Author(s) |
Robinson, Dorothy
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Publication Date |
2007
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Abstract |
Four fertility traits were compared for artificially inseminated (AI) beef cows: A) for cows that calved to the AI sire (from either the initial or follow-up inseminations that season), the number days from initial AI to calving; B) for cows calving either by AI or to a backup bull, the number days from initial AI to calving; C) As trait B for cows that calved, otherwise the maximum of trait B for the contemporary group plus a penalty of 21 days; D) Define the 'start date' for a contemporary group as the date the first cow in the group was AI'd. For cows that calved, trait D was the number of days from the 'start date' to calving, otherwise the maximum of trait D for cows in the group that calved plus a penalty of 21 days. The vast majority of cows received only one insemination in a season, so trait A resembled gestation length and had estimated heritability of 12%. Traits B, C and D had estimated heritabilities of 3.2%, 3.5% and 5.2% respectively; estimated genetic correlations of traits A-D with naturally mated days to calving were 0.48, 0.60, 0.80 and 0.74 respectively. Trait D is therefore the recommended female fertility trait for AI cows. It has a similar frequency distribution to days to calving from natural mating and should be included in a joint analysis with days to calving of naturally mated cows.
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Citation |
Livestock Science, 110(1-2), p. 174-180
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ISSN |
1871-1413
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Link | |
Publisher |
Elsevier BV
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Title |
Days to calving in artificially inseminated beef cows: Comparison of potential traits
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Type of document |
Journal Article
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Entity Type |
Publication
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