The influence of dietary crude protein concentrations,grain types and arginine:lysine ratios on the performance of broiler chickens

摘要

The objective of this study was to investigate the effects of dietary crude protein(CP)concentrations,grain types and arginine:lysine ratios on performance parameters of broiler chickens.The 2×2×2factorial array of dietary treatments harnessed two CP concentrations(210 and 170 g/kg),two feed grains(wheat and sorghum),and two arginine:lysine ratios(104 and 110).Each dietary treatment was offered to 7 replicates of 14 birds per floor pen,a total of 784 off-sex male,Ross 308 broilers,from 14 to 35 d post-hatch.The dietary CP reduction compromised weight gain by 10.0%(2078 versus 2310 g/bird)as a main effect and FCR by 7.51%(1.474 versus 1.371),subject to an interaction.In a three-way interaction(P=0.008),expanded arginine:lysine ratios improved FCR by 2.30%in 170 g/kg CP,sorghum-based diets but compromised FCR by 2.12%in corresponding wheat-based diets.Sorghum was the more suitable feed grain in reduced-CP diets as sorghum generated significant advantages in weight gain of 7.59%(2154versus 2002 g/kg)and FCR of 6.94%(1.421 versus 1.527)in birds offered 170 g/kg CP diets.Both dietary CP and feed grain generated significant and divergent impacts in apparent ileal digestibility coefficients for the majority of 16 assessed amino acids.Dietary CP reductions increased non-bound amino acid inclusions(NBAA)in wheat-based diets(48.96 versus 9.80 g/kg)to a greater extent than sorghum-based diets(35.3 versus 9.50 g/kg)and increasing dietary NBAA inclusions were linearly associated with compromised weight gain(r=-0.834;P<0.001)and FCR(r=0.862;P<0.001).Increasing ratios of free arginine to lysine plasma concentrations were linearly(r=-0.466;P=0.004)related to improvements in FCR.The implications of the observed outcomes are discussed and possible explanations are advanced.