摘要
Abstract
The effects of stocking density and dietary lysine level on growth performance, carcass composition and health status of separate-sex reared broilers were investigated. Using a 2 × 2 × 3 three-factor completely randomized design, 1 314 male and 1 530 female Ross 308 chicks were divided into 12 treatments with 6 replicates (pens) per treatment, respectively. Two stocking densities were designed in this experiment: 26 (lowstocking density, 10 males/m2 or 12 females/m2) and 42 kg market weight/m2( high stocking density,16 males/m2 or 18 females/m2 ), respectively. A series of experimental diets with a 20％ difference in lysine level ( 120％, 100％, and 80％ of NRC recommendation standard) were compared in a 3-phase feeding program. The results showed as follows: high stocking density significantly decreased average daily gain (ADG)( P ＜0. 01 ), and significantly decreased feed to gain ratio ( F/G, P ＜ 0.01 ). On 1 to 35 days of age, high stocking density significantly decreased average daily feed intake ( ADFI, P ＜ 0.01 ), however, the results were the opposite on 36 to 42 days of age ( P ＜0. 01 ). Male broilers had significantly higher ADFI and ADG,and lower F/G compared with female broilers on all feeding phases (P ＜0.01 ). On 1 to 21 and 1 to 42 days of age, sex and dietary lysine level had a significant interaction on ADG ( P ＜ 0. 05 ); on 36 to 42 days of age, sex and stocking density had a significant interaction on ADG and F/G (P ＜0.05). On 1 to 21 days of age, the ADG of male broilers was more severely affected by high stocking density. In contrast, female broilers were more severely affected in ADG and F/G by high stocking density from 36 to 42 days of age. The breast muscle ratio of broilers was significantly decreased by high stocking density ( P ＜ 0. 05 ) and low lysine diet ( P ＜ 0. 01 ). Female broilers had significantly higher breast muscle ratio and abdominal fat ratio compared with male broilers ( P ＜ 0.01 ). High stocking density significantly increased the scores of gait and footpad burn, and the gait score of male broilers were significantly higher than that of female broilers ( P ＜ 0.05 ). These results suggest that lysine requirement of broilers is not altered by stocking density, and the deteriorated effects of high stocking density are sex and age dependent. [ Chinese Journal of Animal Nutrition, 2011,23 (4) :578-588]关键词
性别/饲养密度/饲粮赖氨酸水平/生长性能/胴体组成/健康状态Key words
sex/ stocking density/ dietary lysine level/ growth performance/ carcass composition/ health status分类
农业科技
