Mastitis is an inflammatory disease, affects the dairy industry and has a severe economic impact. During subclinical mastitis, milk production and milk quality deteriorates. Recently, rumen microbial composition has been linked to rumen health, but few studies have investigated the effect of rumen microbiota on mammary health in cows. This study was undertaken to identify the rumen microbial composition and associated microbial fermentation in cows with different somatic cell counts (SCC), with the speculation that cows with different health statuses of the mammary gland have different rumen bacterial composition and diversity. A total of 319 Holstein dairy cows fed the same diet and under the same management were selected and divided into four groups as SCC1 (N = 175), SCC2 (N = 49), SCC3 (N = 49), and SCC4 (N = 46) with 1,000,000 somatic cells/mL, respectively. Further, 20 cows with the lowest SCC and 20 cows with the highest SCC were identified. The rumen microbial composition was profiled using 16S rRNA sequencing, along with measurement of rumen fermentation parameters and milking performance. Compared to low SCC, cows with high SCC showed poorer milk yield, milk composition, and rumen volatile fatty acids concentration, but higher rumen bacterial diversity. Although the predominant rumen bacterial taxa did not vary among the SCC groups, the relative abundance of phyla SR1 and Actinobacteria, unclassified family Clostridiales and genus Butyrivibrio were significantly different. In addition, Proteobacteria and family Succinivibrionaceae were enriched in cows with low SCC. Our results suggest that specific rumen microbes are altered in cows with high SCC.

Mastitis is one of the major problems for the productivity of dairy cows and its classifications have usually been based on milk somatic cell counts (SCCs). In this study, we investigated the differences in milk production, rumen fermentation parameters, and diversity and composition of rumen and hindgut bacteria in cows with similar SCCs with the aim to identify whether they can be potential microbial biomarkers to improve the diagnostics of mastitis. A total of 20 dairy cows with SCCs over 500 × 10³ cells/mL in milk but without clinical symptoms of mastitis were selected in this study. Random forest modeling revealed that Erysipelotrichaceae UCG 004 and the [Eubacterium] xylanophilum group in the rumen, as well as the Family XIII AD3011 group and Bacteroides in the hindgut, were the most influential candidates as key bacterial markers for differentiating “true” mastitis from cows with high SCCs. Mastitis statuses of 334 dairy cows were evaluated, and 96 in 101 cows with high SCCs were defined as healthy rather than mastitis according to the rumen bacteria. Our findings suggested that bacteria in the rumen and hindgut can be a new approach and provide an opportunity to reduce common errors in the detection of mastitis.

The beneficial effects of butyric acid in poultry production are well documented, while the relationship between sodium butyrate (SB) and microcapsule sustained-release sodium butyrate (MSSB), especially in yellow broilers, remains poorly investigated. This study was designed to elucidate the function as well as the potential mechanisms of SB and MSSB in enhancing health in yellow broilers. In total, 360 one-day-old yellow broilers were allocated to three treatment groups. The control group (CON) received a basic diet, while the SB group was provided with 1000 mg/kg of sodium butyrate (SB), and the MSSB received microcapsule sustained-release sodium butyrate (MSSB), all over a period of 56 days. Compared to the CON group, the dietary supplementation of both SB and MSSB showed a lower feed:gain ratio (p < 0.01). No significant (p > 0.05) difference in antioxidant capacity was observed between the three groups. We observed significantly higher levels (p < 0.05) of immunoglobulins and a reduction in concentrations in both the SB and MSSB groups compared to the CON group. Furthermore, both SB and MSSB induced alterations in the diversity, structure, and function of gut microbiota. MSSB demonstrated even more pronounced beneficial effects than SB, particularly in regard to the serum IgA level (p = 0.05), cecal isovalerate concentration (p < 0.05), and villus height (p < 0.01). The sequencing of the gut microbiota revealed that MSSB led to a significant increase in the relative abundance of Clostridia UCG-014, Bacilli RF39, and Oscillospiraceae UCG-005. Predictions of bacterial function indicated changes in KEGG pathways, including an enrichment of tryptophan metabolism (ko00380), and a reduction in fructose and mannose metabolism (ko00051), chloroalkane and chloroalkene degradation (ko00625), and naphthalene degradation (ko00626) in yellow broilers fed with MSSB. Among these, the mediation analysis revealed a causal effect between the Clostridia UCG-014 in the gut and serum IgA, with tryptophan metabolism being a key mediator in this relationship. Our results suggest that dietary MSSB can improve the growth performance, immunity, and gut microbiota of yellow broilers. MSSB increased the abundance of Clostridia UCG-014 and activated the tryptophan metabolism pathway (ko00380), contributing to IgA levels in yellow broilers through this mechanism.

