Yuguo Zhen

Introduction: The health of calves depends on the colonization of rumen microorganisms in the early stages of growth and development. This study explored the effects of different milk volumes on rumen fermentation parameters, rumen microbiota, and rumen metabolites in calves. Methods: Eighteen newborn Holstein calves (birth weight, 39 ± 1.5 kg) were selected and divided into the CON group (fed with the traditional milk volume) and the TRT group (fed with a high milk volume). Rumen fluid samples were collected at 70 days of weaning. This cross-sectional single-site trial lacked baseline data at birth and sequential sampling throughout the suckling period. Therefore, the obtained results only reflect the instantaneous ruminal status of calves at weaning on day 70 and cannot characterize the dynamic alterations in the rumen from birth to weaning. The changes in the rumen microbiota and rumen metabolites in the calves were analyzed via 16S rRNA gene high-throughput sequencing and non-targeted metabolomics. The correlation between rumen microbiota, rumen metabolites, and rumen fermentation parameters was analyzed through Spearman’s correlation analysis, and all correlation tests adopted FDR correction for multiple comparisons. Results: The research results show that there is no significant difference in rumen fermentation parameters when calves are fed with a high milk volume compared with a low milk volume (the traditional milk volume). In both the CON group and TRT groups, Bacillota was the most abundant bacterium, but these differential taxa cannot be defined as validated biomarkers due to the lack of clear intergroup separation in PCoA. The rumen fluid metabolomics results show that the differential metabolites related to the amount of milk fed include phosphocholine, choline, and phosphoethanolamine, which are mainly enriched in the glycerophospholipid metabolic pathway; the OPLS-DA model R²Y = 0.45, Q² = 0.15 indicates weak model predictive power. The relative abundance of various taxonomic groups is related to rumen metabolites and fermentation parameters. Conclusion: In conclusion, under cross-sectional sampling at day 70 with n = 9 per group and limited statistical power, no statistically significant overall shifts of rumen fermentation, microbiota, and metabolome were detected between treatments; we cannot rule out subtle stage-specific biological effects due to high Type II error risk, and all observations are only applicable to the weaning endpoint rather than the whole pre-weaning period.

Factors such as latitude, harvesting stage, and stubble height influence silage quality and harvesting decisions. We aimed to examine how harvest stage and stubble height affect the quality of whole-plant corn silage across different latitudes in Northeast China. Experiments were conducted in five different latitude regions (Shenyang, Changchun, Tongliao, Harbin, and Qiqihar) and assessed three stubble heights (20, 40, and 60 cm) at each harvest maturity stage: milk, initial wax, middle wax, late wax, and full maturity. After fermentation, whole-plant corn silage samples were collected and evaluated for nutritional content, fermentation quality, and toxin levels. Increasing the stubble height increased the dry matter (DM), crude protein, starch, and deoxynivalenol content in the whole-plant corn silage (p < 0.01), but decreased the acid detergent fibre and neutral detergent fibre concentrations (p < 0.01). Delayed harvest increased the DM and vomitoxin content (p < 0.01). The pH decreased initially and then increased as the harvest was delayed (p < 0.01). Meanwhile, NH₃–N and acetic acid content did not differ significantly with delayed harvesting (p > 0.05). At higher latitudes, the optimal harvest period is correspondingly delayed, shortening the harvest time. To maintain silage quality without affecting yield or economics, a 40 cm stubble height is recommended. If delayed, incrementally increasing the stubble height to 60 cm may be warranted to maintain silage quality. We provide data-driven insights to optimise silage production and ruminant nutrition.

