Investigation of Ovarian Follicular Waves and Major Hormonal Profile in Red Chittagong Cattle

Abstract

Red Chittagong Cattle (RCC) is one of the renowned varieties of cattle which is indigenous and most potential type of domestic animal genetic resource in Bangladesh with distinct phenotypic characteristics. Reproductive management might be a process for multiplying this cattle variety. Therefore, the goals of this study were to characterize the follicular waves of RCC and to determine the Progesterone (P 4 ), Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) profile during three consecutive estrus cycle. Follicular wave emergence (Day 0) was identified using trans-vaginal ultrasound technique and follicular growth was then monitored from Day 0 to Day 23 during three consecutive estrus cycle and blood samples were collected. After measuring the growth and diameter of the follicles, hormonal assays of collected blood samples were performed using Enzyme Linked Immunosorbent Assay (ELISA). We found that, both RCC cows and heifers showed two waves inter-ovulatory intervals. The length of inter-ovulatory intervals and the diameter of the ovulatory follicle of RCC cows and heifers were slightly different from each other. The identification of the dominant follicle was confirmed from the start of its deviation from other subordinate follicles till it reached to the maximum diameter and identified as dominant follicle which increases linearly for approximately six days (growing phase). This dominant follicle is remained approximately same size for five days (static phase), and then begins to regress (regressing phase) decreasing the antral diameter. The follicular waves are first detectable as 4 - 5 mm follicles approximately at day 0 and day 10 both for RCC cows and heifers which showed two waves inter-ovulatory intervals. The circulating varied concentrations of LH, FSH and P 4 were determined using ELISA in case of both cows and heifers and the concentration curves followed the similar pattern of change during the estrus cycle. Hence, the knowledge about ovarian follicular waves will create a base line for reproductive management of RCC as well as to allow reproductive biotechnologies to improve and multiply this cattle variety.