This experiment was conducted to study the effects of dietary alfalfa polysaccharides (APS) on performance and egg quality of laying hens under high temperature environment in summer.Five hundred and forty 156-day-old Hy-Line Brown laying hens were randomly allocated to 6 groups with 6 replicates per group and 15 hens per replicate.Hens in control group were fed a basal diet, and those in experimental groups were fed the basal diet supplemented with 250, 500, 1 000, 2 000 and 4 000 mg/kg APS, respectively.The experiment lasted for 6 weeks.The results showed as follows: compared with the control group, 1) diet supplemented with different levels of APS had no significant effects on average egg weight, average daily feed intake, unqualified egg rate and mortality rate (P>0.05).However, diet supplemented with 500, 1 000 and 4 000 mg/kg APS significantly increased egg production (P<0.05), and diet supplemented with 500, 1 000, 2 000 and 4 000 mg/kg APS significantly decreased feed to egg ratio (P<0.05).2) Diet supplemented with different levels of APS had no significant effects on albumen height and Haugh unit (P>0.05).Diet supplemented with 250 mg/kg APS significantly increased yolk color at the end of week 4 and week 6 (P<0.05).Diet supplemented with 500 mg/kg APS significantly decreased egg shape index at the end of week 6 (P<0.05), meanwhile significantly increased yolk color at the end of week 1, week 4 and week 6 (P<0.05).Diet supplemented with 1 000 mg/kg APS significantly improved eggshell color at the end of week 4 and week 6 (P<0.05), significantly increased eggshell strength and thickness at the end of week 1, week 2 and week 4 (P<0.05), significantly decreased egg shape index at the end of week 1 and week 6 (P<0.05), and significantly increased yolk color at the end of week 1, week 2, week 4 and week 6 (P<0.05).Diet supplemented with 2 000 mg/kg APS significantly increased eggshell thickness at the end of week 1 and week 4 (P<0.05), significantly decreased egg shape index at the end of week 6 (P<0.05), and significantly increased yolk color at the end of week 1, week 4 and week 6 (P<0.05).Diet supplemented with 4 000 mg/kg APS significantly improved eggshell color and eggshell strength at the end of week 4 (P<0.05), significantly increased eggshell thickness at the end of week 1 and week 4 (P<0.05), significantly decreased egg shape index at the end of week 6 (P<0.05), and significantly increased yolk color at the end of week 1, week 4 and week 6 (P<0.05).The results indicate that moderate APS supplementation can effectively alleviate heat stress of laying hens and improve performance as well as egg quality of laying hens under high temperature environment in summer, and the optimum supplemental level is 1 000 mg/kg.%本试验旨在研究夏季高温环境下在饲粮中添加苜蓿多糖对蛋鸡生产性能及蛋品质的影响.将540只156日龄海兰褐蛋鸡随机分成6组,每组6个重复,每个重复15只鸡.对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加250、500、1 000、2 000和4 000 mg/kg苜蓿多糖的试验饲粮.试验期为6周.结果显示:与对照组相比,1)饲粮中添加不同水平苜蓿多糖对平均蛋重、平均日采食量、不合格蛋率和死淘率均无显著影响(P>0.05),而添加500、1 000和4 000 mg/kg苜蓿多糖显著提高了蛋鸡的产蛋率(P<0.05),添加500、1 000、2 000和4 000 mg/kg苜蓿多糖显著降低了料蛋比(P<0.05).2)饲粮中添加不同水平苜蓿多糖对蛋白高度和哈夫单位均无显著影响(P>0.05);250 mg/kg苜蓿多糖添加组第4和6周末的蛋黄颜色显著提高(P<0.05);500 mg/kg苜蓿多糖添加组第6周末的蛋形指数显著降低(P<0.05),第1、4和6周末的蛋黄颜色显著提高(P<0.05);1 000 mg/kg苜蓿多糖添加组第4和6周末的蛋壳颜色显著加深(P<0.05),第1、2和4周末的蛋壳强度和蛋壳厚度显著提高(P<0.05),第1和6周末的蛋形指数显著降低(P<0.05),第1、2、4和6周末的蛋黄颜色显著提高(P<0.05);2 000 mg/kg苜蓿多糖添加组第1和4周末的蛋壳厚度显著提高(P<0.05),第6周末的蛋形指数显著降低(P<0.05),第1、4和6周末的蛋黄颜色显著提高(P<0.05);4 000 mg/kg苜蓿多糖添加组第4周末的蛋壳颜色显著加深(P<0.05)且蛋壳强度显著提高(P<0.05),第1和4周末的蛋壳厚度显著提高(P<0.05),第6周末的蛋形指数显著降低(P<0.05),第1、4和6周末的蛋黄颜色显著提高(P<0.05).结果表明,夏季高温环境下,在饲粮中添加适量的苜蓿多糖可以有效缓解蛋鸡的热应激,提高蛋鸡的生产性能,改善蛋品质,且适宜添加量为1 000 mg/kg.
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