2-Hydroxy-4-(Methylthio) Butanoic Acid Isopropyl Ester Supplementation Altered Ruminal and Cecal Bacterial Composition and Improved Growth Performance of Finishing Beef Cattle

Rumen by-pass soybean meal reduced ruminal ammonia but did not improve growth performance and nitrogen utilization in growing Hanwoo heifers

OBJECTIVE

The effects of heat-treated soybean meal (SBM) and citric acid (HCSBM) on the growth performance, rumen fermentation, blood metabolites, nutrient digestibility, and nitrogen (N) utilization were evaluated in growing Hanwoo heifers.

METHODS

Eight growing Hanwoo heifers (initial body weight: 228.5±11.3 kg; age: 9.3±0.3 months) were allocated to a crossover design with two dietary treatments: a control diet containing untreated SBM (Control) and a diet containing HCSBM. There were two 28-day phases in the trial, each containing 14-day measurements and an adaptation period. Growth performance, rumen fermentation parameters, blood metabolites, hematological parameters, apparent digestibility, energy, and N utilization were measured.

RESULTS

No significant differences were observed in the growth performance or energy utilization between the diets. The digestibility of dry matter and crude protein (CP) did not differ between the two diets. HCSBM supplementation increased neutral detergent fiber digestibility (p = 0.0874) and acetate molar proportions (p = 0.0748). The HCSBM diet resulted in lower ruminal ammonia nitrogen concentrations and iso-valerate proportions (p<0.05), indicating reduced ruminal protein degradation. Blood metabolites related to protein metabolism showed no significant differences between treatments. The control group exhibited higher red blood cell counts and hemoglobin and hematocrit levels (p<0.05). N excretion or retention did not significantly differ between the dietary groups.

CONCLUSION

Despite enhanced protection against ruminal protein degradation, HCSBM supplementation did not improve N utilization efficiency or growth performance in growing Hanwoo heifers, possibly because of a sufficient N supply from the high CP content in both diets.

Exploring the growing phase forest musk deer (Moschus berezovskii) dietary energy requirements based on growth performance and gut microbiota analysis

The forest musk deer (FMD) farming industry is currently experiencing rapid growth, yet the dietary energy requirements for FMD remain unclear. Therefore, we explored the optimal dietary digestible energy (DE) for growing phase FMD by providing three diets with different DE levels and analyzing changes in gut microbiota. A total of 20 six-month-old FMD were used in a 62-day trial. Animals were fed either traditional feed (CON, 10.38 MJ/kg DE) or pelleted diets with low (L, 8.87 MJ/kg), medium (M, 10.38 MJ/kg), or high (H, 11.86 MJ/kg) DE levels. The results showed that feeding pelleted diets significantly reduced the incidence of diarrhea (P < 0.05). The average daily gain in the H group was significantly higher than in the M group, and the M group was higher than both the L and CON groups (P < 0.05). Additionally, the H group showed the highest nutrient digestibility and the greatest increase in body measurements (P < 0.05). Analysis of fecal microbiota revealed that α-diversity and the relative abundance of Firmicutes increased with higher dietary energy levels, while the relative abundance of Bacteroidetes decreased. Beneficial bacteria such as Akkermansia and Lachnospira were significantly enriched in the H group. In conclusion, our findings suggest that pelleted diets are suitable for growing phase FMD, with an optimal dietary DE level of 11.86 MJ/kg.

IMPORTANCE

This study underscores the significance of identifying the optimal dietary digestible energy (DE) for growing forest musk deer (FMD). Pelleted diets with a DE level of 11.86 MJ/kg enhanced growth performance, nutrient digestibility, and gut health, while reducing diarrhea and enriching beneficial gut bacteria, offering valuable insights for improving FMD farming practices.

