本试验旨在研究饲喂水平与光照周期对育成蛋鸡生长、营养物质消化率及肝脏瘦素受体(Ob-R)基因表达的影响。试验采用2×2双因子试验设计,即2个光照周期(8L:16D,12L:12D)和2个饲喂水平[自由采食,限饲(自由采食量的80%)],共计4个处理。选用健康的10周龄海兰灰育成蛋鸡320只,随机分成4组,每组4个重复,每个重复20只鸡。试验期为10~18周龄,分别在14和18周龄测定体重、腹脂重,并采集血液和肝脏样本进行相关指标分析。结果表明:自由采食组14周龄体重和18周龄腹脂重均显著高于限饲组(P<0.05)。短光照周期(8L:16D)组的干物质消化率极显著高于长光照周期(12L:12D)组(P<0.01),而限饲组的粗脂肪消化率则显著高于自由采食组(P<0.05)。短光照周期组的14和18周龄肝脏Ob-R基因的相对表达量显著或极显著低于长光照周期组(P<0.05或P<0.01),而限饲组的14周龄肝脏Ob-R基因的相对表达量则显著低于自由采食组(P<0.05)。饲喂水平与光照周期的互作对育成蛋鸡的14和18周龄体重、腹脂重、血清葡萄糖和甘油三酯含量、肝脏Ob-R基因的相对表达量的影响均不显著(P>0.05),对育成蛋鸡营养物质消化率的影响也不显著(P>0.05)。由结果可知,限饲可降低育成蛋鸡的18周龄腹脂重、14周龄肝脏Ob-R基因的相对表达量,提高粗脂肪消化率;短光照周期(8L:16D)可降低育成蛋鸡14和18周龄肝脏Ob-R基因的相对表达量,提高干物质消化率;饲喂水平与光照周期对本试验所测指标均不存在互作效应。

This experiment was conducted to study the effects of feeding level and photoperiod on growth, nutrient digestibility and liver leptin receptor (Ob-R) gene expression of growing layers. A 2×2 two-factor experiment was used in this experiment, the one factor was photoperiod (8L:16D and 12L:12D), and the other factor was feeding level[ad libitum feeding and limited feeding (80% of ad libitum feeding)]. A total of 320 10-week-old healthy Hy-Line Grey growing layers were selected and randomly allotted to 4 groups with 4 replicates in each group and 20 hens in each replicate. The experiment was carried from 10 to 18 weeks of age; the body weight, and abdominal fat weight were measured, and the blood and liver samples were collected to analyze relative indices at 14 and 18 weeks of age. The results showed as follows: the body weight at 14 weeks of age and abdominal fat weight at 18 weeks of age in ad libitum feeding group were significantly higher than those in limited feeding group (P<0.05). The dry matter digestibility in short photoperiod (8L:16D) group was significantly higher than that in long photoperiod (12L:12D) group (P<0.01), and the ether extract digestibility in limited feeding group was significantly higher than that in ad libitum feeding group (P<0.05). The liver Ob-R gene relative expression level at 14 and 18 weeks of age in short photoperiod group was significantly lower than that in long photoperiod group (P<0.05 or P<0.01), and the liver Ob-R gene relative expression level at 14 weeks of age in limited feeding group was significantly lower than that in ad libitum feeding group (P<0.05). The feeding level and photoperiod had no significant interaction effects on body weight, abdominal fat weight, serum glucose and triglyceride contents, and liver Ob-R gene relative expression level of growing layers at 14 and 18 weeks of age (P>0.05), and also had no significant interaction effect on nutrient digestibility of growing layers (P>0.05). The results indicate that limited feeding can decrease the abdominal fat weight at 18 weeks of age and liver Ob-R gene relative expression level at 14 weeks of age, and improve the ether extract digestibility of growing layers; short photoperiod (8L:16D) can decrease the liver Ob-R gene relative expression level at 14 and 18 weeks of age, and improve the dry matter digestibility of growing layers; there are no interaction effects on all measured indices of this experiment between feeding level and photoperiod.