A Multi-Component Protease Alone or Combined with a Protected Blend of Organic Acids and Essential Oils on Measures of Gut Health and Performance in Broilers Fed Low-Digestible Diets

The increasing prices of major feed ingredients have prompted animal nutritionists to use inexpensive raw materials in their diet formulations to lower feed cost. However, due to their relatively lower digestibility, diets formulated with these raw materials often lead to poor gut health status and animal performance. For instance, poor protein digestibility results in the formation of toxic metabolites that can impair gut health and subsequently confer negative effects on broiler performance (Qaisrani et al., 2015; Apajalahti and Vienola, 2016).

A study was conducted to investigate the effects of a multi-component protease alone or in combination with a micro-encapsulated blend of organic acids and essential oils on the growth performance and gut health of broilers fed low-digestible feed ingredients. A total of 1400-one-day-old Ross 308 male broiler chicks, in a completely randomized design study were assigned to receive 1 of 4 dietary treatments: 1) Positive control (corn-soybean meal-based diet, PC), 2) Negative control (corn-wheat-soybean meal-corn DDGS-based diet, NC), 3) NC + 125 g/t protease (NC+PRO), 4) NC + 125 g/t protease + 300 g/t micro-encapsulated organic acids and essential oils (NC+PRO+EOS). All diets were formulated to be iso-caloric and isonitrogenous following the recommendations of the breeder company. Each treatment consisted of 14 replicates with 25 birds per replicate. All chicks were provided feed and water ad libitum for 35 days. Growth performance, gene expression of jejunal tight junction proteins, and caecal fermentation metabolites were determined at the end of the study. Data were subjected to ANOVA using the PROC GLM procedure of SAS and differences between means were determined using Duncan’s multiple range test. At 35 d, body weight gain was similar among treatment groups, but birds fed diets with low-digestible feed ingredients (NC, NC+PRO, and NC+PRO+EOS) had significantly higher feed intake (P < 0.05) than birds fed the PC diet. Consequently, feed conversion ratio (FCR) was significantly increased in NC as compared with PC (1.529 vs. 1.466). In terms of the gene expression of the tight junction proteins, occludin and claudin-1 genes were upregulated (P < 0.05) in birds fed the NC+PRO and NC+P+EOS, respectively, as compared to PC and NC. Caecal ammonia was significantly increased in all diets with low-digestible feed ingredients (NC, NC+PRO, NC+PRO+EOS) relative to PC, but caecal putrescine and cadaverine in NC only was significantly increased as compared to PC, NC+PRO, and NC+PRO+EOS. Overall, feeding broiler chickens with diets containing low-digestible feed ingredients negatively affected feed efficiency, intestinal integrity, and concentrations of protein fermentation metabolites in the caecum. On the other hand, the supplementation of a multi-component protease alone or in combination with a microencapsulated blend of organic acids and essential oils alleviated some of these negative effects and offered positive benefits on measures of gut health.