Abstract: This study aimed to investigate the effects of dietary supplementation with different doses of compound probiotics on production performance，egg quality，reproduction􀆼related traits and organ indices in old aged laying hens. A total of 288 Jingfen laying hens aged 68 weeks with normal egg production were selected and randomly divided into 4 groups based on similar laying rates. The basal diet was supplemented with 0，200，300，and 400 mg/kg of compound probiotics，respectively. The results showed that：dietary supplementation with compound probiotics exhibited certain trends in affecting the laying rate and daily egg mass （EM）（P<0.10）. With the dietary supplementation level of probiotics increased，the laying rate demonstrated a significant linear increase（P=0.047）， while daily EM showed a tendency toward linear increase（P=0.092）. Meanwhile，the unqualified egg rate exhibited a tendency toward linear decrease（P=0.078）. Eggs from the 300 mg/kg group had the highest eggshell strength， significantly exceeding the other 3 groups（P<0.05）. With increasing dietary probiotic levels，Haugh unit displayed a significant quadratic effect characterized by an initial increase followed by a slight decrease（P=0.005）. The number of dominant follicles also showed a trend of initial increase followed by decrease （P=0.078）. Dietary probiotics significantly affected abdominal fat percentage（AF%）（P=0.037），with the lowest value observed in the 300 mg/kg group. Based on the significance（P values）and correlation coefficients（R2）of quadratic polynomial or broken-line models established for Haugh unit and AF% in response to probiotic dosage，and considering all experimental indicators comprehensively，the optimal dietary supplementation level of compound probiotics for aged laying hens was determined to be 300 mg/kg.

Key words: Probiotics, Laying hen, Laying performance, Egg quality, Reproductive traits

摘要： 该文旨在研究饲粮中添加不同剂量的复合益生菌对老年蛋鸡生产性能、蛋品质、繁 殖相关性状与组织器官指数的影响。该研究选取68周龄288只正常产蛋的京粉蛋鸡，按产蛋 率接近一致原则随机分为4组，每组蛋鸡饲粮中分别添加0、200、300、400 mg/kg复合益生菌。 研究结果表明：饲粮中添加复合益生菌对蛋鸡产蛋率和日产蛋量均有一定的影响趋势 （P<0.10），随着饲粮中益生菌添加量增加，产蛋率呈显著的线性升高（P=0.047），日产蛋量也 呈线性升高的趋势（P=0.092），不合格蛋率呈线性降低的趋势（P=0.078）。300 mg/kg组蛋鸡生 产的鸡蛋蛋壳压强最高，显著高于其它3组（P<0.05）；随着蛋鸡饲粮中复合益生菌添加剂量的 增加，鸡蛋哈氏单位呈现出先升高后略降低的显著二次效应（P=0.005），蛋鸡优势卵泡个数也 呈先升高后降低的趋势（P=0.078）。饲粮中添加不同剂量的复合益生菌对蛋鸡腹脂率有显著影 响（P=0.037），300 mg/kg复合益生菌添加组蛋鸡腹脂率最低。根据哈氏单位和腹脂率对饲粮中 添加的复合益生菌剂量反应建立的抛物线或折线模型的显著性P 值和相关性R2值结果和综合 考虑该研究中所有指标的数据结果，最终确定老龄蛋鸡饲粮中复合益生菌最佳添加剂量为 300 mg/kg。

关键词: 益生菌, 蛋鸡, 产蛋性能, 蛋品质, 繁殖性状