Effects of different dietary energy levels on growth performance, meat quality and nutritional composition, rumen fermentation parameters, and rumen microbiota of fattening Angus steers

This study investigates the effects of varying energy levels in diets on Black Angus steers, focusing on growth performance, muscle composition, rumen microbial community, and their interrelationships. Twenty-seven Black Angus steers, aged approximately 22 months and weighing 520 ± 40 kilograms, were randomly divided into three groups: low-energy (LE), medium-energy (ME), and high-energy (HE). Each group consisted of nine individuals. The steers were fed diets with energy levels of 6.657 MJ/kg (LE), 7.323 MJ/kg (ME), and 7.990 MJ/kg (HE) following a 14-day pre-feeding period, with a subsequent 90-day main experimental phase. After the 90-day feeding period, both the HE and ME groups exhibited significantly higher average daily weight gain (ADG) compared to the LE group (p < 0.05). The feed-to-weight ratios were lower in the HE and ME groups compared to the LE group (p < 0.05). The HE group showed significantly higher crude fat content in the longissimus dorsi muscle compared to the LE group (p < 0.05), with total fatty acid content in the muscle surpassing that in the ME and LE groups (p < 0.05). As dietary energy levels increased, the diversity of the rumen microbial community decreased (p < 0.05), and significant differences in bacterial community structure were observed between the LE and HE groups (p < 0.05). The results suggest that higher dietary energy levels enhance growth performance and alter muscle composition in Black Angus steers, while also influencing the rumen microbial community. This study contributes to understanding optimal dietary strategies for finishing Angus cattle to improve beef quality, economic returns, and the development of standardized production procedures.

Rumen Development of Tianhua Mutton Sheep Was Better than That of Gansu Alpine Fine Wool Sheep under Grazing Conditions

The purpose of this experiment was to investigate the differences in rumen tissue morphology, volatile fatty acid content, and rumen microflora between Tianhua mutton sheep and Gansu alpine fine wool sheep under the same grazing conditions. Twelve 30-day-old lambs were randomly selected from two different flocks in Duolong Village and grazed together for a period of 150 days. The rumen tissue was fixed with 4% paraformaldehyde and brought back to the laboratory for H&E staining, the volatile fatty acid content of the rumen contents was detected by gas chromatography, and the rumen flora structure was sequenced by full-length sequencing of the bacterial 16S rRNA gene using the PacBio sequencing platform. The acetic acid and total acid contents of the rumen contents of Tianhua mutton sheep were significantly higher than those of Gansu alpine fine wool sheep (p < 0.05). The rumen papillae height of Tianhua mutton sheep was significantly higher than that of Gansu alpine fine wool sheep (p < 0.05). The diversity and richness of the rumen flora of Tianhua mutton sheep were higher than those of Gansu alpine fine wool sheep, and Beta analysis showed that the microflora structure of the two fine wool sheep was significantly different. At the phylum level, Firmicutes and Bacteroidetes dominated the rumen flora of Tianhua mutton sheep and Gansu alpine fine wool sheep. At the genus level, the dominant strains were Christensenellaceae_R_7_group and Rikenellaceae_RC9_gut_group. LEfSe analysis showed that Prevotella was a highly abundant differential species in Tianhua mutton sheep and lachnospiraccac was a highly abundant differential species in Gansu alpine fine wool sheep. Finally, both the KEGG and COG databases showed that the enrichment of biometabolic pathways, such as replication and repair and translation, were significantly higher in Tianhua mutton sheep than in Gansu alpine fine wool sheep (p < 0.05). In general, there were some similarities between Tianhua mutton sheep and Gansu alpine fine wool sheep in the rumen tissue morphology, rumen fermentation ability, and rumen flora structure. However, Tianhua mutton sheep had a better performance in the rumen acetic acid content, rumen papillae height, and beneficial bacteria content. These differences may be one of the reasons why Tianhua mutton sheep are more suitable for growing in alpine pastoral areas than Gansu alpine fine wool sheep.

Evaluation of Increasing Dietary Concentrations of a Multi-Enzyme Complex in Feedlot Lambs' Rations

The objective of this study was to evaluate the effects of increasing levels of the M-E complex (xylanase, glucanase, cellulase, and invertase) Optimax E® on the performance of growing lambs, their digestibility, and their rumen microbiota, and to estimate NEm, NEg, and ruminal methane levels. Forty lambs (Katahdin x Dorset; 22.91 ± 4.16 kg) were randomly assigned to dietary concentrations of ME (0, 0.2, 0.4, and 0.8% DM) and fed individually for 77 days. Increasing M-E improved feed conversion (p < 0.05) as well as NEm and NEg (p < 0.05), which were associated with increased in vivo DM and NDF digestion (linear and quadratic p < 0.01). Few microbial families showed abundancy changes (Erysipelotrichaceae, Christensenellaceae, Lentisphaerae, and Clostridial Family XIII); however, the dominant phylum Bacteroidetes was linearly reduced, while Firmicutes increased (p < 0.01), resulting in a greater Firmicutes-to-Bacteroidetes ratio. Total Entodinium showed a quadratic response (p < 0.10), increasing its abundancy as the enzyme dose was augmented. The daily emission intensity of methane (per kg of DMI or AGD) was reduced linearly (p < 0.01). In conclusion, adding the M-E complex Optimax E® to growing lambs' diets improves their productive performance by acting synergistically with the rumen microbiota, modifying the Firmicutes-to-Bacteroidetes ratio toward more efficient fermentation, and shows the potential to reduce the intensity of greenhouse gas emissions from lambs.

Effects of non-pelleted or pelleted low-native grass and pelleted high-native grass diets on meat quality by regulating the rumen microbiota in lambs

Diet modulates the rumen microbiota, which in turn can impact the animal performance. The rumen microbiota is increasingly recognized for its crucial role in regulating the growth and meat quality of the host. Nevertheless, the mechanism by which the rumen microbiome influences the fatty acid and amino acid profiles of lambs in the grass feeding system remains unclear. This study aimed to evaluate the effects of different native grass-based diets on animal performance, meat quality, fatty acid compositions, amino acid profiles, and rumen microbiota of lamb. Seventy-two Ujumqin lambs were randomly assigned into three treatments according to the initial body weight (27.39 ± 0.51 kg) and age (6 months ± 6 days). The lambs received three diets: (i) non-pelleted native grass hay with 40% concentrate diet; the native grass and concentrate were fed individually; (ii) pelleted native grass hay with 40% concentrate diet (PHLC); (iii) pelleted native grass hay with 60% concentrate diet (PHHC). The results showed that among the three groups, the PHHC and PHLC diets had markedly (P < 0.05) higher average daily gain and pH45 min, respectively. All amino acid levels were significantly (P < 0.05) decreased in the PHHC diet than in the PHLC diet. The principal coordinate analysis of the ruminal microbiota indicated the markedly distinct separation (P = 0.001) among the three groups. In addition, the correlation analysis showed that the Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-003, Succinivibrio, and Succiniclasticum were significantly (P < 0.05) associated with most of the fatty acid and amino acid profiles. The correlation analysis of the association of microbiome with the meat quality provides us with a comprehensive understanding of the composition and function of the rumen microbial community, and these findings will contribute to the direction of future research in lamb.

IMPORTANCE

Diet modulates the gut microbiome, which in turn impact the meat quality, yet few studies investigate the correlation between the rumen microbiome and the fatty acid profile of meat. Here, the current study develops an experiment to investigate the correlation of the rumen microbiome and fatty acid profile of meat: rumen microbiome responses to feed type and meat quality. The results indicated a unique microbiota in the rumen of lamb in response to diets and meat quality. Associations between utilization and production were widely identified among the affected microbiome and meat quality, and these findings will contribute to the direction of future research in lamb.