Yeast culture (YC) is a microbial product that enhances ruminal fiber breakdown and improves nutrient digestion and utilization. Our previous research showed that oxalic acid (OA) is a crucial metabolite in YC that enhances rumen function. This study aimed to investigate the effects of YC, OA, and their combination (YO) on rumen function, growth, and fattening in sheep. Twenty lambs were divided into 4 groups (ctrl, YC, OA, and YO; n = 5 each) and fed a diet supplemented with 2 levels of YC and 2 doses of OA for 60 days in a 2 × 2 factorial design. Growth and fattening performance, rumen microbiome analysis, serum indices and anti-oxidant levels, and metabolomic profiling were performed. Individual supplementation with YC and OA significantly increased the digestibility of dry matter (DM), organic matter (OM), and crude protein (CP) (p < 0.001); neutral detergent fiber (NDF) (p < 0.05); and acid detergent fiber (ADF) (p < 0.001) and their interaction significantly increased dry matter intake (DMI) (p = 0.05). Serum IgA and IgM levels were higher in the supplemented groups (p < 0.05). Serum calcium levels were higher in the OA and YO groups (p < 0.001). The supplemented groups showed significantly higher growth hormone and superoxide dismutase levels (p < 0.05). The longissimus dorsi muscle had higher levels of iron in the OA and YO groups; zinc in the OA, YO, and YC groups (p < 0.01); and selenium in the YC group (p < 0.05). The OA group had a higher total antioxidant capacity. All supplemented groups showed higher bacterial richness and diversity. Ruminococcus, Succinivibrio, and Fibrobacter were positively correlated with the fermentation and digestibility parameters. The supplementation also altered metabolite levels and types in key physiological pathways. In conclusion, this supplementation improved bacterial composition, nutrient digestibility, weight gain, carcass weight and quality, serum indices, antioxidant levels and metabolomic profiles. This suggests potential for the development of dietary supplements for ruminants.

Whole-plant corn silage is a critical feedstuff in global ruminant production, and its nutrient composition is closely tied to harvest timing. As starch acts as the primary energy source in silage-based diets, investigating changes in starch degradation rate provides a theoretical basis for optimizing the efficient utilization of whole-plant corn and its silage in ruminant production. In this study, whole-plant corn (harvested from the milk stage to full ripening stage) and its corresponding silage were used as experimental materials. An in vitro simulated rumen fermentation system was employed to determine the contents of starch, prolamin, amylose, and amylopectin in the samples. The results showed that with delayed harvest time, starch content in both whole-plant corn and its silage increased significantly; prolamin and amylose contents first decreased, then increased; amylopectin content first rose significantly before decreasing; and both starch disappearance rate and speed exhibited a trend of first increasing, then decreasing. After silage fermentation, the silage had significant increases in starch, amylose, and amylopectin contents, and starch disappearance rate; prolamin content decreased; and starch disappearance speed increased extremely significantly. This study indicates that whole-plant corn harvest time and silage fermentation regulate the ruminal starch degradation pattern by altering starch structure, prolamin content, and the proportion of rapidly degradable starch.

Introduction: Yeast culture (YC) has become a crucial microecological preparation for regulating the ruminal environment and improving ruminant health. Myo-inositol is an effective substance in YC, our study aimed to investigate whether myo-inositol can regulate metabolism and influence the health of dairy cows. Therefore, this study explored the effects of myo-inositol on the health, metabolome, and lactation performance of peripartum dairy cows using both in vitro and in vivo models.Methods: The ANKOM RFS gas production system was used for the in vitro experiment; Twenty four healthy Holstein cows were assigned to CON group (n = 4; no supplementation of YC or myo-inositol), YC group (n = 10; 2 g/kg YC), and IN65 group (n = 10; 2 g/kg YC + 16 mg/kg myo-inositol) for in vivo experiment.Results: The concentrations of five volatile fatty acids (acetic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid), and total volatile fatty acids were significantly higher in the IN65 group compared to the CON group at 6 h in vitro (P < 0.01). Therefore, 2 g/kg YC plus 16 mg/kg myo-inositol was selected for in vivo experiment. It was found that the average milk production of the IN65 group increased by 4.00% and 4.05% respectively, compared to the control group and YC group on day 21 postpartum. The levels of superoxide dismutase (SOD), total antioxidant status (TAS), and total oxidative status (TOS) were significantly higher on day 21 compared to day 1 postpartum (P < 0.01). However, a trend indicating a decrease in immune function was observed in the IN65 group compared to the CON group. These findings suggested that myo-inositol may improve the health of postpartum dairy cows. Additionally, Mantel analysis showed acetic acid was positively correlated with D-glyceric acid and xanthosine. Similarly, D-glyceric acid, inosine 5-monophosphate, and xanthosine were positively correlated with microbiota at the genus, such as Bulleidia and Moryella.Discussion: In summary, myo-inositol influences energy metabolism by modulating rumen microbial abundance, improving dairy cow health, and increasing milk production.

