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Summary. The reasons for low fertility in a flock of inbred sheep were investigated. Of a total of forty-one inbred ewes run with tested rams at normal mating time, sixteen (39%) were unlikely to have carried a lamb to term. Causes included non-ovulation (six ewes), non-cleavage or abnormal cleavage of ova (four ewes) and non-viability of early implanted embryos (six ewes). Out of twenty-six non-inbred half-sibs of similar ages only one potentially infertile ewe was found (non-ovulation).
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Doney et al. (1968) studied this question.
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