Effects of dietary energy levels on microorganisms and short-chain fatty acids of rumen and tight junction proteins in Honghe Yellow cattle

This study was conducted to investigate the effects of dietary energy levels on microorganisms and short-chain fatty acids (SCFAs) of rumen and the expression of tight junction proteins in Honghe Yellow cattle. A total of fifteen male Honghe Yellow cattle were randomly divided into three treatments (five replicates per treatment), consisting of formulated energy concentrations of 5.90 MJ/kg (high-energy diet, group H), 5.60 MJ/kg (medium-energy diet, group M) and 5.30 MJ/kg (low-energy diet, group L). The results showed that compared with group H, the expression of Claudin-1 in rumen epithelium of groups M and L was increased, but the expression of ZO-1 was decreased (p < 0.05). Moreover, compared with group H, group M down-regulated the expression of Occludin and Claudin-1 in the brain (p < 0.05). For rumen bacteria, the dominant phyla included Bacteroidetes and Firmicutes, the abundance of Actinobacteriota in groups M and L was significantly increased compared with group H (p < 0.05). At the genus level, the relative abundance of Corynebacterium, Eubacterium_nodatum_group and Neisseraceae in groups M and L was significantly decreased compared with group H (p < 0.05). For rumen fungi, the dominant phyla included Basidiomycota, Ascomycota and Neocariastigomycota, the relative abundance of Ascomycetes was significantly higher than that of groups M and L compared with group H (p < 0.05). At the genus level, the relative abundance of Neocelimastigaceae and Myceliophthora in groups M and L was significantly reduced compared with group H (p < 0.05). Furthermore, the expression of Claudin-1 in rumen epithelium was significantly positively correlated with Actinobacteriota, Corynebacterium and Neisseriaceae. The expression of ZO-1 in the spinal cord was significantly positively correlated with Myceliophthora. The expression of Occludin in brain was positively correlated with valerate content (p < 0.05). In summary, dietary energy levels affected the rumen microbiota of Honghe Yellow cattle. The expression of Claudin-1 in rumen epithelium and the total SCFAs concentration were increased with decreasing dietary energy levels, but the expression of Claudin-1 in brain and ZO-1 in the spinal cord were reduced with decreasing dietary energy levels. Meanwhile, the rumen microbiota and SCFAs were significantly correlated with the expression of TJP.

Supplementation with Astragalus Root Powder Promotes Rumen Microbiota Density and Metabolome Interactions in Lambs

The gut microbiota is highly symbiotic with the host, and the microbiota and its metabolites are essential for regulating host health and physiological functions. Astragalus, as a feed additive, can improve animal immunity. However, the effects of Astragalus root powder on the rumen microbiota and their metabolites in lambs are not apparent. In this study, thirty healthy Hu sheep lambs with similar body weights (17.42 ± 2.02 kg) were randomly selected for the feeding experiment. Lambs were fed diets supplemented with 0.3% Astragalus root powder, and the rumen microbiota density and metabolome were measured to determine the effects of Astragalus on the health of lambs in the rumen. The results showed that the relative abundance of Butyrivibrio fibrisolvens (Bf), Ruminococcus flavefaciens (Rf), Succiniclasticum (Su), and Prevotella (Pr) in the rumen was increased in the Astragalus group (p < 0.01), and metabolic profiling showed that the metabolites, such as L-lyrosine and L-leucine, were upregulated in the Astragalus group (p < 0.01). KEGG functional annotation revealed that upregulated metabolites were mainly enriched in the pathways of amino acid metabolism, lipid metabolism, fatty acid biosynthesis, and bile secretion in the Astragalus group, and downregulated metabolites were enriched in the pathways of methane metabolism and other pathways. Correlation analysis revealed that butyric acid was positively correlated with Roseburia and Blautia (p < 0.05) and negatively correlated with Desulfovibrio (p < 0.05). Thus, by analyzing the interactions of Astragalus root powder with the density of rumen microorganisms and their metabolites in lambs, it was shown that Astragalus root powder could improve the structure of rumen microbiota and their metabolites and then participate in the regulation of amino acid metabolism, lipid metabolism, immune metabolism, and other pathways to improve the efficiency of energy absorption of the lambs.

Effects of adding Allium mongolicum Regel powder and yeast cultures to diet on rumen microbial flora of Tibetan sheep (Ovis aries)

The purpose of this experiment was to study the effect of Allium mongolicum Regel powder (AMR) and yeast cultures (YC) on rumen microbial diversity in Tibetan sheep in different Ecological niches. A total of 40 male Tibetan lambs with an initial weight of 18.56 ± 1.49 kg (6 months old) were selected and divided into four groups (10 sheep/pen; n = 10). In the Control Group, each animal was grazed for 8 h per day, in Group I, each animal was supplemented with 200 g of concentrate per day, in Group II, each animal was supplemented with 200 g of concentrate and 10 g of AMR per day, in Group III, each animal was supplemented with 200 g of concentrate and 20 g of YC per day. The experiment lasted 82 days and consisted of a 7-day per-feeding period and a 75-day formal period. The results indicated that at the phylum level, the abundance of Bacteroidota and Verrucomimicrobiota in L-Group II and L-Group III was increased, while the abundance of Proteobacteria was decreased in the LA (Liquid-Associated) groups. The proportion of F/B in S-Group II and S-Group III was increased compared to S-Group I and S-CON in the SA (Soild-Associated) group. At the genus level, the abundance of uncultured_rumen_bacterium and Eubacterium_ruminantium_group in L-Group II and L-Group III was increased. Furthermore, while the abundance of Rikenellaceae_RC9_gut_group was decreased in the LA, the abundance of Prevotella and Eubacterium_ruminantium_group was increased in the S-Group II and S-Group III compared to S-Group I and S-CON. The abundance of probable_genus_10 was the highest in S-Group II in the SA group. After the addition of YC and AMR, there was an increase in rumen microbial abundance, which was found to be beneficial for the stability of rumen flora and had a positive impact on rumen health.

Multi-omics revealed rumen microbiota metabolism and host immune regulation in Tibetan sheep of different ages

The rumen microbiota and metabolites play an important role in energy metabolism and immune regulation of the host. However, the regulatory mechanism of rumen microbiota and metabolite interactions with host on Tibetan sheep's plateau adaptability is still unclear. We analyzed the ruminal microbiome and metabolome, host transcriptome and serum metabolome characteristics of Tibetan sheep at different ages. Biomarkers Butyrivibrio, Lachnospiraceae_XPB1014_group, Prevotella, and Rikenellaceae_RC9_gut_group were found in 4 months, 1.5 years, 3.5 years, and 6 years Tibetan sheep, respectively. The rumen microbial metabolites were mainly enriched in galactose metabolism, unsaturated fatty acid biosynthesis and fatty acid degradation pathways, and had significant correlation with microbiota. These metabolites further interact with mRNA, and are co-enriched in arginine and proline metabolism, metabolism of xenobiotics by cytochrome P450, propanoate metabolism, starch and sucrose metabolism, gap junction pathway. Meanwhile, serum metabolites also have a similar function, such as chemical carcinogenesis - reactive oxygen species, limonene and pinene degradation, and cutin, suberine and wax biosynthesis, thus participating in the regulation of the body's immune and energy-related metabolic processes. This study systematically revealed that rumen microbiota, metabolites, mRNA and serum metabolites of Tibetan sheep were involved in the regulation of fermentation metabolic function and immune level of Tibetan sheep at different ages, which provided a new perspective for plateau adaptability research of Tibetan sheep at different ages.

Exploring the Rumen Microbiota and Serum Metabolite Profile of Hainan Black Goats with Different Body Weights before Weaning

The critical role of the rumen microbiota in the growth performance of livestock is recognized, yet its significance in determining the body weight of goat kids before weaning remains less understood. To bridge this gap, our study delved into the rumen microbiota, serum metabolome, rumen fermentation, and rumen development in goat kids with contrasting body weights before weaning. We selected 10 goat kids from a cohort of 100, categorized into low body weight (LBW, 5.56 ± 0.98 kg) and high body weight (HBW, 9.51 ± 1.01 kg) groups. The study involved sampling rumen contents, tissues, and serum from these animals. Our findings showed that the HBW goat kids showed significant enrichment of VFA-producing bacteria, particularly microbiota taxa within the Prevotellaceae genera (UCG-001, UCG-003, and UCG-004) and the Prevotella genus. This enrichment correlated with elevated acetate and butyrate levels, positively influencing rumen papillae development. Additionally, it was associated with elevated serum levels of glucose, total cholesterol, and triglycerides. The serum metabonomic analysis revealed marked differences in fatty acid metabolism between the LBW and HBW groups, particularly in encompassing oleic acid and both long-chain saturated and polyunsaturated fatty acids. Further correlational analysis underscored a significant positive association between Prevotellaceae_UCG-001 and specific lipids, such as phosphatidylcholine (PC) (22:5/18:3) and PC (20:3/20:1) (r > 0.60, p < 0.05). In summary, this study underscores the pivotal role of the rumen microbiota in goat kids' weight and its correlation with specific serum metabolites. These insights could pave the way for innovative strategies aimed at improving animal body weight through targeted modulation of the rumen microbiota.

Dietary β-hydroxybutyric acid improves the growth performance of young ruminants based on rumen microbiota and volatile fatty acid biosynthesis

Introduction

The ketone body β-hydroxybutyric acid (BHB) plays critical roles in cellular proliferation and metabolic fuel utilization; however, its effects on the rumen microbiota remain unknown.

Methods

Here, three doses of BHB (low, medium, and high) were supplemented to early-weaned goat kids.

