Effects of Microencapsulated Organic Acids and Essential Oils Blend and Protease Supplementation on the Growth Performance and Gut Health of Broiler Chickens

The present study aimed to investigate the effect of microencapsulated organic acids and essential oils blend and protease supplementation on growth performance and gut health of broilers fed high levels of wheat grain and corn DDGS diets. A total of 1,750 male Ross 308 broilers chicks were randomly assigned to 5 treatments with 14 replicates of 25 birds using a completely randomized design study. The treatments were: 1) corn–soybean meal basal diet (CS); 2) CS with wheat grain and corn distiller’s dried grain basal diet (WD); 3) WD with a microencapsulated organic acids and essential oils blend supplement at 300 mg/kg (EOA); 4) WD with protease supplement at 125 mg/kg (PRO); and 5) WD with EOA and PRO (EOA + PRO). Gut morphology, tight junction (TJ) mRNA expression in the jejunum, and cecal microbial metabolites were measured. From d 1-35, the feed intake and feed conversion ratio (FCR) increased (P < 0.01) in the WD group. However, birds fed the PRO + EOA diet had a similar FCR to that of the CS group (P ˃ 0.05). At d 35, the TJ mRNA gene expression of claudin-1 was upregulated (P < 0.01) in the EOA group, while occludin mRNA gene expression was upregulated (P < 0.01) in the PRO and EOA groups compared to the CS and WD groups. At d 35 of age, the crypt depth and villus height:crypt depth ratio were decreased and increased (P < 0.01), respectively, in the PRO and EOA groups compared to the CS and WD groups. Birds fed WD diets had higher (P < 0.01) ammonia, cadaverine and putrescine levels than those fed the CS diet. The CS group had cecal putrescine similar to those of the PRO, EOA and PRO + EOA groups. Dietary supplementation of EOA produced a synergistic effect with protease by decreasing putrefactive proteins in the lower gut. These factors may reduce the negative effects of corn distiller’s dried grain and wheat grain on the gut health of broilers.