Nisin as a Novel Feed Additive: The Effects on Gut Microbial Modulation and Activity, Histological Parameters, and Growth Performance of Broiler Chickens

Simple Summary In an era with an increasing number of antibiotic-resistant bacteria strains, there is a need to find a novel and efficient alternative to the antibiotics commonly used in animal nutrition. As natural proteins synthesized by most known bacteria, bacteriocins are considered future candidates. To date, nisin (E234), the best-known bacteriocin, is used as a preservative against food-borne pathogens such as Listeria monocytogenes in the food industry. However, there are scarce data about the application of nisin in the diet of livestock, including poultry. In this study, we evaluated the effect of nisin in broiler chicken diets on selected microbial populations, the activities of which are related to gastrointestinal health, growth performance, and gut histomorphology. We found that nisin application positively affects the feed conversion ratio and exerts a similar effect as the ionophore coccidiostat monensin in the case of microbiota modulation. Additionally, nisin supplementation decreased microbial fermentation in the jejunum. No changes in ileal histomorphology or internal organ weights were noted. We conclude that nisin may be considered a natural and safe antimicrobial agent and growth promoter in broiler chicken nutrition. Abstract Two independent experiments were performed to evaluate the effect of nisin alone or with monensin on gut microbiota, gut microbial activities, and histomorphology (exp 1) and the effect of nisin application in a doseresponse manner on the growth performance of broiler chickens (exp 2). A total of 900 one-day-old female Ross 308 chicks (400, exp 1; 500, exp 2) were randomly distributed to four groups (exp 1; 10 replicate pens per treatment with 10 birds each), i.e., NA, no additives; MON, monensin (100 ppm); NIS, nisin (2700 IU/kg diet); and MON + NIS, a mixture of monensin (100 ppm) and nisin (2700 IU/kg diet); or 5 treatments (exp 2), NA, no additives; NIS100, nisin (100 IU/kg diet); NIS200, nisin (200 IU/kg diet); NIS400, nisin (400 IU/kg diet); and NIS800, nisin (800 IU/kg diet). Nisin supplementation positively affected the microbiota of the gut by reducing potentially pathogenic bacterial populations in the jejunum and ceca. The bacterial fermentation in the jejunum was significantly lowered by nisin addition. The addition of nisin from 100 IU to 800 IU decreased the FCR value over the entire experimental period. According to the results, nisin can be considered a natural dietary supplement for broiler chickens.