Results

Compared with controls, the beneficial effects of BHB on growth and rumen development were observed in goats at 90 days of age (d). The low dose of dietary BHB increased the concentration of rumen acetate, propionate, and butyrate on d90. The sequencing results of the rumen microbiota revealed marked shifts in rumen microbial community structure after early-weaned goat kids consumed BHB for 2 months. The signature bacterial ASVs for each treatment were identified and were the main drivers contributing to microbial interactions in the rumen. The bacteria associated with rumen weight were also correlated with body weight. Some classified bacterial signatures, including Prevotella, Olsenella umbonate, and Roseburia faecis, were related to rumen volatile fatty acids and host development.

Conclusion

Overall, dietary BHB altered rumen microbiota and environments in young goats, which contributed to rumen development and growth.

Analysis of Rumen Degradation Characteristics, Attached Microbial Community, and Cellulase Activity Changes of Garlic Skin and Artemisia argyi Stalk

The purpose of this study was to study the chemical composition, rumen degradation characteristics, surface attached microbial community and cellulase activity of garlic skin (GS) and Artemisia argyi stalk (AS), in order to explain their feeding value. Four 14-month-old healthy Min Dong male goats with permanent rumen fistula were selected as experimental animals. The rumen degradation characteristics of GS and AS were determined by using the nylon bag method, and the bacterial composition, cellulase activity and their relationship on the surface of the two groups were analyzed with high-throughput sequencing of 16S rRNA gene. The results showed that in GS and AS, the effective degradation rate (ED) values of dry matter (DM) were 42.53% and 37.12%, the ED values of crude protein (CP) were 37.19% and 43.38%, the ED values of neutral detergent fiber (NDF) were 36.83% and 36.23%, and the ED values of acid detergent fiber (ADF) were 33.81% and 34.77%. During rumen degradation, the richness and evenness of bacteria attached to the AS surface were higher. At the phylum level, Bacteroidetes and Firmicutes were always the main rumen bacteria in the two groups. At the genus level, fiber-degrading bacteria such as Prevotella, Treponema, and Ruminococcus showed higher levels in GS (p < 0.05). Compared with GS, the activity of β-glucosidase (BG enzyme), endo-β-1,4-glucanase (C1 enzyme), exo-β-1,4-glucanase (Cx enzyme) and neutral xylanase (NEX enzyme) attached to AS surface showed a higher trend. Correlation analysis showed that the relative abundance of Succinivibrio and Rikenellaceae_RC9_gut_group was positively correlated with the rumen degradability of nutrients in GS, and the relative abundance of Christensenellaceae R-7_group, Succinivibrio and Ruminococcus was positively correlated with the rumen degradability of nutrients in AS. The conclusion of this study shows that AS has more potential to become ruminant roughage than GS. In addition, this study also revealed the relationship between cellulase activity and bacteria, which provided new information for us to better analyze the effects of GS and AS on the rumen of ruminants and provided an important theoretical basis for the development and utilization of agricultural by-products.

Effects of allicin on growth performance, antioxidant profile, and microbiota compared to monensin of growing goats

Allicin is a sulfur-containing compound extracted from raw garlic (Allium sativum L.). We compared the effect of allicin addition on growth performance, serum biochemical parameters, and rumen microbiota of goats compared to monensin. Twenty-four Anhui white goats were assigned randomly to one of three dietary treatments: 1) a basal diet (CON); 2) the basal diet with allicin addition at 750 mg per head per day (AC); 3) the basal diet with monensin addition at 30 mg per kg of diet (MS). Animals were fed for 8 weeks. Results showed the average daily gain, and feed efficiency was increased with allicin and monensin addition. Serum levels of IgG, total superoxide dismutase, and glutathione peroxidase were higher in the AC group than those in the CON and MS groups. The microbiota analysis revealed that monensin addition mainly affected genera related to carbohydrate and protein metabolism, and allicin mainly affected genera related to energy metabolism and intestinal health. In conclusion, allicin could improve growth performance and have advantages over monensin in improving the antioxidant capacity and immune function of goats. Allicin may be a potential alternative to monensin.

Enhancing rumen microbial diversity and its impact on energy and protein metabolism in forage-fed goats

Introduction

This study explores if promoting a complex rumen microbiota represents an advantage or a handicap in the current dairy production systems in which ruminants are artificially reared in absence of contact with adult animals and fed preserved monophyte forage.

Methods

In order to promote a different rumen microbial diversity, a total of 36 newborn goat kids were artificially reared, divided in 4 groups and daily inoculated during 10 weeks with autoclaved rumen fluid (AUT), fresh rumen fluid from adult goats adapted to forage (RFF) or concentrate (RFC) diets, or absence of inoculation (CTL). At 6 months of age all animals were shifted to an oats hay diet to determine their ability to digest a low quality forage.

Results and discussion

Early life inoculation with fresh rumen fluid promoted an increase in the rumen overall microbial diversity which was detected later in life. As a result, at 6 months of age RFF and RFC animals had higher bacterial (+50 OTUs) and methanogens diversity (+4 OTUs) and the presence of a complex rumen protozoal community (+32 OTUs), whereas CTL animals remained protozoa-free. This superior rumen diversity and presence of rumen protozoa had beneficial effects on the energy metabolism allowing a faster adaptation to the forage diet, a higher forage digestion (+21% NDF digestibility) and an energetically favourable shift of the rumen fermentation pattern from acetate to butyrate (+92%) and propionate (+19%) production. These effects were associated with the presence of certain rumen bacterial taxa and a diverse protozoal community. On the contrary, the presence of rumen protozoa (mostly Entodinium) had a negative impact on the N metabolism leading to a higher bacterial protein breakdown in the rumen and lower microbial protein flow to the host based on purine derivatives urinary excretion (-17% to -54%). The inoculation with autoclaved rumen fluid, as source of fermentation products but not viable microbes, had smaller effects than using fresh inoculum. These findings suggest that enhancing rumen microbial diversity represents a desirable attribute when ruminants are fed forages in which the N supply does not represent a limiting factor for the rumen microbiota.

Exploration of the rumen microbial diversity and carbohydrate active enzyme profile of black Bengal goat using metagenomic approach

Black Bengal goats possess a rich source of rumen microbiota that helps them to adapt for the better utilization of plant biomaterial into energy and nutrients, a task largely performed by enzymes encoded by the rumen microbiota. Therefore the study was designed in order to explore the taxonomic profile of rumen microbial communities and potential biomass degradation enzymes present in the rumen of back Bengal goat using Illumina Nextseq-500 platform. A total of 83.18 million high-quality reads were generated and bioinformatics analysis was performed using various tools and subsequently, the predicted ORFs along with the rRNA containing contigs were then uploaded to MG-RAST to analyze taxonomic and functional profiling. The results highlighted that Bacteriodetes (41.38-59.74%) were the most abundant phyla followed by Firmicutes (30.59-39.96%), Proteobacteria (5.07-7.61%), Euryarcheaota (0.71-7.41%), Actinobacteria (2.05-2.75%). Genes that encode glycoside hydrolases (GHs) had the highest number of CAZymes, and accounted for (39.73-37.88%) of all CAZymes in goat rumen. The GT families were the second-most abundant in CAZymes (23.73-23.11%) and followed by Carbohydrate Binding module Domain (17.65-15.61%), Carbohydrate Esterase (12.90-11.95%). This study indicated that goat rumen had complex functional microorganisms produce numerous CAZymes, and that can be further effectively utilised for applied ruminant research and industry based applications.

Astragalus additive in feed improved serum immune function, rumen fermentation and the microbiota structure of early-weaned lambs

AIM

The purpose of this study was to determine the mechanism of Astragalus activity on the immune function, rumen microbiota structure, and rumen fermentation of early-weaned lambs.

METHODS AND RESULTS

Thirty healthy early-weaned lambs with similar body weights (17.42 ± 2.02 kg) were selected for the feeding experiment. The control group (KB) was fed a basal diet, and the Astragalus group (HQ) was fed 0.3% Astragalus additive on the basis of a basic diet. The formal trial period was 60 days. The results showed that the concentrations of blood immunoglobulin A (IgA) and immunoglobulin M (IgM) in the HQ group were significantly higher than those in the KB group (P < 0.05). Compared with the KB group, the concentrations of acetic acid, butyric acid, and total volatile fatty acids (VFAs) in the HQ group were higher (P < 0.01). The expression levels of the rumen epithelial-related genes MCT1, MCT4, NHE2, and ZO1 in the Astragalus group were significantly higher than those in the KB group (P < 0.05). 16S rRNA analysis showed that at the phylum level, Bacteroidetes in the HQ group significantly increased (P < 0.01); at the genus level, Prevotella (P < 0.01) and Succiniclasticum (P < 0.01) in the HQ group were found at significantly higher abundances than those in the KB group, and the results of microbiota gene and function prediction showed that "energy metabolism," "glycan biosynthesis and metabolic" pathways were significantly enriched in the HQ group (P < 0.05).

