Nisin and monensin affect rumen and colon fermentation and microbiota differently in fattening Hu sheep

Hongwei Duan¹^,², Jun Jiang¹^,², Han Zhang¹^,², Lu Li¹^,², Jiazhi Luo¹^,², Junshi Shen¹^,²^,^*, Shengyong Mao¹^,², Weiyun Zhu¹^,², Zhongtang Yu³

¹*Laboratory of Gastrointestinal Microbiology, National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing 210095, China.

²†Ruminant Nutrition and Feed Engineering Technology Research Center, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.

³§Department of Animal Sciences, The Ohio State University , Columbus OH 43210, United States.

^*Corresponding Author: Junshi Shen, *Laboratory of Gastrointestinal Microbiology, National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing 210095, China. †Ruminant Nutrition and Feed Engineering Technology Research Center, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China. E-mail: shenjunshi@njau.edu.cn.

© Copyright 2025 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Mar 17, 2025; Revised: Jun 10, 2025; Accepted: Jul 08, 2025

Published Online: Aug 19, 2025

Abstract

Nisin, a well-established bacteriocin utilized in the food industry, has been recognized as a potential substitute for monensin in livestock applications. This study aims to evaluate and compare the effects of nisin and monensin supplementation on ruminal and colonic microbiota and their fermentation profiles in fattening Hu sheep. Thirty-six male Hu sheep (23.5 ± 1.0 kg) were assigned to one of three dietary treatments using a randomized block design. The treatments included: (1) a control group receiving a basal diet (CON); (2) the basal diet supplemented with 40 mg/kg dry matter (DM) of monensin (MON); and (3) the basal diet supplemented with 274.5 mg/kg DM of a nisin (NIS). The trial lasted for 9 weeks. At the end of the experiment, one sheep from each pen (18 sheep in total) was randomly selected for humane slaughter, and rumen and colon content samples were collected for the analysis of fermentation products and microbiota composition. The inclusion of NIS and MON did not impact the final slaughter performance or rumen development in Hu sheep. NIS supplementation resulted in a decrease in the populations of total bacteria, fungi, and methanogens, while simultaneously increasing the abundance of specific fiber-degrading bacteria, such as those within the family <italic>Ruminococcaceae</italic>, compared to the CON group. However, NIS did not alter the structure or abundance of individual bacterial taxa in the colon. While NIS showed no notable effect on rumen fermentation, it exerted a marked influence on fermentation in the colon. Conversely, MON led to a reduction in the abundance of Gram-positive bacteria, such as Firmicutes, while increasing the prevalence of Gram-negative bacteria, including Bacteroidetes and Proteobacteria, in the rumen; these effects were even more pronounced in the colon. As a result, the addition of MON influenced fermentation processes in both the rumen and the colon. In conclusion, NIS supplementation significantly impacted the rumen microbiota and colonic fermentation in Hu sheep, with its primary effects observed in the rumen. In contrast, MON influenced both the rumen and colonic bacterial communities, demonstrating a notably more pronounced effect on the colonic microbiota.

Keywords: Nisin; monensin; Fattening Hu Sheep; Rumen and Colon Fermentation; Microbiota