The aims of this study were to reveal the magnitude of the differences in protein structures at a cellular level as well as protein utilization and availability among soybean meal (SBM), canola meal (CM), and rapeseed meal (RSM) as feedstocks in China. Experiments were designed to compare the three different types of feedstocks in terms of: 1) protein chemical profiles; 2) protein fractions partitioned according to Cornell Net Carbohydrate and Protein System; 3) protein molecular structures and protein second structures; 4) special protein compounds-amino acid (AA); 5) total digestible protein and energy values; 6) in situ rumen protein degradability and intestinal digestibility. The protein second structures were measured using FT/IR molecular spectroscopy technique. A summary chemical approach in NRC model was applied to analyze truly digestible protein. The results showed significant differences in both protein nutritional profiles and protein structure parameters in terms of α-helix, β-sheet spectral intensity and their ratio, and amide I, amide II spectral intensity and their ratio among SBM, CM and RSM. SBM had higher crude protein (CP) and AA content than CM and RSM. For dry matter (DM), SBM and CM had a higher DM content compared with RSM (P < 0.05), whereas no statistical significance was found between SBM and CM (P = 0.28). Effective degradability of CP and DM did not demonstrate significant differences among the three groups (P > 0.05). Intestinal digestibility of rumen undegradable protein measured by three-step in vitro method showed that there was significant difference (P = 0.05) among SBM, CM and RSM, which SBM was the highest and RSM was the lowest with CM in between. NRC modeling results showed that digestible CP content in SBM was significantly higher than that of CM and RSM (P < 0.05). This study suggested that SBM and CM contained similar protein value and availability for dairy cattle, while RSM had the lowest protein quality and utilization.

Objective: The objective of this study was to explore the effects of maize straw treated with calcium oxide (CaO) and various moisture, on the composition and molecular structure of the fiber, and gas production by fermentation in an in vitro rumen environment.Methods: The experiment used 4×3 Factorial treatment. Maize straws were treated with 4 concentrations of CaO (0%, 3%, 5%, and 7% of dry straw weight) and 3 moisture contents (40%, 50%, and 60%). Scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray fluorescence spectroscopy were employed to measure the surface texture, secondary molecular structure of carbohydrate, and calcium (Ca) content of the maize straw, respectively. The correlation of secondary molecular structures and fiber components of maize straw were analyzed by CORR procedure of SAS 9.2. In vitro rumen fermentation was performed for 6, 12, 24, 48, and 72 h to measure gas production.Results: Overall, the moisture factor had no obvious effect on the experimental results. Neutral detergent fiber (NDF), acid detergent fiber, acid detergent lignin, hemicellulose and cellulose contents decreased (p<0.05) with increasing concentrations of CaO treatment. Surface and secondary molecular structure of maize straw were affected by various CaO and moisture treatments. NDF had positive correlation (p<0.01) with Cell-H (H, height), Cell-A (A, area), CHO-2-H. Hemicellulose had positive correlation (p<0.01) with Lignin-H, Lignin-A, Cell-H, Cell-A. Ca content of maize straw increased as the concentration of CaO was increased (p<0.01). Gas production was highest in the group treated with 7% CaO.Conclusion: CaO can adhere to the surface of the maize straw, and then improve the digestibility of the maize straw in ruminants by modifying the structure of lignocellulose and facilitating the maize straw for microbial degradation.