CONCLUSION

As a feed additive, Astragalus can improve the immunity of early-weaned lambs, the structure of the rumen microbiota of lambs, and the fermentation capacity of the rumen.

The impact of lactating Hu sheep's dietary protein levels on lactation performance, progeny growth and rumen development

This study aimed to investigate whether lactating Hu sheep's dietary protein levels could generate dynamic effects on the performance of their offspring. Twelve ewes with similar parity were fed iso-energy diets which contained different protein levels (P1: 9.82%, P2: 10.99%) (n = 6), and the corresponding offspring were divided into SP1 and SP2 (n = 12). At 60 days, half of the lambs were harvested for further study: the carcass weight (p = 0.043) and dressing percentage (p = 0.004) in the SP2 group were significantly higher than SP1. The acetic acid (p = 0.007), propionic acid (p = 0.003), butyric acid (p < 0.001) and volatile fatty acids (p < 0.001) in rumen fluid of SP2 were significantly lower than SP1. The expression of MCT2 (p = 0.024), ACSS1 (p = 0.039) and NHE3 (p = 0.006) in the rumen of SP2 was lower than SP1, while the HMGCS1 (p = 0.026), HMGCR (p = 0.024) and Na+/K+-ATPase (p = 0.020) was higher than SP1. The three dominant phyla in the rumen are Bacteroidetes, Proteobacteria and Firmicutes. The membrane transport, amino acid metabolism and carbohydrate metabolism of SP1 were relatively enhanced, the replication and repair function of SP2 was relatively enhanced. To sum up, the increase of dietary protein level significantly increased the carcass weight and dressing percentage of offspring and had significant effects on rumen volatile fatty acids, acetic acid activation and cholesterol synthesis related genes. HIGHLIGHTSIn the early feeding period, the difference in ADG of lambs was mainly caused by the sucking effect.The increase in dietary protein level of ewes significantly increased the carcass weight and dressing percentage of offspring.The dietary protein level of ewes significantly affected the volatile fatty acids (VFAs) and genes related to acetic acid activation and cholesterol synthesis in the rumen of their offspring.The membrane transport, amino acid metabolism and carbohydrate metabolism of the offspring of ewes fed with a low protein diet were relatively enhanced.The replication and repair function of the offspring of ewes fed with a high protein diet was relatively strengthened.

Interaction between Rumen Epithelial miRNAs-Microbiota-Metabolites in Response to Cold-Season Nutritional Stress in Tibetan Sheep

Tibetan sheep are already well adapted to cold season nutrient stress on the Tibetan Plateau. Rumen, an important nutrient for metabolism and as an absorption organ in ruminants, plays a vital role in the cold stress adaptations of Tibetan sheep. Ruminal microbiota also plays an indispensable role in rumen function. In this study, combined multiomics data were utilized to comprehensively analyze the interaction mechanism between rumen epithelial miRNAs and microbiota and their metabolites in Tibetan sheep under nutrient stress in the cold season. A total of 949 miRNAs were identified in the rumen epithelium of both cold and warm seasons. A total of 62 differentially expressed (DE) miRNAs were screened using FC > 1.5 and p value < 0.01, and a total of 20,206 targeted genes were predicted by DE miRNAs. KEGG enrichment analysis revealed that DE miRNA-targeted genes were mainly enriched in axon guidance(ko04360), tight junction(ko04530), inflammatory mediator regulation of TRP channels(ko04750) and metabolism-related pathways. Correlation analysis revealed that rumen microbiota, rumen VFAs and DE miRNAs were all correlated. Further study revealed that the targeted genes of cold and warm season rumen epithelial DE miRNAs were coenriched with differential metabolites of microbiota in glycerophospholipid metabolism (ko00564), apoptosis (ko04210), inflammatory mediator regulation of TRP channels (ko04750), small cell lung cancer (ko05222), and choline metabolism in cancer (ko05231) pathways. There are several interactions between Tibetan sheep rumen epithelial miRNAs, rumen microbiota, and microbial metabolites, mainly through maintaining rumen epithelial barrier function and host homeostasis of choline and cholesterol, improving host immunity, and promoting energy metabolism pathways, thus enabling Tibetan sheep to effectively respond to cold season nutrient stress. The results also suggest that rumen microbiota have coevolved with their hosts to improve the adaptive capacity of Tibetan sheep to cold season nutrient stress, providing a new perspective for the study of cold season nutritional stress adaptation in Tibetan sheep.

Microbiability of milk composition and genetic control of microbiota effects in sheep

Recently, high-dimensional omics data are becoming available in larger quantities, and models have been developed that integrate them with genomics to understand in finer detail the relationship between genotype and phenotype, and thus improve the performance of genetic evaluations. Our objectives are to quantify the effect of the inclusion of microbiome data in the genetic evaluation for dairy traits in sheep, through the estimation of the heritability, microbiability, and how the microbiome effect on dairy traits decomposes into genetic and nongenetic parts. In this study we analyzed milk and rumen samples of 795 Lacaune dairy ewes. We included, as phenotype, dairy traits and milk fatty acids and proteins composition; as omics measurements, 16S rRNA rumen bacterial abundances; and as genotyping, 54K SNP chip for all ewes. Two nested genomic models were used: a first model to predict the individual contributions of the genetic and microbial abundances to phenotypes, and a second model to predict the additive genetic effect of the microbial community. In addition, microbiome-wide association studies for all dairy traits were applied using the 2,059 rumen bacterial abundances, and the genetic correlations between microbiome principal components and dairy traits were estimated. Results showed that in general the inclusion of both genetic and microbiome effect did not improve the fit of the model compared with the model with the genetic effect only. In addition, for all dairy traits the total heritability was equal to the direct heritability after fitting microbiota effects, due to a microbiability being almost zero for most dairy traits and heritability of the microbial community was very close to zero. Microbiome-wide association studies did not show operational taxonomic units with major effect for any of the dairy traits evaluated, and the genetic correlations between the first 5 principal components and dairy traits were low to moderate. So far, we can conclude that, using a substantial data set of 795 Lacaune dairy ewes, rumen bacterial abundances do not provide improved genetic evaluation for dairy traits in sheep.

Research progress on the regulation of production traits by gastrointestinal microbiota in dairy cows

The composition and abundance of microorganisms in the gastrointestinal tract of cows are complex and extensive, and they play a crucial role in regulating nutrient digestion, absorption, maintaining digestive tract stability, and promoting the production and health of the host. The fermentation carried out by these microorganisms in the gastrointestinal tract is fundamental to the health and productivity of cows. Rumen microorganisms produce the majority of enzymes required to break down feed substrates, such as cellulose, protein, lipids, and other plant materials, through fermentation. This process provides energy metabolism substrates that satisfy approximately 70% of the host's energy requirements for physiological activities. Gut microorganisms primarily decompose cellulose that is difficult to digest in the rumen, thereby providing heat and energy to the hosts. Additionally, they have an impact on host health and productivity through their role in immune function. Understanding the composition and function of the cow gut microbiota can help regulate dairy cattle breeding traits and improve their health status. As a result, it has become a popular research topic in dairy cattle breeding. This article provides a review of the composition, structure, physiological characteristics, and physiological effects of the cow gut microbiota, serving as a theoretical foundation for future studies that aim to utilize the gut microbiota for dairy cattle breeding or improving production traits. It may also serve as a reference for research on gut microbiota of other ruminants.

Effects of Fumarate and Nitroglycerin on In Vitro Rumen Fermentation, Methane and Hydrogen Production, and on Microbiota

This study aimed to investigate the effects of fumarate and nitroglycerin on rumen fermentation, methane and hydrogen production, and microbiota. In vitro rumen fermentation was used in this study with four treatment groups: control (CON), fumarate (FA), nitroglycerin (NG) and fumarate plus nitroglycerin (FN). Real-time PCR and 16S rRNA gene sequencing were used to analyze microbiota. The results showed that nitroglycerin completely inhibited methane production and that this resulted in hydrogen accumulation. Fumarate decreased the hydrogen accumulation and improved the rumen fermentation parameters. Fumarate increased the concentration of propionate and microbial crude protein, and decreased the ratio of acetate to propionate in FN. Fumarate, nitroglycerin and their combination did not affect the abundance of bacteria, protozoa and anaerobic fungi, but altered archaea. The PCoA showed that the bacterial (Anosim, R = 0.747, p = 0.001) and archaeal communities (Anosim, R = 0.410, p = 0.005) were different among the four treatments. Compared with CON, fumarate restored Bacteroidetes, Firmicutes, Spirochaetae, Actinobacteria, Unclassified Ruminococcaceae, Streptococcus, Treponema and Bifidobacterium in relative abundance in FN, but did not affect Succinivibrio, Ruminobacter and archaeal taxa. The results indicated that fumarate alleviated the depressed rumen fermentation caused by the inhibition of methanogenesis by nitroglycerin. This may potentially provide an alternative way to use these chemicals to mitigate methane emission in ruminants.

