Evaluación de un programa de sincronización e inducción de celos utilizando prostaglandina, GnRH y estradiol, considerando los factores que afectan el desempeño reproductivo en vacas lecheras

Abstract

This study was conducted between June 2012 and March 2013 in Hacienda San Ramon, in the municipality of Caluco, Sonsonate which had about 650 Holstein milking cows. By collecting reproductive performance data obtained during three years, the Presynch-Heatsynch® program was evaluated for synchronization and induction of estrus and the effect of the factors: parity, temperature and humidity index (THI), mastitis, metritis, lameness and body condition (BC) on reproductive performance. We used information from 1830 births in three years between October 1, 2009 and September 30, 2012. During year 3 (October 1, 2011 to September 30, 2012), cows that calved were included in the program Presynch Heatsynch®, on day 37 postpartum (PP) they received an injection of 150 mg of prostaglandin F2 IM and an additional equal dose on day 51 postpartum. Cows in estrus were inseminated, The ones that did not cycle received 21 mg of GnRH MI at day 65 PP, 150 mg of prostaglandin MI at days 72 and 73 PP, 1 mg of estradiol cypionate (ECP) IM . Cows were inseminated at estrus seen 24 hours after (ECP). During the three years of the study, the following information was collected: date of birth, estrus, insemination, conception, parity. With these data, we calculated the parameters (variables): days to first estrus, days to first service, services per conception and days open of each animal. We also recorded the occurrence of postpartum mastitis, metritis and lameness and body condition (only year 3). We evaluated the effects of the protocol, year, parity and BC over the variables using a general linear model and a DMS test. We evaluated the effects on the variables of the synchronization program, mastitis, metritis and lameness with a T student test. We assessed the effects of month of the year and the ITH on the conception rate were using a linear general model. We used the SPSS software and considered the significant differences with a probability of less than 5% (p> .05). The effect of the program was significant in all evaluated parameters (p<0.001). delaying the presentation of the first estrus by nine days, but reducing by 10 days the interval to the first insemination, by 38 the days open and the services per conception by 0.6 and the annual pregnancy rate it was increased by 5% and the conception rate by 10%. Gilts had lower scores on the evaluated variables (p <0.001). compared to adults. The presence of mastitis, metritis and lameness had a significant impact on the parameters; days open were higher in cows with mastitis (177 vs 131), metritis (181 vs. 115) and lameness (224 vs 148) than in healthy cows (p <0.001). The month of the year and the temperature and humidity index (THI), were reflected in the seasonality of conceptions, increasing fertility (> 33%) during the cooler months (November-February) and reducing it to less than 20% during months with higher THI. Cows with lower body condition at calving had lower reproductive performance on the evaluated parameters (p <0.001). The use of Presynch-Heatsynch® program improved reproductive performance of livestock, reducing the cost on days open and resulting in a greater number of replacement females and lactating cows.