Effects of dietary Clostridium butyricum and rumen protected fat on meat quality, oxidative stability, and chemical composition of finishing goats.

BACKGROUND: Clostridium butyricum (CB) is a probiotic that can regulate intestinal microbial composition and improve meat quality. Rumen protected fat (RPF) has been shown to increase the dietary energy density and provide essential fatty acids. However, it is still unknown whether dietary supplementation with CB and RPF exerts beneficial effects on growth performance and nutritional value of goat meat. This study aimed to investigate the effects of dietary CB and RPF supplementation on growth performance, meat quality, oxidative stability, and meat nutritional value of finishing goats. Thirty-two goats (initial body weight, 20.5 ± 0.82 kg) were used in a completely randomized block design with a 2 RPF supplementation (0 vs. 30 g/d) × 2 CB supplementation (0 vs. 1.0 g/d) factorial treatment arrangement. The experiment included a 14-d adaptation and 70-d data and sample collection period. The goats were fed a diet consisted of 400 g/kg peanut seedling and 600 g/kg corn-based concentrate (dry matter basis). RESULT: Interaction between CB and RPF was rarely observed on the variables measured, except that shear force was reduced (P < 0.05) by adding CB or RPF alone or their combination; the increased intramuscular fat (IMF) content with adding RPF was more pronounced (P < 0.05) with CB than without CB addition. The pH24h (P = 0.009), a* values (P = 0.007), total antioxidant capacity (P = 0.050), glutathione peroxidase activities (P = 0.006), concentrations of 18:3 (P < 0.001), 20:5 (P = 0.003) and total polyunsaturated fatty acids (P = 0.048) were increased, whereas the L* values (P < 0.001), shear force (P = 0.050) and malondialdehyde content (P = 0.044) were decreased by adding CB. Furthermore, CB supplementation increased essential amino acid (P = 0.027), flavor amino acid (P = 0.010) and total amino acid contents (P = 0.024) as well as upregulated the expression of lipoprotein lipase (P = 0.034) and peroxisome proliferator-activated receptor γ (PPARγ) (P = 0.012), and downregulated the expression of stearoyl-CoA desaturase (SCD) (P = 0.034). The RPF supplementation increased dry matter intake (P = 0.005), averaged daily gain (trend, P = 0.058), hot carcass weight (P = 0.046), backfat thickness (P = 0.006), concentrations of 16:0 (P < 0.001) and c9-18:1 (P = 0.002), and decreased the shear force (P < 0.001), isoleucine (P = 0.049) and lysine content (P = 0.003) of meat. In addition, the expressions of acetyl-CoA carboxylase (P = 0.003), fatty acid synthase (P = 0.038), SCD (P < 0.001) and PPARγ (P = 0.022) were upregulated due to RPF supplementation, resulting in higher (P < 0.001) content of IMF. CONCLUSIONS: CB and RPF could be fed to goats for improving the growth performance, carcass traits and meat quality, and promote fat deposition by upregulating the expression of lipogenic genes of Longissimus thoracis muscle.

Realizing High Capacity and Zero Strain in Layered Oxide Cathodes via Lithium Dual-Site Substitution for Sodium-Ion Batteries.

Sodium-ion batteries have garnered unprecedented attention as an electrochemical energy storage technology, but it remains challenging to design high-energy-density cathode materials with low structural strain during the dynamic (de)sodiation processes. Herein, we report a P2-layered lithium dual-site-substituted Na0.7Li0.03[Mg0.15Li0.07Mn0.75]O2 (NMLMO) cathode material, in which Li ions occupy both transition-metal (TM) and alkali-metal (AM) sites. The combination of theoretical calculations and experimental characterizations reveals that LiTM creates Na-O-Li electronic configurations to boost the capacity derived from the oxygen anionic redox, while LiAM serves as LiO6 prismatic pillars to stabilize the layered structure through suppressing the detrimental phase transitions. As a result, NMLMO delivers a high specific capacity of 266 mAh g-1 and simultaneously exhibits the nearly zero-strain characteristic within a wide voltage range of 1.5-4.6 V. Our findings highlight the effective way of dual-site substitution to break the capacity-stability trade-off in cathode materials for advanced rechargeable batteries.