Determining hemicellulose (HM) degradation is crucial for evaluating the nutritional value of ruminant diets. Our previous study showed that oxalic acid (OA) regulates rumen fermentation. Building on this research, the present study examined the effects of OA supplementation in different hemicellulose diets on sheep rumen fermentation, microbial diversity, and metabolite production in vitro. Diets with low and high HM levels (10.3% and 17%, respectively) and supplemented with seven concentrations of OA (0, 2.5, 5, 10, 20, 40, 80 mg/kg DM) were evaluated. Tests were conducted under both low (HM10.3%) and high (HM17%) hemicellulose conditions; however, the addition of 10 mg/kg DM oxalic acid could have better effects under low hemicellulose (HM10.3%), with higher concentrations of acetic, propionic, and butyric acids, as well as total acids. A 2 × 2 factorial design was used to collect rumen fluid after 12 h of fermentation to analyze microbial populations and metabolites. OA supplementation at 10 mg/kg DM significantly increased the relative abundances of several bacterial genera, including Prevotella, Butyrivibrio, Ruminococcus, Sharpea, RFN20, Bulleidia, Olsenella, and Bifidobacterium (p < 0.05). A positive correlation was observed between Butyrivibrio and Sharpea and the production of isobutyric and isovaleric acids (p < 0.01), indicating that these bacteria play a role in volatile fatty acid (VFA) production. Furthermore, rumen metabolites involved in mineral absorption and lipid metabolism, including α-tocopherol, L-glutamic acid, and ginkgolide B, were upregulated. In summary, supplementation with oxalic acid in HM diets alters rumen fermentation, enhances nutrient digestibility, promotes microbial diversity, and influences metabolic pathways. Thus, OA supplementation should be tailored to specific dietary conditions for optimal effects.

Determining hemicellulose (HM) degradation is crucial for evaluating the nutritional value of ruminant diets. Our previous study showed that oxalic acid (OA) regulates rumen fermentation. Building on this research, the present study examined the effects of OA supplementation on sheep rumen fermentation, microbial diversity, and metabolite production in vitro. Diets with low and high HM levels (10.3% and 17%, respectively) and supplemented with seven concentrations of OA (0, 2.5, 5, 10, 20, 40, 80 mg/kg DM) were evaluated. Tests were conducted under both low (HM10.3%) and high (HM17%) hemicellulose conditions; however, addition of 10 mg/kgDM oxalic acid could have better effects under low hemicellulose (HM10.3%), with higher concentrations of acetic, propionic, and butyric acids, as well as total acids. A 2 × 2 factorial design was used to collect rumen fluid after 12 h of fermentation for analysis of microbial populations and metabolites. OA supplementation at 10 mg/kg DM significantly increased the relative abundances of several bacterial genera, including Prevotella, Butyrivibrio, Ruminococcus, Sharpea, RFN20, Bulleidia, Olsenella and Bifidobacterium (P < 0.05). A positive correlation was observed between Butyrivibrio and Sharpea and the production of isobutyric and isovaleric acids (P < 0.01), indicating these bacteria play a role in volatile fatty acid (VFA) production. Furthermore, rumen metabolites involved in mineral absorption and lipid metabolism, including α-tocopherol, L-glutamic acid, and ginkgolide B, were upregulated. In summary, supplementation with oxalic acid in HM diets alters rumen fermentation, enhances nutrient digestibility, promotes microbial diversity, and influences metabolic pathways. Thus, OA supplementation should be tailored to specific dietary conditions for optimal effects.

Introduction: Yeast culture (YC) enhances ruminant performance, but its functional mechanism remains unclear because of the complex composition of YC and the uncertain substances affecting rumen fermentation. The objective of this study was to determine the composition of effective metabolites in YC by exploring its effects on rumen fermentation in vitro, growth and slaughter performance, serum index, rumen fermentation parameters, rumen microorganisms, and metabolites in lambs.Methods: In Trial 1, various YCs were successfully produced, providing raw materials for identifying effective metabolites. The experiment was divided into 5 treatment groups with 5 replicates in each group: the control group (basal diet without additives) and YC groups were supplemented with 0.625‰ of four different yeast cultures, respectively (groups A, B, C, and D). Rumen fermentation parameters were determined at 3, 6, 12, and 24 h in vitro. A univariate regression model multiple factor associative effects index (MFAEI; y) was established to correlate the most influential factors on in vitro rumen fermentation with YC metabolites (x). This identified the metabolites promoting rumen fermentation and optimal YC substance levels. In Trial 2, metabolites in YC not positively correlated with MFAEI were excluded, and effective substances were combined with pure chemicals (M group). This experiment validated the effectiveness of YC metabolites in lamb production based on their impact on growth, slaughter performance, serum indices, rumen parameters, microorganisms, and metabolites. Thirty cross-generation rams (Small tail Han-yang ♀ × Australian white sheep ♂) with good body condition and similar body weight were divided into three treatment groups with 10 replicates in each group: control group, YC group, pure chemicals combination group (M group).Results: Growth performance and serum index were measured on days 30 and 60, and slaughter performance, rumen fermentation parameters, microorganisms, and metabolites were measured on day 60. The M group significantly increased the dressing percentage, and significantly decreased the GR values of lambs (p < 0.05). The concentration of growth hormone (GH), Cortisol, insulin (INS), and rumen VFA in the M group significantly increased (p < 0.05).Discussion: These experiments confirmed that YC or its screened effective metabolites positively impact lamb slaughter performance, rumen fermentation, and microbial metabolism.