Effects of different forage proportions in fermented total mixed ration on muscle fatty acid profile and rumen microbiota in lambs

Objective

The objectives of this study were to evaluate the effects of different forage proportions in the fermented total mixed ration (FTMR) on growth performance, muscle fatty acid profile, and rumen microbiota of lambs.

Methods

Thirty 6-month-old small tail Han sheep × Ujumqin lambs with initial body weight (BW) of 27.8 ± 0.90 kg were selected for the test and divided into two groups of 15 sheep in each treatment (three pens per treatment and five lambs per pen) according to the principle of homogeneity. Two isoenergetic and isonitrogenous diets were formulated according to the NRC. The diet treatments were designed as (1) OH treatment containing 25% alfalfa hay and 35% oat hay, and (2) AH treatment containing 35% alfalfa hay with 25% oat hay. The forage-to-concentrate ratio for both diets was 65: 35 (DM basis). Three replicates were randomly selected from each treatment to determine growth performance, fatty acid profile and rumen bacterial communities in lambs.

Results

Results revealed no statistically significant (p > 0.05) differences in dry matter intake and average daily gain between the two diet groups. Cholesterol and intramuscular fat were significantly (p > 0.05) higher in the AH group, while no statistically significant difference (p > 0.05) was found in pH24 value. The muscle fatty acid compositions of lambs were obviously (p < 0.05) influenced by the diet treatments. Compared with the OH group, the C16:1, C17:0, and C20:3n6 contents were higher (p < 0.05) in the AH group, whereas the content of C18:1n9c, C20:1, C18:3n3, and C22:6n3 was obviously (p < 0.05) increased in the OH group. The monounsaturated fatty acid (MUFA) contents were significantly higher in the OH group, whereas no significant differences (p > 0.05) were detected in saturated fatty acid (SFA) and polyunsaturated fatty acid (PUFA) contents among the two diet treatments. Bacterial composition was generally separated into two clusters based on principal coordinate analysis, and the OH group had a higher Shannon index. The relative abundance at the genes level of the Rikenellaceae_RC9_gut_group was obviously (p < 0.05) increased in the AH group and the relative abundances of Prevotella_1, Fibrobacter, and Bacteroidales_UCG_001_unclassified were obviously (p < 0.05) enriched in the OH group. Integrated correlation analysis also underscored a possible link between the muscle fatty acid compositions and significantly altered rumen microbiota.

Conclusion

Overall, oat-based roughage in FTMR could promote a beneficial lipid pattern in the Longissimus lumborum muscles of lambs. These findings provide a potential insight into diet effects on fatty acid profile and the rumen microbiome of lambs, which may help make decisions regarding feeding.

Dietary Palygorskite-Based Antibacterial Agent Supplementation as an Alternative to Antibiotics Improves Growth Performance, Blood Parameters, and Rumen Microbiota in Sheep

This research aimed to investigate the effects of a palygorskite-based antibacterial agent (PAA) as an alternative to antibiotics on growth performance, blood parameters, and rumen microbiota in sheep. A total of 120 sheep were randomly divided into five groups of six replicates with four sheep each. Sheep were fed a basal diet, an antibiotic diet supplemented with 500 g/t chlortetracycline (CTC), and a basal diet supplemented with 500, 1000, and 2000 g/t PAA for 80 d, respectively. Supplementation with 2000 g/t PAA and 500 g/t CTC increased the average daily gain (ADG) of sheep compared with the control group (p < 0.05). Diets supplemented with 2000 g/t PAA and 500 g/t CTC reduced (p < 0.05) the feed:gain ratio (F/G ratio) in the overall periods. Dietary supplementation with 1000 g/t PAA significantly increased albumin and total protein (p < 0.05). A significant positive correlation was found between growth hormone concentration and PAA supplementation (p < 0.05). In addition, compared to the control group, the CTC group had higher growth hormone concentration and lower lipopolysaccharide concentration (p < 0.05). No difference was observed between the five groups in terms of rumen fermentation characteristics (p > 0.05). At the phylum level, the relative abundance of Proteobacteria was lower in the PAA 2000 and CTC 500 groups than in the control and PAA 500 groups (p < 0.05). At the genus level, a significant decrease (p < 0.05) in the relative abundance of RuminococcaceaeUCG-010 was observed in the PAA 1000, PAA 2000, and CTC 500 groups compared with that in the control group. In addition, the relative abundance of Prevotella1 (p < 0.05) was higher in the PAA 2000 group than in the control group. These findings indicate that dietary supplementation with PAA has ameliorative effects on growth performance, blood parameters, and rumen microbiota, with an optimal dosage of 2000 g/t for sheep.

Effects of Chromium Propionate and Calcium Propionate on Lactation Performance and Rumen Microbiota in Postpartum Heat-Stressed Holstein Dairy Cows

Chromium propionate (Cr-Pro) and calcium propionate (Ca-Pro) are widely applied in dairy production, especially in the alleviation of heat stress (HS). HS can reduce the abundance of rumen microbiota and the lactation performance of dairy cows. The present work mainly focused on evaluating the effects of Cr-Pro and Ca-Pro on the performance, ruminal bacterial community, and stress of postpartum HS dairy cows as well as identifying the differences in their mechanisms. Fifteen multiparous postpartum Holstein cows with equivalent weights (694 ± 28 kg) and milk yields (41.2 ± 1.21 kg/day) were randomly divided into three groups: control (CON), Cr-Pro (CRPR), and Ca-Pro (CAPR). The control cows received the basal total mixed ration (TMR) diet, while the CRPR group received TMR with 3.13 g/day of Cr-Pro, and the CAPR group received TMR with 200 g/day of Ca-Pro. The rumen microbial 16S rRNA was sequenced using the Illumina NovaSeq platform along with the measurement of ruminal volatile fatty acids (VFAs) and milking performance. Cr-Pro and Ca-Pro improved lactation performance, increased the rumen VFA concentration, and altered the rumen microbiota of the HS dairy cows. Cr-Pro significantly improved the milk yield (p < 0.01). The richness and diversity of the microbial species significantly increased after feeding on Ca-Pro (p < 0.05). Gene function prediction revealed increased metabolic pathways and biological-synthesis-related function in the groups supplemented with Cr-Pro and Ca-Pro. Our results indicate that the application of Cr-Pro or Ca-Pro can provide relief for heat stress in dairy cows through different mechanisms, and a combination of both is recommended for optimal results in production.

Early life supplementation with a natural blend containing turmeric, thymol, and yeast cell wall components to optimize rumen anatomical and microbiological development and productivity in dairy goats

Ruminants are born with an anatomically, microbiologically, and metabolically immature rumen. Optimizing the rearing of young ruminants represent an important challenge in intensive dairy farms. Therefore, the objective of this study was to evaluate the effects of dietary supplementation of young ruminants with a plant extract blend containing turmeric, thymol, and yeast cell wall components such as mannan oligosaccharides and β-glucans. One hundred newborn female goat kids were randomly allocated to 2 experimental treatments, which were unsupplemented (CTL) or supplemented with the blend containing plant extracts and yeast cell wall components (PEY). All animas were fed with milk replacer, concentrate feed, and oat hay, and were weaned at 8 wk of age. Dietary treatments lasted from wk 1 to 22 and 10 animals from each treatment were randomly selected to monitor feed intake, digestibility, and health-related indicators. These latter animals were euthanized at wk 22 of age to study the rumen anatomical, papillary, and microbiological development, whereas the remaining animals were monitored for reproductive performance and milk yield during the first lactation. Results indicated that PEY supplementation did not lead to feed intake or health issues because PEY animals tended to have a higher concentrate intake and lower diarrheal incidence than CTL animals. No differences between treatments were noted in terms of feed digestibility, rumen microbial protein synthesis, health-related metabolites, or blood cell counts. Supplementation with PEY promoted a higher rumen empty weight, and rumen relative proportion to the total digestive tract weight, than CTL animals. This was accompanied with a higher rumen papillary development in terms of papillae length and surface area in the cranial ventral and caudal ventral sacs, respectively. The PEY animals also had higher expression of the MCT1 gene, which is related to volatile fatty acid absorption by the rumen epithelium, than CTL animals. The antimicrobial effects of the turmeric and thymol could explain the decreased the rumen absolute abundance of protozoa and anaerobic fungi. This antimicrobial modulation led to a change in the bacterial community structure, a decrease in the bacteria richness, and to the disappearance (i.e., Prevotellaceae_UCG-004, Bacteroidetes_BD2-2, Papillibacter, Schwartzia, and Absconditabacteriales_SR1) or decline of certain bacterial taxa (i.e., Prevotellaceae_NK3B31_group, and Clostridia_UCG-014). Supplementation with PEY also decreased the relative abundance of fibrolytic (i.e., Fibrobacter succinogenes and Eubacterium ruminantium) and increased amylolytic bacteria (Selenomonas ruminantium). Although these microbial changes were not accompanied with significant differences in the rumen fermentation, this supplementation led to increased body weight gain during the preweaning period, higher body weight during the postweaning period, and higher fertility rate during the first gestation. On the contrary, no residual effects of this nutritional intervention were noted on the milk yield and milk components during the first lactation. In conclusion, supplementation with this blend of plant extracts and yeast cell wall component in early life could be considered as a sustainable nutritional strategy to increase body weight gain and optimize the rumen anatomical and microbiological development in young ruminants, despite having minor productive implications later in life.