Circ007071 Inhibits Unsaturated Fatty Acid Synthesis by Interacting with miR-103-5p to Enhance PPARγ Expression in the Dairy Goat Mammary Gland.

Understanding more precisely the mechanisms controlling the metabolism of fatty acid in the mammary gland of dairy goats is essential for future improvements in milk quality. Particularly since recent data have underscored a key role for circular RNAs (circRNAs) in the mammary gland function, high-throughput sequencing technology was used to identify expression levels of circRNAs in the mammary tissue of dairy goats during early and peak lactation in the present study. Compared with early lactation, results demonstrated that the expression level of circ007071 during peak lactation was 12.02-fold up-regulated. Subsequent studies in goat mammary epithelial cells (GMECs) revealed that circ007071 stimulated the synthesis of triglycerides (TAG) and cholesterol, as well as increased the content of saturated fatty acids (C16:0 and C18:0). More importantly, using a double luciferase reporting system allowed us to detect the circ007071 sequence at a binding site of miR-103-5p, indicating that it targeted this miRNA. Overexpression of circ007071 significantly decreased the abundance of miR-103-5p and led to inhibition of TAG synthesis. In contrast, the abundance of peroxisome proliferator-activated receptor γ (PPARγ), a target gene of miR-103-5p, was reinforced with the overexpression of circ007071. Thus, we conclude that one key function of circ007071 in the regulation of milk fat synthesis is to attenuate the inhibitory effect of miR-103-5p on PPARγ via direct interactions with miRNA. As a result, the process of TAG and saturated fatty acid is able to proceed.

The gas production, ruminal fermentation parameters, and microbiota in response to Clostridium butyricum supplementation on in vitro varying with media pH levels.

The aim of this study was to investigate the gas production (GP), dry matter disappearance (DMD), fermentation parameters, and rumen microbiota in response to Clostridium butyricum (CB) supplementation in batch culture using a high forage substrate. The doses of CB were supplemented at 0 (Control), 0.5 × 106, 1 × 106, and 2 × 106 CFU/bottle, respectively, at either media pH 6.0 or pH 6.6. The 16S rRNA gene sequencing was used to detect the microbiota of fermentation culture in control and 1 × 106 CFU/bottle after 24 h of incubation. The results showed that the GP (p < 0.001), DMD (p = 0.008), total volatile fatty acid (VFA) concentration (p < 0.001), acetate to propionate ratio (p < 0.001), and NH3-N concentration (p < 0.001) were greater at media pH 6.6 than pH 6.0. Furthermore, the linearly increased DMD (pH 6.0, p = 0.002; pH 6.6, p < 0.001) and quadratically increased butyrate proportion (pH 6.0, p = 0.076; pH 6.6, p < 0.053) and NH3-N concentration (pH 6.0, p = 0.003; pH 6.6, p = 0.014) were observed with increasing doses of CB. The Alpha diversity indexes of OTU number and Chao1 were higher (p = 0.045) at media pH 6.6 than pH 6.0, but they were not affected by CB supplementation. The PCoA analysis (unweighted uniFrac) demonstrated that the clustering of the bacterial microbiota of control and CB were distinctly separated from each other at media pH 6.0. At the phylum level, the abundance of Bacteroidota (p < 0.001) decreased, whereas that of Firmicutes (p = 0.026) increased when the media pH was elevated from 6.0 to 6.6. Supplementation of CB increased relative abundances of Rikenellaceae_RC9_gut_group (p = 0.002), Christensenellaceae_R-7_group (p < 0.001), and NK4A214_group (p = 0.002) at genus level. Interactions between media pH and CB addition were observed for bacteria at both phylum and genus levels. These results indicated that increasing the media pH level and CB supplementation increased in vitro rumen digestibility, and altered the ruminal fermentation pattern (by media pH) and microbiota.

