Biochanin A is a naturally occurring flavonoid compound that is found in plant species such as red clover (Trifolium pretense) and alfalfa (Medicago sativa). Flavonoids have been reported to regulate ruminal fermentation, and the objective of this study was to evaluate the effects of biochanin A on ruminal microbial composition and nitrogen metabolism. The experiment was performed by in vitro batch culturing of a control (without biochanin A) and a biochanin A treatment. Following a 24-h incubation, gas production and the amounts of ammonia-nitrogen (NH₃-N), volatile fatty acid (VFA), and amino acids were measured. Microbial population using 16S rRNA gene sequence. We found that the addition of biochanin A significantly increased microbial gas production; but had no effect on VFA production. Biochanin A supplementation also resulted in reduced microbial urease activity with half the maximal inhibitory concentration of 320 nM and also inhibited the degradation rates of total amino acids, valine, lysine, methionine and leucine by 18%, 56%, 37%, 13%, and 12%, respectively. This inhibition of urease activity and amino acid decomposition resulted in a significant reduction in the NH₃-N concentration. High-throughput sequencing of the 16S rRNA sequence to monitor microbial composition showed that biochanin A significantly reduced the abundance of the proteolytic bacteria Prevotella and ureolytic bacteria Selenomonas, but increased the abundance of the lactic acid metabolizing bacteria Veillonella and Megasphaera. In conclusion, biochanin A reduced the production of ammonia by inhibiting proteolytic bacteria and their decomposition of urea and amino acids.

The aim of this study was to investigate the effects of different combinations of molasses levels and slow-release urea on Holstein fattening bulls. Sixty Holstein fattening bulls of a similar age, weight, and health status were randomly divided into four groups of fifteen Holstein fattening bulls each. All of the treatments were as follows: (1) basic diet group (CON); (2) 2% molasses slow-release urea group (LMU); (3) 4% molasses slow-release urea group (MMU); and (4) 6% molasses slow-release urea group (HMU). The results of the study showed that the MMU had an outstanding performance, with a 13.3% increase in average daily weight gain compared with the control group, a significant decrease in feed conversion ratio (p < 0.05), and a significant increase in apparent digestibility of crude protein (p < 0.05). In terms of serum biochemical indices, blood ammonia and alanine aminotransferase (ALT) concentrations were significantly higher in the MMU than in the CON (p < 0.05). The rumen pH of all treatment groups was lower than that of the CON (p < 0.05), whereas the concentrations of microbial crude protein (MCP), as well as acetic acid, propionic acid, and total volatile fatty acids (TVFA) were significantly higher in both the MMU and HMU (p < 0.05). The dominant phyla in each group were Bacteroidetes, Firmicutes, and Patescibacteria, and the relative abundance of Bacteroidetes in the MMU increased by 5.47% compared with that in the CON. In the MMU, Prevotellaceae, Lachnospiraceae, and Ruminococcaceae increased by 9.03%, 0.67%, and 3.43%, respectively, compared with the CON. The economic benefit analysis showed that the daily feeding cost of fattened cattle in the MMU was reduced by RMB 1.62 yuan, and the daily farming benefit of each cow was increased by RMB 7.19 yuan. In conclusion, the MMU was effective in improving the growth performance of fattening cows, optimizing rumen fermentation, reducing cost, and increasing profit, which is a nutritional strategy with great application value.

In this study we revealed the diversity of active ureolytic bacteria in the rumen by compared ureC amplicons between gDNA and cDNA. Rumen fluid was collected from four Holstein dairy cows with rumen fistulas at 0, 2, and 6 h after morning feeding. Total microbial gDNA and RNA were isolated, and the RNA was reverse-transcribed into cDNA. The ureC gene amplicons of gDNA and cDNA were produced and sequenced by MiSeq. These results revealed that the sampling time had no significant difference on the alphssa and beta diversity indices of the ureolytic bacteria. The Shannon diversity of the ureC gene for cDNA was greater than that for gDNA (p < 0.05). There were significant difference in the beta diversity of ureolytic bacteria between gDNA and cDNA (p < 0.01), which indicates a shift in the community of active ureolytic bacteria. Approximately 67% of ureC sequences from cDNA could not be confidently classified at the genus level. The active ureolytic bacteria were mainly from Helicobacter, Herbaspirillum, Clostridium, Paenibacillus, Synechococcus, and Sphingobacterium sp. Changes in the operational taxonomic units revealed that the top abundant ureC genes were mostly consistent between gDNA and cDNA, and most differences occurred in the ureC genes with lower abundances. These results revealed distinct ureolytic bacteria community profiles based on gDNA and cDNA. The dominant ureolytic bacteria had high transcriptional activity, and the differential were mainly distributed in the genus of low abundance.

