Effects of replacing commercial zinc bacitracin with insect meal (Macrotermes subhylanus) on caeca bacteria composition, haematology, and growth performance in commercial broiler chicks at the starter phase

Abstract

The effects of Macrotermes subhylanus meal as a substitute for zinc bacitracin on the composition of caecal bacteria, haematology, and performance parameters were evaluated in broiler chicks during the starter phase. Three isoproteic and isoenergetic diets, NC (negative control; basal diet only), PC (positive control; basal diet with 0.05 g of zinc bacitracin per kg DM) and InsecM (basal diet with 100 g of insect meal per kg DM), were used in this study. A total of 150 one-day-old broiler chicks were randomly assigned to each of the 3 treatments, with 10 chicks per replicate and 5 replicates per treatment in a completely randomised design. Data on bacterial composition, apparent nutrient digestibility, blood profiles, and growth parameters were measured on day 14 and analysed using DADA2 and SAS software for statistical purposes. The results revealed that Firmicutes was the predominant (P < 0.05) phylum, proportionate to Actinobacteriota, Bacteroidota, Cyanobacteria, Proteobacteria, Verrucomicrobiota, and Vertebrata in chicks fed an InsecM diet compared to those on NC and PC diets. Furthermore, the NC diet reduced (P < 0.05) apparent dry matter (83.2%) and crude protein, while crude fibre digestibility (75.62%) was significantly lower in the InsecM diet. The apparent crude protein (CP) digestibility on the InsecM diet was significantly improved (86.24%) when compared to the NC and PC diets. Plasma enzyme alanine aminotransferase was also significantly reduced by an InsecM diet (0.87 U/L). However, uric acid (0.27 mmol/l) was elevated (P < 0.05) in chicks fed an InsecM diet. Body weight gain (483.28 g/bird) and the feed conversion ratio (1.12) were improved in chicks fed the InsecM diet. It is concluded that broiler chicks on a diet containing 100 g of M. subhylanus meal per kg DM and those on a diet with 0.05 g zinc bacitracin improved caecal bacterial composition, CP digestibility, and growth performance, without causing negative effects on the birds' metabolic pathways and health status. Nonetheless, further studies are encouraged to confirm these findings.