Effect of yeast with bacteriocin from rumen bacteria on growth performance, caecal flora, caecal fermentation and immunity function of broiler chicks

The aim of the current study was to investigate the effects of bacteriocin of Ruminococcus albus 7 that is expressed by yeast on growth performance, caecal flora, caecal fermentation and immunity function of broilers. A total of 180, one-day-old healthy broiler chicks were randomly divided into three groups: control, bacteriocin (2.5 g/kg feed) and nosiheptide (NHT) (2.5 mg/kg, as antibiotic control). Growth performance, caecal flora, caecal fermentation products and immunoglobulin (Ig) concentration were determined when chicks were 21 and 35 days old. The gene expression of avian beta-defensin (AvBD) and mucin (MUC2) were measured at 35 days old. The supplementation of bacteriocin and NHT had no significant effect on body weight gain (BWG) during the experimental period. Bacteriocin supplementation significantly enhanced the growth of Lactobacillus (P < 0.05) and resulted in higher lactate concentration (P < 0.01) in broiler caeca at 21 days old. Both bacteriocin and NHT supplementation resulted in lower Escherichia coli (P = 0.072) and Enterococcus (P = 0.038) counts than in the control group at 35 days old. The bacteriocin treatment group tended to increase bile IgA and showed higher bile IgA than the NHT treatment group (P = 0.059) at 35 days old. Higher levels of AvBD1, AvBD4 and MUC2 gene expression were observed in the NHT treatment group (P < 0.05), but expression of AvBD9 was significantly decreased in both bacteriocin and NHT treatment groups (P < 0.05). In conclusion, bacteriocin supplementation elevated the caecal Lactobacillus counts and affected the immunity function. These benefits suggested that bacteriocin supplementation could be a potential alternative to antibiotics in broiler feed.