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Reproductive and some peri-natal variables in a mixed breed beef cattle herd
1South Australian Research and Development Institute, Adelaide, S. A., Australia South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, S. A., Australia.
Summary
Days to calving (DC) is a useful beef cattle reproductive variable, but its non-normal distribution presents challenges. Further research into alternative female reproductive traits is recommended for improved genetic evaluations.
Area of Science:
- Animal Science
- Reproductive Biology
- Beef Cattle Genetics
Background:
- Reproductive efficiency is crucial in beef cattle production.
- Key reproductive and perinatal variables include calving success (CS), days to calving (DC), birth weight (BW), and calving ease (CE).
- Understanding the heritability and correlations of these traits is essential for genetic improvement programs.
Purpose of the Study:
- To estimate repeatabilities for CS, DC, BW, and CE in a mixed-breed beef herd.
- To investigate the correlations between these reproductive and perinatal traits.
- To assess the suitability of DC as a reproductive variable in beef cattle.
Main Methods:
- Data collected from a mixed-breed beef cattle herd (Hereford, Jersey × Hereford, Simmental × Hereford).
- Repeatabilities estimated using analysis of variance.
- Correlations analyzed, including the effects of data transformations on DC.
Main Results:
- Repeatabilities varied: DC (0.10-0.12), CS (0.08), BW (0.26), and CE (0.03).
- High residual correlations were found between CS and DC (≥ -0.68).
- Correlations of DC with BW (0.26-0.28) and CE (0.10-0.12) were consistent across transformations.
Conclusions:
- Days to calving (DC) is a practical reproductive variable but its non-normal distribution poses analytical challenges.
- While DC has utility, the search for more appropriate female reproductive traits for genetic evaluation should continue.
- Birth weight (BW) showed moderate repeatability, suggesting potential for selection, while calving ease (CE) had low repeatability.
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