β-1,3-Glucan, Precision Biotic, and Bacillus subtilis as Antibiotic Growth Promoter Alternatives: Effects on Broiler Performance, Gut Morphology, and Serum Biochemistry

The objective of the current study was to compare β-1,3-glucan, glycan-based precision biotic (PB), and Bacillus subtilis as alternatives to antibiotic growth promoters (AGPs) on gut morphology, nutrient utilization, blood biochemical parameters, and performance of broilers.For this purpose, a total of 500 one-dayold broiler chicks were randomly assigned to five experimental treatments, with 10 replicates of 10 birds each.Experimental birds were reared on a basal diet without AGP (CON) or the basal diet supplemented with AGP (100 g/ton), β-1,3-glucan (300 g/ton), a glycan-based PB (250 g/ton), and Bacillus subtilis (500 g/ton) in the diet.In the grower, finisher and overall phases, higher body weight, body weight gain and an improved (lower) FCR were observed in birds fed diet supplemented with PB (P<0.05).Similarly, the nutrient digestibility results showed that the highest digestibility was observed in birds fed a diet supplemented with PB (P<0.05).Moreover, the intestinal histology results showed that PB supplementation in diet increased villus height and goblet cell count in the jejunum and ileum (P<0.05).Similarly, PB dietary supplementation increased villus height, villus width, and crypt depth in duodenum (P<0.05).The results showed that supplementation with AGPs, and AGP alternatives positively influenced blood metabolites; total protein and albumin were highest in the PB group, while AST was lowest in the PB and β-1,3-glucan groups (P<0.05).Based on the results, it is concluded that AGP generally, while PB specifically, exhibited consistent positive responses on performance, nutrient digestibility, intestinal histology and blood biochemical indices in broilers.