Selection on somatic cell score to improve resistance to mastitis in the United States.
نویسندگان
چکیده
Increased genetic susceptibility to mastitis has accompanied the rapid genetic increase in milk yield, and genetic selection for mastitis resistance should be considered. Somatic cell score is recommended as an indicator trait to achieve genetic improvement for mastitis resistance. Heritability of somatic cell score is around 10%, and genetic correlation between somatic cell score and clinical mastitis is around .6 to .8. Selection for lower somatic cell score is consistent with the goal of maximizing genetic improvement for total economic merit and should be included in breeding programs. National genetic evaluations for somatic cells scores will use the same animal models and methods as are currently used for milk yield traits. Reliabilities of PTA for somatic cell scores will be smaller than for yield traits because of lower heritability and availability of records from fewer cows. Several forms are proposed for reporting genetic evaluations of somatic cells to producers, and advantages and disadvantages are discussed. Using somatic cell scores for breeding decisions would marginally decrease genetic gain for milk yield and increase total economic merit. Optimal selection indexes would slow the rate of increase in mastitis, rather than decrease its incidence.
منابع مشابه
Breeding, Selection and Somatic Cell Counts: Where Are We Today?
Genetics can help prevent mastitis and reduce somatic cell count. The purpose of this article is to inform producers, veterinarians, extension personnel, artificial breeding personnel, and genetics specialists about the methods and usefulness of genetics to improve milk quality. The USDA Animal Improvement Programs Laboratory [AIPL] has published genetic evaluations for Somatic Cell Score (SCS)...
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ورودعنوان ژورنال:
- Journal of dairy science
دوره 77 2 شماره
صفحات -
تاریخ انتشار 1994