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.

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.

Active dry yeast (ADY) as a feed additive has been proven to have functions such as enhancing feed digestion and utilization rates, strengthening the body’s immunity, alleviating stress and improving rumen fermentation. This experiment mainly explores the effects of a new type of ADY on the production performance, rumen fermentation and nutrient digestibility of dairy cows. A total of 100 Holstein cows with similar milk yield (46.9 ± 8.5 kg/d), days in milk (66.7 ± 5.4 d), and parity (2.5 ± 1.0) were selected and randomly allocated into four groups (25 cows per group). The treatments were as follows: (1) Control group (CON), cows fed the basal diet only; (2) ADY I group (ADY I), basal diet supplemented with 5 g/d of common ADY (RF7, 1 × 10¹⁰ CFU/g) per cow; (3) Low ADY II group (LADY II), basal diet supplemented with 5 g/d of Actisaf Sc48 (viable yeast cell concentration is 1 × 10¹⁰ CFU/g) per cow; (4) High ADY II group (HADY II), basal diet supplemented with 10 g/d of Actisaf Sc48 per cow. The 10-week experimental period consisted of a 1-week adaptation period followed by a 9-week formal experimental period. The results showed that, compared with the CON group, mean dry matter intake (DMI) increased by 3.48%, 5.35%, and 6.96% in the ADY I, LADY II, and HADY II groups, respectively (p < 0.05), with a significant treatment × time interaction (p < 0.001). Compared with the CON and ADY I groups, the HADY II group showed increases in milk yield of 5.76% and 4.76% and in apparent crude protein (CP) digestibility of 5.22% and 3.17%, respectively (p < 0.05). Milk lactose concentration was 3.43% higher in the HADY II group than in the ADY I group (p < 0.05). Additionally, milk linolelaidic acid concentration was lower in LADY II and HADY II than in CON (p < 0.05). Compared with the CON group, the LADY II and HADY II groups showed increases in ruminal total volatile fatty acid (TVFA) concentrations of 42.11% and 44.72% and in acetate concentrations of 45.76% and 46.71%, respectively (p < 0.05). In this trial, the group receiving ADY II at 10 g/cow/day showed the best overall performance. However, this finding does not establish 10 g/cow/day as the optimal inclusion level for this product. Future studies should compare the two products at matched doses and integrate multi-omics analyses with functional validation and economic evaluation to clarify their mechanisms of action and guide practical supplementation.