Effects of citric acid and heat-treated soybean meal on rumen fermentation characteristics, methane emissions, and microbiota: an in vitro study

This study aimed to assess the impact of citric acid (CA) and heat-treated soybean meal (SBM) on rumen fermentation characteristics, methane production, and microbiota through an in vitro experiment. Untreated SBM, heat-treated SBM (HSBM), CA-treated SBM (CSBM), and SBM treated with a combination of heat and CA (HCSBM). Parameters assessed in in vitro were gas production, methane emissions, dry matter degradability (IVDMD), crude protein degradability (IVCPD), ammonia nitrogen (NH3-N), microbial crude protein (MCP), volatile fatty acids (VFA), pH, and microbiota composition. The HCSBM exhibited the lowest gas production and theoretical maximum gas production (p < 0.01). Methane production (%) was significantly reduced in both CSBM and HCSBM (p < 0.01), with the lowest methane emissions (mL/g dry matter, DM) observed in HCSBM (p < 0.01). The IVCPD was significantly reduced in both the HSBM and HCSBM groups (p < 0.01). HCSBM had the lowest NH3-N and MCP concentrations (p < 0.01). Total VFA production was the lowest in HCSBM (p < 0.01), with a higher proportion of acetate and lower proportions of propionate (p < 0.01). HCSBM reduced the enrichment of Thermoplasmatota compared to HSBM (p < 0.05) and decreased the enrichment of the coenzyme M biosynthesis pathway in the microbial functional profiles compared to SBM and CSBM (p < 0.05). Additionally, an increase in fiber-degrading bacteria, particularly Fibrobacterota, was observed in HCSBM (p < 0.05). These findings suggest that the HCSBM may effectively reduce ruminal protein degradation and methane emissions. Further in vivo studies are necessary to validate these results and assess their practical application in ruminant nutrition.

Alterations in Methionine Cycle and Wnt/MAPK Signaling Associated with HMBi-Induced Cashmere Growth in Goats

Methionine (Met) was the first limiting amino acid identified in cashmere goats, and 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi) can effectively provide Met and encourage cashmere growth in goats. However, existing studies have primarily centered on the trait of cashmere growth and have not delved into the underlying molecular and physiological mechanisms by which HMBi promotes cashmere growth in goats. In the present study, we combined metabolomic and transcriptomic approaches to reveal the effects of HMBi supplementation and its impact on the gene expressions and metabolic profiles within the skin tissue of Liaoning cashmere goats. A total of 14 female Liaoning cashmere goats were randomly allocated to the control (CON) and HMBi groups. The CON group received a basal diet, and the HMBi group was fed the basal diet plus 1.27% HMBi. Our results show that HMBi supplementation significantly increased (p < 0.05) the cashmere length and decreased the cashmere diameter in the goats. The metabolomics results show that the HMBi supplementation increased (variable importance in projection >1 and p < 0.05) the concentrations of Met, 2-Hydroxy-4-methylthiobutanoic acid (HMB), proline betaine, and 10-hydroxydecanoic acid in the skin tissue of the goats. For HMB degradation and Met cycle-related genes, compared with the CON diets, the HMBi diets elevated (p < 0.05) LDHD, MAT1A, and AHCY by 86.33%, 154.54%, and 147.89% in the skin tissue, respectively. Regarding genes related to cell proliferation and differentiation, the HMBi supplementation increased (p < 0.05) CCND1, CDK4, IVL, and BMP4 by 113.31%, 107.93%, 291.33%, and 186.21%, respectively. The results of the transcriptome evaluation show that the differential expression genes were mainly enriched (p < 0.05) in the Wnt and MAPK signaling pathways. In summary, these findings indicate that the Met cycle, Wnt, and MAPK play important roles in the process of HMBi, promoting cashmere growth in Liaoning cashmere goats.

