The objective of this experiment was to investigate the effects of Lactobacillus plantarum and molasses on the nutrient composition, fermentation quality, bacterial count, aerobic stability, and microflora of alfalfa silage in sandy grasslands. The experimental treatments included control (CK), 10⁶ CFU/g Lactobacillus plantarum (L), 5% molasses (M), and 10⁶ CFU/g Lactobacillus plantarum + 5% molasses (LM). The nutrient composition, fermentation quality, bacterial count, aerobic stability, and microflora were determined after 14 days and 56 days of ensiling, respectively. The results showed that the addition of L, M, and LM reduced dry matter loss (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) content, and increased water-soluble carbohydrates (WSC) and ether extract (EE) content, compared to the CK group. Meanwhile, more lactic acid (LA) and accelerated fermentation were observed, causing the pH value to drop below 4.5 in the L, M, and LM groups after 56 days of ensiling. The addition of L, M, and LM promoted lactic acid bacteria (LAB), and inhibited yeast. The addition of L significantly increased the content of acetic acid (AA). In terms of microflora, the addition of L, M, and LM made Firmicutes become the dominant bacterial phylum earlier, while Lactobacillus, Weissella, and Pediococcus had a higher abundance. According to the result of Pearson's correlation, there is a very significant negative correlation between pH value and Lactobacillus (P < 0.01) and a very significant positive correlation between pH value and Lactococcus, Enterobacter, Enterococcus, and Leuconostoc (P < 0.01), which may be inhibited by Lactobacillus under the decreased pH value. The results of the prediction of microbial genes indicated that the addition of M could enhance the carbohydrate metabolism and membrane transport metabolism, which may contribute to LA production by LAB metabolism. In general, L, M and LM all improved the fermentation quality and reduced the loss of nutrients to varying degrees, but considering the fermentation quality, the overall effects of M and LM were better than L. M and LM are recommended to be used as silage additives in the process of alfalfa silage in sandy grasslands to improve the quality.

The present study assessed the effects of oligosaccharide-chelated organic trace minerals (OTM) on the growth performance, digestive enzyme activity, blood parameters, slaughter performance, and meat quality indexes of mutton sheep. A total of 60 East Ujumuqin × small-tailed Han crossbred mutton sheep were assigned to two groups (10 duplicates per group) by body weight (26.12 ± 3.22 kg) according to a completely randomized design. Compared to the CON group, the results of the OTM group showed: (1) no significant changes in the initial body weight, final body weight, dry matter intake, average daily gain, and feed conversion ratio (p > 0.05); (2) the activities of trypsin, lipase, and amylase in the jejunum were significantly increased (p < 0.05); (3) serum total protein, albumin, and globulin of the blood were significantly increased (p < 0.05), and the growth factor interleukin IL-10 was significantly higher (p < 0.05), while IL-2, IL-6, and γ-interferon were significantly lower (p < 0.05). Immunoglobulins A, M, and G were significantly higher (p < 0.05); (4) the live weight before slaughter, carcass weights, dressing percentage, eye muscle areas, and GR values did not differ significantly (p > 0.05); (5) shear force of mutton was significantly lower (p < 0.05), while the pH_45min, pH_24h, drip loss, and cooking loss did not show a significant difference (p > 0.05). The content of crude protein was significantly higher (p < 0.05), while the ether extract content was significantly reduced (p < 0.05), but no significant difference was detected between moisture and ash content; (6) the total amino acids, essential amino acids, semi-essential amino acids, and umami amino acids were significantly increased (p < 0.05). Although umami amino acids were not significant, the total volume increased (p > 0.05). Among these, the essential amino acids, threonine, valine, leucine, lysine in essential amino acids and arginine were significantly increased (p < 0.05). Also, non-essential amino acids, glycine, serine, proline, tyrosine, cysteine, and aspartic acid, were significantly higher (p < 0.05). The content of alanine, aspartate, glutamic acid, phenylalanine, and tyrosine in umami amino acids was significantly higher (p < 0.05).

