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Reproductive performance of Holstein cows receiving somatotropin.
J E Luna-Dominguez1, R M Enns, D V Armstrong
1Department of Animal Sciences, University of Arizona, Tucson 85721-0038, USA.
Journal of Dairy Science
|July 25, 2000
Summary
Concerns about bovine somatotropin (bST) impacting dairy cow fertility were investigated. Results showed bST treatment significantly reduced pregnancy rates, suggesting an extended voluntary waiting period is advisable for treated cows.
Area of Science:
- Dairy Science
- Animal Reproduction
- Veterinary Medicine
Background:
- Dairy producers express concerns regarding potential fertility compromises in cows treated with bovine somatotropin (bST).
- High-producing Holstein herds in Arizona and southern California were studied, with milk production exceeding 10,700 kg/yr.
Purpose of the Study:
- To evaluate the reproductive performance of dairy cows treated with bovine somatotropin (bST).
- To assess the impact of bST on pregnancy rates and first-service conception in high-producing Holstein cows.
Main Methods:
- A total of 205 Holstein cows (100 multiparous, 105 primiparous) were randomly assigned to receive bST or no treatment (controls).
- Reproductive data were collected over a 180-day interval postcalving, following a 60-day voluntary waiting period.
Main Results:
- Pregnancy diagnosis within 180 days postpartum revealed a significantly lower pregnancy rate in bST-treated cows (48.5%) compared to controls (65.4%).
- First-service conception rates did not significantly differ between the bST-treated group and the control group.
Conclusions:
- Bovine somatotropin (bST) treatment was associated with a significant reduction in overall pregnancy rates in high-producing dairy cows.
- An extended voluntary waiting period and breeding interval is recommended for dairy cows receiving bST to potentially mitigate negative reproductive effects.