Dietary n-3 Polyunsaturated Fatty Acid Affects the Onset of Prostaglandin F_2α Induced Oestrus in the Goat (Capra hircus)

The objective of the present study was to examine the effect of dietary n-3 PUFA supplementation on oestrus response in the goat following synchronization with prostaglandin analogue. Parous cycling goats (n=17/group) were fed a concentrate diet supplemented with either fish oil (FO) or palm oil (PO). The FO provided n-3 EPA and DHA @ 156 mg kg⁻¹ body weight while PO was given @ 0.6 ml kg⁻¹ body weight to make the diet isocaloric. Oestrus was synchronized using two dose of prostaglandin F_2α (PGF_2α) at 11 days apart, with first PG on day 25 of oil supplementation. Goats were observed for oestrus twice a day using a vasectomized teaser buck following second injection of PGF_2α. _{The number and diameter of preovulatory follicle (POF) on the day of oestrus was studied using transrectal ultrasonography. The mean interval from PGF2α administration to the onset of oestrus was significantly (χ²df1=7.003, P=0.008) longer in FO than PO supplemented goats (48.71±3.78 vs 37.41±1.75 h). The proportion of goats showed oestrus within 48 h was 94.11% in the PO group (16/17), while it was 58.82% in the FO group (10/17). However, the oestrus duration was not affected by the FO supplementation. The number of POF was higher in the FO group than the PO (2.23±0.14 vs. 1.82±0.15; P=0.054); however the diameter of POF did not differ among the group (6.90±0.10 vs. 6.77±0.14; P>0.05). In conclusion, the supplementation of goats with n-3 PUFA rich FO delayed the onset of PGF2α induced oestrus and increased the POF number on the day of oestrus.}