The quality of Tibetan sheep meat from pastures was synergistically regulated by the rumen microbiota and related genes at different phenological stages

Meat quality is a key indicator of meat performance in ruminants, and its mechanism and regulation are also key to ruminant research. Studies have shown that animal meat quality is related to the gut microbiota. In this study, RT-qPCR and 16S omics were employed to assess meat quality and intestinal microbiota. The objective was to investigate the influence of seasonal variations on the meat quality of Tibetan sheep ewes by examining the rumen microflora, meat quality attributes, and associated gene expression profiles over three distinct months: May, August, and December.The results indicate that muscle tenderness was significantly greater (p < 0.001) in the grass period than in the regrowth and dry grass periods and was highest in the longest dorsal muscle. The cooking rate of the foreleg muscle was significantly greater (p < 0.05) than that during the regrowth and dry grass periods, and the pH24h significantly differed (p < 0.05) across the different seasonal periods. The crude protein content of the longest back muscle and the foreleg muscle was significantly greater (p < 0.001) than that of the wither and grass stages during the regrowth period and slightly decreased during the grass stage. The crude fat and crude ash contents of the three groups differed significantly, and the fat content during the grass stage was significantly (p < 0.05) greater than that during the regrowth stage and the wither stage. Expression analysis of genes related to meat quality revealed that the expression of the ADSL gene was significantly greater (p < 0.05) in the anterior and posterior leg muscles during the grass period than during the regrowth and wilting periods, whereas the expression of the FABP3 gene was lower than that during these two periods. Correlation analysis revealed that Rikenellaceae_RC9_gut_group was significantly positively correlated (p < 0.05) with shear forceand cooked meat percentage and significantly negatively correlated (p < 0.05). Ruminococcus and Butyrivibrio were significantly positively correlated (p < 0.05) with CAST and highly significantly positively correlated (p < 0.05). In conclusion, meat quality during different seasons is regulated by the rumen microbiota and their associated genes.

Changes in the growth performance, serum biochemistry, rumen fermentation, rumen microbiota community, and intestinal development in weaned goats during rumen-protected methionine treatment

Rumen-protected methionine (RPM) such as coated methionine (CM) and 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester (HMBi) was usually used in dairy cows, but how RPM affects meat goats remains unclear. In this study, thirty weaned male Jianzhou Da'er goats were randomly assigned to one of three treatments: fed basal diet or basal diet supplemented with 0.12% CM or 0.22% HMBi, with the aim of examining their impact on growth performance, serum biochemistry, rumen fermentation, rumen microbiota, and intestinal development in meat goats. The findings indicate that HMBi supplementation led to an increase in body weight, feed intake, and feed-to-gain ratio, whereas CM only resulted in an increase in feed intake (all p < 0.05). Both CM and HMBi resulted in an increase in serum total cholesterol (TC), blood urea nitrogen (BUN), alkaline phosphatase (ALP), and aspartate aminotransferase (AST), albeit with a decrease in serum triglycerides (TG) and β-hydroxybutyric acid (BHB, all p < 0.05). Both CM and HMBi supplementation decreased the rumen butyric acid concentration (both p < 0.05). The 16S rRNA sequencing showed that HMBi supplementation significantly increased the total abundance of Bacteroidetes and Firmicutes. Both CM and HMBi supplements increased the abundance of Rikenella and Proteiniphilum but decreased the abundance of Eisenbergiella, Enterocloster, Massilioclostridium, Eubacterium, Angelakisella, Blastopirellula, Christensenella, and Pseudoruminococcus. CM supplementation specifically increased the abundance of Desulfobulbus, Sodaliphilus, and Coprococcus while decreasing the prevalence of Anaerocella, Mogibacterium, and Collinsella. The supplementation of HMBi significantly enhanced the abundance of Paraprevotella, Bacilliculturomica, Lachnoclostridium, Dysosmobacter, Barnesiella, and Paludibacter, while decreasing the abundance of Butyrivibrio and Pirellula. Moreover, the administration of both CM and HMBi supplementation resulted in an increase in the ammonia-producing and sulfate-reducing bacteria, whereas a decrease was observed in the ammonia-oxidating, health-associated, and disease-associated bacteria. Correlational analysis revealed that TG and BHB had a positive correlation with disease-associated and ammonia-oxidating bacteria, whereas they had a negative correlation with ammonia-producing bacteria. The serum BUN, ALP, and AST were positively correlated with ammonia-producing bacteria but were negatively correlated with ammonia-oxidating bacteria. Furthermore, both CM and HMBi supplementation improve the development of the small intestine, with HMBi having a better effect. In summary, this study indicates that both CM and HMBi supplementation improve lipid metabolism, nitrogen utilization, and intestinal development. The growth promotion effect of HMBi supplementation may be attributed to the increased abundance of volatile fatty acid-producing and nitrogen-utilizing bacteria and improved intestinal development.