Oral administration of Pinus koraiensis cone essential oil reduces rumen methane emission by altering the rumen microbial composition and functions in Korean native goat (Capra hircus coreanae)

This study aimed to investigate Pinus koraiensis cone essential oil (PEO) as a methane (CH₄) inhibitor and determine its impact on the taxonomic and functional characteristics of the rumen microbiota in goats. A total of 10 growing Korean native goats (Capra hircus coreanae, 29.9 ± 1.58 kg, male) were assigned to different dietary treatments: control (CON; basal diet without additive) and PEO (basal diet +1 g/d of PEO) by a 2 × 2 crossover design. Methane measurements were conducted every 4 consecutive days for 17-20 days using a laser CH₄ detector. Samples of rumen fluid and feces were collected during each experimental period to evaluate the biological effects and dry matter (DM) digestibility after PEO oral administration. The rumen microbiota was analyzed via 16S rRNA gene amplicon sequencing. The PEO oral administration resulted in reduced CH₄ emission (eructation CH₄/body weight^0.75, p = 0.079) without affecting DM intake; however, it lowered the total volatile fatty acids (p = 0.041), molar proportion of propionate (p = 0.075), and ammonia nitrogen (p = 0.087) in the rumen. Blood metabolites (i.e., albumin, alanine transaminase/serum glutamic pyruvate transaminase, creatinine, and triglyceride) were significantly affected (p < 0.05) by PEO oral administration. The absolute fungal abundance (p = 0.009) was reduced by PEO oral administration, whereas ciliate protozoa, total bacteria, and methanogen abundance were not affected. The composition of rumen prokaryotic microbiota was altered by PEO oral administration with lower evenness (p = 0.054) observed for the PEO group than the CON group. Moreover, PICRUSt2 analysis revealed that the metabolic pathways of prokaryotic bacteria, such as pyruvate metabolism, were enriched in the PEO group. We also identified the Rikenellaceae RC9 gut group as the taxa potentially contributing to the enriched KEGG modules for histidine biosynthesis and pyruvate oxidation in the rumen of the PEO group using the FishTaco analysis. The entire co-occurrence networks showed that more nodes and edges were detected in the PEO group. Overall, these findings provide an understanding of how PEO oral administration affects CH₄ emission and rumen prokaryotic microbiota composition and function. This study may help develop potential manipulation strategies to find new essential oils to mitigate enteric CH₄ emissions from ruminants.

Dietary Guanidine Acetic Acid Improves Ruminal Antioxidant Capacity and Alters Rumen Fermentation and Microflora in Rapid-Growing Lambs

Guanidine acetic acid (GAA) has been reported to improve growth performance, nutrient utilization, and meat quality in livestock. This study aimed to investigate whether coated GAA (CGAA) in comparison with uncoated GAA (UGAA) could have different effects on rumen fermentation, antioxidant capacity, and microflora composition in the rumen. Seventy-two lambs were randomly arranged in a 2 × 3 factorial experiment design with two diets of different forage type (OH: oaten hay; OHWS: oaten hay plus wheat silage) and three GAA treatments within each diet (control, diet without GAA addition; UGAA, uncoated GAA; CGAA, coated GAA). The whole feeding trial lasted for 120 days. The lambs in the OH group presented lower total volatile fatty acid (VFA), alpha diversity, Firmicutes, NK4A214_group, and Lachnospiraceae_NK3A20_group than those on the OHWS diet in the last 60 days of the feeding stage (p < 0.05). Regardless of what GAA form was added, dietary GAA supplementation increased the total VFA, microbial crude protein (MCP), adenosine triphosphate (ATP), and antioxidant capacity in rumen during lamb feedlotting (p < 0.05). However, molar propionate proportion, acetate:propionate ratio (A:P), and relative Succiniclasticum abundance decreased with GAA addition in the first 60 days of the growing stage, while the molar butyrate proportion and NK4A214_group (p < 0.05) in response to GAA addition increased in the last 60 days of feeding. These findings indicated that dietary GAA enhanced antioxidant capacity and fermentation characteristics in the rumen, but the addition of uncoated GAA in diets might cause some dysbacteriosis of the rumen microbiota.

Maternal rumen and milk microbiota shape the establishment of early-life rumen microbiota in grazing yak calves

Early-life gut microbial colonization and development exert a profound impact on the health and metabolism of the host throughout the life span. The transmission of microbes from the mother to the offspring affects the succession and establishment of the early-life rumen microbiome in newborns, but the contributions of different maternal sites to the rumen microbial establishment remain unclear. In the present study, samples from different dam sites (namely, oral, rumen fluid, milk, and teat skin) and rumen fluid of yak calves were collected at 6 time points between d 7 and 180 postpartum to determine the contributions of the different maternal sites to the establishment of the bacterial and archaeal communities in the rumen during early life. Our analysis demonstrated that the dam's microbial communities clustered according to the sites, and the calves' rumen microbiota resembled that of the dam consistently regardless of fluctuations at d 7 and 14. The dam's rumen microbiota was the major source of the calves' rumen bacteria (7.9%) and archaea (49.7%) compared with the other sites, whereas the potential sources of the calf rumen microbiota from other sites varied according to the age. The contribution of dam's rumen bacteria increased with age from 0.36% at d 7 to 14.8% at d 180, whereas the contribution of the milk microbiota showed the opposite trend, with its contribution reduced from 2.7% at d 7 to 0.2% at d 180. Maternal oral archaea were the main sources of the calves' rumen archaea at d 14 (50.4%), but maternal rumen archaea became the main source gradually and reached 66.2% at d 180. These findings demonstrated the potential microbial transfer from the dam to the offspring that could influence the rumen microbiota colonization and establishment in yak calves raised under grazing regimens, providing the basis for future microbiota manipulation strategies during their early life.

Effects of direct-fed Bacillus subtilis and Bacillus licheniformis on production performance and milk fatty acid profile in dairy cows

The aim of the study was to determine the effect of a Bacillus-based direct-fed microbial on performance of mid-lactating Holstein dairy cows and on their milk fatty acid composition. Six multiparous cows fitted with a rumen cannula were used in a randomized replicated crossover design. Cows received 200 g/d of either whey powder as a control or BioPlus 2B (Chr. Hansen), a commercial direct-fed microbial providing Bacillus subtilis and Bacillus licheniformis, representing a daily dose of 6.4 × 10¹¹ cfu, and using whey powder as a carrier. The 2 experimental periods lasted 14 d and were separated by a 7-d washout interval. Samples were collected on d 0, 13, and 14 of each period. Data from d 0 were used as covariate. Significance was declared at P ≤ 0.05 and tendency at 0.05 <P ≤ 0.10. There was a 10-fold increase in the relative concentration of bacteria from the Bacillus subtilis group in the rumen when feeding direct-fed Bacillus compared with control. Treatment did not affect ruminal pH, NH₃-N, or concentrations of acetate, propionate, and butyrate. However, direct-fed Bacillus increased ruminal concentrations of isovalerate and isobutyrate (tendency). Treatments did not affect lactation performance. Supplying direct-fed Bacillus enhanced milk relative concentration of anteiso 13:0 by 27.3% and of anteiso 15:0 by 6.5% and tended to increase concentrations of iso 14:0 (+41.8%) relative to control. When expressed on a yield basis, direct-fed Bacillus increased the secretion of anteiso 13:0 and decreased that of 11:0, 15:0, 17:0 (tendency), and cis-9 17:1. These variations, although limited in magnitude, indicate that milk branched-chain fatty acid composition is sensitive to ruminal microbiota modifications without changes in chemical composition of the diet.

