Follicular dynamics during the non-reproductive season in Miranda jennies

Abstract

ennies’ follicular wave patterns have not yet been addressed during the non-breeding and transition seasons in anoestrous jennies. Twelve non-pregnant females of the Miranda donkey breed were followed to describe follicular wave characteristics during the non-reproductive season and determine the anoestrous effect in follicular wave patterns. Five jennies enrolled in this study experienced anoestrus during the non-breeding season, but all retained the continuous emergence of follicular waves. The average duration of the waves from emergence to peak was 11.2 ± 0.021 days (3–29 days). The duration of the different type of waves was 9.91 ± 0.034 days for minor waves,12.5 ± 0.232 days for major secondary waves and 12.5 ± 0.057 for major primary waves. The major waves were significantly longer than the minor waves (p < .001). Older jennies presented longer waves (p = .021). In the jennies presenting anoestrus, the wave duration during anoestrus (11.2 ± 0.125 days, n = 31) was not different from the waves detected in the preceding and subsequent ovulatory cycles (11.3 ± 0.084 days, n = 43) (p = .978). The number of follicular waves emerging in each ovulatory cycle (n = 59) was 2.36 ± 0.011, varied from 1 to 4. Only in a small proportion of cycles, one wave (0.8%) was recorded, with 41 cycles (67.2%) presenting two waves; fourteen cycles presenting three waves (24.6%); and three cycles (6.6%) showing 4 waves. It was concluded that follicular waves do occur in anoestrous jennies during the non-breeding season with two-wave cycles being common.