Antimicrobial Effects of Plant-Based Supplements on Gut Microbial Diversity in Small Ruminants

Abstract

Every year in the United States, approximately 48 million people are affected by bacterial illnesses that are transmitted through food, leading to 3000 fatalities. These illnesses typically stem from food animals and their by-products, which may harbor dangerous pathogens like Salmonella enterica, Listeria monocytogenes, enterohemorrhagic Escherichia coli O157:H7, and Campylobacter jejuni. Factors that contribute to contamination include manure used as a soil amendment, exposure to polluted irrigation water, and contact with animals. To improve food safety, researchers are studying pre-slaughter intervention methods to eliminate bacterial contamination in live animals. While small ruminants are vital to global agriculture and income generation for small farms, traditional feeding practices involve supplements and antibiotics to boost performance, which contributes to antibiotic resistance. Hence, researchers are looking for friendly bacterial strains that enhance both animal and human health without impacting livestock productivity. The global trend is to minimize the use of antibiotics as feed supplements, with many countries prohibiting or limiting their use. The aim of this review is to provide a comprehensive insight on the antioxidant capabilities, therapeutic attributes, and applications of bioactive compounds derived from sweet potato tops (SPTs), rice bran (RB) and radish tops (RTs). This overview provides an insight on plant parts that are abundant in antioxidant and prebiotic effects and could be used as value-added products in animal feed and pharmaceutical applications. This review was based on previous findings that supplementation of basal diets with natural supplements represents a multifaceted intervention that will become highly important over time. By remarkably reducing the burden of foodborne pathogens, they apply to multiple species, are cheap, do not require withdrawal periods, and can be applied at any time in food animal production.

Keywords: antimicrobial resistance; dietary supplements; microbial diversity; microbiome; pre-slaughter intervention.

Figure 1

The selection of “traditional” food safety interventions before slaughter incorporates emerging food safety issues, including antibiotic replacement, genome sequencing of microbiomes and cost–benefit analysis. (1) Preparation of plant-derived supplements. Extraction involves a steam distillation process in the case of essential oils or grinding into powder for crude extracts. (2) Supplements may be mixed in feed or drinking water for easy administration. (3) Fecal and ruminal sample collection. (4) Morphological identification of bacteria, (5) Molecular identification of bacteria and genome sequencing of marker genes. (6) Microbiome data analysis.

Figure 2

The mechanism of the plant-based supplements as interventions in the gut microbiota when used individually or synergistically with probiotic supplements. Bioactive elements in plant extracts together with probiotics promote the proliferation of beneficial bacteria while suppressing colonization by pathogenic bacteria (e.g., competitive exclusion). Beneficial bacteria enhance gut barrier integrity, promote the degradation of dietary fiber and the overall balance between the intestinal microbiome and produced metabolites, including short-chain fatty acids (SCFAs).