Inbreeding of artificially bred dairy cattle in the northeastern United States.
نویسندگان
چکیده
Inbreeding coefficients of artificially bred Ayrshire, Guernsey, Holstein, Jersey, and Brown Swiss cows were calculated from relationships between sires and maternal male ancestors. Percentages of inbred cows and average inbreeding coefficients of inbred cows were: Ayrshire, 26 and 11%; Guernsey, 11 and 4%; Holstein, 31 and 1%; Jersey 23 and 2%; and Brown Swiss, 23 and 2%. Percentages of inbred cows and average inbreeding coefficients of all cows increased over time whereas average coefficients of inbred cows decreased over time. These temporal trends may be due in part to having more pedigree information available for cows born in later years. Effects of inbreeding on milk and fat yields of first lactation (2 times milked, 305-day mature equivalent), 48-mo stayability, and first calving interval were estimated with a model including effects for fixed herd-year-seasons, fixed sire and maternal grandsire groups, random sires and maternal grandsires within groups, and random residual. Regression coefficients of milk (kg), fat (kg), 48-mo stayability (proportion of cows surviving to 48 mo of age), and calving interval (days) on inbreeding coefficient (%) were: Ayrshire -27.1, -1.2, -.005, .23; Guernsey -19.3, -.97, -.007, .27; Holstein -21.1, -.78, -.003, .09; Jersey -14.8, -.80, -.002, .63; and Brown Swiss -39.5, -1.36; -.011, .03. There is no cause for concern over current inbreeding, but active inbreeding is not recommended.
منابع مشابه
Effects of inbreeding on milk and fat production, stayability, and calving interval of registered Ayrshire cattle in the northeastern United States.
Inbreeding coefficients of 30,794 registered Ayrshire cows were calculated from relationships between sire and maternal male ancestors. Average inbreeding coefficient of all cows was less than 1% and of the 5,202 inbred cows was 5.4%. Fewer than 2% of inbred cows had coefficients greater than 15%. Percent of inbred cows increased from 23% of cows born in 1972 to 43% in 1980. Over the same perio...
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ورودعنوان ژورنال:
- Journal of dairy science
دوره 67 1 شماره
صفحات -
تاریخ انتشار 1984