Research Center for Animal Science, Graduate School of Integrated Science for Life, Hiroshima University, Hiroshima, Japan.
Fukuoka Prefecture Dairy Cooperative Association, Fukuoka, Japan.
J Vet Med Sci. 2024 Nov 15;86(11):1198-1204. doi: 10.1292/jvms.24-0292. Epub 2024 Sep 27.
To identify new criteria for selecting recipient dairy cows for embryo transfer (ET), we retrospectively examined the effects of the composition of early lactation milk on fertility risk in ET. This study investigated the association between milk fat (FAT), milk protein (PRO), and milk urea nitrogen (MUN) levels during early lactation, based on production records, and subsequent fertility risk in ET using contingency table analysis and multivariable logistic regression analysis, which included five confounding variables. The results showed that MUN levels during early lactation were negatively associated with fertility risk in ET, while FAT and PRO levels showed no clear association. A reduction in MUN levels during the peak lactation period suggests a deficiency in dry matter intake, an inadequate protein supply, and an imbalance in the ratio of proteins to fermentable carbohydrates in the rumen, which may have adversely impacted fertility risk in ET. Monitoring MUN levels is crucial for maintaining a proper protein balance. The results obtained in this study suggest that MUN levels in the early lactation phase obtained from production records can be used as a predictor of fertility in recipients to improve the fertility risk in ET. No special techniques or costs are required for using production records, making them easy to use in clinical practice. Our findings provide valuable insights for optimizing cost-effectiveness and fertility risk in ET and their clinical applications.
为了确定选择接受胚胎移植（ET）的受体奶牛的新标准，我们回顾性地研究了早期泌乳牛奶成分对 ET 中生育风险的影响。本研究根据生产记录，调查了早期泌乳期间牛奶脂肪（FAT）、牛奶蛋白（PRO）和牛奶尿素氮（MUN）水平与 ET 中随后的生育风险之间的关系，使用列联表分析和多变量逻辑回归分析，包括五个混杂变量。结果表明，早期泌乳期间的 MUN 水平与 ET 中的生育风险呈负相关，而 FAT 和 PRO 水平则没有明显的关联。泌乳高峰期 MUN 水平降低表明干物质摄入不足、蛋白质供应不足以及瘤胃中蛋白质与可发酵碳水化合物的比例失衡，这可能对 ET 中的生育风险产生不利影响。监测 MUN 水平对于维持适当的蛋白质平衡至关重要。本研究结果表明，从生产记录中获得的早期泌乳阶段的 MUN 水平可以用作受体生育能力的预测指标，以提高 ET 中的生育风险。使用生产记录不需要特殊技术或成本，使其易于在临床实践中应用。我们的研究结果为优化 ET 中的成本效益和生育风险及其临床应用提供了有价值的见解。
