College of Animal Science, Xinjiang Agricultural University, Urumqi, China.
Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture of China, National Engineering Laboratory of Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China.
Animal. 2021 Jan;15(1):100027. doi: 10.1016/j.animal.2020.100027. Epub 2021 Jan 11.
Lactose and somatic cell score (SCS) are major economic traits of milk. However, for many countries, they are typically not directly considered in the national genetic evaluation of Simmental cattle. This study aimed to estimate the genetic relationships between lactose, SCS, and growth traits of Simmental cattle to provide information for the national genetic evaluation of the selection of traits of this cattle population. The data of 1781 animals with 6519 records obtained over a period of 41 years (1975-2016) were collected from Xinjiang Hutubi Farm, China. The analyzed traits included 305 days of milk yield (305MY), milk fat percentage (MFP), milk protein percentage (MPP), milk lactose percentage (MLP), total solids (TS), SCS, body height (BH), body length (BL), chest girth (CG), abdominal circumference (AC), rump width (RW), rump length (RL), leg circumference (LC), and cannon circumference (CC). The multiple-trait repeatability model was adopted to estimate (co)variance components using the average information-restricted maximum likelihood method implemented using the DMU statistical package. The heritability estimates for milk components and growth traits ranged from 0.09 (SCS) to 0.51 (BH). Genetic correlations for milk components ranged from 0.03 ± 0.14 (MFP and MLP) to 0.81 ± 0.08 (MFP and MPP). Genetic correlation between MLP and SCS was moderate and negative (-0.50 ± 0.15) compared with that among other traits. Genetic correlations between the milk components and growth traits ranged from 0.00 ± 0.07 (305MY and RW) to -0.64 ± 0.15 (MLP and BL). Genetic correlations of BL, LC, RW, and RL with MLP were moderate to high and negative ranging from -0.39 to -0.64. Somatic cell score showed the highest correlation with BL (0.41) followed by LC (0.21). An increase in MLP would result in an increase in 305MY or TS and a decrease in BL, LC, RW, and RL. Additionally, a decrease in SCS would occur with the selection of increased MLP and reduced BL. We conclude that selection based on easily and inexpensively measured growth traits could improve the milk quality from Simmental cattle.
乳糖和体细胞评分（SCS）是牛奶的主要经济性状。然而，对于许多国家来说，在西门塔尔牛的国家遗传评估中通常不直接考虑这些性状。本研究旨在估计西门塔尔牛的乳糖、SCS 和生长性状之间的遗传关系，为该牛群的性状选择提供国家遗传评估信息。从中国新疆呼图壁农场收集了 1781 头动物 41 年（1975-2016 年）的 6519 个记录的数据。分析的性状包括 305 天产奶量（305MY）、乳脂率（MFP）、乳蛋白率（MPP）、乳乳糖率（MLP）、总固体（TS）、SCS、体高（BH）、体长（BL）、胸围（CG）、腹围（AC）、臀宽（RW）、臀长（RL）、腿围（LC）和坐骨围（CC）。采用多性状重复力模型，利用 DMU 统计软件包中实现的平均信息限制最大似然法估计（协）方差分量。牛奶成分和生长性状的遗传力估计值范围为 0.09（SCS）至 0.51（BH）。牛奶成分之间的遗传相关范围为 0.03±0.14（MFP 和 MLP）至 0.81±0.08（MFP 和 MPP）。MLP 和 SCS 之间的遗传相关性适中且为负（-0.50±0.15），而其他性状之间的遗传相关性适中且为正。牛奶成分与生长性状之间的遗传相关性范围为 0.00±0.07（305MY 和 RW）至-0.64±0.15（MLP 和 BL）。BL、LC、RW 和 RL 与 MLP 的遗传相关性为中等至高度负相关，范围为-0.39 至-0.64。SCS 与 BL（0.41）的相关性最高，其次是 LC（0.21）。MLP 的增加会导致 305MY 或 TS 的增加和 BL、LC、RW 和 RL 的减少。此外，随着 MLP 的选择增加和 BL 的减少，SCS 会下降。我们得出的结论是，基于易于测量和经济的生长性状进行选择可以提高西门塔尔牛的牛奶质量。
