Dietary Encapsulated Essential Oils Improve Production Performance of Coccidiosis-Vaccine-Challenged Broiler Chickens

SIMPLE SUMMARY: The in-feed antibiotics have been banned worldwide, and anticoccidial drugs are also expected to be removed from the formulated, complete feeds. Thus, looking for alternatives to anticoccidials has been on the increase. Essential oils are naturally derived substances containing the aromatic components of herbs and spices and exhibit antibacterial/anticoccidial, antioxidant, and immune modulating-effects, the properties in poultry. These beneficial biological properties of essential oils make them be considered potential anticoccidial agents. Forthermore, encapsulating essential oils is known to be an effective and efficient strategy to slowly release their active components upon passing the gastrointestinal tract. This study was conducted to examine the effects of encapsulated thymol- and carvacrol-based essential oils on productivity and gut health of chickens challenged with high dose of coccidiosis vaccine. ABSTRACT: The present study was conducted to evaluate the encapsulated essential oils (EEO) as an alternative to anticoccidials using a coccidiosis vaccine challenged model in broiler chickens. A total of 600 one-day-old male broiler chicks were provided with no added corn/soybean-meal-based control diet or diets that contained either salinomycin (SAL) or thymol- and carvacrol-based EEO at 60 and 120 mg per kg of diet. Before challenge at 21 days, each treatment had 10 replicates except for the no-added control group, which had 20 replicates. On day 21, half of the control groups were orally challenged with a coccidiosis vaccine at 25 times higher than the recommended vaccine dose. During 22 to 28 days (i.e., one-week post coccidiosis vaccine challenge), the challenged chickens had a decrease (P < 0.05) in body weight gain and feed intake but an increase in feed conversion ratio compared with the non-challenged, naïve control chickens. However, dietary EEO significantly counteracted (P < 0.05) coccidiosis-vaccine-induced depression in body weight gain and feed intake. Inclusion of dietary EEO linearly decreased (P < 0.05) the concentrations of the volatile fatty acids. Dietary SAL and EEO affected gut morphology in chickens at 20 days post-hatch. Dietary EEO linearly (P = 0.073) increased serum catalase activity as the inclusion level increased. Collectively, our study shows that dietary EEO increased coccidiosis-vaccine-induced growth depression and altered gut physiology in broiler chickens. Our study adds to the accumulating evidence that dietary EEO is proven to be an effective alternative to anticoccidials for broiler chickens.