Effect of vitamin E on reproductive performance in cows synchronized with different synchronization methods

This study was conducted to investigate the effect of vitamin E treatment on reproductive performance of cows synchronized with different synchronization methods. Eigthy-four holstein cows, which are raised at similar management- feeding conditions in Afyonkarahisar city, were used as material. The cows were selected from healthy animals between 3-7 years old, at least once giving birth, on post partum 45-60 days, and not having any reproductive problem.The cows were synchronized with 3 different synchronization methods and inseminated by artificial insemination. The cows that were synchronized by double PGF2? injections 11 days apart, ovsynch and CIDR insertion were divided into two sub-groups as control and treatment (vitamin E) within each synchronization group. Ten ml blood samples were taken immediately after second PGF2? injections in PGF2? group, immediately after PGF2? injections in ovsynch group, and immediately after CIDR removal in CIDR group, and then 4 ml physiological saline was injected to all control subgroups while 4 ml vitamin E (300 mg/ 2 ml) injected to all treatment subgroups. Second injections of phsyological saline vitamin E and were administered to all control and treatment subgroups, respectively immediately after the animals were artificially inseminated by recto-vaginal method. Then second blood samples were also taken on day 3 after the insemination. Estrous intensities, which were detected by clinical examination at the time of insemination, were scored. Vitamin E and MDA levels were determined in all blood samples. All the animals were examined for pregnancy on day 60 after insemination.No statistically significant difference was determined between different synchronization groups, and between control and treatment subgroups within same synchronization group with respect to oestrus intensity and vitamin E levels.No statistically significant difference was determined between synchronization groups, and between control and treatment subgroups within same synchronization group of cows that were synchronized with PGF2? and ovsynch protocol in terms of MDA levels in first and second blood samples. There was a statistically significant difference between MDA levels of first and second blood samples in both control (p<0.01) and treatment (p<0.001) subgroup cows which were synchronized with CIDR synchronization method. Pregnancy rates for control and treatment subgroups of PGF2? synchronization method were 40% and 53.3%, respectively, for control and treatment subgroups of ovsynch protocol were 23.1% and 46.7%, respectively, and for control and treatment subgroups of CIDR synchronization method were 46.2% and 53.8%, respectively. No statistically significant difference was determined between different synchronization groups, and between control and treatment subgroups within same synchronization group with respect to pregnancy rates. A significant positive correlation was found between pregnancy rates and MDA levels in all groups (r= 0,853, p<0.05).In conclusion, although administration of vitamin E to cows which were synchronized with different synchronization methods provides a slight increase in pregnancy rates, it significantly prevents the CIDR induced-lipid peroxidation.