Effects of Dietary Energy Levels on Growth Performance, Nutrient Digestibility, Rumen Barrier and Microflora in Sheep

Dietary energy is crucial for ruminants' performance and health. To determine optimal dietary energy levels for growing sheep, we evaluated their growth performance, nutrient digestibility, rumen fermentation, barrier function, and microbiota under varying metabolic energy (ME) diets. Forty-five growing Yunnan semi-fine wool sheep, aged 10 months and weighing 30.8 ± 1.9 kg, were randomly allocated to five treatments, each receiving diets with ME levels of 8.0, 8.6, 9.2, 9.8 or 10.4 MJ/kg. The results showed that with increasing dietary energy, the average daily gain (ADG) as well as the digestibility of dry matter (DM) and organic matter (OM) increased (p < 0.05), while the feed conversion ratio (FCR) decreased linearly (p = 0.01). The concentration of total VFA (p = 0.03) and propionate (p = 0.01) in the rumen increased linearly, while rumen pH (p < 0.01) and the acetate-propionate ratio (p = 0.01) decreased linearly. Meanwhile, the protein contents of Claudin-4, Claudin-7, Occludin and ZO-1 as well as the relative mRNA expression of Claudin-4 and Occludin also increased (p < 0.05). In addition, rumen bacterial diversity decreased with the increase of dietary energy, and the relative abundance of some bacteria (like Saccharofermentans, Prevotella and Succiniclasticum) changed. In conclusion, increasing dietary energy levels enhanced growth performance, nutrient digestibility, rumen fermentation, and barrier function, and altered the rumen bacterial community distribution. The optimal dietary ME for these parameters in sheep at this growth stage was between 9.8 and 10.4 MJ/kg.

Differential responses of rumen and fecal fermentation and microbiota of Liaoning cashmere goats after 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester supplementation

The 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi), a rumen protective methionine, has been extensively studied in dairy cows and beef cattle and has been shown to regulate gastrointestinal microbiota and improve production performance. However, knowledge of the application of HMBi on cashmere goats and the simultaneous study of rumen and hindgut microbiota is still limited. In this study, HMBi supplementation increased the concentration of total serum protein, the production of microbial protein in the rumen and feces, as well as butyrate production in the feces. The results of PCoA and PERMANOVA showed no significant difference between the rumen microbiota, but there was a dramatic difference between the fecal microbiota of the two groups of Cashmere goats after the HMBi supplementation. Specifically, in the rumen, HMBi significantly increased the relative abundance of some fiber-degrading bacteria (such as Fibrobacter) compared with the CON group. In the feces, as well as a similar effect as in the rumen (increasing the relative abundance of some fiber-degrading bacteria, such as Lachnospiraceae FCS020 group and ASV32), HMBi diets also increased the proliferation of butyrate-producing bacteria (including Oscillospiraceae UCG-005 and Christensenellaceae R-7 group). Overall, these results demonstrated that HMBi could regulate the rumen and fecal microbial composition of Liaoning cashmere goats and benefit the host.

