饲粮色氨酸对43～63日龄黄羽肉鸡生长、胴体品质、体成分沉积及下丘脑5-羟色胺的影响

Effects of Dietary Tryptophan Level on Growth Performance, Carcass Traits, Whole-body Nutrient Retention and Hypothalamic Serotonin Concentration in Chinese Color-feathered Chicks Aged from 43 to 63 Days

本试验旨在研究饲粮色氨酸对43-63日龄黄羽肉鸡生产性能、胴体品质、体成分沉积以及下丘脑5-羟色胺含量等的影响,以确定43-63日龄黄羽肉鸡色氨酸需要量。选用1 600只43日龄岭南黄鸡,采用5×2两因子设计,设5个饲粮色氨酸水平(0.11%、0.14%、0.17%、0.20%和0.23%)和公母2个性别。结果表明,基础饲粮中添加色氨酸可显著改善黄羽肉公、母鸡的生产性能,提高机体蛋白质沉积和下丘脑中5-羟色胺浓度,改善公鸡的胴体品质。不同性别黄羽肉鸡的生产性能、胴体品质和体蛋白质沉积量间存在显著差异(P<0.05)。与母鸡相比,公鸡采食较多,饲料利用率和体蛋白质沉积量较高,导致其增重较快,胴体产出和腿肉产量较高。公鸡的日采食量、胸肌率和腹脂率对饲粮中色氨酸浓度变化比母鸡更敏感。根据二次回归模型估测公鸡和母鸡获得最大日增重95%处的饲粮总色氨酸含量为0.181%和0.185%(每日需要量为0.184和0.169 g/d),可消化色氨酸含量分别为0.162%和0.166%(每日需要量为0.165和0.152 g/d),色氨酸与赖氨酸比例分别为20.1:100和20.6:100。公、母鸡获得最大体蛋白质沉积的饲粮中总色氨酸和可消化色氨酸含量为0.17%和0.15%。

The trial was conducted to study effects of dietary tryptophan （Trp） level on growth performance, carcass traits, whole-body nutrient retention and hypothalamic serotonin concentration in order to determine Trp requirements of Chinese color-feathered chicks aged from 43 to 63 days. One thousand and six hundred Chinese color-feathered chicks at 43 days of age were used. Five dietary treatments were compared in a 5 × 2 factorial design with five dietary Trp levels （0.11%, 0.14%, 0.17%, 0.20% and 0.23%） and two genders. The results indicated that supplementation of synthetic Trp increased growth performance, whole-body protein retention and hypothalamic serotonin concentration in both female and male chicks, and improved carcass traits of male chicks. There were significant differences in growth performance, carcass traits and whole-body protein retention between female and male chicks （P〈O. 05）. Feed intake, feed utilization and whole-body protein retention of male chicks were higher than those of female chicks, resulting in that male chicks grew faster and yielded more meat than female chicks Daily feed intake, breast muscle peeentage and abdominal fat percentage in response to dietary Trp concentrations is more sensitive for male chicks than for female chicks. Dietary total Trp concentration, digestible Trp concentration and total Trp/Lys ratio to gain 95% of the maximum ADG were 0. 181%,0. 162% and 20.1 ： 100 for male chicks, and 0. 185%, 0. 166% and 20.6 ： 100 for female chicks, respectively. Daily requirements of total Trp and digestible Trp to gain maximum ADG were 0. 184 and 0. 165 g/d for male chicks, and 0. 169 and 0. 152 g/d for female chicks. Dietary total Trp and digestible Trp concentration for both male and female chicks to gain maximum retention rate of body protein were 0.17 % and 0.15 %.