FOLLICULAR DYNAMICS IN ANOESTRUS CROSSBRED COWS

Abstract

In-vivo follicular developmental pattern was characterized in postpartum anoestrus (PPA) crossbred cows using the ultrasound imaging technology. A total of 12 PPA and six normally cycling cows were selected and investigated. In PPA cows, the ultrasonographic examination of ovaries was initiated randomly on any day and examined every other day continuously for a period of 25 days. In cyclic animals, the ovaries were ultrasonographically monitored every other day from the day of observed oestrus (Day 0) to Day 10 targeting the dominant follicle (DF) of first follicular wave. Ultrasonographic monitoring of the follicular turnover in PPA cows revealed that both the ovaries exhibited dynamic follicular activity. A maximum of two waves could be recorded during the observation period of 25 days, with each wave extending for a period of 8 – 10 days. The follicular wave of PPA exhibited coordinated growth, static and regression phases, with significantly (P < 0.05) prolonged static phase than their counterpart in normally cycling cows. Eventhough the DFs attained >10mm diameter, the animal did not evince any symptom of oestrum which might be due to deficient steroidogenic capacity of the follicular cells as a result of aberrant follicular microenvironment.