Response of growth performance and cecum microbial community to cyclic heat stress in broilers

Heat stress (HS) can affect growth performance through alterations in specific gut microbiota, which greatly threatens poultry production. How HS affects the mechanisms of microbial changes in the poultry cecum and the complex interactions between cecal microbial changes and growth performance have not yet been well evaluated. This study was conducted to examine the changes in growth performance and cecal microbiotal community in cyclic heat stress (CHS)-treated broilers. A total of 200 twenty-eight-day-old female Arbor Acres (AA) broilers were equally allotted into neutral ambient temperature group (TN group, 24 ± 1°C, 24 h/day) and CHS group (33 ± 1°C, 8 h/day) with five replicates of 10 broilers each, respectively. Growth performance, cecum microbial diversity, flora composition, and community structure were analyzed on days 35 and 42. The decreased average daily feed intake (ADFI), average daily gain (ADG), and the increased feed/gain ratio (F:G) were observed in heat-stressed broilers on days 35 and 42. The alpha and beta diversity index had no significant changes at the two experimental periods (P > 0.05). At the genus level, CHS significantly increased the relative abundance of Enterococcus at 42 days (P < 0.05). Based on the analysis of linear effect size feature selection, CHS made an enriched Reyranella and a reduced Romboutsia and Ruminiclostridium at 35 days of age (P < 0.05). CHS made an enriched Weissella and Enterococcus at 42 days of age (P < 0.05). The present study revealed that CHS reduces broiler growth performance and alters the microbial community of the cecum microbiota and the abundance of species. These findings are of critical importance to alleviate the negative effects of CHS on broiler chickens' growth performance by maintaining gut microbial balance.

Effect of Methionine Hydroxy Analog on Hu Sheep Digestibility, Rumen Fermentation, and Rumen Microbial Community In Vitro

This experiment was conducted to evaluate the effects of a methionine hydroxy analog (MHA) on in vitro gas production, rumen fermentation parameters, and rumen microbiota. Two different MHA, 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi) and the calcium salt of the hydroxy analog of methionine (MHA-Ca), were selected for in vitro experiments. The treatments were the Control group (0% of MHA), HMBi group (2%HMBi), and MHA-Ca group (2%MHA-Ca). Dry matter digestibility was measured after 12 h and 24 h of fermentation, and fermentation parameters and microbial composition were analyzed after 24 h. HMBi and MHA-Ca showed increased (p = 0.001) cumulative gas production in 3 h. The total volatile fatty acids, microbial protein (MCP) concentration, acetate, and acetate to propionate ratio in the HMBi and MHA-Ca groups were significantly higher than those in the Control group (p = 0.006, p = 0.002, p = 0.001, p = 0.004), and the NH₃-N concentrations in the HMBi and MHA-Ca groups were significantly lower than those in the Control group (p = 0.004). The 16S rRNA sequencing revealed that the HMBi group had a higher (p = 0.039, p = 0.001, p = 0.027) relative abundance of Bacteroidetes, Firmicutes, and Synergistetes and a lower relative abundance of Proteobacteria (p = 0.001) than the Control group. At the genus level, Prevotella abundance was higher (p = 0.001), while Ruminobacter abundance was lower (p = 0.001), in the HMBi and MHA-Ca groups than in the Control group. Spearman's correlation analysis showed that the relative abundance of Prevotella_1, Streptococcus, and Desulfovibrio was positively correlated with dry matter digestibility, MCP, and fermentation parameters. MHA, thus, significantly increased gas production and altered the rumen fermentation parameters and microbiota composition of sheep.

Effects of Dietary Capsaicin and Yucca schidigera Extracts as Feed Additives on Rumen Fermentation and Microflora of Beef Cattle Fed with a Moderate-Energy Diet

Capsaicin (CAP) and Yucca schidigera extract (YSE) are two types of plant extracts that can change rumen fermentation. This study was conducted to investigate whether supplementation of beef cattle diets with CAP and YSE for 90 days would affect rumen fermentation and microflora. Forty-five healthy Angus steers (initial body weight = 510.54 ± 41.27 kg) were divided into three groups: control (CON), CAP, and YSE. Ammonia nitrogen (NH3-N) and total volatile fatty acid (TVFA) concentrations were significantly higher in the YSE group than in the CON group and significantly lower in the CAP group than in the CON group. At the phylum level, YSE increased the relative abundances of Bacteroidota and Patescibacteria and reduced that of Bacillota. At the genus level, CAP and YSE both increased the relative abundances of genera subordinate to Bacteroidota and decreased the relative abundances of genera subordinate to Bacillota. Our study shows that YSE and CAP have different effects on rumen fermentation and microflora after long-term supplementation.

