain and feed consumption were achieved in the experimental groups.
All the broilers of the control and experimental 4 groups were fed with the starter feed mix in the
first period of the trial: diet contained 23.0% protein and 310 Kkal metabolizable energy (Table 1). As
result, 21 day-old broilers fed on diet with the same EPR had no statistically significant differences
observed in live weights of broilers (700-710g) and daily food consumption between control and
experimental groups (P<0.05), which is natural.
In the second period of broilers fattening (22-35 days) the higher results in live body weight were
received in Ist experimental group (with 135 EPR) than the control group (with 150.0 EPR), protein
content 23 and 21%, respectively.
In hot southern condition, the effectiveness of using diets with high protein and energy content is
approved by the results obtained for IV, III and especially II experimental groups (with 25% of
protein), their live body weight significantly differed (P<0.001) as compared to the control group. The
same results were received of II, III and IV experimental groups broilers fattening at the early age, but
the changes in results of growing period is associated with the energy high content, while the three
groups contained the same amount of protein -25%.
3
The results in the final feeding period (36-42 days) of II experimental group (ration with 22.9%
protein; 150 EPR) obviously exceeded (by 3.9-15.5%) the other groups. The results of II experimental
group is overrating.
Table 1 The content of metabolizable energy, protein and EPR in the diets of experimental broilers.
Age, day
1-21
/Starter/
Groups
control
I experimental
II experimental
III experimental
IV experimental
22-35
/Grower/
36-42
/Finisher/
Met.
Energy,
Kkal
Crude
protein,
%
EPR
Met.
Energy,
kJ
Crude
protein,
%
EPR
Met.
Energy,
kJ
Crude
protein,
%
EPR
310.0
310.0
310.0
310.0
310.0
23.0
23.0
23.0
23.0
23.0
135
135
135
135
135
315.1
310.2
327.9
325.1
319.8
21.0
23.0
24.9
24.9
24.9
150
135
132
131
128
320.0
320.0
345.0
341.5
334.4
20.0
20.0
22.9
21.9
20.9
160
160
150
156
160
Taking into consideration the fact that broiler chickens consume less amount of feed mix in hot
environment condition, as compared to the other seasons, it is clear from our experiment that broilers
must receive diets with high protein and energy content and thus ensure their body requirements for
the nutrients.
Though the dietary protein and energy content, so as the EPR of control and I experimental groups
were the same in the first and final period of fattening – 23.0; 310.0; 135 and 20.0; 320.0; 160
respectively, but the protein high content received at growing period acted positively on weight gain
temps and high live weights observed in I experimental group - 2010.3g. On the other hand we can
indicate that the low protein content in the second period of fattening /22-35 day/ resulted in I
experimental group broilers’ live weight losses in the final period, as compared with the II; III and IV
experimental groups. The results once again prove the importance of protein high content in the early
age of poultry feeding, especially in hot climate.
Table 2 Broilers’ live weight, weight gain and feed conversion.
Groups
Day-old
chicks live
weight, g
Weight
gain, g
Live
weight at
21 day, g
Live
weight at
35 day, g
Live
weight at
42 day, g
Total
weight
gain, g
Feed
conversion per
1kg of weight
gain, kg
control
I experimental
II experimental
III experimental
IV experimental
40.0
40.0
40.0
40.0
40.0
46.4
46.9
53.8
51.7
49.6
700.2
700.9
709.8
705.6
710.0
1690.4
1710.1
1866.2
1811.4
1790.8
1990.6
2010.3
2300.0
2211.8
2124.1
1950.6
1970.3
2260.0
2171.8
2084.1
2.05
2.02
1.77
1.84
1.91
A statistically highly significant difference was found between the II experimental group and
control groups at the end of the trial, Figure 1: II experimental group exceeded the control group by
live weight on 15.5%. This group was followed by the broilers of III and IV experimental groups on
11.1; 6.7 %, respectively, and finally, I experimental group exceeded the control group on 0.9%.
This results are in agreement with those of V.I.Hakobyan (1971), which experimental found out
the desirable amount of protein and EPR in the diet of broilers for summer season: at the age of 1-28
day it was 25% protein and 138 EPR, for 29-63 day – 23.0% and 162, respectively (Hakobyan V.I.,
1971).
Nowadays we can indicate the high speed of poultry industry development, changes in
environmental conditions and shortening of broilers’ fattening period, so we judge that the huge
genetic force of broilers’ crosses will show higher results in southern environmental conditions by
4
using diets with high protein and energy content spending less feed per 1 kg of live gain. Considering
these facts the using of diets with optimum energy-protein ratio differentiated by seasons is very
important in specific environmental conditions of south (on example of Armenia).
g
2300
2250
2200
2150
2100
2050
2000
1950
1900
Age (42 day)
Control
I exp.
II exp.
III exp.
IV exp.
Figure 1 The average live weight of broilers at the end of trial.
The principle aim to overcome the deleterious effect of high temperatures on broiler performance,
should base on reducing the heat produced by the bird wherever possible. This may be accomplished
by reducing food intake during the period of heat stress, but ensuring them with necessary amount of
protein and energy in diet. The temperature as a major component of the climate effects on
performance of broiler chickens. The high performance makes them more susceptible to
environmental heat load. Heat stress is worldwide problem in poultry production and causes enormous
economic losses every year. High temperature influences intake, digestion, absorption and metabolism
of energy and protein. This determines both intake and the optimal composition of the feed. Protein
utilization strongly interacts with energy metabolism under these conditions.