Background: Hydroxytryptophan (5-HTP) can regulate the synthesis of 5-Hydroxytryptamine (5-HT) and melatonin (MT). In a previous metabolome analysis, we found that 5-HTP is an effective ingredient in yeast culture for regulating rumen fermentation. However, research on the effect of this microbial product (5-HTP) as a functional feed additive in sheep production is still not well explained. Therefore, this study examined the effects of 5-HTP on sheep rumen function and growth performance using in vitro and in vivo models.Methods: A two-factor in vitro experiment involving different 5-HTP doses and fermentation times was conducted. Then, in the in vivo experiment, 10 sheep were divided into a control group which was fed a basal diet, and a 5-HTP group supplemented with 8 mg/kg 5-HTP for 60 days.Results: The results showed that 5-HTP supplementation had a significant effect on in vitro DMD, pH, NH₃-N, acetic acid, propionic acid, and TVFA concentrations. 5-HTP altered rumen bacteria composition and diversity indices including Chao1, Shannon, and Simpson. Moreover, the in vivo study on sheep confirmed that supplementing with 8 mg/kg of 5-HTP improved rumen fermentation efficiency and microbial composition. This led to enhanced sheep growth performance and increased involvement in the tryptophan metabolic pathway, suggesting potential benefits.Conclusion: Dietary 5-HTP (8 mg/kg DM) improves sheep growth performance by enhancing ruminal functions, antioxidant capacity, and tryptophan metabolism. This study can provide a foundation for the development of 5-HTP as a functional feed additive in ruminants’ production.

Introduction: Peripartal cows are susceptible to a negative energy balance due to inadequate nutrient intake and high energy requirements for lactation. Improving the energy metabolism of perinatal dairy cows is crucial in increasing production in dairy cows.Methods: In this study, we investigated the impact of rumen-protected branched-chain amino acid (RPBCAA) on the production performance, energy and lipid metabolism, oxidative stress, and immune function of primiparous dairy cows using metabolomics through a single-factor experiment. Twenty healthy primiparous Holstein cows were selected based on body condition scores and expected calving date, and were randomly divided into RPBCAA (n = 10) and control (n = 10) groups. The control group received a basal diet from calving until 21 d in milk, and the RPBCAA group received the basal diet and 44.6 g/d RPLeu, 25.14 g/d RPIle, and 25.43 g/d RPVal.Results: In comparison to the control group, the supplementation of RPBCAA had no significant effect on milk yield and milk composition of the dairy cows. Supplementation with RPBCAA significantly increased the concentrations of insulin, insulin growth factor 1, glucagon, and growth hormones, which are indicators of energy metabolism in postpartum cows. The very low density lipoprotein, fatty acid synthase, acetyl coenzyme A carboxylase, and hormone-sensitive lipase contents of the RPBCAA group were significantly greater than that of the control group; these metrics are related to lipid metabolism. In addition, RPBCAA supplementation significantly increased serum glutathione peroxidase and immunoglobulin G concentrations and decreased malondialdehyde concentrations. Liquid chromatography–mass spectrometry (LC-MS) analysis revealed 414 serum and 430 milk metabolic features. Supplementation with RPBCAA primarily increased concentrations of amino acid and lipid metabolism pathways and upregulated the abundance of serotonin, glutamine, and phosphatidylcholines.Discussion: In summary, adding RPBCAA to the daily ration can influence endocrine function and improve energy metabolism, regulate amino acid and lipid metabolism, mitigate oxidative stress and maintain immune function on primiparous cows in early lactation.