Response to the sexually active buck effect in Beni Arouss goats primed with progestagens during the anoestrus and breeding seasons

Abstract

The response to buck effect (BE) was studied in Beni Arouss goats during anoestrus (AS) and breeding season (BS). Prior to AS, bucks were exposed to artificial long days during 75 days followed by a natural photoperiod. Goats of group 1 were treated for 11 days with 20 mg of fluorogestone acetate (FGA) combined to 300 IU of eCG and 50 µg of cloprostenol injected 48 h prior to FGA-removal. Goats of group 2 and 3 were subjected to the same treatments, but eCG injection was replaced by a sexually active buck introduced 0 (group 2) or 48 hours (group 3) before FGA-removal. During the AS, 77% of goats induced by the BE showed an oestrus at [60–74] hr following FGA-removal for group 3 and [71–77] hr for group 2 (p < .05). In group 1, 77% of goats displayed an LH surge [24–40] hr after FGA-removal and 67% developed a luteal phase, but no LH surge or luteal response was detected in groups 2 and 3. During the BS, oestrus response reached 100% in goats synchronised with the BE ([22–68] hr in groups 2 and 3). In all groups, 84% of the goats displayed an LH surge at [30–70] hr post-treatment and 69% displayed luteal phase within 3–8 days post-treatment. After 11–15 days, the occurrence of ovulations followed by normal luteal phase was raised in all groups (91%). It was concluded that photostimulated bucks failed to induce and synchronise ovulation in goats previously treated with 20 mg of FGA and 50 µg of cloprostenol during anoestrus. Highlights The response to the buck effect was studied in Beni Arouss goats during anoestrus and breeding season. The use of sexually active bucks to induce and to synchronise oestrus and ovulation in goats treated with 20 mg of FGA and cloprostenol during the anoestrus season is not efficient in comparison with an hormonal treatment based on administration of FGA, eCG and cloprostenol. The same protocol appears as an adequate alternative for oestrus and ovulation synchronisation during the breeding season.