The fermentation substrate was supplemented with 0% guanidinoacetic acid (GAA) (control group, CON), 0.2% GAA (GAA02), 0.4% GAA (GAA04), 0.6% GAA (GAA06) and 0.8% GAA (GAA08) for 48 h of in vitro fermentation. Gas production was recorded at 2, 4, 6, 8, 12, 24, 36, and 48 h of fermentation. The gas was collected, and the proportions (%, v/v) of H₂, CH₄ and CO₂ were determined. The rumen fermentation parameters, including pH, ammonia nitrogen (NH₃-N), microbial protein (MCP) and volatile fatty acids (VFAs), were also determined. Furthermore, the bacterial community structure was analyzed through 16S rRNA high-throughput sequencing. The gene functions were predicted using PICRUSt1 according to the Kyoto Encyclopedia of Genes and Genomes (KEGG). The results showed that with the increase in GAA supplementation levels, the MCP and the concentration of rumen propionate were significantly increased, while the concentration of isovalerate was significantly decreased (p < 0.05). The results of microbial diversity and composition showed that the Shannon index was significantly decreased by supplementation with GAA at different levels (p < 0.05), but the relative abundance of norank_f_F082 and Papillibacter in the GAA06 group was significantly increased (p < 0.05). Especially in group GAA08, the relative abundances of Bacteroidota, Prevotella and Prevotellaceae_UCG-001 were significantly increased (p < 0.05). The results of gene function prediction showed that the relative abundances of the functions of flagellar assembly, bacterial chemotaxis, plant–pathogen interaction, mismatch repair and nucleotide excision repair were significantly decreased (p < 0.05), but the relative abundances of bile secretion and protein digestion and absorption were significantly increased (p < 0.05). In conclusion, supplementation with 0.8% GAA enhanced in vitro rumen fermentation parameters, increased the relative abundance of Prevotella and Prevotellaceae_UCG-001 in the rumen, and increased the metabolic pathways of bile secretion and protein digestion and absorption.

In the present study, we investigated the effects of cellulase and Lactiplantibacillus plantarum (L. plantarum) on the fermentation quality, microbial diversity, gene function prediction, and in vitro rumen fermentation parameters of the Caragana korshinskii (C. korshinskii) silage. The experimental treatment groups included control (CK), cellulase (C), L. plantarum (L), and cellulase + L. plantarum (CL). Triplicate silos were sampled after 14 and 56 days of ensiling. The microbial diversity of C. korshinskii silage at 56 days was analyzed using Illumina MiSeq sequencing technology, and the effects of C. korshinskii silage on rumen fermentation were evaluated by the in vitro artificial rumen gas production method. The results showed that the addition of cellulose and L. plantarum treatments reduced ammonia-nitrogen (NH₃-N), dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber content during ensiling. Compared with the CK group, higher lactic acid content was observed in the silage of the C and L groups, but the CL group had a higher acetic acid (AA) content. Compared with the CK group, the relative abundance of Lactiplantibacillus significantly increased, but that of Enterococcus, Weissella, Enterobacter, and Pediococcus significantly decreased in all other groups except the C group (p < 0.05). The results of gene function prediction were as follows: pyruvate kinase, 1-phosphofructokinase, and fructokinase were lactate production enzymes, which suggested the association of the high AA content in the CL group to the high abundance of 6-phosphate glucose dehydrogenase. The abundance of H + -transporting ATPase and ATP-binding cassette (ABC) transporters in the L and CL groups was higher than that in the CK groups. Metabolism of terpenoids and polyketides, mismatch repair, DNA replication, nucleotide excision repair, and homologous recombination increased in the CL group compared with those in the CK group. Compared with the CK group, NH₃-N and microbial protein content and the degradation rates of DM and NDF increased in the L and CL groups. To conclude, the L and CL groups had increased Lactiplantibacillus abundance, improved fermentation quality, and high DM degradation rates compared with the CK group.

