The cactus effect: an alternative to the lupin effect for increasing ovulation rate in sheep reared in semi-arid regions?

The present study evaluated the effects of supplementation with cactus cladodes on follicular dynamics and ovulatory response of sheep reared in semi-arid areas. A total of 76 ewes were distributed into two equal groups supplemented with either concentrated feed or cactus cladodes. After 30 days of supplementation, no differences were found between feeding regimens on the final live weight (LW; 41.5 ± 0.6 and 42.1 ± 0.7 kg in the Concentrate and Cactus groups respectively) and body condition score (BCS; 1.8 ± 0.3 and 1.8 ± 0.4 for Concentrate and Cactus group respectively). Moreover, no differences were found between the initial and the final values of both LW and BCS; thus, there were no effects of supplementation on any of both parameters. Analysis of follicular population showed that, during the follicular phase induced by ram effect, the number of follicles reaching ovulatory size increased in both groups. However, the number was always higher in Cactus ewes and, at oestrus, Cactus ewes had 1.6 ± 0.2 and Concentrate sheep had 1.2 ± 0.2 large follicles (p < 0.05). Thereafter, ovulation rate was affected by duration of supplementation; being higher in sheep fed with cactus for 6-10 days (1.7 ± 0.1) than in ewes supplied with cactus for more than 11 days (1.3 ± 0.1; p < 0.05), in sheep fed with concentrate for 6-10 days (1.2 ± 0.1; p < 0.01) and even than in individuals subjected to classical flushing with concentrate (1.3 ± 0.1; p < 0.05).