China Animal Husbandry and Veterinary Medicine ›› 2021, Vol. 48 ›› Issue (12): 4520-4529.doi: 10.16431/j.cnki.1671-7236.2021.12.020

• Genetics and Breeding • Previous Articles     Next Articles

Analysis of Influencing Factors and Estimation of Genetic Parameters for Lactose Percentage in Holstein Cows in Beijing

YU Houmo1, ZHU Lei1,2, ZHANG Hailiang1, CHANG Yao1, YANG Tongtong1, GUO Gang3, LIU Lin4, WANG Yachun1   

  1. 1. Key Laboratory of Animal Genetics, Breeding and Reproduction (MARA), National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China;
    2. College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China;
    3. Beijing Sunlon Livestock Development Company Limited, Beijing 100176, China;
    4. Beijing Dairy Cattle Center, Beijing 100192, China
  • Received:2021-06-24 Online:2021-12-20 Published:2021-12-02

Abstract: In order to explore the impacts of non-genetic factors on test-day lactose percentage(LP) in Holstein cows, and estimate the heritability of test-day LP and its genetic correlations with somatic cell score (SCS) and milk yield (MY), the test-day DHI records of 11 554 lactating cows from 6 herds were collected from 2017 to 2019 in Beijing.A mixed linear model was used to analyze the impacts of influencing factors affecting test-day LP, and the repeatability model were employed to estimate the genetic parameters for test-day LP, SCS and MY using the DMUAI module of DMU software.Furthermore, the genetic trend of test-day LP was also analyzed.The results showed that the average of test-day LP was 5.10% in Holstein cows in Beijing.The parity, lactation stage, herd, test year and test season had extremely significant impacts on LP (P<0.01).The heritability estimate for test-day LP was 0.097, which was higher than that of SCS, and the repeatability estimate was 0.162 in Holstein cows in Beijing.In general, an increasing trend was observed according to estimated breeding value of test-day LP from 1994 to 2019.The genetic correlations of LP with SCS (-0.49) and MY (0.28) were moderate to low, which indicated the cows with higher LP would have the higher MY and the lower somatic cell count.In this study, the results were beneficial for in-depth genetic modeling analysis for test-day LP, and the genetic foundation of test-day LP was initially revealed.

Key words: lactose percentage; somatic cell score; milk yield; dairy cows; breast health

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