This strategies would be useful not only in environmentally controlled facilities, were high
temperature still prevail at certain times of the year, but also they would be more valuable in
conditions in which the environment can be modified only minimally.
The increasing proportion of poultry production in tropical and subtropical regions makes it
necessary to reconsider nutritional and climatological strategies permanently.
Thus, the definitive variant for hot summer condition should be considered the II, III and IV
experimental groups rations with high protein and energy content, but low feed consumption - 1.77;
1.84 and 1.91 kg feed per kg live weight gain, respectively.
References
ALLEMAN, F. and LECLERCQ, B. (1997) Effect of dietary protein and environmental temperature
on growth performance and water consumption of male broiler chickens. British Poultry Science 38:
607-610.
BOGDANOV, G.A. (1990) Feeding of farm animals: 105-494 (in Russia)
BUYSE, J., DECUYPERE, E., BERGHMAN, L., KUHN, E. R. and VANDESANDE, F. (1992)
Effect of dietary protein content on episodic growth hormone secretion and on heat production of
male broiler chickens. British Poultry Science 33: 1101-1109.
CAHANER, A. and LEENSTRA, F. (1992) Effects of the high temperature on growth and
efficiency of male and female broilers from lines selected for high weight gain, favourable feed
conversion, and high or low fat content. Poultry Science 71: 1237-1250.
5
CAHANER, A., PINCHASOV, Y. and NIR, I. (1995) Effects of dietary protein under high ambient
temperature on body weight, breast meat yield, and abdominal fat deposition of broiler stocks
differing in growth rate and fatness. Poultry Science 74: 968-975.
CHARLES, D.R. (2002) Responses to the thermal environment. In.: Poultry environment problems,
A guide to solutions (Charles, D.A. and Walker, A.W. Eds.), Nottingham University Press,
Nottingham, United Kingdom: 1-16.
CHENG, T.K., HAMBRE, M.L. and COON, C.N. (1997) Responses of broilers to dietary protein
levels and amino acid supplementation to low protein diets at various environmental temperatures.
Journal of Applied Poultry Research 6: 18-33.
DAGHIR, N.J. (1995) Poultry production in hot climate (Wallingford, CAB International).
GOUS, R.M. and MORRIS, T.R. (2005) Nutritional interventions in alleviating the effects of high
temperatures in broiler production. World’s Poultry Science Journal 61: 463-472.
HAKOBYAN, V.I. (1971) The principles and particularities of balancing hen's feeding in continental
south climate / on example of Armenia/ Dissertation paper for Professor Degree of
Agriculture: 100-173. (in Russia)
HOWLIDER, M.A.R. and ROSE, S.P. (1987) Temperature and the growth of broilers. World’s
Poultry Science Journal 43: 228-237.
KUBENA, L.F., DEALTON, J.W., REECE, F.N., MAY, D. and VARDAMAN, T.H. (1972) The
influence of temperature and sex on the amino acid requirements of the broilers. Poultry Science 51:
1391-1396.
LIN, H., JIAO, H.C., BUYSE, J. and DECUYPERE, E. (2006) Strategies for preventing heat stress
in poultry. World’s Poultry Science Journal 62: 71-80.
MARKS, H.L. and PESTI, G.M. (1984) The role of protein level and diet form in water
consumption and abdominal fat pad deposition of broilers. Poultry Science 63: 1617-1625.
MARSDEN, A. and MORRIS, T.R. (1987) Quantitative review of the effects of environmental
temperature on feed intake, egg output and energy balance in laying pullet. British Poultry Science
28: 693-704.
MCLEOD, M.G. (1992) Energy and nitrogen intake, expenditure and retention at 320C in growing
fowl given diets with wide range of energy and protein content. British Journal of Nutrition. 67:
195-206.
OKOLELOVA, T.M. (1990) Poultry feeding: 3-10 (in Russia)
OLOMU, J.M. and OFFIONG, S.A. (1980) The effects of different protein and energy levels and
time of change from starter to finisher ration on the performance of broiler chickens in the tropics.
Poultry Science 54: 828-835.
SHANE, S.M. (1988) Factors influence health and performance of poultry in hot climates. Poultry
Biology 1: 247-269.
TEETER, R.G. (1994) Optimizing production of heat stressed broilers. Poultry Digest 26: 10-24.
TEMIM, S., CHAGNEAU, A.M., GUILLAUMIN, S., PERESSON, R., GERAERT, P.A. and
TESSERAUD, S. (1999) Effects of chronic heat exposure and protein intake on growth,
performance, nitrogen retention and muscle development in broiler chickens. Reproduction
Nutrition Development 39: 145-156.
TEMIM, S., CHAGNEAU, A.M., GUILLAUMIN, S., PERESSON, R. and TESSERAUD, S.
(2000) Chronic heat exposure alters protein turnover of three different skeletal muscles in finishing
broiler chickens fed 20 or 25% protein diets. Journal of Nutrition 130: 813-819.
VIEIRA, S.L. and MORAN, E.T. (1999) Effects of delayed placement and used litter on broiler
yields. Journal of Applied Poultry Research 8: 75-80.
YAHAV, S. (2000) Domestic fowl – strategies of confront environmental conditions. Avian and
Poultry Biology Reviews 11: 81-95.
WALDROUP, P.W., MITCHELL, R.J., PAYNE, J.R. and HAZEN, K.R. (1976) Performance of
chicks fed diets formulated to minimize excess levels of essential amino acids. Poultry Science 55:
243-253.
6