Effects of supplementation with lysophospholipids on performance, nutrient digestibility, and bacterial communities of beef cattle.

An experiment was conducted to investigate the influences of supplemental lysophospholipids (LPL) on the growth performance, nutrient digestibility, and fecal bacterial profile, and short-chain fatty acids (SCFAs) of beef cattle. Thirty-six Angus beef cattle [565 ± 10.25 kg body weight (BW)] were grouped by BW and age, and randomly allocated to 1 of 3 treatment groups: (1) control (CON, basal diet); (2) LLPL [CON supplemented with 0.5 g/kg LPL, dry matter (DM) basis]; and (3) HLPL (CON supplemented with 0.75 g/kg, DM basis). The Angus cattle were fed a total mixed ration that consisted of 25% roughage and 75% concentrate (dry matter [DM] basis). The results reveal that LPL inclusion linearly increased the average daily gain (P = 0.02) and the feed efficiency (ADG/feed intake, P = 0.02), while quadratically increasing the final weight (P = 0.02) of the beef cattle. Compared with CON, the total tract digestibilities of DM (P < 0.01), ether extract (P = 0.04) and crude protein (P < 0.01) were increased with LPL supplementation. At the phylum-level, the relative abundance of Firmicutes (P = 0.05) and ratio of Firmicutes: Bacteroidetes (P = 0.04) were linearly increased, while the relative abundances of Bacteroidetes (P = 0.04) and Proteobacteria (P < 0.01) were linearly decreased with increasing LPL inclusion. At the genus-level, the relative abundances of Clostridium (P < 0.01) and Roseburia (P < 0.01) were quadratically increased, and the relative abundances of Ruminococcus was linearly increased (P < 0.01) with LPL supplementation. Additionally, increasing the dose of LPL in diets linearly increased the molar proportion of butyrate (P < 0.01) and total SCFAs (P = 0.01) concentrations. A conclusion was drawn that, as a promising feed additive, LPL promoted growth performance and nutrient digestibility, which may be associated with the change of fecal microbiome and SCFAs.

Effect of Clostridium butyricum Supplementation on in vitro Rumen Fermentation and Microbiota With High Grain Substrate Varying With Media pH Levels.

Clostridium butyricum (C. butyricum) can survive at low pH, and it has been widely used as an alternative to antibiotics for the improvement of feed efficiency and animal health in monogastrics. A recent study suggested that the improved ruminal fermentation with supplementing C. butyricum is may be associated with increasing the abundance of rumen microbiota in Holstein heifers, as ruminal pH plays a key role in rumen microbiota and the probiotics are often active in a dose-dependent manner. The objective of this study was to determine the effects of increasing the doses of C. butyricum on gas production (GP) kinetics, dry matter disappearance (DMD), fermentation characteristics, and rumen microbiota using a high grain substrate in batch culture varying with media pH levels. The doses of C. butyricum were supplemented at 0 (control), 0.5 × 106, 1 × 106, and 2 × 106 CFU/bottle, respectively, at either media pH 6.0 or pH 6.6. The fermentation microbiota at 0 and 1 × 106 CFU/bottle were determined using the 16S rRNA high throughput sequencing technology. Overall, the GP, DMD, total volatile fatty acid (VFA) concentration, and the ratio of acetate:propionate were higher (P <0.01) at media pH 6.6 than at pH 6.0. However, there was interaction between pH × dose of C. butyricum for rate constant of GP (P = 0.01), average GP rate (P = 0.07), and volume of GP (P = 0.06); with the increase in C. butyricum supplementation, the GP kinetics were not changed at media pH 6.0, but the volume (P = 0.02), rate of GP (P = 0.01), and average GP rate (P = 0.01) were quadratically changed at media pH 6.6. The DMD was not affected by increasing the supplementation of C. butyricum. The molar proportions of propionate (P <0.09), butyrate (P <0.06), and NH3-N concentration (P = 0.02) were quadratically changed with increasing supplementation of C. butyricum regardless of media pH levels. The interactions between media pH level and dose of C. butyricum supplementation were noticed for alpha diversity indexes of Shannon (P = 0.02) and Evenness (P = 0.04). The alpha diversity indexes increased (P <0.05) except for Chao1 with supplementation of C. butyricum. The unweighted uniFrac analysis showed that the group of control at media pH 6.0 and control at media pH 6.6, and supplementation of C. butyricum and control at media pH 6.0 clustered separately from each other. At the phylum level, relative abundance (RA) of Bacteroidota was lower (P <0.01) and Firmicutes was higher (P <0.01) at media pH 6.6 than pH 6.0. Moreover, RA of Proteobacteria decreased (P <0.05) with supplemented C. butyricum at either media pH 6.6 or pH 6.0. At media pH 6.6, RA of Rikenellaceae_RC9_gut_group and Prevotella were decreased, and CAG-352 was increased (at genus level) compared to pH 6.0. Supplementation of C. butyricum decreased RA of Rikenellaceae_RC9_gut_group and increased CAG-352 at media pH 6.0. It could hence be concluded that manipulating media pH level and supplementation of C. butyricum effectively modulated in vitro rumen fermentation characteristics and microbiota but in a dose depending manner of C. butyricum addition.

