Comparison of follicular development and pregnancy rates following estrus synchronization by two differerent methods in cows

Aim : Intensive studies are being carried out to determine right time of estrus to decrease the time spent on this work in order to increase the pregnancy rates in cows. In recent years, estrous synchronization programs have been developed in which different hormonal preparations are being used alone or in combination. This aim of this study was to compare the efficacy of two different methods of synchronization together with the time on estrus detection in field conditions, prevention of labor loss, application of fixed time artificial insemination for animals showing silent heats and pregnancy rates. Material and Method : Present study was conducted in a special dairy cow operated in Erzurum province. A total 16 Simental breed cows of postpartum 45th day or more with one parturition were selected and divided into two groups. The cows in the first group were treated with PGF2α for 11 days and the animals in the second group were given intravaginal progesterone for 10 days. The first group was inseminated twice at 72 and 96 hours of 2nd injection of PGF2α, whereas animals in the second group were inseminated at 48 and 72 hours after removal of progesterone. Ultrasonography was used to observe follicular development at the time of artifical insemination and for diagnosis of pregnancy 35 days' post insemination. Results: On the day of artificial insemination, graaf follicle diameters were 9.1 ± 1.12 mm in Group 1 and 19.0 ± 2.56 mm in Group 2 (P = 0.16). The results were statistically non-significant. On the other hand, pregnancy rates were 4/8 (50%) in Group 1 and 3/8 (37.5%) in Group 2. Since there is no statistical difference between the two groups, it is concluded that both methods can be used for synchronization but the number of animals should be increased in order to obtain more clear results.