In this study, we aimed to establish the correlation between ruminal fermentation parameters and the bacterial community by comparing those of the goat, sheep, and cow, thus illustrating the main bacteria causing the difference in rumen fermentation among goats, sheep, and cows and providing a new idea for improving the feed digestibility of ruminants. Rumen fluid from goats (Taihang White cashmere goat, n = 6), sheep (Hu sheep, n = 6), and cows (Holstein cow, n = 6) was collected using oral intubation and immediately brought back to the laboratory for a fermentation test with the same total mixed ration (TMR) feed in vitro. The rumen bacterial composition was measured by high-throughput sequencing of 16S rRNA genes in the MiSeq platform, the gas production (GP) was recorded after 2, 4, 6, 8, 10, 12, 24, 36, and 48 h of fermentation, and the feed nutrient digestibility and the rumen fluid parameters were determined after 48 h of fermentation. The results showed that the 48 h GP of the sheep group was higher than that of the cow group (p < 0.05), and the theoretical maximum GP was higher than that of the goat and cow groups (p < 0.05). The organic matter digestibility (OMD), dry matter digestibility (DMD), crude protein digestibility (CPD), and gross energy digestibility (GED) of the sheep group were higher than those of the goat and cow groups (p < 0.05). The ammonia nitrogen (NH₃-N), microbial protein (MCP), and total volatile fatty acids (TVFA) concentrations of the sheep group were higher than those of the other groups (p < 0.05), and the pH of the sheep group was lower than those of the other groups (p < 0.05). The 16S rRNA gene sequencing revealed that bacterial composition also differed in the rumens of the sheep, goat, and cow groups (ANOSIM, p < 0.05). We then used a random forest machine learning algorithm to establish models to predict the fermentation parameters by rumen bacterial composition, and the results showed that rumen bacterial composition could explain most of the ruminal fermentation parameter variation (66.56%, 56.13%, 65.75%, 80.85%, 61.30%, 4.59%, 1.41%, −3.13%, 34.76%, −25.62%, 2.73%, 60.74%, 76.23%, 47.48%, −13.2%, 80.16%, 4.15%, 69.03%, 32.29%, and 89.96% for 48 h GP, a (GP of quickly degraded part), b (GP of slowly degraded part), c (GP rate), a + b (theoretical maximum GP), DMD, OMD, GED, CPD, NDFD, ANDF, pH, NH₃-N, MCP, acetic acid, propionic acid, butyric acid, valeric acid, TVFA, and A:P (acetic acid–propionic acid ratio), respectively). A correlation analysis revealed that Lactobacillus, Prevotellaceae_UCG-003, Selenomonas, Peptostreptococcus, and Olsenella significantly correlated with most in vitro fermentation parameters (p < 0.05). A comprehensive analysis showed that rumen fermentation parameters and bacterial composition differed in goats, sheep, and cows. The ruminal fermentation parameters of GP, a, b, c, a + b, pH, NH₃-N, propionic acid, valeric acid, and A:P could be accurately predicted by rumen bacteria (explanation > 55% of variation), and the Lactobacillus, Prevotellaceae_UCG-003, Olsenella, Selenomonas, and Peptostreptococcus were the main bacteria that affected the in vitro fermentation parameters of goats, sheep, and cows.

Changes in physiological and biochemical parameters are crucial for the reproductive performance and health of perinatal ewes. This study investigated the temporal variations in feed intake, nutrient digestibility, serum parameters, and ruminal fermentation on days 21, 14, and 7 before lambing (Q21, Q14, and Q7) and days 3, 7, and 14 after lambing (H3, H7, and H14). The results showed that dry matter intake (DMI) and glucose (Glu) gradually decreased (p < 0.05) before lambing and increased (p < 0.05) after lambing. The digestibility of dry matter (DMD), crude protein (CPD), and acid detergent fiber (ADFD) increased (p < 0.05) before lambing, then decreased (p < 0.05) on day H3, and then increased (p < 0.05) on day H14. The rumen pH, NH₃-N, and triglycerides (TG) gradually increased (p < 0.05) before lambing and were higher (p < 0.05) on day Q7 than after lambing. The concentrations of acetate, butyrate, and total volatile fatty acids (T-VFA) were lower (p < 0.05) on day Q7 than those on days Q21 and Q14, then increased (p < 0.05) after lambing. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations gradually decreased (p < 0.05) in perinatal ewes. BHBA and NEFA concentrations were lower (p < 0.05) on day Q21 than those from days Q14 to H14. The rumen microbiota compositions were different (p < 0.05) in perinatal ewes, and g_Anaerovibrio, g_Lachnobacterium, and g_Schwartzia were positively correlated (p < 0.05) with DMI, Glu, acetate, propionate, and T-VFA, and negatively correlated (p < 0.05) with LDL-C. g_Bacillus was negatively correlated (p < 0.05) with DMI, Glu, acetate, propionate, butyrate, and T-VFA, but positively correlated (p < 0.05) with rumen pH and LDL-C. In summary, the DMI, nutrient digestibility, rumen fermentation, and serum parameters changed during the perinatal period of ewes, and the changes in DMI, serum glucose, acetate, propionate, and T-VFA were related to the rumen bacteria.

