摘要
Abstract
Two experiments are conducted to investigate the effects of low crude protein (CP) amino acid-supplemented diets
on growth performance,nitrogen (N) excretion and carcass quality of broilers.In experiment 1,six hundred (half males
and half females) one-day-old Arbor Acre broilers were raised during d 1 to 21,d 22 to 42 and d 43 to 49.Five diets contai-
ning different protein levels were used during each of the three periods including the starter period (22.8%,21.9%,
21.0%,19.5% and 19.0％ CP,d 1 to 21),grower period (20.1%,18.8%,17.8%,16.5% and 16.0% CP,d 22 to 42)
and finisher period (18.0%,16.9%,15.9％,15.0% and 13.8% CP,d 43 to 49).All diets were formulated to meet the to-
tal amino acid requirements for methionine,lysine and threonine.In experiment 2,five diets approximately containing the
CP level as those used in the starter and grower periods in experiment 1 were supplemented with sufficient crystalline amino
acids to meet the digestible amino acid requirements for all essential amino acids (EAA).The results showed as follows:re-
ducing dietary CP level had no significant effect on growth performance during each period in experiment 1 (P>0.05).In
experiment 2,weight gain and feed conversion ratio were both decreased in starter period (P<0.01) but not in the grower
period and the entire period (P>0.05).There were no significant differences in carcass quality among all treatments in
both experiments (P>0.05),except that a linear increase in fat deposition occurred as dietary CP was reduced in experi-
ment 1 (P<0.05).Reducing dietary CP level decreased linearly N excretion (P<0.01),and decreased plasma glycine and
phenylalanine concentrations in experiment 2 (P<0.05).In conclusion,birds fed low protein diets supplemented with ami-
no acids can produce similar growth and carcass quality to those fed high protein diets in the present study.
The present study.关键词
肉仔鸡/低蛋白质/生长性能/胴体品质/氮排泄Key words
broiler/low protein/growth performance/carcass quality/nitrogen excretion分类
农业科技
