The objective of this study was to determine the effect of age at photostimulation on sexual maturity and performance of layer breeders. A total of 192 fourteen-wk-old White Leghorn (WL) breeder hens were randomly allocated to 4 treatments of 48 birds each, with 2 replicates per treatment. The birds were photostimulated at 16 (PS16), 18 (PS18), 20 (PS20), and 22 (PS22) wk of age. Four birds per treatment were randomly selected to evaluate sexual organ development at 1 D before photostimulation and 2, 4, and 6 wk after photostimulation. The ovary weight, large yellow follicles number (LYF), oviduct weight, and oviduct length of PS18 increased sharply after photostimulation. Conversely, the increase in PS16 was not observed until 2 wk after photostimulation. There was no difference in age at sexual maturity between treatments (P > 0.05). The PS16 had the longest interval (28 D) from photostimulation to 5% egg production, while PS22 reached 5% egg production 7 D before photostimulation. The PS22 had lower peak production (P = 0.02) and less egg production (P = 0.02) than other treatments. The PS16 had more broken and abnormal eggs (P = 0.01) and lower hatchability (P = 0.04) than other treatments. In conclusion, photostimulation at 16 and 22 wk of age decreases hatchability and egg production, respectively, and photostimulation at 18 wk is appreciated for the WL breeder hens.

中文翻译：

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光刺激时的年龄对蛋鸡繁殖力和蛋生性能的影响。

这项研究的目的是确定光刺激时的年龄对蛋鸡育种者性成熟和性能的影响。总共192只十四周龄的白色来格霍恩（WL）育种母鸡被随机分配到4种处理方法中，每只处理48只鸟，每处理重复2次。在16周（PS16），18周（PS18），20周（PS20）和22周（PS22）的周龄对鸟类进行光刺激。每种治疗随机选择四只鸟，以评估光刺激前1天和光刺激后2、4和6周的性器官发育。光刺激后，PS18的卵巢重量，大黄色卵泡数（LYF），输卵管重量和输卵管长度急剧增加。相反，直到光刺激后2周才观察到PS16的增加。两次治疗之间的性成熟年龄无差异（P> 0.05）。PS16从光刺激到产卵5％的间隔最长（28 D），而PS22在光刺激前7 D达到产卵的5％。PS22的峰值产量较低（P = 0.02），鸡蛋产量较低（P = 0.02）。与其他处理相比，PS16的破损卵和异常卵更多（P = 0.01），孵化率较低（P = 0.04）。总之，在16周龄和22周龄时进行光刺激会降低孵化率和产蛋量，而WL种鸡在18周龄时会受到光刺激。01），且孵化率低于其他处理（P = 0.04）。总之，在16周龄和22周龄时进行光刺激会分别降低孵化率和产蛋量，而对于WL种鸡来说，在18周龄时进行光刺激是值得赞赏的。01），且孵化率低于其他处理（P = 0.04）。总之，在16周龄和22周龄时进行光刺激会分别降低孵化率和产蛋量，而对于WL种鸡来说，在18周龄时进行光刺激是值得赞赏的。