Bacillus licheniformis (B. licheniformis) is a probiotic known for its ability to enhance host resistance against pathogenic infections. This study aimed to evaluate the protective effects and underlying mechanisms of B. licheniformis in a mouse model challenged with Clostridium perfringens (C. perfringens). C57BL/6J mice were pretreated with B. licheniformis for 21 days before oral infection with C. perfringens. The probiotic administration significantly prevented infection-induced weight loss and immune organ enlargement. Serum cytokine analysis revealed that B. licheniformis increased anti-inflammatory IL-4 and IL-10 levels while reducing pro-inflammatory IL-1β, IL-6, and TNF-α levels. Histological analysis showed that B. licheniformis preserved intestinal morphology and inhibited epithelial cell apoptosis. Moreover, the probiotic mitigated the infection-induced decline in volatile fatty acid (VFA) production. 16S rRNA gene sequencing revealed that B. licheniformis reshaped the cecal microbiota, characterized by the increased abundance of Lachnospiraceae_NK4A136_group, Muribaculaceae, and Parabacteroides, and reduced abundance of Alistipes. Untargeted metabolomic profiling identified differential metabolites—including D-glucono-1,5-lactone, D-erythrose 4-phosphate, and D-sedoheptulose 7-phosphate—enriched in the pentose phosphate pathway, suggesting a regulatory role in redox homeostasis and host response. Collectively, these results indicate that B. licheniformis exerts protective effects against C. perfringens infection by modulating inflammation, apoptosis, microbial composition, and metabolic pathways. This work provides new insights into the application of B. licheniformis as a functional microbial feed additive in livestock disease prevention.

Weaning stress in piglets severely restricts swine production efficiency due to growth retardation, immune suppression, and intestinal dysfunction. This study investigated the effects of dietary pyrroloquinoline quinone (PQQ) on 36 weaned piglets (22 ± 1 days old) allocated to six groups (0, 1, 2, 4, 8 and 16 mg/kg PQQ) for 28 days. Results showed that 4–8 mg/kg PQQ improved average daily gain and feed conversion ratio (p < 0.05), enhanced serum immunoglobulin (IgA, IgG) and antioxidant enzyme (T-AOC, SOD, GSH-Px) levels, and reduced inflammatory cytokines (TNF-α, IL-1β, IL-6) (p < 0.05). PQQ modulated gut microbiota, increasing Lactobacillus and Bifidobacterium, and elevated short-chain fatty acid production (p < 0.05). Metabolomic analysis revealed upregulated tricarboxylic acid (TCA) cycle intermediates (citric acid, isocitric acid and malic acid), indicating improved mitochondrial function (p < 0.05). Overall, 4 mg/kg PQQ optimally alleviates weaning stress by enhancing immunity, gut health, and energy metabolism, offering a promising strategy for piglet nutrition.

With the increasing demand for enhancing livestock production performance and optimizing feed efficiency, this study aimed to investigate the effects of fermented total mixed ration (FTMR) containing different proportions of rice straw and sheath and leaves of Zizania latifolia on systemic nutrient metabolism and oxidative metabolism under host genetic regulation and on growth performance of heifers. A total of 157 heifers aged 7–8 months were selected, and their hair was collected for whole-genome sequencing. They were randomly assigned into four groups of 18 to 21 cattle each and fed FTMR containing varying levels of rice straw (21% in LSF, 28% in MSF, 35% in HSF) or 31% sheath and leaves of Zizania latifolia (ZF) for a two-month period. At the end of trial, blood and urine samples were collected to measure biochemical indexes and metabolomics. The results showed that high rice straw content and ZF diets could increase blood glucose and non-protein nitrogen in heifers, that is, blood glucose and urea nitrogen levels in HSF and ZF groups were higher than those in LSF and MSF groups (p < 0.05). Meanwhile, the two diets could improve the antioxidant level of heifers. Urine metabolomics analysis between the groups identified three differential metabolic pathways, including 11 metabolites. Among them, l-homoserine and o-acetylserine had significant SNPs associated with them, which promoted glutathione metabolism. Although there was no significant effect of diet on heifers’ average daily gain (ADG) in body weight (p > 0.05), there was substantial inter-individual variation in metabolites among all animals, as further correlation analyses illustrated. Twenty-eight metabolites were significantly associated with ADG (R > 0.3, p < 0.05). Four of them were identified as biomarkers, primarily regulating energy metabolism and oxidative balance. In conclusion, feeding HSF and ZF FTMR enhances glutathione metabolism and antioxidant capacity in heifers, positioning key metabolites as candidates for ADG markers. This integrative omics approach underscores the potential for enhancing livestock productivity and promoting sustainable agricultural practices.