Evaluation of salinomycin for an extended period in laying replacement hens

The clinical efficacy of salinomycin premix (Pisacox®) administered in feed to replacement pullets to control coccidiosis was evaluated by dosing during 4 or 14 weeks. The productive performance, signs, and lesions associated with coccidiosis and direct oocyst counts were analyzed in 3 000 Bovans White pullets distributed in 3 groups of 1 000 birds having the same diet: control group (Ctrl) without coccidiostat; Sal4 group with the administration of salinomycin for 4 weeks; and Sal14 group that received salinomycin for 14 weeks. Predictably, in both Sal4 and Sal14 treatments, lower oocyst counts than in the control were observed. However, it was more evident with Sal14 towards the end of the trial, whose oocyst count was < 5 000 g of feces. This response can be associated with better productivity variables. The coccidial-type intestinal lesions detected in control were classified as severe (2.55), while Sal4 and Sal14 presented values of 1.0 and 0 (mild lesions and normal appearance, respectively). The accumulated mortality associated with coccidiosis was statistically higher in the Ctontrol group (9.8 %) (P < 0.001), 1.33 % for Sal4, and 0.2 % for Sal14 (P < 0.05, between these two groups). In conclusion, using salinomycin for 4 weeks successfully controls clinical coccidiosis. However, the lower rate of coccidiosis, the improvement in productive variables, and the lower accumulated mortality in Sal14 allow for the proposal of including the treatment with salinomycin for 14 weeks in replacement pullets.