Evaluation of Growth Performance, Nitrogen Balance and Blood Metabolites of Mutton Sheep Fed an Ammonia-Treated Aflatoxin B1-Contaminated Diet.

Experiments were conducted to evaluate the effects of an aflatoxin B1 (AFB1)-contaminated diet treated with ammonia on the diet detoxification and growth performance, nutrient digestibility, nitrogen utilization, and blood metabolites in sheep. Twenty-four female mutton sheep with an initial body weight of 50 ± 2.5 kg were randomly assigned to one of three groups: (1) control diet (C); (2) aflatoxin diet (T; control diet supplemented with 75 µg of AFB1/kg of dry matter); and (3) ammoniated diet (AT; ammoniated aflatoxin diet). The results showed decreases (p < 0.05) in average daily feed intake, nutrient digestibility of dry matter, crude protein and ether extract, and retained nitrogen, and an increase (p < 0.05) in urine nitrogen excretion in sheep fed diet T compared with those fed the other diets. In comparison to C and AT, feeding T decreased (p < 0.05) the concentrations of total protein, immunoglobulin A, immunoglobulin G, immunoglobulin M, superoxide dismutase, and total antioxidants and increased (p < 0.05) the concentrations of alanine amino transferase, malondialdehyde, and interleukin-6. In summary, ammonia treatment has the potential to decrease the concentration of AFB1 and alleviate the adverse effects of AFB1.

Circ003429 Regulates Unsaturated Fatty Acid Synthesis in the Dairy Goat Mammary Gland by Interacting with miR-199a-3p, Targeting the YAP1 Gene.

Fatty acid composition is a key factor affecting the flavor and quality of goat milk. CircRNAs are now recognized as important regulators of transcription, and they play an important role in the control of fatty acid synthesis. Thus, understanding the regulatory mechanisms controlling this process in ruminant mammary glands is of great significance. In the present study, mammary tissue from dairy goats during early lactation and the dry period (nonlactating) were collected and used for high-throughput sequencing. Compared to levels during the dry period, the expression level of circ003429 during early lactation was lower (12.68-fold downregulated). In isolated goat mammary epithelial cells, circ003429 inhibited the synthesis of triglycerides (TAG) and decreased the content of unsaturated fatty acids (C16:1, C18:1, and C18:2), indicating that this circRNA plays an important role in regulating lipid synthesis. A binding site for miR-199a-3p in the circ003429 sequence was detected, and a dual-luciferase reporter system revealed that circ003429 targets miR-199a-3p. Overexpression of circ003429 (pcDNA-circ003429) downregulated the abundance of miR-199a-3p. In contrast, overexpression of miR-199a-3p increased TAG content and decreased mRNA abundance of Yes-associated protein 1 (YAP1) (a target gene of miR-199a-3p), and TAG content was decreased and mRNA abundance was increased in response to overexpression of circ003429. These results indicate that circ003429 alleviates the inhibitory effect of miR-199a-3p on the mRNA abundance of YAP1 by binding miR-199a-3p, resulting in subsequent regulation of the synthesis of TAG and unsaturated fatty acids.

