Factors affecting birth weight, dystocia and preweaning survival in sheep
Data from 3535 purebred (PB) and 3178 crossbred (XB) lambs were analyzed to determine the attention that should be given to dystocia and lamb survival in selection programs for terminal sire breeds. Both dystocia and lamb mortality were quadratically related to birth weight. Dystocia increased lamb mortality by 8.6 (PB) and 4.8 percent (XB). Single-born lambs were heavier at birth and had fewer deaths than multipleborn lambs. Single-born XB lambs also had more dystocia than multiple-born lambs. The 0.13 ¦ 0.03 heritability estimate for dystocia was not changed by accounting for differences in birth weight. Selection for increased size and growth rate in terminal sire breeds with little concern about dystocia or preweaning survival seems warranted, especially if they are to be mated with highly prolific ewes
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| Format: | biblioteca |
| Published: |
1977
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| Subjects: | OVINOS, REPRODUCCION, DISTOCIA, PESO AL NACIMIENTO, MORTALIDAD, CORDERO, |
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