Application of Organic Acids and Essential Oils as Alternatives to Antibiotic Growth Promoters in Broiler Chickens

Simple Summary It is essential to find alternatives to antibiotic growth promoters (AGP) after the restriction of AGP in the broiler industry. Organic acids (OAs) and essential oils (EOs) are considered promising alternatives to AGP to improve the growth performance and gut health of chickens due to their strong antimicrobial and antioxidant effects. In this study, OAs, EOs and their combinations were evaluated as AGP alternatives in broiler chickens. The supplementation of EOs improved feed efficiency in the starter phase compared to the control group, and the supplementation of OAs enhanced feed efficiency in the finisher phase compared to the control group with AGP. Hence, the supplementation of EOs and OAs could be potential AGP alternatives in the starter and finisher phase of broiler production, respectively. This study was conducted to evaluate the effects of OAs and EOs on growth performance, serum biochemistry, antioxidant enzyme activities, intestinal morphology, and digestive enzyme activities to replace AGP in broilers. Six hundred one-day-old broilers were allotted to five treatments with six replicates: (1) negative control (NC; basal diet); (2) positive control (PC; NC + 50 mg/kg bacitracin methylene disalicylate); (3) organic acids (OA; NC + 2000 mg/kg OA); (4) essential oils (EO; NC + 300 mg/kg EO); and (5) OA + EO (NC + 2000 mg/kg OA + 300 mg/kg EO). In the starter phase, the PC, EO, and OA + EO groups had a significantly lower feed conversion ratio (FCR) compared to the NC group. While the final body weight (BW) of broilers fed OAs was similar compared to broilers fed PC (p > 0.1), the FCR of the OA group tended to be lower than the PC group on D 42 (p = 0.074). The OA group had the higher serum GLOB:ALB (albumin) and ileal villus height and crypt depth (VH:CD) ratios compared to the EO group. Thus, the supplementation of EOs and OAs could substitute AGP in the starter and finisher phase, respectively.