Effect of lameness on follicular dynamics in crossbred cows

Lameness impedes reproduction in dairy cows. It is not clear whether follicular dynamics is also involved. Ovarian ultrasonography was performed once daily for one to two interovulatory intervals in the cyclic cows that were either normal (N) or lame (L). A 2-wave pattern of follicular growth predominated and was therefore utilized to compare the follicular dynamics during six and 13 interovulatory intervals, respectively, in six N and 10 L cows. At wave emergence, the follicular characteristics were similar between the N and the L cows. Subsequently, the L cows compared to the N cows exhibited an increased number of small (P<0.05), medium (P<0.01) and large (P<0.05) sized-follicles during the anovulatory and ovulatory follicular waves; delayed selection of the dominant follicle in the anovulatory (day 3.6 ± 0.2 versus day 2.8 ± 0.1; P<0.05) as well as the ovulatory wave (day 5.6 ± 0.2 versus day 2.8 ± 0.1; P<0.01) and longer persistence of the ovulatory follicle (10.9 versus 9.4 days; P<0.05). It was concluded that the follicular composition and characteristics were disturbed in the lame cycling cows.