College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
Department of Animal Sciences, The Ohio State University, Columbus 43210.
J Dairy Sci. 2022 Sep;105(9):7386-7398. doi: 10.3168/jds.2021-21519. Epub 2022 Jul 22.
Saccharomyces cerevisiae products (SCP) have the potential to promote the growth and development of the gastrointestinal tract and immunity in young livestock animals. However, the effects of SCP supplementation on calves are inconsistent among the reported studies in the literature. Hence, we performed a meta-analysis to comprehensively assess the effects of SCP on the growth performance, ruminal fermentation parameters, nutrients digestibility, ruminal histological morphology, serum immune response, and fecal pathogen colony counts in calves. We searched the Web of Science, ScienceDirect, PubMed, and China National Knowledge Infrastructure for relevant studies published up to October 1, 2021. After screening against a set of criteria, the data of 36 studies were included in our meta-analysis (2,126 calves in total). We evaluated the quality of the data using sensitivity analysis and assessed publication bias. Our meta-analysis revealed several important findings. First, SCP supplementation increased the ruminal short-chain fatty acid concentration, ruminal papilla height, and fiber digestibility, pointing toward stimulation of the development of the rumen in calves. Second, SCP supplementation increased the serum concentrations of total protein, IgA, and IgG but decreased fecal pathogen colony counts, suggesting that SCP could help calves to promote immunity (especially maintaining circulating concentrations of immunoglobulins in preweaning calves) and resistance to pathogens. Third, a subgroup analysis between preweaning and postweaning calves showed that SCP increased average daily gain and dry matter intake preweaning but not postweaning, suggesting that SCP is better supplemented to preweaning calves to achieve the best results. Forth, based on the dose-response curve, 24 to 25 g/d might be the optimal dose range of SCP supplementation (into starter feed) preweaning to achieve the best overall effect, meanwhile, we need more studies to improve the consistency and accuracy of the dose-response curve prediction. Overall, SCP supplementation improved growth performance, rumen development, and immunocompetence in calves, particularly in preweaning calves.
酿酒酵母产品（SCP）有可能促进幼畜的胃肠道生长发育和免疫力。然而，在文献中报道的研究中，SCP 补充对犊牛的影响并不一致。因此，我们进行了一项荟萃分析，以全面评估 SCP 对犊牛生长性能、瘤胃发酵参数、养分消化率、瘤胃组织形态学、血清免疫反应和粪便病原菌菌落计数的影响。我们在 Web of Science、ScienceDirect、PubMed 和中国知网中搜索了截至 2021 年 10 月 1 日已发表的相关研究。经过一系列标准筛选后，36 项研究的数据被纳入我们的荟萃分析（共有 2126 头犊牛）。我们使用敏感性分析评估了数据质量，并评估了发表偏倚。我们的荟萃分析揭示了一些重要的发现。首先，SCP 补充增加了瘤胃短链脂肪酸浓度、瘤胃乳头高度和纤维消化率，表明 SCP 刺激了犊牛瘤胃的发育。其次，SCP 补充增加了血清总蛋白、IgA 和 IgG 浓度，但降低了粪便病原菌菌落计数，表明 SCP 可以帮助犊牛促进免疫力（特别是在断奶前保持循环中的免疫球蛋白浓度）和抵抗病原体。第三，在断奶前和断奶后犊牛的亚组分析中，SCP 增加了断奶前的平均日增重和干物质采食量，但不增加断奶后的日增重，表明 SCP 最好在断奶前补充以达到最佳效果。第四，基于剂量-反应曲线，24 至 25 克/天可能是 SCP 补充（进入开食料）的最佳剂量范围，以获得最佳的整体效果，同时，我们需要更多的研究来提高剂量-反应曲线预测的一致性和准确性。总体而言，SCP 补充提高了犊牛的生长性能、瘤胃发育和免疫能力，尤其是在断奶前犊牛。
