EFFECT OF BODY CONDITION AND SEASON ON THE YIELD AND QUALITY OF CATTLE EMBRYOS

Abstract

Unsatisfactory reproductive performance in dairy cows has been associated with environmental influences, such as season, chronic and acute changes in dietary intake and body composition. These factors can affect fertility especially ovarian function and yield and quality of oocytes and embryos. In our study the cow ´s body condition affected the overall embryo recovery rate (proportion of collected embryos to palpated corpora lutea). The significantly higher number of embryos was collected from cows with BCS 2.5- 2.75 (68.32 % embryo recovery rate) and 3.0- 3.25 (63.30 %) compared to the cows with BCS 2.0-2.25 (53.33%) and 3.5-4.0 (47.87%; P<0.01) and compared to the cows with BCS 4.5-5.0 (21.43%; P<0.001). On the other hand, highest percentage of transferable embryos was yielded in the BCS 3.5-4.0. Also the season significantly affected embryo recovery rate. The significantly higher (P<0.001) percentage of embryos was recovered during spring months (59.60% recovery rate) compared to summer months (37.04%) and slightly increased again during the autumn (48.30%; P>0.05). On the contrary, the yield of transferable embryos was higher (P<0.05) during the autumn months (78.94%) compared to spring (58.38%) or summer (60.00%) months. In conclusion, body condition and season may affect the yield and quality of bovine embryos. Higher embryo yield was recorded in average BCS (2.5-3.25) cows, whilst most transferable embryos were obtained in the higher BCS (3.5-4.0). Our results indicate that the best season for collection of transferable bovine embryos is autumn.