The efficacy of vitamin c administration on some blood parameters and pregnancy rates in dairy cows under heat stress

The aim of this study was to investigate the efficacy of vitamin C administration for increasing reduced pregnancy rates due to heat stres in cows during summer season. Study material consist of 80 Holstein-Friesian dairy cows which are between 3 to 7 years old, has given a birth at least and their last calving date passed minimum 45-80 days. They are from a dairy cattle farm in Milas district of Muğla. Selected study material of 80 Hostein-Friesian were divided into 2 groups as application group (G:1 n=40) and control group (G:2 n=40). The day of artificial insemination was chosen as Day 0. Intramuscularly Vitamin C (4 mg/kg) injected on Day 0, Day 4, Day 8 and Day 12 between 09.00-10.00 am to application group. 10 ml isotonic NaCl was injected by intramuscular way to the control group. 11 cows were chosen randomly from each groups and blood samples were taken from vena jugularis on Day 0, Day 4, Day 8 and Day 12 between 12.00-13.00 pm. Serum and plasma samples were stored at -20 ̊C in freezer. Republic of Turkey Ministry of Water Affairs and Forestry, General Directorate of Meteorology, Turkish state Meteorological Data Archive System's data was used to determine the temperature value and the temperature humidity index. In the course of working days, temperature humidity index was higher than calculated number of verge 72 and determinated to consist a heat stress moderately. For both groups, pregnancy examinations were done by ultrasound at 30 days after insemination. Pregnancy rates were found 32,5 % (n=13) in application group and 22,5 % (n=9) in control group, respectively. Serum P4, GSH, MDA and plasma 8-OHdG levels were determined by using ELISA method. According to statistical evaluation; although there were no statistical diffrences between days of application group and days of control group (p>0.05), 8-OHdG levels were determined statistically important in application and control group between Day4, Day 8 and Day 12 (p<0.05). In conclusion, the administration of Vitamin C after insemination during postpartum period; caused decreasing in 8-OHdG levels, probably increasing in pregnancy rates. Although MDA levels were not found important, probably decreasing its levels. Furthermore, there was no effect on P4 and GSH levels.