Two-Phase Transition Induced Amorphous Metal Phosphides Enabling Rapid, Reversible Alkali-Metal Ion Storage.

Metal phosphides as anode materials for alkali-metal ion batteries have captured considerable interest due to their high theoretical capacities and electronic conductivity. However, they suffer from huge volume expansion and element segregation during repetitive insertion/extraction of guest ions, leading to structure deterioration and rapid capacity decay. Herein, an amorphous Sn0.5Ge0.5P3 was constructed through a two-phase intermediate strategy based on the elemental composition modulation from two crystalline counterparts and applied in alkali-metal ion batteries. Differing from crystalline P-based compounds, the amorphous structure of Sn0.5Ge0.5P3 effectively reduces the volume variation from above 300% to 225% during cycling. The ordered distribution of cations and anions in the short-range ensures the uniform distribution of each element during cycles and thus contributes to durable cycling stability. Moreover, the long-range disordered structure of amorphous material shortens the ion transport distance, which facilitates diffusion kinetics. Benefiting from the aforementioned effects, the amorphous Sn0.5Ge0.5P3 delivers a high Na storage capacity of 1132 mAh g-1 at 0.1 A g-1 over 100 cycles. Even at high current densities of 2 and 10 A g-1, its capacities still reach 666 and 321 mAh g-1, respectively. As an anode for Li storage, the Sn0.5Ge0.5P3 similarly also exhibits better cycling stability and rate performance compared to its crystalline counterparts. Significantly, the two-phase transition strategy is generally applicable to achieving other amorphous metal phosphides such as GeP2. This work would be helpful for constructing high-performance amorphous anode materials for alkali-metal ion batteries.

Quantitative proteomic analysis of trachea in fatting pig exposed to ammonia.

Ammonia (NH3) is considered as the main pollutant in livestock houses and air environment, and its adverse effects on animal and human health have attracted widespread attention. However, trachea proteomics respond to NH3 is lacking, which is crucial to understanding how NH3 induces respiratory damage. In this study, we performed labeled quantitative proteomic (TMT-MS) analysis in the trachea of fatting pigs exposed to NH3 for 30 days. The proteomic results were then validated by Immunohistochemistry (IHC) and Parallel Reaction Monitoring (PRM). The results showed that a total of 126 differentially abundant proteins (DAPs) were identified (fold change <0.83 or > 1.2 and P < 0.05), including 70 differentially up-regulated proteins (DUPs) and 56 differentially down-regulated proteins (DDPs). These proteins were mainly located in intracellular regions and involved in immune response, metabolism and protein synthesis. The results of DAPs (EHHADH, RPL28, SLC25A6, TUBB6, CD14, CTSS, RPS11, RPL19, SLC25A5, RPS8, FABP3, RPL21, RPL34, RPL32, PDIA3, FBP1, HSPH1, SAR1A and SEC24C) verified by IHC and PRM were consistent with the proteomic results. The results of this study provided a basis and a novel insight for understanding the mechanism of NH3-induced tracheal injury. SIGNIFICANCE: Ammonia (NH3) is considered as the main pollutant in livestock houses and air environment, and its adverse effects on animal and human health have attracted widespread attention. However, trachea proteomics respond to NH3 is lacking, which is crucial to understanding how NH3 induces respiratory damage. Therefore, in this study, labeled quantitative proteomics (TMT-MS) was used to detect trachea tissue samples from finishing pigs in NH3 exposure group and control group, and PRM method was used to further verify the highly abundant proteins in NH3 exposure samples, so as to identify new diagnostic markers for NH3 poisoning. The results of this study provided a basis and a novel insight for understanding the molecular pathological mechanism of NH3-induced tracheal injury.

