PARTICULARITIES OF FOLLICULOGENESIS DURING THE OESTROUS CYCLE IN COWS WITH THE REPEAT BREEDING SYNDROME

Abstract

Particularities of folliculogenesis during the oestrous cycle in cows with the repeat breeding syndrome were detected. It was found that the repeat breeders that previously had suffered from endometritis or retention of the placenta, as well as animals with post-oestrual metrorrhagia show considerable shifts in the dynamics of follicular growth both with two and three waves of follicular development. In repeat breeders with no genital patho-morphological abnormalities there were no found considerable changes in the dynamics of follicular development compared to healthy animals. The two-wave oestrous cycles were registered in 70.6% of repeat breeders in the absence of clinical signs of genital pathology; in 50% of cows with the repeat breeding syndrome that previously had had endometritis or retention of placenta; in 66.7% of cows with post-oestrual metrorrhagia and in 66.7% of healthy animals. In cows with two waves of follicle growth, the duration of the oestrous cycle was shorter (the difference between healthy animals and cows with post-oestrual metrorrhagia made 3.4 days, P<0.025). The duration of the 1st wave of follicular growth was shorter in animals with the three-wave follicular growth. The maximum duration of the 1st wave of follicular growth was registered in the repeat breeders that previously had endometritis or retention of placenta, as well as in the animals with post-oestrual metrorrhagia (7.6 and 8.3 days against 6.4 days in healthy cows, respectively, P<0.025). The duration of the 1st wave of follicular growth in cows with two waves of follicular development did not differ significantly. In healthy cows with two waves of follicular growth, in comparison with animals with the repeat breeding syndrome, the second growth wave was longer and averaged 10.5 days. It was the shortest in cows with post-oestrual metrorrhagia (7.3 days, P<0.05). The duration of this wave was significantly shorter in cows with endometritis and retention of placenta (8.6 days, P<0.05). In healthy cows with three growth waves of follicles, the duration of the 2nd growth wave was 8.6 days. The most significant changes in follicle growth were found in repeat breeders with three growth waves that had suffered from endometritis or retention of placenta, and in animals with the repeat breeding syndrome,and post estrual metrorrhagia. In cows with post-oestrual metrorrhagia the duration of the 2nd growth wave in comparison with healthy animals was shorter by 2.4 days (P>0.05), and the third wave, on the contrary, was longer by 1.2 days (P<0.1).