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Calving Difficulty: Difference between revisions
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===Contempory Group=== | ===Contempory Group=== | ||
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The same [[Contemporary Groups | contemporary group]] definition for [[Birth Weight | birth weight]] should be used for calving difficulty. This includes year/season of birth, management group. Some organizations that use threshold analysis for determining calving ease [[Expected Progeny Differences | EPDs]] will not divide calving difficulty contemporary group by sex of the calf in order to increase the number of contemporary groups with variation. If other methods for analysis are used such as random regression or a linear model, then the contempporary group should be divided by sex of calf. | |||
===Genetic Evaluation=== | ===Genetic Evaluation=== | ||
Revision as of 16:16, 25 June 2019
Calving difficulty is a subjective measure of the degree of dystocia. Dystocia can be caused by a large pre-natal calf, small pelvic area of the dam, lack of sufficient uterine contractions, insufficient dilation of the cervix, or mispositioned calf prior to parturition. Calving ease EPD are produced from calving difficulty scores and birth weight observations.
Phenotype
Producers are asked to score the degree of calving difficulty using the following subjective scores:
| Score | Description |
|---|---|
| 1 | No difficulty, no assistance required |
| 2 | Minor difficulty, some assistance |
| 3 | Major difficulty, usually mechanical assistance |
| 4 | Caesarian section or other surgery |
| 5 | Abnormal presentation |
Cows that calve without assistance between daily checks can be assumed to have calved without assistance even if the calving was not observed. A score of 1 should be reported for these. All calvings should receive a score even if the calf is born dead.
Adjusted Value
No adjustments are made to calving difficulty scores.
Contempory Group
The same contemporary group definition for birth weight should be used for calving difficulty. This includes year/season of birth, management group. Some organizations that use threshold analysis for determining calving ease EPDs will not divide calving difficulty contemporary group by sex of the calf in order to increase the number of contemporary groups with variation. If other methods for analysis are used such as random regression or a linear model, then the contempporary group should be divided by sex of calf.