Overexpression of Toll-Like Receptor 4 Affects Autophagy, Oxidative Stress, and Inflammatory Responses in Monocytes of Transgenic Sheep.

Toll-like receptor 4 (TLR4) is a critical pattern recognition receptor that plays a critical role in the host innate immune system's recognition of Gram-negative bacteria. Since it is the lipopolysaccharide (LPS) receptor, it links the activated inflammatory response with autophagy and oxidative stress. Autophagy, or type II programmed cell death, was reported to have defensive functions in response to the production of inflammatory cytokines and oxidative stress. To explore the relationship between autophagy, inflammation, and oxidative stress, a TLR4-enriched transgenic (Tg) animal model (sheep) was generated. Autophagy activity in the Tg blood monocytes was significantly higher than in the wild-type animal under LPS stress, and it returned to normal after transfection of TLR4 siRNA. Pretreatment with 3-methyladenine (3-MA) inhibited autophagy and enhanced oxidative stress and the production of TNF-α. The LPS-induced reactive oxygen species (ROS) level was markedly increased in the Tg group at an early stage before quickly returning to normal values. In addition, suppressing ROS production by N-acetyl-L-cysteine down-regulated the number of intracellular autophagosomes and the expression of Beclin-1, ATG5, and cytokines IL-1ß, IL-6, and TNF-α. Further mechanistic investigation suggested that the TLR4-associated p38 mitogen-activated protein kinase (MAPK) signaling pathway was involved in autophagy and oxidative stress. P38 MAPK promotes intracellular autophagy, ROS production, and inflammatory response. Moreover, TLR4 over-expression suppressed oxidative stress and the production of inflammatory cytokines and increased autophagy activity in vivo. Taken together, our results showed that LPS induced autophagy, which was related to TLR4-mediated ROS production through the p38 MAPK signaling pathway. In addition, our study also provided a novel transgenic animal model to analyze the effects of TLR4 on autophagy, oxidative stress, and inflammatory responses.

PRL/microRNA-183/IRS1 Pathway Regulates Milk Fat Metabolism in Cow Mammary Epithelial Cells.

The aim of the study was to understand the internal relationship between milk quality and lipid metabolism in cow mammary glands. A serial of studies was conducted to assess the molecular mechanism of PRL/microRNA-183/IRS1 (Insulin receptor substrate) pathway, which regulates milk fat metabolism in dairy cows. microRNA-183 (miR-183) was overexpressed and inhibited in cow mammary epithelial cells (CMECs), and its function was detected. The function of miR-183 in inhibiting milk fat metabolism was clarified by triglycerides (TAG), cholesterol and marker genes. There is a CpG island in the 5'-flanking promoter area of miR-183, which may inhibit the expression of miR-183 after methylation. Our results showed that prolactin (PRL) inhibited the expression of miR-183 by methylating the 5' terminal CpG island of miR-183. The upstream regulation of PRL on miR-183 was demonstrated, and construction of the lipid metabolism regulation network of microRNA-183 and target gene IRS1 was performed. These results reveal the molecular mechanism of PRL/miR-183/IRS1 pathway regulating milk fat metabolism in dairy cows, thus providing an experimental basis for the improvement of milk quality.

Fecal bacterial community of finishing beef steers fed ruminally protected and non-protected active dried yeast.