The purpose of this work was to study the dose effects of fruit oligosaccharide (FOS) supplementation on rumen fermentation parameters, methane (CH₄) production and skatole production. The rumen fluid of Hu sheep was collected through their fistula and immediately transferred to the laboratory for rumen fermentation in vitro. The experimental diet was supplemented with 0%, 0.2%, 0.8%, 1.2%, 1.8% and 2.4% FOS in the basal diet. Gas production (GP) and CH₄ production were measured and recorded at 2, 4, 6, 8, 10, 12, 24, 36 and 48 h. After 48 h of fermentation, degradation rates of nutritional components, fermentation parameters and skatole content were determined. The results showed that the GP, the nutrient degradation rates and the fermentation parameters of rumen linearly increased with increasing doses of FOS supplementation (p < 0.05). There was a quadratic trend between FOS addition and CH₄ production and skatole content in rumen fluid (p < 0.05). We also observed the CH₄ production in the 1.2% FOS-treated group was significantly lower than the other FOS-treated groups. Skatole content of the 0.2%, 0.8% and 1.2% FOS-treated groups were significantly lower than the other FOS-treated groups (p < 0.05). Our findings indicated that the effect of FOS on rumen fermentation parameters, CH₄ production and skatole production in vitro was dose-dependent. To improve the digestibility of nutrients and the fermentation parameters of rumen, a higher FOS dosage might be helpful. However, if CH₄ and skatole production is a concern, a dose of FOS at 1.2% is recommended.

The objective of this study was to investigate the differences in the energy metabolites, immunity, antioxidant capacity, and rumen microbiota of ewes with different numbers of fetuses. Thirty healthy ewes were selected and divided into single- (SL, n = 10), twin- (TL, n = 10), and triplet-fetal (PL, n = 10) ewes according to the number of fetuses. Sampling was carried out on days 21 (Q21) and 7 (Q7) before lambing. The results show no differences (p > 0.05) in the DMI and BW of ewes with different numbers of fetuses, and the body condition score (BCS) of PL ewes was lower (p < 0.05) than that of SL ewes. The concentrations of β-hydroxybutyric acid (BHBA), non-esterified fatty acids (NEFA), interleukin-2 (IL-2), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) in the PL ewes were higher (p < 0.05), while the glucose (Glu), triglyceride (TG), total cholesterol (TC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) values were lower (p < 0.05) than those of the SL ewes. ANOSIM analysis showed that the rumen bacterial structure of the SL, TL, and PL ewes was different on days Q21 and Q7. The relative abundance of Firmicutes and Bacteroidota in the rumen was affected (p < 0.05) by the number of fetuses: the relative abundance of Firmicutes (Ruminococcus, Butyrivibrio, Christensenellaceae_R-7_group, Lachnospiraceae_AC2044_group, Lachnospiraceae_XPB1014_group, and Anaeroplasma) was higher (p < 0.05), while that of Bacteroidota (Prevotella, Prevotellaceae_UCG-003, and Prevotellaceae_UCG-001) was lower (p < 0.05) in the SL ewes than in the PL ewes. In summary, the rumen microbial structure and energy metabolites of ewes in late gestation with different numbers of fetuses were different. Triplet-fetal ewes were characterized by lower BCS and antioxidant capacity and were prone to the triggering of inflammatory responses.