Using GnRH to Improve Cow Fecundity after Calving

Abstract

At dairy cows, the increase in milk production is associated with the decrease of heat manifestation and conception rates. GnRH is mostly used for treatment of different problems of the reproductive function and for improving the pregnancy rates in cows. The aim of our paper was to contribute to increase of conception rates, at cows with ovarian activity, at first AI after calving. The experiments were conducted on 58 cows, from Romanian Black Spotted breed (Frezian) and 53 cows from Romanian Spotted breed (Simmental). The animals were divided into lots as follows: for Romanian Black Spotted breed 33 of the cows in were in experimental lot and 25 were in control lot, for Romanian Spotted breed 29 ere in experimental lot and 24 were in control lot. The females form experimental lots were treated with 100 mcg (2ml) Ovarelin (GnRH), at the first AI, after VWP. At the cows form Romanian Black Spotted, from the 33 females in experimental lot, 12 did not return into heat after insemination, which represents a conception rate of 36.4%. At the cows form Romanian Spotted, form the 29 cows in experimental lot 8 did not return into heat after insemination, representing a conception rate of 44.8%. Administration of 100 mcg GnRH (2 ml Ovarelin) at the time of AI determines a significant increase of the conception rate with 8.4-11.5%, compared with control lot. It appears that the cows from Romanian Spotted reacts better at GnRH treatment (44.8% conception rate), compared with Romanian Black Spotted (36.4 % conception rate).