Our previous study suggested that supplementation of high-grain diets with ruminally protected and non-protected active dried yeast (ADY) may potentially reduce manure pathogen excretion by feedlot cattle. We hypothesized that feeding ruminally protected ADY might change the fecal bacterial community of finishing cattle. The objective of this study was to investigate the effects of feeding ruminally protected and non-protected ADY to finishing beef steers on their fecal bacterial community. Fresh fecal samples were collected on day 56 from 50 steers fed one of five treatments: 1) control (no monensin, tylosin, or ADY), 2) antibiotics (ANT, 330 mg monensin + 110 mg tylosin·steer-1d-1), 3) ADY (1.5 g·steer-1d-1), 4) encapsulated ADY (EDY; 3 g·steer-1d-1), and 5) a mixture of ADY and EDY (MDY; 1.5 g ADY + 3 g EDY·steer-1d-1). Bacterial DNA was extracted from fecal samples and sequenced using a MiSeq high-throughput sequencing platform. A total number of 2,128,772 high-quality V4 16S rRNA sequences from 50 fecal samples were analyzed, and 1,424 operational taxonomic units (OTU) were detected based on 97% nucleotide sequence identity among reads, with 769 OTU shared across the five treatments. Alpha diversity indices, including species observed, Chao estimate, abundance-based coverage estimator, Shannon, Simpson, and coverage, did not differ among treatments, and principal coordinate analysis revealed a high similarity among treatments without independent distribution. Bacteroidetes and Firmicutes were dominant phyla in the fecal bacterial community for all treatments, with a tendency (P < 0.10) for greater relative abundance of Bacteroidetes but lesser Firmicutes with ANT, EDY, and MDY compared with control steers. Prevotella was the dominant genus in all treatments and steers supplemented with ANT, EDY, and MDY had greater (P < 0.05) relative abundance of Prevotella than control steers, but lesser (P < 0.03) relative abundance of Oscillospira. No differences between ADY and control were observed for the aforementioned variables. Fecal starch contents were not different among treatments, but the relative abundance of Bacteroidetes, as well as Prevotella at genera level, tended (P < 0.06) to be positively correlated to fecal starch content. We conclude that supplementing ruminally protected or non-protected ADY or ANT had no effect on diversity and richness of fecal bacteria of finishing beef cattle, whereas feeding protected ADY or ANT to finishing beef steers altered the dominant fecal bacteria at phylum and genus levels. Therefore, supplementation of ruminally protected ADY may potentially improve intestinal health by stimulating the relative abundance of Prevotella.

Screening of live yeast and yeast derivatives for their impact of strain and dose on in vitro ruminal fermentation and microbial profiles with varying media pH levels in high-forage beef cattle diet.

BACKGROUND: Yeast products showed beneficial effects with respect to stabilizing ruminal pH, stimulating ruminal fermentation and improving production efficiency. Batch cultures were conducted to evaluate the effects of yeast products on gas production (GP), dry matter disappearance (DMD) and fermentation characteristics of high-forage substrate. The study was a two media pH (5.8 and 6.5) × five yeasts (three live yeasts, LY: LY1, LY2, LY3; two yeast derivatives, YD: YD4, YD5) × four dosages factorial arrangement, with monensin (Mon) assigned as a positive control. RESULTS: Greater (P < 0.01) GP, DMD, volatile fatty acid (VFA) concentration, ratio of acetate to propionate (A:P) and copy numbers of Fibrobacter succinogenes and Ruminococcus flavefaciens were observed at pH 6.5 than at pH 5.8. The GP kinetics, DMD, VFA concentration, A:P and NH3 -N concentration differed (P < 0.05) among yeasts but varied with media pH or yeast dosages. Increasing doses of LY3 linearly increased DMD (P < 0.04) and VFA concentration (P < 0.001) at media pH 5.8. The DMD linearly (P < 0.02) increased with increased addition of YD4 (pH 6.5) and YD5 (pH 5.8) and the ratio of A:P linearly decreased (P < 0.01) with the addition of YD4 or YD5 at pH 5.8. Overall greater (P < 0.05) GP, A:P (pH 5.8) and DMD (pH 6.5) were observed with yeast products than with Mon. CONCLUSION: LY3 appeared to be an interesting candidate for improving rumen digestibility and fermentation efficiency, particularly at low media pH. YD4 or YD5 improved fermentation efficiency and can be potentially fed as an alternative to Mon. © 2019 Her Majesty the Queen in Right of Canada Journal of the Science of Food and Agriculture © 2019 Society of Chemical Industry.