这项研究的目的是评估饲养过程中能量限制喂养对如高层育种者性成熟和生殖性能的影响。将总共2,400个8周龄的如高层饲养员随机分配到5组(每组480个小母鸡)中的一组,进行8次重复,并饲喂5种营养相似的饮食中的一种,除了从8至18周龄校正的表观代谢能(AMEn)含量(2,850、2,750、2,650、2,550和2,450kcalAMEn/kg)。每日饲料量限制为每公斤随意饲粮(对照)饲喂2,850kcalAMEn的蛋鸡消耗的绝对日粮量。从18到52岁,所有母鸡均随意饲喂基础日粮。18周龄蛋鸡体重随能量限制的增加呈线性下降(P<0.001),但在随意喂食3周内就赶上了(P=0.290)。随着饲养过程中能量限制的增加,18、21和24周龄母鸡体重的变异系数线性下降(分别为P=0.010、0.025和0.041)。能量限制喂养在18、20和22岁时延迟性器官发育,包括黄色大卵泡的数量,输卵管长度,输卵管长度指数,输卵管指数,卵巢基质指数(P<0.05),推迟性成熟,包括产卵的年龄以及产卵5%和50%的年龄(分别为P=0.042、0.004和0.029)。因此,随着能量限制程度的增加,产蛋量从5%线性下降到50%(P=0.001),能量限制饲喂组母鸡的产蛋量低于随意饲喂组母鸡(6.36、6.43、6.4和4.61%vs.14.29%;P<0.05)从18到20周龄。此外,随着能量限制的增加,蛋重线性增加(P<0.001),最严重的能量限制喂养组的蛋鸡比随意喂养和较轻的能量限制喂养组的蛋鸡更多(149.57vs.144.34、142.66、143.63和141.78;P<0.05)。在生育率方面没有观察到显著差异,可育卵的孵化率,和卵的孵化率(分别为P=0.381、0.790和0.605)。总之,中等能量限制(85.97%,2,450vs.2,850kcalAMEn/kg)从8到18周龄增加了蛋的重量,并且在整个产蛋期内,天然蛋鸡的产卵量增加了,对18至52周的生产性能没有不利影响,或52周龄时的生育能力和孵化率。
The aim of this study was to assess the effects of energy-restricted feeding during rearing on the sexual maturation and reproductive performance of Rugao layer breeders. A total of 2,400 8-wk-old Rugao layer breeders were randomly assigned to one of 5 groups (480 pullets per group) with eight replicates and were fed one of 5 diets that were nutritionally similar with the exception of apparent metabolizable energy corrected for nitrogen (AMEn) content (2,850, 2,750, 2,650, 2,550, and 2,450 kcal AMEn/kg) from 8 to 18 wks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2,850 kcal AMEn per kg diet ad libitum (control). From 18 to 52 wks of age, all hens were fed basal diets ad libitum. The body weight of layer breeders at 18 wks of age decreased linearly with increasing energy restriction (P < 0.001), but caught up within 3 wks of ad libitum feeding (P = 0.290). The coefficient of variation of the body weight of the hens at 18, 21, and 24 wks of age decreased linearly (P = 0.010, 0.025, and 0.041, respectively) with increasing energy restriction during rearing. Energy-restricted feeding delayed sexual organ development at 18, 20, and 22 wks of age, including the number of large yellow follicles, oviduct length, oviduct length index, oviduct index, and ovary stroma index (P < 0.05), and delayed sexual maturity, including the age at laying the first egg and the age at 5% and 50% egg production (P = 0.042, 0.004, and 0.029, respectively). Consequently, egg number from 5% to 50% egg production decreased linearly as the degree of energy restriction increased (P = 0.001) and egg production of hens in the energy-restricted feeding groups was lower than that of hens in the ad libitum feeding group (6.36, 6.43, 6.4, and 4.61% vs. 14.29%; P < 0.05) from 18 to 20 wks of age. Furthermore, egg weight increased linearly as energy restriction increased (P < 0.001) and laying hens in the most severe energy-restricted feeding group had more setting eggs (normal eggs weighing >40 g) than hens in the ad libitum feeding and lighter energy-restricted feeding groups (149.57 vs. 144.34, 142.66, 143.63, and 141.78; P < 0.05). No significant differences were observed in fertility, hatchability of fertile eggs, and hatchability of setting eggs (P = 0.381, 0.790, and 0.605, respectively). In conclusion, moderate energy restriction (85.97%, 2,450 vs. 2,850 kcal AMEn/kg) from 8 to 18 wks of age increased egg weight as well as the production of setting eggs in native layer breeders throughout the laying period, without adverse effects on productive performance from 18 to 52 wks of age, or fertility and hatchability at 52 wks of age.