Inducción de ciclos estrales en vacas lecheras con anestro posparto utilizando progesterona y hormonas gonadotróficas

Kizur, A.; Garrido, M.J.; Konrad, J.L.; Crudeli, G.A.: Induction of oestrus with progesterone, chorionic gonadotropin and antero-hipofisary extract in postpartum anoestrus dairy cows. Rev. vet. 26: 1, 13-16, 2015. The aim of the present study was to induce oestrus in postpartum anoestrus dairy cows after the application of two hormonal treatments. With this purpose a group of 89 dairy cows in anoestrus, with 60 or more days from calving, were selected in the south region of Chile. The animals were randomly allocated in three groups. Groups 1 and 2 received an intravaginal device with 1.38 g of progesterone for 7 days. Group 1 received two doses of 50 mg of horse anterior pituitary extract (HAP) on days 7 and 8, and group 2 received 400 UI of equine chorionic gonadotrophin (eCG) on day 7. Group 3 was left as control, without treatment. Oestrus induction was evaluated by two times daily detection and was statistically higher (p<0.05) in cows that received gonadotrophic treatments (groups 1 and 2) compared to control cows. The treatments significantly reduced the interval treatment to first service in cows that receive HAP (11.8 days) and eCG (13 days), compared to control cows (34.2 days). The percentage of ovulated cows was greater in the groups receiving HAP (48.4%) and eCG (56.7%) compared to controls (14.3%). The pregnancy rate was significantly improved (p<0.05) within 25 days in cows treated with HAP (35.5%) over the control group (10.7%). The gonadotrophic treatments may be useful tools for the reproductive management of postpartum anestrus in dairy cows.