227OVARIAN FOLLICULAR DYNAMICS IN POSTPARTUM MEDITERRANEAN ITALIAN BUFFALOES

Abstract

In cattle and buffaloes resumption of ovarian activity, as expressed by first post partum ovulation and follicle turnover leading to periodic estrus cycles and ovulations, can be affected by many factors among which uterine infections and dietary supplementation play a leading role. In addition, buffaloes are considered seasonal animals characterized by a tendency to reproduce in correspondence to a decrease of day length. This aspect may further affect their reproductive efficiency by delaying or interrupting ovarian activity if calving occurs in transitional (i.e., from end winter into beginning of spring) or unfavourable (spring-summer) periods of the year, when an increase of daylight hours occurs. The aim of this study, carried out in the months of February to May, was to understand the effect of increasing daylight hours over resumption of postpartum ovarian follicular dynamics and estrus cycles. Mixed parity Mediterranean Italian buffaloes (n=20) were monitored daily by ultrasonography from calving until first postpartum ovulation and following cycle or until 60 days if no ovulations had been recorded. Ultrasound monitoring was performed by using a 7.5MHz linear-array probe and an Aloka SSD-500 monitor. No pharmacological intervention was allowed during the course of the study and animals were kept under similar feeding and farm management conditions. All animals exhibited a mild to moderate uterine inflammation (n=13; 65%) or aspecific infection (n=7; 35%) after calving. Infections were manifested as purulent discharge and as ultrasound detection of highly echogenic debries in the uterine lumen. Only one animal retained pathological accumulation in both horns for the entire duration of the study. Among the 20 buffaloes under study, 12 (60%) exhibited postpartum ovulations, ranging from 9 to 45 days. In eight buffaloes (40%), such ovulations occurred in the ovary contralateral to the ovary bearing the gravidic CL. Following postpartum ovulations, seven buffaloes (35%) underwent a complete cycle leading to ovulation. Three of such cycles (15%) culminated with a second ovulation in the same ovary where post partum ovulations had occurred. Among the full cycles following postpartum ovulations, four of them were one-wave, with a range of 8 to 19 days, whereas the remaining three cycles were two-wave with a range of 17 to 22 days. Eight buffaloes (40%) were reported in anovulatory condition following parturition, although in four of them both ovaries displayed a typical follicle turnover. In conclusion, resumption of ovarian activity and reproductive efficiency in water buffaloes can be affected by increasing day length as evidenced by a high rate of postpartum anovulatory conditions and reduced follicle turnover.