Lan Yang

Enterotoxigenic Escherichia coli (ETEC) remains a leading cause of neonatal diarrhea in piglets, calves, and lambs, yet antibiotic curtailment demands nutrition-based solutions. This review takes a novel barrier-centric perspective to evaluate how yeast culture mitigates neonatal livestock diarrhea caused by ETEC. Unlike previous probiotic or prebiotic reviews, this review focuses specifically on multifaceted components of yeast culture and map their protective effects on each intestinal barrier layer. Across challenge and field studies, yeast culture supplementation reduced neonatal diarrhea incidence relatively by up to 40% to 60% and improved weight gain, highlighting its practical efficacy. Consistent biological correlates include preserved tight junction protein expression and epithelial permeability, thicker mucus and higher goblet-cell count, increased mucosal secretory immunoglobulin A (sIgA) with tempered cytokine responses, and microbiota shifts toward colonization enhanced colonization resistance and short-chain fatty acid production, thereby collectively fortifying the gut against ETEC adhesion and toxin-induced damage. Despite these promising outcomes, challenges remain in optimizing yeast formulation and dosage, and further research is needed to address gaps in species-specific application and long-term efficacy. Overall, yeast culture may provide a multi-target, antibiotic-free strategy to reduce ETEC-associated diarrhea by restoring barrier function and microbiota homeostasis.

Yeast culture is a safe and environmentally friendly nutritional supplement that improves the antioxidant capacity, immune function, and intestinal health of monogastric animals. This study explored the effects of compound yeast culture and yeast source on the antioxidant capacity, immune function, and intestinal microflora of weaned lambs. Eighteen weaned lambs were randomly assigned to the basal diet (NYC), basal diet supplemented with yeast source (40 g/day; DYC), and basal diet supplemented with compound yeast culture (50 g/day; GYC) groups. There where six replicates per group and one lamb per replicate. The experiment lasted 42 d. The DYC and GYC groups exhibited significantly increased villus height and villus height-to-crypt depth ratio (P < 0.05), and the DYC group had reduced crypt depth (P < 0.05); both exhibited significantly increased glucagon-like peptide-2, Insulin-like growth factor 1, and mucin 2 mRNA expression, as well as serum total anti-oxidizing capability, glutathione peroxidase, total superoxide dismutase, and catalase activities (P < 0.05). The DYC and GYC groups exhibited significantly increased acid phosphatase (ACP) activity (P < 0.05), immunoglobulin G content, secretory immunoglobulin A content, and interleukin-10, transforming growth factor beta, B-cell activating factor, A proliferation-inducing ligand (APRIL), Chemokine ligand 25, Inducible NO synthase, and poly(lactic-co-glycolic acid) (plgA) mRNA expression (P < 0.05). The GYC group had significantly increased ACPcontent and APRIL and plgA mRNA expression (P < 0.05). Jejunal microbial markers in the DYC and GYC groups positively correlated with intestinal barrier-related indicators. In conclusion, the compound yeast culture and yeast source equally showed improved antioxidant capacity, immune function, and intestinal health in weaned lambs.

Microecological preparations exert beneficial effects on the health of young ruminant animals; however, the mechanism is unclear. As a result, the present study analyzed the effects of yeast cultures on the growth properties, microbiome, and metabolism of weaned lambs. In this study, a total of 20 weaned lambs were randomly, stochastically divided into four teams: the control group (Group A) were fed a basic diet; Group B were fed with Saccharomyces cerevisiae BC strain culture (30 g/head/d); Group C were fed with Kluyveromyces marquez XR4 strain culture (30 g/head/d); Group D were fed with a composite culture of the two yeast strains (30 g/head/d). The study lasted for 40 days, with daily records of lamb feed intake and weight. Lamb feces were collected regularly for metagenomic sequencing and metabolomics analysis. The average daily weight gain and average daily yield of Group D lambs were significantly higher than those of Group A lambs (p < 0.01). The feed utilization rate in the yeast-fed groups was considerably higher than in the control group (p < 0.05), indicating that the addition of yeast crops to lamb feed might improve lamb feed performance. Bacteroides and the mTOR signaling pathway were dramatically enriched in the intestines of weaned lambs in the yeast-culture-fed groups, and their expression levels of ketones and benzoic acid compounds were significantly upregulated. These results indicated that yeast culture had excellent effects on weaned lambs in regulating immunological functioning and the intestinal environment, protecting the enteric mucosal barrier, improving digestion and nutritional absorption, and enhancing antioxidant function. In summary, adding yeast culture to weaned lamb feed can generate a positive effect on its productivity performance and gut health. These findings provide novel insights into promoting the health of young ruminants.