Lactic Acid Bacteria and Bacteriocins in Feed Preservation: Mechanisms and Antifungal Properties

Abstract

Ensilage consists of the fermentation of sugars to lactic acid independent of the forage by epiphytic microorganisms, lactic acid bacteria (LAB), which vary in number and composition during fermentation. Silage is a means of preserving forage for extended periods of time when fresh forage is limited or seasonally unavailable, and its inadequate fermentation and poor feed management favour the proliferation of pathogens and contribute to silage spoilage. LAB is a group of microorganisms widely distributed in nature, with lactic acid as the main metabolite produced after sugar fermentation. Some LAB produce antimicrobial peptides with low toxicity and proteinaceous nature, known as bacteriocins, which have a broad spectrum of activity against Gram-positive and Gram-negative bacteria, protozoa, fungi, and viruses and can therefore be effective in silage preservation. Among those species, fungal growth leads to nutrient and dry matter losses, reduced palatability, reduced silage intake and consequently reduced animal performance. While laboratory studies provide compelling evidence of their antifungal properties, the practical application of LAB in silage systems must be evaluated with an understanding of the complexities of real-world conditions. LAB inoculants primarily enhance silage quality by driving acidification and promoting a desirable fermentation profile. While bacteriocins can provide an additional layer of microbial control, their efficacy is best realised when combined with proper management practices. This integrated approach ensures that the conditions for optimal fermentation are maintained, allowing LAB to exert their beneficial effects effectively. However, the complexities of silage fermentation necessitate a broader perspective that includes environmental management and forage quality. LAB and bacteriocins are valuable tools, but their success depends on their integration into a comprehensive silage management strategy.