The purpose of this study was to investigate the effects of changes in rumen microbial adaptability on rumen fermentation and nutrient digestion in Horqin beef cattle during different seasons of grazing and supplementary feeding. Four healthy female Horqin beef cattle were selected as experimental animals for grazing and supplementary feeding. The feed, feces, and rumen fluid were collected in spring (March), summer (June), autumn (September), and winter (December) to determine nutrient digestibility, rumen fermentation parameters and microflora. The microflora was sequenced with 16S rRNA. The results revealed that the rumen volatile fatty acid, ammonia nitrogen and microbial protein concentrations in summer were significantly higher than those in the other seasons (P < 0.05). The digestibility of dry matter, organic matter, crude protein and ether extracts decreased significantly in autumn and winter (P < 0.05), especially in winter. Compared with autumn, the rumen bacterial diversity of beef cattle increased significantly in spring (P < 0.05). The results of the rumen microflora revealed that Prevotella was the most dominant bacteria in the rumen of beef cattle in summer, and Rikenellaceae_RC9_gut_group was the most dominant bacteria in the other seasons. The low quality of forage in spring, autumn and winter resulted in an increase in the relative abundance of Rikenellaceae_RC9_gut_group, NK4A214_group, and Christensenellaceae_R-7_group, etc., which are associated with fibre decomposition. In addition, nucleotide metabolism and glycan biosynthesis and metabolism increased significantly in bacteria in the summer (P < 0.05). The results revealed the dynamic adaptability of the rumen microbiota to seasonal and dietary changes and provide references for the grazing and supplementary feeding of Horqin beef cattle in different seasons.

Methane is an important component of greenhouse gases, and ruminant production is a significant source of methane emissions. At present, flavonoid feed additives have certain applications in methane inhibition in ruminants. However, the effects of different doses of quercetin on rumen fermentation parameters, rumen bacteria and archaea are still unclear. Therefore, this study investigated the effects of quercetin on in vitro rumen fermentation parameters, methane production, and microflora in beef cattle. A completely randomized design was adopted. Quercetin was added to the fermentation substrates at 0% (group C), 0.5% (group Q1), 1% (group Q2) and 1.5% (group Q3). Anaerobic fermentation was carried out at 39°C for 48 h, gas production (GP) was recorded at different times, gas composition was determined, and methane (CH₄) production was calculated. Fermentation parameters and dry matter digestibility (DMD) were determined after 48 h. Moreover, rumen fluid was collected for rumen bacterial and archaeal flora determination. The results were as follows: (1) After 32 h of fermentation, the GP decreased in response to the addition of quercetin. With increasing quercetin concentration, the theoretical maximum gas production decreased quadratically before 20 h (P_quadratic = 0.032). There was a quadratic increase in gas production (P_quadratic = 0.024). With increasing quercetin supplementation, the NH3-N content increased quadratically (P_quadratic = 0.027). MCP increased linearly and quadratically with quercetin (P_linear = 0.002, P_quadratic = 0.005), whereas DMD decreased linearly and quadratically with quercetin (P_linear = 0.013, P_quadratic = 0.032). Both 0.5 and 1% quercetin significantly reduced the butyrate content (P_quadratic = 0.002). With the addition of quercetin, the levels of butyrate, isobutyrate, isovalerate, and total volatile fatty acid (TVFA) first decreased but then increased (P_quadratic < 0.05). (2) With increasing quercetin concentration, methane production (P_quadratic = 0.009) and the methane proportion (P_quadratic < 0.001) decreased quadratically. (3) The ACE index and Chao1 index increased quadratically with quercetin supplementation (P_quadratic < 0.05). The relative abundance of Succiniclasticum in groups Q1 and Q3 increased, whereas the relative abundances of norank_f__norank_o__Rickettsiales and Curtobacterium decreased in all quercetin groups at the genus level (P < 0.05). (4) Quercetin supplementation did not affect the diversity of the archaeal community, but the relative abundance of Methanobrevibacter in group Q2 decreased. Overall, quercetin influenced in vitro rumen fermentation and the bacterial flora to decrease methane production and promote rumen nitrogen utilization and MCP synthesis.