595 - Effects of protein level and digestibility on the...

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595 2011 Poultry Science 90 :595–603 doi: 10.3382/ps.2010-01098 Key words: protein , digestibility , broiler , growth performance , carcass yield ABSTRACT A study was conducted to evaluate the effects of dietary protein level and protein digestibility on the growth performance and carcass characteristics of broilers from 1 to 35 d of age. Broiler chickens (n = 320) were fed 4 different ideal protein-balanced, isoca- loric diets in a 2 × 2 factorial design with 2 levels of protein [high protein (HiPro; 20 and 18% or 200 and 180 g/kg) and low protein (LoPro; 18 and 16% or 180 and 160 g/kg) on d 1 to 14 and d 15 to 35, respectively] and 2 levels of protein digestibility [high digestibility (HiDig) and low digestibility (LoDig); approximately 85% and 80% CP digestibility, respectively]. The Hi- Dig diets were formulated using soybean meal and fishmeal, whereas the LoDig diets used wheat distill- ers dried grains with solubles and meat and bone meal as the primary protein sources. The standardized ileal digestibility (SID) values of the wheat distillers dried grains with solubles and meat and bone meal (56.5 and 72.0% SID for lysine, respectively) were measured be- fore the experiment to improve the accuracy of the diet formulations. During the starter phase, the interaction was significant for ADG; birds fed the LoPro-LoDig diet grew slower than birds fed the other 3 diets ( P < 0.05). During the grower phase, the interaction was sig- nificant for ADFI; birds fed the LoPro-LoDig diet had the lowest ADFI compared with those fed the other 3 diets. The interaction between protein level and digest- ibility was significant for the SID of most of the AA and was significantly higher for birds fed the HiPro- HiDig diet compared with those fed the other 3 diets. Total breast meat yield was significantly higher in birds fed the HiPro diets than in those fed the LoPro di- ets, whereas birds fed the HiDig diets had significantly more abdominal fat than those fed the LoDig diets. The results suggest that low-protein diets can support growth performance equal to high-protein diets when highly digestible ingredients are used. However, maxi- mum breast meat yield requires a high-protein diet and is not affected by ingredient digestibility. Effects of protein level and digestibility on the growth and carcass characteristics of broiler chickens 1 G. P. Widyaratne and M. D. Drew 1 Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A8 INTRODUCTION A considerable amount of research has been done to evaluate the effects of low-protein, amino acid ( AA )- supplemented diets on the growth performance and carcass characteristics of broiler chickens. However, conflicting results from these studies do not allow a clear conclusion on the effects of these diets in practi- cal broiler production. Some research evaluating the effect of low CP, AA-supplemented diets have reported inferior performance on broiler productivity (Edmonds
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This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of South Pacific.

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595 - Effects of protein level and digestibility on the...

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