This study aims to investigate differences in metabolism regarding the transition cows. Eight cows were selected for the test. Serum was collected on antepartum days 14th (ap14) and 7th (ap7) and postpartum days 1st (pp1), 7th (pp7), and 14th (pp14) to detect biochemical parameters. The experiment screened out differential metabolites in the antepartum (ap) and postpartum (pp) periods and combined with metabolic pathway analysis to study the relationship and role between metabolites and metabolic abnormalities. Results: (1) The glucose (Glu) levels in ap7 were significantly higher than the other groups (p < 0.01). The insulin (Ins) levels of ap7 were significantly higher than pp7 (p = 0.028) and pp14 (p < 0.01), and pp1 was also significantly higher than pp14 (p = 0.016). The insulin resistance (HOMA-IR) levels of ap7 were significantly higher than ap14, pp7, and pp14 (p < 0.01). The cholestenone (CHO) levels of ap14 and pp14 were significantly higher than pp1 (p < 0.01). The CHO levels of pp14 were significantly higher than pp7 (p < 0.01). The high density lipoprotein cholesterol (DHDL) levels of pp1 were significantly lower than ap14 (p = 0.04), pp7 (p < 0.01), and pp14 (p < 0.01), and pp14 was also significantly higher than ap14 and ap7 (p < 0.01). (2) The interferon-gamma (IFN-γ) and tumor necrosis factor α (TNF-α) levels of ap7 were significantly higher than pp1 and pp7 (p < 0.01); the immunoglobulin A (IgA) levels of pp1 were significantly higher than ap7 and pp7 (p < 0.01); the interleukin-4 (IL-4) levels of pp7 were significantly higher than ap7 and pp1 (p < 0.01), the interleukin-6 (IL-6) levels of ap7 and pp1 were significantly higher than pp7 (p < 0.01). (3) Metabolomics identified differential metabolites mainly involved in metabolic pathways, such as tryptophan metabolism, alpha-linolenic acid metabolism, tyrosine metabolism, and lysine degradation. The main relevant metabolism was concentrated in lipid and lipid-like molecules, organic heterocyclic compounds, organic acids, and their derivatives. The results displayed the metabolic changes in the transition period, which laid a foundation for further exploring the mechanism of metabolic abnormalities in dairy cows in the transition period.

This study assessed whether harvest time and microbial anaerobic fermentation could affect ruminal degradability and intestinal digestibility of whole Zhang hybrid millet, and estimate the effect of microbial anaerobic fermented whole Zhang hybrid millet as feedstuff on milk yield and milk quality. Protein degradation and intestinal digestion were determined using in situ nylon bag technique and three-step in vitro method, respectively. Results showed that harvest time, microbial anaerobic fermentation, or their interaction significantly affected EDDM, EDCP, and EDNDF (p < 0.05). In vitro fermentation was significantly influenced by harvest time. Early harvested samples appeared to have higher Total volatile fatty acid (TVFA) and lower acetate: propionate ratio than late harvested ones (p < 0.01). However, significant effect of harvest time and fermentation was failed to find in the estimation of rumen-undegradable protein (RUP) (p > 0.05). Microbial anaerobic fermented whole Zhang hybrid millet as feedstuff provided similar milk compositions compared with controls, and it significantly reduced SCC (p = 0.04). Milk yield was numerically higher in whole Zhang hybrid millet groups. In conclusion, harvest time and microbial anaerobic fermentation could further improve ruminal utilization of whole Zhang hybrid millet. Whole Zhang hybrid millet could be an alternative feedstock for dairy cows with acceptable safety profile and potential benefit in milk production.

As an important limiting factor, lignin hinders the utilization rate of maize straw in ruminants. CaO treatment increases the feed digestibility of maize straw by disrupting the ester bonds between hemicellulose, cellulose, and lignin in maize straw. Our previous research found that CaO treatment of corn straw may increase its feed digestibility by altering the rumen microbes’ abundance. This study further investigated the molecular mechanism of CaO treatment to enhance feed utilization and also examined its ongoing effects on rumen metabolites. Rumen fluid was collected to analyze microbial metabolites using liquid chromatography–mass spectrometry (LC–MS) non-targeted metabolomics. Maize straw (moisture content of 60%) treated with four levels of CaO (0%, 3%, 5%, and 7%) was used as the fermentation substrate for a 6 h in vitro culture. Based on the effect of CaO-treated maize straw on the rumen microbial diversity, no significant differences were observed in microbial composition between the 0% and 3% treatment groups or between the 5% and 7% treatment groups. However, the microbial structure of the 0% and 3% treatment groups differed from that of the 5% and 7% groups. Therefore, the four levels were divided into a low-efficiency group (LE group: 0% and 3% levels) and a high-efficiency group (HE group: 5% and 7% levels) for principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Compared with the LE group, most of the ruminal metabolites that showed increased levels in the HE group were products of lignin degradation. Among these differential metabolites, Dihydro-3-coumaric acid had a significant positive correlation with Prevotella and fermentation indicators like acetate, propionate, and butyrate. KEGG analysis showed differential metabolites were primarily enriched in the amino acid metabolism, tryptophan metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis, and cyanoamino acid metabolism. The higher CaO concentration in the HE group effectively disrupted most covalent bonds with lignin, significantly enhancing cellulose degradation and ultimately supporting improved rumen metabolism.