Induction of accessory corpus luteum in cows by gonadotropin-releasing hormone administrated after insemination
2014
Musilova, D., University of Veterinary and Pharmaceutical Sciences, Brno (Czech Republic). Clinic of Ruminant and Swine Diseases | Bartonek, J., University of Veterinary and Pharmaceutical Sciences, Brno (Czech Republic). Clinic of Ruminant and Swine Disease | Cech, S., University of Veterinary and Pharmaceutical Sciences, Brno (Czech Republic). Clinic of Ruminant and Swine Disease | Palenik, T., University of Veterinary and Pharmaceutical Sciences, Brno (Czech Republic). Clinic of Ruminant and Swine Disease | Dolezel, R., University of Veterinary and Pharmaceutical Sciences, Brno (Czech Republic). Clinic of Ruminant and Swine Disease
Sufficiency of progesterone limits conception rate in dairy cows. This study evaluates the effect of gonadotropin-releasing hormone on induction of accessory corpus luteum, progesterone concentrations and pregnancy in dairy cows. The hormone (0.05 mg) was administrated intramuscularly to cows with one corpus luteum on day 5Â7 (Group E1, n = 57) or 11Â13 (Group E2, n = 40) after insemination; control groups C1 (n = 54) and C2 (n = 41) were not treated. Detection of pregnancy by ultrasound examination and measurement of serum progesterone concentration was performed on day 25Â39 and around day 90 after insemination. The occurrences of two corpora lutea in groups E1 and E2 versus C1 and C2 were 43.9% and 33.5% vs. 3.7% and 9.8% (P less than 0.001). Progesterone concentrations were 5.9 +/- 2.92 ng/ml and 7.8 +/- 2.35 ng/ml in untreated and treated cows (P = 0.016), respectively. Conception rates in groups E1 and E2 were 100% and 86.7% in cows bearing two corpora lutea, and only 16.7% and 38.9% in cows bearing one corpus luteum (P less than 0.01); similarly as in groups E1 and E2 compared to groups C1 and C2 (49.1% and 50% vs. 50% and 31.7%). Pregnancy rates around day 90 in groups E1 and E2 compared to groups C1 and C2 were 45.6% and 45% vs. 42.6% and 26.8%, respectively. Administration of gonadotropin-releasing hormone on day 5Â7 or 11Â13 after insemination was efficient to induce accessory corpus luteum and increase the concentration of serum progesterone but had no effect on the conception rate.
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