Context Probiotics are attracting wide attention today as a non-antibiotic feed additive in layer feed, and the number of studies in this field is on the increase. However, the results of the effects of probiotic-yeast supplementation on egg-production indices in laying hens are contradictory. Aim Therefore, the aim of the present study was to use meta-analytical methods to ascertain whether yeast-based diets improve feed intake (FI), feed conversion ratio (FCR), hen-day egg production (HDEP), egg mass (EM), egg weight (EW), Haugh unit (HU) and eggshell thickness (EST) in laying hens. Methods A search of four electronic databases for studies on the impact of yeast supplementation on egg-production indices published in English using a combination of search terms yielded 164 studies. Sixteen research publications with 20 771 laying hens met the criteria for inclusion in the meta-analysis. Data were pooled via random-effects model and are presented as standardised mean differences (SMD) with 95% confidence intervals (CI) for each effect size. Key results HDEP and EM showed a significant increase in the SMD of 11.3% (95% CI: 0.037–0.118, P = 0.003) and 22.5 g egg/hen.day (95% CI: 0.095–0.356, P 5 g/kg feed. The results indicated that trial country was a predictor of FI, FCR, EM, HDEP and EST in layers fed yeast-based rations. Conclusion These results suggest that feeding probiotic-yeast at <5 g/kg feed improved FCR, HDEP and EM in laying hens. Implications The results of the present meta-analysis will help poultry nutritionists develop the guidelines for standardising the experimental designs of future experiments on the use of probiotic yeast to enhance the productivity of laying hens.

中文翻译：

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益生菌酵母（酿酒酵母）干预对蛋鸡采食量、饲料效率和产蛋指标影响的荟萃分析

背景益生菌作为蛋鸡饲料中的一种非抗生素饲料添加剂，在当今受到广泛关注，并且该领域的研究数量不断增加。然而，益生菌-酵母补充剂对蛋鸡产蛋指数的影响结果是矛盾的。目的 因此，本研究的目的是使用荟萃分析方法确定酵母基日粮是否能提高采食量 (FI)、饲料转化率 (FCR)、母鸡产蛋量 (HDEP)、蛋重 (EM) )、蛋重 (EW)、哈夫单位 (HU) 和蛋鸡的蛋壳厚度 (EST)。方法 使用搜索词组合搜索四个电子数据库，以研究酵母补充剂对以英文发表的产蛋指数的影响，产生了 164 项研究。包含 20 771 只蛋鸡的 16 篇研究出版物符合纳入荟萃分析的标准。数据通过随机效应模型汇总，并以每个效应大小的 95% 置信区间 (CI) 的标准化平均差 (SMD) 表示。主要结果 HDEP 和 EM 显示 SMD 显着增加 11.3%（95% CI：0.037–0.118，P = 0.003）和 22.5 克鸡蛋/母鸡天（95% CI：0.095–0.356，P 5 g/kg结果表明，试验国家是饲喂以酵母为基础的日粮的蛋鸡的 FI、FCR、EM、HDEP 和 EST 的预测因子。结论 这些结果表明，饲喂 <5 g/kg 的益生菌酵母可提高 FCR、HDEP 和蛋鸡中的 EM。