Due to antimicrobial properties,
nisin is one of the most commonly used and investigated
bacteriocins for food preservation. Surprisingly,
nisin has had limited use in animal feed as well as there are only few reports on its influence on microbial ecology of the gastrointestinal tract (GIT). The present study therefore aimed at investigating effects of dietary
nisin on broiler chicken GIT microbial ecology and performance in comparison to
salinomycin, the widely used
ionophore coccidiostat. In total, 720 one-day-old male Ross 308 chicks were randomly distributed to six experimental groups. The positive control (PC) diet was supplemented with
salinomycin (60 mg/kg). The
nisin (NI) diets were supplemented with increasing levels (100, 300, 900 and 2700 IU
nisin/g, respectively) of the
bacteriocin. The negative control (NC) diet contained no additives. At slaughter (35 days of age), activity of specific bacterial
enzymes (α- and β-
glucosidases, α-
galactosidases and β-
glucuronidase) in crop, ileum and caeca were significantly higher (P<0.05) in the NC group, and
nisin supplementation decreased the
enzyme activities to levels observed for the PC group. A similar inhibitory influence on bacterial activity was reflected in the levels of
short-chain fatty acids (SCFA) and putrefactive SCFA (PSCFA) in digesta from crop and ileum; no effect was observed in caeca. Counts of Bacteroides and Enterobacteriacae in ileum digesta were significantly (P<0.001) decreased by
nisin and
salinomycin, but no effects were observed on the counts of Clostridium perfringens, Lactobacillus/Enterococcus and total bacteria. Like
salinomycin,
nisin supplementation improved broiler growth performance in a dose-dependent manner; compared to the NC group, the
body weight gain of the NI₉₀₀ and NI₂₇₀₀ groups was improved by 4.7 and 8.7%, respectively. Our findings suggest that dietary
nisin exerts a mode of action similar to
salinomycin and could be considered as a dietary supplement for broiler chickens.