Uso de diferentes indutores de ovulação em protocolo Cosynch em vacas de corte

Abstract

It was evaluated the efficiency of lecirelin acetate and human chorionic gonadotrophin (hCG) to replace gonadorelina in Cosynch protocols for beef cows. Thirty-two cows were assigned to three treatments (T): T1 (n = 10) received 100μg injections of the analogue of gonadotropin-releasing hormone (GnRH), gonadorelin, in D0 , then the application of 150μg of d-cloprostenol, on D7 and 100μg of GnRH analogue, gonadorelin, D9; T2 (n = 11) received injections of 25 mcg of GnRH analogue, ethyl lecirelin on d0 followed by the application of 150μg of d- cloprostenol on D7 and 25 mcg of GnRH analogue, ethyl lecirelin, D9 and T3 (n = 11) received injections of hCG 1.000UI in D7; 150μg d-cloprostenol on D7 and 1.000UI hCG D9. All hormones were administered intramuscularly (IM). The artificial inseminations fixed-time were performed at D9 protocol, after hormone application. Evaluation of estrous behavior was initiated on D7 of the protocol, the animals were observed rufiados and 12 in 12 hours, until the end of estrus. The percentage of females in estrus was evaluated, the onset of estrus, the end of estrus, duration of estrus, the interval between the application of PGF2a and the onset of estrus, the interval between the application of PGF2a and end of estrus rate cost of pregnancy and protocols. There was no difference for any of the variables (P> 0.05). The percentage of animals in estrus was 20.00, 45.00 and 18.00%, for T1, T2 and T3, respectively. The duration of estrus was 13.66 ± 1.10 hours (h), for T1, 17.78 ± 8.9 h for T2 and 11.93 ± 0.66 h for T3. The interval between the application of PGF2a and estrus onset was 41.27 ± 7.85 h, for T1, 51.58 ± 16.86 h for T2 and 49.94 ± 19.76 h for T3. The interval between the application of PGF2a and end of estrus doi 54.96 ± 8.94 h, for T1, 69.36 ± 7.97 h for T2 and 61.88 ± 19.10 h for T3. The pregnancy rate was 20.00, 18.00, and 9.00 % for T1, T2 and T3, respectively. The costs of the protocols were £ 15.00, R $ 12.67 and R $ 17.88 for T1, T2 and T3, respectively. The use of hCG or of lecirelin acetate to replace Gonadorelin in Cosynch protocols did not alter estrous behavior and pregnancy rate of beef cows.