The aim of this study was to evaluate the effects of lentinan (LNT) on the quality of colostrum produced by perinatal dairy cows and the health status of their newborn calves. A total of 40 expectant Holstein cows, matched for parity and expected date of delivery, were selected and randomly divided into four groups: a control group fed a total mixed diet (TMR); a low LNT group (10 g/d, LLNT); a medium LNT group (20 g/d, MLNT); and a high LNT group (40 g/d, HLNT). The study commenced 21 days prior to parturition and continued for three weeks. Colostrum was collected from the cows immediately after delivery and subsequently fed to the newborn calves. The results indicated that colostrum milk protein production and IgG production in the MLNT group were significantly increased (p < 0.05). Following colostrum gavage, serum SOD and IgG in both the MLNT and HLNT groups showed significant increases (p < 0.05), while MDA and IL-1β levels were significantly decreased (p < 0.05). Moreover, calves in the MLNT and HLNT groups experienced lower incidences of diarrhea, pneumonia, and overall morbidity compared to those in the control group. In conclusion, LNT enhanced the quality of colostrum in perinatal cows and contributed to the health of newborn calves through colostrum. This study offers new research avenues for improving the health of newborn calves and provides a theoretical foundation for the development of LNT as a novel feed additive.

This study aimed to evaluate the effects of eight plant essential oils on in vitro ruminal fermentation. The oils tested were verbena (VE), cinnamon (CE), rosemary (RE), Torreya grandis (TG), ginger (GE), fennel (SF), thyme (TE), and oregano (OE). Each was supplemented at five graded doses (0, 0.75, 1.5, 3, and 6% of the substrate DM) during 24 h incubations. The results demonstrated that adding 3% CE significantly increased the in vitro dry matter degradation rate (IVDMD) while enhancing microbial protein (MCP) synthesis efficiency and acetate concentration. The addition of 1.5% SF increased MCP and total volatile fatty acid (TVFA) concentrations without affecting ruminal ammonia nitrogen levels, and 0.75% TE enhanced nitrogen utilization efficiency while maintaining primary fermentation pathways and ammonia nitrogen levels. Although 0.75% OE did not alter overall fermentation intensity or nitrogen metabolism, it specifically regulated volatile fatty acid metabolic pathways, significantly promoting butyrate production. Through preliminary screening, four essential oils (CE, SF, TE, OE) that positively influenced rumen fermentation were selected and combined into five distinct blends: T1 (CE + SF + TE), T2 (CE + SF + OE), T3 (CE + TE + OE), T4 (SF + TE + OE), and T5 (CE + SF + TE + OE). In vitro 24 h fermentations with varying inclusion levels (0, 0.75, 1.5, 3% of the substrate DM), in comparison with the CON, showed that the T2 group significantly outperformed the other four formulations in nitrogen metabolism and IVDMD, while substantially reducing methane content. Simpson’s index of microbial diversity was markedly elevated, alongside an increased relative abundance of key bacterial genera—Selenomonas and Succinibacter. Considering comprehensive performance metrics and economic viability, the 1.5% T2 was selected as the optimal formulation.

This study investigated the effects of supplementing rumen-protected lysine (RPL; 60 g/d) and methionine (RPM; 30 g/d) on nutrient digestibility, rumen fermentation, and microbial composition in 30 early-lactation Holstein dairy cows under both heat stress (HS) and non-heat stress (NHS) conditions. Cows were paired based on parity, milk yield, and body weight, and then assigned to one of two dietary treatments: the control group (CON), receiving the basal diet only, or the RPLM group, which received the basal diet supplemented with 60 g/d of RPL and 30 g/d of RPM (n = 15 per group). All animals underwent a transition from HS to NHS conditions during the experimental period, allowing for within-animal comparison across thermal environments. Results demonstrated that RPLM supplementation significantly improved the apparent digestibility of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) (p < 0.05), with a significant treatment × environment interaction observed for DM digestibility (p < 0.01). Under HS conditions, RPLM reduced ruminal NH₃-N concentration (p < 0.05) and increased total volatile fatty acids (TVFA), acetate, and butyrate levels (p < 0.01), suggesting enhanced nitrogen utilization and energy metabolism. No significant effects were observed on ruminal pH or the acetate-to-propionate ratio. 16S rRNA sequencing revealed that RPLM supplementation increased the relative abundance of fiber-degrading and butyrate-producing taxa, including NK4A214_group, Christensenellaceae_R-7_group, norank_f__Muribaculaceae, and norank_f__F082. These microbial taxa exhibited strong positive correlations with DM and CP digestibility (p < 0.001). LEfSe analysis further confirmed their status as key microbial biomarkers in the RPLM-NHS group. Collectively, concurrent supplementation of RPL and RPM modulates the ruminal microbiota, alleviates HS-induced reductions in digestive efficiency, and enhances overall nutrient utilization in dairy cows.