饲养密度和高蛋白质饲粮代谢能水平对公母分饲肉鸡生长性能和腿部健康的影响

Effects of Stocking Density,Sex and Dietary Metabolizable Energy Level in a High-Protein Diet on Growth Performance and Leg Health of Broiler Chickens

本试验旨在研究饲养密度与高蛋白质(前期23%,后期21%)饲粮代谢能水平对公母分饲肉鸡生长性能和腿部健康的影响。试验采用2(性别)×2(饲养密度)×3(饲粮代谢能水平)三因子完全随机设计,选用1日龄罗斯308(Ross 308)肉鸡公雏1 872只和母雏2 160只,随机分成12个组,每组8个重复。试验设高、低2个饲养密度,以出栏体重计,分别为42[高饲养密度(HSD),16公/m2或18母/m2]和26 kg/m2[低饲养密度(LSD),10公/m2或12母/m2]。试验饲粮分前期(1~21日龄)和后期(22~35日龄)2个阶段配制,饲粮代谢能设高、中、低3个水平,其中,高代谢能(HME)水平饲粮前期和后期的代谢能水平分别为12.81和13.23 MJ/kg,中代谢能(MME)水平饲粮前期和后期的代谢能水平分别为12.18和12.60 MJ/kg,低代谢能(HME)水平饲粮前期和后期的代谢能水平分别为11.55和11.97 MJ/kg。结果表明:1)饲养密度与饲粮代谢能水平对肉鸡的平均日增重和料重比有显著交互作用(P<0.05)。1~21日龄时,随着饲粮代谢能水平增加,HSD组平均日增重的增加幅度和料重比的降低幅度均小于LSD组;22~35日龄时结果正好相反。性别与饲养密度对肉鸡的平均日采食量有显著交互作用(P<0.05)。随着饲养密度增加,公鸡平均日采食量的降低幅度大于母鸡。2)HSD极显著降低肉鸡的胸肌率(P<0.01),母鸡的胸肌率和腹脂率显著高于公鸡(P<0.05)。饲粮代谢能水平和饲养密度对肉鸡的腿肌率有显著交互作用(P<0.05)。随着饲粮代谢能水平增加,LSD组肉鸡的腿肌率降低,而HSD组基本不变。3)高饲粮代谢能水平极显著降低肉鸡的脚垫损伤评分(P<0.01),公鸡的步态评分和脚垫损伤评分显著高于母鸡(P<0.05),垫料水分含量显著低于母鸡(P<0.05)。饲粮代谢能水平与饲养密度对肉鸡的脚垫损伤评分有显著交互作用(P<0.05)。随着饲粮代谢能水平增加,HSD组脚垫损伤评分的降低幅度大于LSD组。以上结果表明,高饲养密度降低肉鸡的平均日增重,增加料重比;35日龄前,公鸡比母鸡的空间需求更高;提高高蛋白质饲粮的代谢能水平可以缓解HSD对肉鸡生长性能和脚垫健康的不利影响。

This study w as conducted to investigate the effects of stocking density,sex and dietary metabolizable energy( M E) level in a high-protein( 23% in early phase and 21% in later phase) diet on grow th performance and leg health of broiler chickens. According a 2( sex) × 2( stocking density) × 3( dietary M E level)three-factor completely randomized design,1 872 male and 2 160 female 1-day-old Ross 308 broiler chickens w ere allotted into 12 groups w ith 8 replicates per group. Tw o stocking densities w ere designed in this experiment: 42 [high stocking densities( HSD),16 males/m2 or 18 females/m2]and 26 kg market weight/m2[low stocking densities( LSD),10 males/m2 or 12 females/m2],respectively. The experiment contained early phase( 1 to 21 days of age) and later phase( 22 to 35 days of age),and dietary M E levels divided into high,middle and low levels. The M E levels of high M E( HM E) level diet w ere 12.81 and 13.23 M J/kg,the M E levels of middle M E( M M E) level diet w ere 12.18 and 12.60 M J/kg,and the M E levels of low M E( LM E) level diet w ere 11.55 and 11.97 M J/kg in early phase and later phase,respectively. The results show ed as follow s: 1) stocking density and dietary M E level had significant interactions on average daily gain( ADG) and the ratio of feed to gain( F/G)of broiler chickens( P<0.05). Increase range of ADG and decrease range of F/G from 1 to 21 days of age in HSD group w ere low er than those in LSD group w ith the increase of dietary M E level,how ever,the results w ere the opposite from 22 to 35 days of age. Sex and stocking density had significant interaction on average daily feed intake( ADFI) of broiler chickens( P<0.05). Decrease range of ADFI of male broilers was higher than that of female broilers w ith the increase of stocking density. 2) HSD significantly decreased breast muscle yield of broiler chickens( P<0.01),and breast muscle yield and abdominal fat percentage of female broilers w ere significantly higher than those of male broilers( P<0.05). Stocking density and dietary M E level had significant interactions on thigh muscle yield of broiler chickens( P<0.05). Thigh muscle yield of broiler chickens in LSD group w as decreased,but there w as no change in HSD group w ith the increase of dietary M E level. 3) Dietary HM E level significantly decreased footpad burn score of broiler chickens( P<0.01),gait score and footpad burn score of male broilers w ere significantly higher than thaose of female broilers( P<0.05),and litter moisture content of male broilers w as significantly low er than that of female broilers( P<0.05). Stocking density and dietary M E level had significant interaction on footpad burn score of broiler chickens( P <0.05). Decrease range of footpad burn score in HSD group w as higher than that of LSD group. In conclusion,HSD decreases ADG and increases F/G of broiler chickens,male broilers need more space than the female before 35 days of age,increasing M E level in the high-protein diet can alleviate the negative effects of HSD on grow th performance and footpad health.[Chinese Journal of Animal Nutrition,2017,29( 10) : 3530-3540]