Research Institute for Farm Animal Biology, Institute of Genome Biology, 18196 Dummerstorf, Germany.
Research Institute for Farm Animal Biology, Institute of Genome Biology, 18196 Dummerstorf, Germany; Desert Research Center, Department of Animal and Poultry Breeding, Dokki, Giza Governorate 3751254, Egypt.
J Dairy Sci. 2023 Jul;106(7):4682-4697. doi: 10.3168/jds.2022-22935. Epub 2023 May 10.
Increasing the nitrogen-utilization efficiency (NUE) of dairy cows by breeding selection would offer advantages from nutritional, environmental, and economic perspectives. Because data collection of NUE phenotypes is not feasible in large cow cohorts, the cow individual milk urea concentration (MU) has been suggested as an indicator trait. Considering the symbiotic interplay between dairy cows and their rumen microbiome, individual MU was thought to be influenced by host genetics and by the rumen microbiome, the latter in turn being partly attributed to host genetics. To enhance our knowledge of MU as an indicator trait for NUE, we aimed to identify differential abundant rumen microbial genera between Holstein cows with divergent genomic breeding values for MU (GBVMU; GBV vs. GBV, where H and L indicate high and low MU phenotypes, respectively). The microbial genera identified were further investigated for their correlations with MU and 7 additional NUE-associated traits in urine, milk, and feces in 358 lactating Holsteins. Statistical analysis of microbial 16S rRNA amplicon sequencing data revealed significantly higher abundances of the ureolytic genus Succinivibrionaceae UCG-002 in GBV cows, whereas GBV animals hosted higher abundances of Clostridia unclassified and Desulfovibrio. The entire discriminating ruminal signature of 24 microbial taxa included a further 3 genera of the Lachnospiraceae family that revealed significant correlations to MU values and were therefore proposed as considerable players in the GBVMU-microbiome-MU axis. The significant correlations of Prevotellaceae UCG-003, Anaerovibrio, Blautia, and Butyrivibrio abundances with MU measurements, milk nitrogen, and N content in feces suggested their contribution to genetically determined N-utilization in Holstein cows. The microbial genera identified might be considered for future breeding programs to enhance NUE in dairy herds.
通过选育来提高奶牛的氮利用效率（NUE），从营养、环境和经济角度来看都具有优势。由于在大型牛群中收集 NUE 表型数据不可行，因此人们提出了奶牛个体奶尿素浓度（MU）作为指示性状。考虑到奶牛与其瘤胃微生物组之间的共生相互作用，个体 MU 被认为受宿主遗传和瘤胃微生物组的影响，而后者部分归因于宿主遗传。为了提高我们对 MU 作为 NUE 指示性状的认识，我们旨在确定 MU 基因组育种值（GBV）差异较大的荷斯坦奶牛的瘤胃微生物分类群（GBV 与 GBV，其中 H 和 L 分别表示高和低 MU 表型）。进一步研究了这些微生物分类群与 MU 以及尿液、牛奶和粪便中另外 7 个与 NUE 相关的性状的相关性，共检测了 358 头泌乳荷斯坦奶牛。对瘤胃 16S rRNA 扩增子测序数据的统计分析显示，在 GBV 奶牛中，产脲微生物属 Succinivibrionaceae UCG-002 的丰度明显更高，而 GBV 动物中 Clostridia unclassified 和 Desulfovibrio 的丰度更高。24 种微生物分类群的整个鉴别性瘤胃特征包括厚壁菌门的另外 3 个属，它们与 MU 值呈显著相关，因此被提议为 GBVMU-微生物组-MU 轴中的重要参与者。Prevotellaceae UCG-003、Anaerovibrio、Blautia 和 Butyrivibrio 丰度与 MU 测量值、牛奶氮和粪便中 N 含量的显著相关性表明它们对荷斯坦奶牛的遗传决定的氮利用有贡献。所确定的微生物分类群可以考虑用于未来的繁殖计划，以提高奶牛群的 NUE。
