Magro S, Costa A, Cesarani A, Degano L, De Marchi M
Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padova, 35020 Legnaro, Italy.
Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano dell'Emilia, Italy.
J Dairy Sci. 2025 Feb;108(2):1778-1789. doi: 10.3168/jds.2024-25487. Epub 2024 Nov 8.
The Simmental breed is widely known for its resilience, robustness, and resistance to disease, and the incidence of ketosis in this breed is therefore generally lower compared with Holsteins. Blood concentrations of nonesterified fatty acids (NEFA), BHB, and urea provide valuable information about the metabolic, health, and nutritional status of lactating animals. In the present study, we estimated h of BHB, NEFA, and urea in blood predicted from milk mid-infrared spectra and assessed their genetic correlation with milk yield and composition traits in the Italian Simmental cattle breed using phenotypes of 3,549 cows in 207 herds. Two sets were considered: early (1,920 records, 1 per cow, between 5 and 35 DIM) and whole (14,378 records, at least 3 per cow, between 5 and 305 DIM) lactation. In early lactation, h estimates were 0.06 for blood BHB as-is, 0.06 for log-transformed BHB, 0.18 for NEFA, 0.14 for log-transformed NEFA, and 0.05 for blood urea. In the whole lactation, the h were 0.09 for blood BHB as-is, 0.16 for log-transformed BHB, 0.03 for NEFA, 0.04 for log-transformed NEFA, and 0.04 for blood urea. As far as the genetic correlations were concerned, blood BHB was positively correlated with NEFA and blood urea. Blood BHB and NEFA were generally positively correlated with milk fat-to-protein ratio and milk, but only the first was negatively correlated with lactose content and positively with SCS. Sires' EBVs for BHB with accuracy ≥0.60 were extrapolated for a posteriori evaluation of the daughters' observed performance. The progeny of the top 5% of sires exhibited, on average, lower blood BHB, NEFA, and urea compared with the daughters of the bottom 5%. Overall, it is highly recommended to monitor the genetic variability of the metabolic traits in the dual-purpose Italian Simmental breed to monitor the incidence of metabolic diseases in future generations.
西门塔尔牛品种以其适应力强、体格健壮和抗病能力而广为人知，因此该品种酮病的发病率通常低于荷斯坦奶牛。血液中非酯化脂肪酸（NEFA）、β-羟丁酸（BHB）和尿素的浓度为泌乳动物的代谢、健康和营养状况提供了有价值的信息。在本研究中，我们根据牛奶中红外光谱预测了血液中BHB、NEFA和尿素的h，并利用207个牛群中3549头奶牛的表型评估了它们与意大利西门塔尔牛品种的产奶量和乳成分性状的遗传相关性。考虑了两组数据：早期泌乳期（1920条记录，每头奶牛1条，泌乳天数在5至35天之间）和整个泌乳期（14378条记录，每头奶牛至少3条，泌乳天数在5至305天之间）。在早期泌乳期，血液中BHB原样的h估计值为0.06，对数转换后的BHB为0.06，NEFA为0.18，对数转换后的NEFA为0.14，血液尿素为0.05。在整个泌乳期，血液中BHB原样的h为0.09，对数转换后的BHB为0.16，NEFA为0.03，对数转换后的NEFA为0.04，血液尿素为0.04。就遗传相关性而言，血液中BHB与NEFA和血液尿素呈正相关。血液中BHB和NEFA通常与乳脂蛋白比和乳产量呈正相关，但只有前者与乳糖含量呈负相关，与体细胞评分呈正相关。对准确性≥0.60的BHB的种公牛估计育种值（EBV）进行外推，以便对女儿的观察性能进行事后评估。与排名后5%的种公牛的女儿相比，排名前5%的种公牛的后代平均血液中BHB、NEFA和尿素含量较低。总体而言，强烈建议监测意大利兼用西门塔尔牛品种代谢性状的遗传变异性，以监测后代代谢疾病的发病率。