Impact of Molasses on Ruminal Volatile Fatty Acid Production and Microbiota Composition In Vitro

The aim of this study was to assess if molasses could modify VFA production and the rumen microbial community in vitro. Three beet (treatment Beet) and three cane (treatment Cane) molasses preparations were randomly selected from a variety of samples collected worldwide and incubated in vitro with rumen fluid along with a control sample (treatment CTR, in which no molasses was used). Flasks for VFA analysis were sampled at 0, 1, 2, 3, 4, 6, 8, and 24 h of each incubation. For microbiota analysis, samples from each fermentation flask after 12 and 24 h were subjected to microbial DNA extraction and V3-V4 16S rRNA gene sequencing on an Illumina MiSeq platform. Total net VFA production was higher in the beet and cane preparations than in the control (CTR) group at 24 h (33 mmol/L, 34 mmol/L, and 24.8 mmol/L, respectively), and the composition of VFAs was affected by the inclusion of molasses: acetic acid increased in the CTR group (73.5 mol%), while propionic acid increased in the beet and cane molasses (19.6 mol% and 18.6 mol%, respectively), and butyric acid increased, especially in the cane group (23.2 mol%). Molasses even influenced the composition of the rumen microbiota, and particularly the relative abundance of the most dominant family in the rumen, Prevotellaceae, which decreased compared to CTR (37.13%, 28.88%, and 49.6%, respectively). In contrast, Streptococcaceae (19.62% and 28.10% in molasses compared to 6.23% in CTR), Veillonellaceae (6.48% and 8.67% in molasses compared to 4.54% in CTR), and Fibrobacteraceae (0.90% and 0.88% in molasses compared to 0.62% in CTR) increased in the beet and cane groups compared to the CTR group. Another important finding is the lower proportion of Methanobacteriaceae following the addition of molasses compared to CTR (0.26%, 0.28%, and 0.43%, respectively). This study showed the impact of molasses in influencing VFA production and composition as a result of a modified rumen microbial composition.

Dietary potential probiotics and enzymes complex modulates the performance and rumen microbiota in weaned goats

AIMS

This trial was performed to investigate the effects of combined feeding of Candida utilis CICC 31170, Bacillus coagulans R11, and Lactobacillus acidophilus NCFM and a multi-enzyme complex on the growth performance, immune parameters, feed digestibility, and rumen microbiota of weaned goats.

METHODS AND RESULTS

Thirty weaned goats were randomly divided into CON, PRB, and COB groups and fed different diets. End weight and ADG increased significantly in the PRB and COB groups (P < 0.05), and ADFI increased significantly in COB (P < 0.05). On day 80, there was a significant increase in IL-10 content in PRB and COB compared to the CON (P < 0.05). Highly significant increases in rumen papilla width, epithelial cell thickness, stratum spinosum+basale thickness, and stratum corneum thickness were found in PRB and COB (P < 0.05). COB group significantly increased the gene expression of HMGCL and MCT1 in rumen epithelium (P < 0.001). The COB group had the tendency to increase the feed digestibility of dry matter and crude fat compared with the CON group (P < 0.10). The abundance of Prevotellaceae_unclassified was significantly higher in PRB (P < 0.05), and the abundance of Fibrobacteres was significantly higher in COB in comparison to those in CON (P < 0.05).

CONCLUSIONS

The results indicate that the dietary potential probiotics and enzymes complex could modulate the growth performance, immunity, feed digestibility, and rumen microbiota in weaned goats.

Dietary spirulina supplementation modifies rumen development, fermentation and bacteria composition in Hu sheep when consuming high-fat dietary

Introduction

This study aims to investigate the long-term effects of spirulina supplementation in a high-fat diet (HFD) on rumen morphology, rumen fermentation, and the composition of rumen microbiota in lambs. Spirulina is a blue-green microalgae that has been shown to have high nutritional value for livestock.

Methods

Fifty-four lambs were randomly divided into three groups: a normal chow diet (NCD) group, a high-fat diet (HFD) group, and a high-fat diet supplemented with 3% spirulina (HFD+S) group. Rumen morphology, rumen fermentation, and rumen microbiota were analyzed at the end of the study.

Results

Spirulina supplementation improved the concentration of volatile fatty acids and rumen papilla length. Additionally, there was a tendency for an increase in rumen weight and an upregulation of the genes Claudin-1, Claudin-4, and Occludin in the HFD+S group. Pyrosequencing of the 16S ribosomal RNA gene also showed that spirulina supplementation significantly changed the rumen microbiota composition in the HFD group, with a decrease in richness and diversity. Specifically, the relative abundance of Prevotella 9 and Megasphaera was significantly increased in the HFD group compared to the NCD group, while spirulina supplementation reversed these changes.

Discussion

This study suggests that 3% spirulina supplementation can improve rumen development and fermentation, and effectively relieve rumen microbe disorders in lambs caused by a high-fat diet. However, further research is needed to confirm the findings and to examine the long-term effects of spirulina supplementation in different types of livestock and under different dietary conditions.

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 Two Different Straw Pellets on Yak Growth Performance and Ruminal Microbiota during Cold Season

The Tianzhu white yaks (Bos grunniens) live on the Qinghai-Tibet Plateau. During winter, a lack of resources and low nutritional levels seriously affect their growth performance. In this study, we aimed to explore the effect of supplementation straw pellets on the growth performance and ruminal microbiota of yaks. Overall, at 6 (6M, n = 24), 18 (18M, n = 26), 30 (30M, n = 20), 42 (42M, n = 24), and 54 (54M, n = 22) month old Tianzhu white yaks were selected (total n = 116) and divided into the mixed straw + grazing (MSG), corn straw + grazing (CSG), and the grazing control (G) groups according to age and gender. Their growth performance was measured as per different dietary treatments. The rumen microbial community structure and levels of VFAs were analyzed from the 6M, 30M, and 54M male yaks from each group. The supplementary diets led to an increase in the ADG, which was the highest in the MSG group. The MSG group exhibited the highest level of acetate and total VFAs (TVFAs) among the three groups (p < 0.05). In addition, the 16S rRNA sequencing results proved that the microbial composition was dominated by the members of Firmicutes and Bacteroidetes. Christensenellaceae R-7 group was significantly abundant in the CSG and MSG groups compared to the G group (p < 0.05). Principal coordinate analysis (PCoA) revealed that the bacterial community structure of rumen in the MSG and CSG groups was considerably different from that in the G group; 6M samples exhibited different rumen microbial diversity compared with the other samples. Correlation analysis revealed that Christensenellaceae_R-7_group was positively correlated with the levels of acetate, TVFAs, and ADG. These results demonstrated that mixed straw pellets improved the growth performance of yaks, increased the abundance of Christensenellaceae R-7_group involved in cellulose degradation in the rumen, and produced large amounts of VFAs, which were absorbed by yaks, thus increasing their ADG. This study provides new insights into the effects of straw pellet supplementation on the changes in the rumen microbiota and growth performance of yaks.

Effects of milk replacer feeding level on growth performance, rumen development and the ruminal bacterial community in lambs

Feeding with a suitable level of milk replacer (MR) can improve the survival rate and stimulate the growth potential of early lambs. However, feeding excessive MR might be detrimental to rumen development and microbial colonization. Herein, we investigated the effects of feeding different levels of MR on rumen digestive function and ruminal microorganisms. Fourteen healthy male Hu lambs with similar birth weights and detailed pedigree records were divided into two groups to receive low (2% of average body weight per day) and high (4% of average body weight per day) levels of MR. We analyzed the effects of the MR feeding level on growth performance, fiber degradation rates, rumen fermentation parameters, enzyme activities and rumen histomorphology. We found that feeding with a high level of MR improved the average daily gain of early lambs, but decreased the starter intake, rumen weight and papillae length. We also analyzed the effects of the MR feeding level on the rumen microbiota using 16S-rRNA amplicon sequencing data. The results showed that high a MR feeding level increased the rumen microbial diversity but decreased the abundance of many carbohydrate degrading bacteria. Several bacterial genera with significant differences correlated positively with rumen cellulase activity and the acid detergent fiber degradation rate. Our results suggested that a high level of MR could improve the growth performance of early lambs in the short term; however, in the long term, it would be detrimental to rumen development and have adverse effects on the adaptation process of the microbiota to solid feed.