Effect of methionine hydroxy analog feed supplements: Significant alteration and enrichment of rumen microbiota and metabolome in Hu sheep

Methionine hydroxy analogs (MHA) are widely used as the main sources of methionine in ruminant feed production. The purpose of this study was to explore the effect of using MHA supplements such as MHA as a salt of calcium (MHA-Ca) and 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester (HMBi) as sources of methionine on the rumen microbiota and metabolome in Hu sheep. Seventy-two healthy Hu sheep were randomly assigned to three dietary treatment groups: control, MHA-Ca, and HMBi groups. The results showed that the concentrations of total volatile fatty acids, acetate, and propionate were higher in the HMBi group than in the control group. The HMBi and MHA-Ca groups had higher alpha diversity values than those in control group. We compared the rumen microbiota by using 16S rRNA gene sequencing. At the phylum level, the HMBi group had a higher relative abundance of Firmicutes and a lower relative abundance of Synergistetes than did the control group. At the genus level, the control group had a higher relative abundance of Treponema_2 than did the HBMi group and a higher relative abundance of Prevotellaceae_UCG_004 than did the MHA-Ca group. Metabolomic analyses revealed that fatty acids, amino acids, lipids, organic acids, sugars, amines, and nucleosides were significantly altered in both MHA-Ca and HMBi groups. Metabolites with significant differences were enriched in amino acid and carbohydrate metabolisms, such as phenylalanine metabolism, biosynthesis of amino acids, tryptophan metabolism, galactose metabolism, and tyrosine metabolism. Above all, the findings presented in this study indicate that MHA alter the rumen microbiota and metabolites and that different forms of MHA have different impacts. The results of our study contribute to a better understanding of the effects of MHA.

Effect of the ratio of dietary metabolizable energy to nitrogen content on production performance, serum metabolites, rumen fermentation parameters, and bacterial diversity in yaks

This study examined the effect of the ratio of dietary metabolizable energy (MJ) to nitrogen (g) content (ME:N) on average daily gain (ADG), blood biochemical indices, rumen fermentation parameters, and rumen bacterial community in yaks. Thirty-six male yaks, aged 2–3 years, were divided into three groups and received a ME:N ratio of 0.42 (HY), 0.36 (MY,) or 0.32 (LY) MJ/g. Dry matter intake ranged between 3.16 and 3.63 kg/d and was lesser (p < 0.001) in the LY group than the other two groups. ME intake increased (p < 0.001) with an increase in the ME:N ratio, while N intake did not differ among groups. The ADG was 660 g/day for the MY group, which was higher (p < 0.005) than the 430 g/day in the LY group, while the HY group gained 560 g/day and did not differ from the other two groups. Feed intake to ADG ratio ranged between 5.95 and 7.95, and numerically was highest in the LY group and lowest in the MY group. In general, the concentration of ruminal total volatile fatty acids (p < 0.03) and molar proportions of propionate (p < 0.04), increased, while the molar proportion of acetate (p < 0.005) and the acetate:propionate ratio decreased (p < 0.001) with a decrease in the ME:N ratio. The molar proportion of butyrate did not differ among groups (p = 0.112). Group MY had higher ruminal NH₃-N content than group HY and had a higher serum glucose content but lower urea content, lactate dehydrogenase, and creatine kinase content than group LY. In ruminal bacteria at the phylum level, the relative abundance of Firmicutes (F) was greater and of Bacteroidetes (B) was lesser, while the F:B ratio was greater in group MY than in groups HY an LY. We concluded that the yaks consuming the diet containing a ME:N ratio of 0.36 MJ/g had the best performance of the three groups.