A field study on Citrus aurantium L. var. dulcis peel essential oil and Yucca schidigera saponins efficacy on broiler chickens health and growth performance during coccidiosis infection in rural free-range breeding system

•Yucca schidigera saponins and Citrus aurantium oil reduce the coccidia shedding.•Yucca schidigera saponins and Citrus aurantium oil reduce coccidiosis gut lesions.•Yucca schidigera saponins and Citrus aurantium oil improve broiler chickens' growth. Avian coccidiosis caused by Eimeria spp. is a relevant disease for poultry usually prevented by synthetic coccidiostats. Citrus aurantium L. var. dulcis peel essential oil (CEO), and Yucca schidigera’s saponins (Ys) were tested as valid natural alternatives to coccidiostats drugs. Their anticoccidial effects, gut health and growth performance of broiler chickens were investigated with discovery-driven research by a field trial during the broiler chicken production cycle in a rural free-range farm with a history of coccidiosis infection. One hundred forty 1-d-old female broiler chickens were assigned to 4 experimental treatment groups (35 broiler chicks each), fed ad libitum with a coccidiostats-free diet, during 9 wk of the trial (63 d). The treatment groups included: control (C); CEO (1 ml/L); Ys pure extract (0.05 ml/L); and CEO + Ys (CEO 1 ml/L + Ys 0.05 ml/L), administered by drinking water. Fecal coccidia oocyst count (OPG), and growth performance were evaluated weekly. On wk 9 all broiler chickens were slaughtered, and serum biochemical indices and intestinal lesions were histologically evaluated and scored. Results showed that from the 6th to 9th wk, the treated groups had lower OPG than the C group (P < 0.05), with the lower value observed in the CEO and Ys groups. More severe coccidiosis intestinal lesions attributable to E. maxima were detected in the C group. All chickens showed a variable degree of intestinal lymphoplasmacytic and heterophilic inflammation without differences in the histological and intestinal lesion scores. At the end of the trial, the body weight (BW) was greater in the treated groups compared to the C group (P < 0.05). However, no differences in FI, WDI, FCR, mortality, and organ weights were evidenced. Albeit within the physiological range, serum AST, cholesterol, total proteins, albumin, and P were higher in the Ys group (P < 0.05), compared to the C group, which was also observed in the CEO + Ys group for the cholesterol, total protein and albumin content. The CEO and Ys biologically active metabolites, even if taken in moderate concentrations, can help to reduce the OPG and gut damage during the coccidia infection, improving the broiler chicken's growth performance.