The effect of modified G6G (G6G/PRID) protocol on ovarian activities and pregnancy rate in cows and heifers

The Effect of Modified G6G (G6G/PRID) Protocol on Ovarian Activities and Pregnancy Rate in Cows and Heifers In this study, in cows and heifers synchronized with the G6G/Ovsynch protocol by adding progesterone (PRID) to the protocol; ovarian activities were investigated and it was aimed to increase pregnancy rates after to be obtained after fixed-time artificial insemination practices. In the study, Holstein cows (n:181) and heifers (n:100) was divided into four groups as; Group 1: Cow G6G (cow control group, n:79), Group 2: Cow G6G/PRID (cow study group, n:102), Group 3: Heifer G6G (heifer control group, n:50), Group 4: Heifer G6G/PRID (heifer study group, n:50) and used. G6G/Ovsynch protocol was applied to the animals in the control groups (Group 1 and Group 3). G6G/PRID protocol was applied to the animals in the study groups (Group 2 and Group 4); G6G/Ovsynch protocol and intravaginal PRID (progesterone) was administered between days 8-15 of the protocol. In ultrasonographic examinations, structures on the ovaries were measured and recorded on day 0 (CL), day 8 (DF), day 15 (CL) and at the time of insemination (OF) of the protocol. Pregnancy examinations done between 30-35 days after AI. First insemination pregnancy rates obtained after fixed-time AI were evaluated as a fertility parameter. It was determined that the first insemination pregnancy rates in cows were 56.96% in the control group (G6G), 51.96% in the study group (G6G/PRID), and in heifers, the first insemination pregnancy rates were 64% in the control group (G6G), 68% in the study group (G6G/PRID) and there was no statistical difference between the groups (p>0.05). When the pregnancy rates at first insemination in primiparous and multiparous cows were evaluated; it was determined that pregnancy rates were numerically higher in multiparous cows in the control and study groups compared to primiparous cows. When the pregnancy rates of CL0 (+) and CL0 (-) animals in cows and heifers at first insemination were evaluated; it was determined that pregnancy rates were numerically higher in CL0 (+) cows and heifers in the study group (G6G/PRID), and in CL0 (-) cows and heifers in the control group (G6G). It was determined that the vaginal discharge score at the time of PRID removal did not adversely affect pregnancy rates in cows and heifers in the study groups. According to the results obtained, it was determined that the relationship between DF and OF mean diameters and pregnancy was not statistically significant between the G6G and Modified G6G (G6G/PRID) protocols compared in cows and heifers (p>0.05) and the relationship between CL mean diameters and pregnancy was significant in cows (p<0.05), but not in heifers (p>0.05). It was determined that the addition of progesterone to the G6G protocol in cows did not have a positive effect on pregnancy rates. However, it was determined that pregnancy rates in heifers were higher in the study group with progesterone supplementation compared to the control group (p>0.05), and the Modified G6G (G6G/PRID) protocol provided a numerical increase in pregnancy rates in heifers. Keywords: Cattle, G6G/Ovsynch, PRID, Progesterone, Synchronization