Effect of Gonadotropin-Releasing Factor (GnRH) and Antioxidants on the Rate of Estrous Repetition Dairy Cows

The aim of this study was to assess the effect of the administration of a gonadotrophin-releasing factor (GnRH) and antioxidants (vitamin E and selenium) on the rate of repetitions of estrous behavior in dairy cows with and without a history of reproductive problems. The work was conducted in an female Production Unit (APU) of dairy cattle in the State of Mexico, 300 females in production were used. The study was divided into six lots of 50 animals each. Lot A with GnRH: A1 without repetitions and A2 with repetitions. Lot B with antioxidants: B1 without repetitions and B2 with repetitions. Lot C with GnRH + antioxidants: C1 without repetitions and C2 with repetitions. The results were as follows: In lot A1 without GnRH, 49 animals were diagnosed as pregnant and remaining as repeater during rectal palpation 21-24 days after insemination. In lot A2 with GnRH, only 1cow was diagnosed pregnant and the remaining 49 repeated estrous. In lot B1 without Antioxidants, 24 animals were diagnosed as pregnant and 26 repeated estrous. In lot B2 with Antioxidants, 26 females were diagnosed pregnant and the remaining 24 repeaters. In lot C1 without GnRH + Antioxidants, 24 females were diagnosed as pregnant, while 26 females as repeaters. In lot C2 with Antioxidants + GnRH), 49 were diagnosed as pregnant cows and 1 repeated estrous. At the end of the experiment, the 300 cows represented 100%, 173 were pregnant which is equivalent to 58% and the remaining 127, repeated estrous to 21 days equivalent to 42%.. Shows that treatment based on GnRH + Antioxidants, had better results than using the individual treatments. In the following figure shows the % of cows with repetitive 3 treatments, treatment with antioxidants obtained the highest number of repeaters cows. In conclusion, treatment with GnRH in cows with no history of reproductive problems, was the best, with a result of 98% (49 females lot A1), the same value was obtained from treatment with GnRH and antioxidants in cows with a history of reproductive problems (49 females lot C2), which was the best treatment to reduce the rate of cows with estrous repetition