Effect of different levels of n-3 polyunsaturated fatty acids rich fish oil supplementation on the ovarian and endometrial functions in the goat (Capra hircus)

Abstract

Decreasing the ratio of n-6 to n-3 polyunsaturated fatty acid (PUFA) through dietary manipulation improves the reproductive functions in the dairy cow. This study was conducted to determine the effect of dietary supplementation of n-3 PUFA rich fish oil that provided different levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to determine the optimum dose with respect to endometrial and ovarian functions in the doe. Normal cyclic goats (n = 20) were divided into four groups (n = 5/group) and the fish oil was supplemented for 55 days such that EPA and DHA content were 0, 72, 156 and 312 mg/Kg body weight for CON, LOW, MED and HIGH groups, respectively. The diet was made isonitrogenous and isocaloric. Estrus was synchronized by two PG regimen at 11 days apart with first PG on day 25 of supplementation. Experimental does were observed from second PG till day 17 post-estrus. Ovarian ultrasound revealed that the follicular attributes were comparable among the groups; however, the diameter of CL on day 5 post-estrus was significantly larger in the MED group. Fish oil supplementation even at the lowest dose significantly decreased the serum estradiol (E2) and basal as well as oxytocin (OXT) induced PGFM during the late luteal phase of the estrous cycle (P < 0.05). Further, the MED group showed a significant decrease in the serum E2 on day 17 post-estrus as compared to LOW group. A significant increase in the progesterone (P4) on day 14 post-estrus was recorded in the MED group. Neither the effect of treatment nor time was significant either on day 16 or 17 post-estrus with respect to PGEM following OXT challenge (P > 0.05). It is concluded that the dietary fish oil inhibited OXT induced PGF2α release and decreased E2 during the late luteal phase of the estrous cycle in the doe, which will have a favourable effect on the maternal recognition of pregnancy. In addition, MED level (156 mg/Kg body weight) increased the CL size and circulating P4 during the luteal phase.