Effectiveness of epidural and GnRH administration on dairy cows pregnancy rate following artificial insemination in high temperature environment

The aim of the study was to investigate effectiveness of epidural and GnRH injection 12 days after artificial insemination. We suggested that GnRH injection can prevent embryo loss associated with insufficient production of progesteron and can increase progesteron level and pregnancy rate inducing luteal function in high-producing lactating dairy cows in the summer.The study was applied in Aydın from July to September. 42 healthy and fertile Holstein lactating dairy cows were chosen under balanced ration on a commercial farm in this study. Their ages were ranged from 3 to 7 years old. All the cows were older than fiftieth day of postpartum. Clinical and rectal examination was performed to determine healthy and fertile cows. Cows were randomly divided into three groups. All the groups were synchronized with ovsynch protocol (GnRH-7d-PGF2?-48h-GnRH, artificial insemination between 16 and 22 hours after second GnRH administration). GnRH (2ml) was administered via epidural injection in first group 12 days after AI. GnRH (2ml) was administered via intramuscular injection in second group 12 days after AI. %0,9NaCL (2ml) was administered via epidural injection in third group 12 days after AI.Rectal examination was implemented between 60 and 62 days after AI to determine pregnant cows. Number of pregnant cows and pregnancy rate was found, group 1 (5, %35, 7), group 2 (5, %35, 7) and group 3 (4, %28, 6). There were no statistically significant differences between groups (p> 0, 05).In conclusion, although epidural GnRH implementation increased pregnancy rate under heat stress, there was no statistically significant differences between groups. However, further studies with high numbers of animals are need to be examined. The research will be more reliable if more cows participate in a longer period. In this way, we can have more detailed data results and accurate knowledge about effects of epidural and GnRH implementation on dairy cows pregnancy rate following AI under heat stress.Key Words: cow, heat stress, epidural, GnRH