Sexual and ovarian activity of crossbred ewes fed different types of roughage during seasonal anestrus

Abstract

Twenty Barki X Awassi crossbred ewes were used in this study to evaluate the sexual and ovarian activity of ewes fed different types of roughages during seasonal anestrus. Ewes were allotted to two groups according to the type of roughage. Ewes in the first group were fed Egyptian clover (Trifolum alexandrinum) (n=10; clover group); while the ewes in the second group where fed corn silage (n=10; silage group) for 50days. Both groups also received a daily commercial concentrate mixture. After 30days from the onset of the nutritional treatment, estrus was synchronized using two intramuscular injection of 125μg of cloprostenol, 9days apart. Sexual activity of the ewes was observed daily during the entire experimental period. Further, ovarian activity of each ewe was monitored using transrectal ultrasonography, from 48h after the second PGF2α injection (follicular phase). Serum estradiol (E2) and progesterone (P4) concentrations were determined during the follicular phase, together with serum progesterone concentrations being determined during the luteal phase (11days after the second PGF2α injection). Results revealed that the mean total number of follicles/ewe and mean diameter of the largest follicles (mm) tended to decrease in the clover group (1.2±0.2 and 6.6±0.4mm, respectively), compared to those in the silage group (1.8±0.3 and 7.6±0.3mm, respectively). These differences were however not significant. Although, the mean number of ovulatory follicles/ewe was similar in both treatment groups (0.8±0.2 in the clover and 0.7±0.2 in silage groups, respectively), the serum estradiol concentration decreased (P>0.05) in the clover group (50.8±6.4pg/ml), compared to that of the silage group (61.1±7.7pg/ml). Serum progesterone levels during the follicular and luteal phases indicated that the percentage of ewes ovulating was in line for both the clover (66.7%) and the silage (50%) groups. However, all ewes in the clover group failed to show signs of overt estrus after estrous synchronization, while 40% of the ewes in the silage group exhibited signs of estrus after estrous synchronization, and conceived (P<0.05). These data may suggest that the phytoestrogen compounds in Egyptian clover may interact with other environmental cues during seasonal anestrus, and thus decrease the reproductive performance of the ewes.