Effects of dietary water-soluble extract of rosemary supplementation on growth performance and intestinal health of broilers infected with Eimeria tenella.

This study was conducted to explore the effect of dietary supplementation of water-soluble extract of rosemary (WER) on growth performance and intestinal health of broilers infected with Eimeria tenella (E. tenella), and evaluate the anticoccidial activity of WER. 360 one-day-old Chinese indigenous male yellow-feathered broiler chickens were randomly allocated to six groups: blank control (BC) group and infected control (IC) group received a basal diet; positive control (PC) group, received a basal diet supplemented with 200 mg/kg diclazuril; WER100, WER200, and WER300 groups received a basal diet containing 100, 200, and 300 mg/kg WER, respectively. On d 21, all birds in the infected groups (IC, PC, WER100, WER200 and WER300) were orally gavaged with 1 mL phosphate-buffered saline (PBS) of 8×104 sporulated oocysts of E. tenella, and birds in the BC group were administrated an aliquto of PBS dilution. The results showed that dietary supplementation of 200 mg/kg WER increased average daily gain (ADG) of broilers compared to the IC group from d 22 to d 29 (P < 0.001). The anticoccidial index values of 100, 200 and 300 mg/kg WER were 137.49, 157.41 and 144.22, respectively, which indicated that WER exhibited a moderate anticoccidial activity. Compared to the IC group, the groups supplemented with WER (100, 200 and 300 mg/kg) significantly lowered fecal occyst output (P < 0.001) and cecal coccidia oocysts, alleviated intestinal damage and maintained the integrity of intestinal epithelium. Dietary supplementation with WER significantly improved antioxidant capacity, elevated the levels of secretory immunoglobulin A, and diminished inflammation within the cecum, particularly at a dosage of 200 mg/kg. The results of this study indicated that dietary supplementation with 200 mg/kg WER could improve broiler growth performance and alleviate intestinal damage caused by coccidiosis.