The primary objective of this study was to investigate the influence of high and low inclusions of nonbound amino acid(NBAA)in standard and reduced-crude protein(CP),wheat-based diets on growth performance in broiler ...The primary objective of this study was to investigate the influence of high and low inclusions of nonbound amino acid(NBAA)in standard and reduced-crude protein(CP),wheat-based diets on growth performance in broiler chickens.Dietary treatments were formulated to either 210 or 180 g/kg CP.The210 g/kg CP diets contained either 12.1 or 21.1 g/kg NBAA and 180 g/kg CP diets contained either 44.0 or55.5 g/kg NBAA.The formulations also generated different dietary starch:protein ratios which impacted on starch-protein digestive dynamics.Each of the four dietary treatments were offered to 7 replicates of15 birds housed in floor pens from 14 to 35 days post-hatch or a total of 420 male Ross 308 chickens.Growth performance,relative abdominal fat-pad weights,breast muscle and leg shank yields were determined.Ileal starch and protein(N)digestibility coefficients,disappearance rates and starch:protein disappearance rate ratios were defined.Apparent ileal digestibility coefficients and disappearance rates of 16 amino acids were determined at 35 days post-hatch and free concentrations of 20 amino acids in systemic plasma were determined at 34 days post-hatch.The transition from 210 to 180 g/kg CP diets depressed weight gain by 11.3%(1742 versus 1964 g/bird)and FCR by 10.4%(1.606 versus 1.455),although both parameters were subject to treatment interactions.The treatment interaction(P<0.001)observed for FCR was because high NBAA inclusions significantly improved FCR by 4.17%(1.424 versus1.486)in birds offered 210 g/kg CP diets,but significantly depressed FCR by 3.36%(1.632 versus 1.579)in180 g/kg CP diets.A quadratic relationship(r=0.860;P<0.001)between dietary NBAA inclusions and FCR was detected,which indicated that when NBAA inclusions exceed 18.5 g/kg efficiency of feed conversion deteriorated.However,a multiple linear regression(r=0.913;P<0.001)was detected for FCR where both NBAA inclusions and analysed dietary starch:protein ratios were significantly(P<0.001)related to FCR.This relationship indicates that growth performance of broiler chickens offered wheatbased diets is strongly influenced by dietary NBAA inclusions coupled with dietary starch:protein ratios and consideration is given to the possible underlying mechanisms.展开更多
基金AgriFutures Chicken-meat for funding the project “Optimising amino acid profiles and energy in reducedprotein diets”(PRJ010520)the financial support provided by Australian Government Research Training Program Scholarship (RTP) received by PhD student Mr Shemil Macelline
文摘The primary objective of this study was to investigate the influence of high and low inclusions of nonbound amino acid(NBAA)in standard and reduced-crude protein(CP),wheat-based diets on growth performance in broiler chickens.Dietary treatments were formulated to either 210 or 180 g/kg CP.The210 g/kg CP diets contained either 12.1 or 21.1 g/kg NBAA and 180 g/kg CP diets contained either 44.0 or55.5 g/kg NBAA.The formulations also generated different dietary starch:protein ratios which impacted on starch-protein digestive dynamics.Each of the four dietary treatments were offered to 7 replicates of15 birds housed in floor pens from 14 to 35 days post-hatch or a total of 420 male Ross 308 chickens.Growth performance,relative abdominal fat-pad weights,breast muscle and leg shank yields were determined.Ileal starch and protein(N)digestibility coefficients,disappearance rates and starch:protein disappearance rate ratios were defined.Apparent ileal digestibility coefficients and disappearance rates of 16 amino acids were determined at 35 days post-hatch and free concentrations of 20 amino acids in systemic plasma were determined at 34 days post-hatch.The transition from 210 to 180 g/kg CP diets depressed weight gain by 11.3%(1742 versus 1964 g/bird)and FCR by 10.4%(1.606 versus 1.455),although both parameters were subject to treatment interactions.The treatment interaction(P<0.001)observed for FCR was because high NBAA inclusions significantly improved FCR by 4.17%(1.424 versus1.486)in birds offered 210 g/kg CP diets,but significantly depressed FCR by 3.36%(1.632 versus 1.579)in180 g/kg CP diets.A quadratic relationship(r=0.860;P<0.001)between dietary NBAA inclusions and FCR was detected,which indicated that when NBAA inclusions exceed 18.5 g/kg efficiency of feed conversion deteriorated.However,a multiple linear regression(r=0.913;P<0.001)was detected for FCR where both NBAA inclusions and analysed dietary starch:protein ratios were significantly(P<0.001)related to FCR.This relationship indicates that growth performance of broiler chickens offered wheatbased diets is strongly influenced by dietary NBAA inclusions coupled with dietary starch:protein ratios and consideration is given to the possible underlying mechanisms.