Effects of forage type on the rumen microbiota, growth performance, carcass traits, and meat quality in fattening goats

Forages fed to goats influence ruminal microbiota, and further contribute to affect growth performance, meat quality and its nutritional composition. Our objective for current study was to investigate the effects of different forages on growth performance, carcass traits, meat nutritional composition, rumen microflora, and the relationships between key bacteria and amino acids and fatty acids in the longissimus dorsi and semimembranosus muscles of goats. Boer crossbred goats were separately fed commercial concentrate diet supplemented with Hemarthria altissima (HA), Pennisetum sinese (PS), or forage maize (FG), and then slaughtered 90 days after the beginning of the experiment. Growth performances did not vary but carcass traits of dressing percentage, semi-eviscerated slaughter percentage, and eviscerated slaughter percentage displayed significant difference with the treatment studied. Meats from goats fed forage maize, especially semimembranosus muscles are rich in essential amino acids, as well as an increase in the amount of beneficial fatty acids. Our 16S rRNA gene sequencing results showed that the Firmicutes, Bacteroidetes, and Proteobacteria were the most dominant phyla in all groups but different in relative abundance. Further, the taxonomic analysis and linear discriminant analysis effect size (LEfSe) identified the specific taxa that were differentially represented among three forage treatments. The spearman's correlation analysis showed that rumen microbiota was significantly associated with the goat meat nutritional composition, and more significant positive correlations were identified in semimembranosus muscles when compared with longissimus dorsi muscles. More specifically, the lipid metabolism-related bacteria Rikenellaceae_RC9_gut_group showed positively correlated with meat amino acid profile, while genera Oscillospiraceae_UCG-005 were positively correlated with fatty acid composition. These bacteria genera might have the potential to improve nutritional value and meat quality. Collectively, our results showed that different forages alter the carcass traits, meat nutritional composition, and rumen microflora in fattening goats, and forage maize induced an improvement in its nutritional value.

Influence of a sodium-saccharin sweetener on the rumen content and rumen epithelium microbiota in dairy cattle during heat stress

The effect of a saccharin-based artificial sweetener was tested on animal performance measures and on the microbial communities associated with the rumen content and with the rumen epithelium during heat stress. Ten cannulated Holstein-Friesian milking dairy cattle were supplemented with 2 g of saccharin-based sweetener per day, top-dressed into individual feeders for a 7-day adaptation period followed by a 14-day heat stress period. A control group of ten additional cows subjected to the same environmental conditions but not supplemented with sweetener were included for comparison. 16S rRNA gene amplicon sequencing was performed on rumen content and rumen epithelium samples from all animals, and comparisons of rumen content microbiota and rumen epithelial microbiota were made between supplemented and control populations. Supplementation of the saccharin-based sweetener did not affect the rumen content microbiota, but differences in the rumen epithelial microbiota beta-diversity (PERMANOVA, P = 0.003, R2 = 0.12) and alpha-diversity (Chao species richness, P = 0.06 and Shannon diversity, P = 0.034) were detected between the supplemented and control experimental groups. Despite the changes detected in the microbial community, animal performance metrics including feed intake, milk yield, and short-chain fatty acid (acetic, propionic, and butyric acid) concentrations were not different between experimental groups. Thus, under the conditions applied, supplementation with a saccharin-based sweetener does not appear to affect animal performance under heat stress. Additionally, we detected differences in the rumen epithelial microbiota due to heat stress when comparing initial, prestressed microbial communities to the communities after heat stress. Importantly, the changes occurring in the rumen epithelial microbiota may have implications on barrier integrity, oxygen scavenging, and urease activity. This research adds insight into the impact of saccharin-based sweeteners on the rumen microbiota and the responsivity of the rumen epithelial microbiota to different stimuli, providing novel hypotheses for future research.

Dietary Supplementation of Fruit from Nitraria tangutorum Improved Immunity and Abundance of Beneficial Ruminal Bacteria in Hu Sheep

The fruit of Nitraria tangutorum (FNT) is reputed to possess medicinal properties; however, its effect on sheep (Ovis aries) is unknown. The aim of this study was to fill this gap. In a 3 × 3 Latin square design, six 12-month-old rumen-fistulated Hu rams (56.2 ± 8.26 kg; mean ± SD) were penned individually and offered one of three levels of FNT, namely, 0 g/d (control; CON), 16 g/d (N₁₆), and 48 g/d (N₄₈). The concentration of serum immunoglobulin G increased linearly (p = 0.03) with an increasing intake of FNT. The serum concentration of β-hydroxybutyrate in the N₄₈ group was lower than in the CON group (p = 0.01) and decreased linearly with increasing FNT (p = 0.001). The concentration of serum lactate dehydrogenase tended to decrease (p = 0.07) linearly with an increase in FNT intake, while the concentration of glucose did not differ among groups (p = 0.14) but displayed a quadratic curve with an increase in FNT (p = 0.05). The rumen concentration of lipase decreased linearly with increasing FNT (p = 0.04). The rumen fermentation variables were not affected by FNT. The FNT intake increased the abundance of beneficial ruminal bacteria, such as Lachnoclostridium, Rhodocyclaceae, and Candidatus Arthromitus. Prevotella, Rikenellaceae_RC9_gut_group, Ruminococcus, Olsenella, Lachnospiraceae_NK3A20_group, and Quinella were the dominant bacterial genera in all treatments. We conclude that FNT can improve immunity and increase the relative abundance of beneficial ruminal bacteria in sheep.

Rumen microbiota responses to the enzymatic hydrolyzed cottonseed peptide supplement under high-concentrate diet feeding process

In current dairy production, dietary energy is always excessively provided with a high-concentrate diet feeding to improve milk production. However, this feeding practice disturbed the rumen microbial ecosystem and the balance between ruminal energy and nitrogen, resulting in decreased nutrient fermentability, which in turn declined the milk yield of dairy cows. Therefore, supplementation of dietary degradable nitrogen may be helpful for high dairy production. In this study, we evaluated the regulatory effects of easily utilized enzymatic hydrolyzed cottonseed peptide (EHP) supplements on rumen microbiota communities and rumen nutrient fermentability under high-concentrate feeding. For this purpose, a gradient concentrate of EHP (from 0.2 to 1.0%) was added to the high-concentrate basal substrates for an in vitro experiment. Each treatment contained three replicates, with three bottles in each replicate. Rumen fermentable parameters included microbial protein content, volatile fatty acids, and ammonia-N; the rumen nutrient degradability of dry matter, crude protein, neutral detergent fiber, acid detergent fiber, ether extracts, calcium, and phosphorus were further investigated after in vitro fermentation for 72 h. Then, rumen microbiota communities and their correlation with ruminal fermentation parameters and rumen nutritional degradability were analyzed to understand the regulatory mechanism of the EHP supplements on rumen fermentability. Results indicate that treatment with 0.6% of EHP supplements had the highest content of acetate, butyrate, and neutral detergent fiber degradability among all treatments. Furthermore, EHP supplements significantly increased the relative abundance of rumen cellulose and starch-degrading bacteria such as Ruminococcus, Bifidobacterium, and Acetitomaculum, and the high nitrogen utilizing bacteria Butyrivibrio and Pseudobutyrivibrio, which may further promote the rumen carbohydrate and nitrogen metabolism. In summary, supplementation of easily degraded small peptides helps reestablish rumen energy and nitrogen balance to promote the rumen fermentable functions and nutritional degradability under high-concentrate diet feeding circumstances. These findings may further promote dairy production.

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.

Silage Mixtures of Alfalfa with Sweet Sorghum Alter Blood and Rumen Physiological Status and Rumen Microbiota of Karakul Lambs

The study investigated the effects of feeding mixtures of alfalfa (AF) and sweet sorghum (SS) at different ratios of silages in terms of the physiological status of blood and rumen, and rumen microbiota in lambs. A total of 30 four-month-old male Karakul lambs with 25.5 ± 1.4 kg mean initial body weight were randomly allocated to five groups, with six lambs in each group. Five experimental diets containing 40% of one of the five AF−SS mixed silages (containing 0%, 20%, 40%, 60%, and 80% AF on a fresh weight basis, respectively) and 60% of other ingredients were formulated. Overall, the results showed that the mixed silage with more AF tended to increase serum antioxidant capacity, dry matter (DM) intake, and rumen fermentation metabolites. The AF−SS mixed silages containing AF at 60% and 80% caused a significant linear increase (p < 0.05) in the activity of total antioxidant capacity. The superoxide dismutase in the Karakul lamb responded with significant linear and quadratic increases (p < 0.01) as the ratio of AF was increased in the AF−SS mixed silages. Feeding diets with AF in silage mixtures at the ratio of 60% significantly increased (p < 0.05) the concentration of ruminal total volatile fatty acids (tVFA), acetate, and ammonia-N. However, no statistical significance (p > 0.05) was found in the alpha diversity of rumen microbes among the tested groups (p > 0.05). Principal coordinates analysis could clearly discriminate the differences between the five groups (p = 0.001). The relative abundance of Firmicutes in the rumen were significantly higher with AF at 40% in the AF−SS silage-based diet than those with AF at 0%, and 20% ratios. The abundance of Ruminococcus_albus had a significant linear increase (p < 0.05), as the ratio of AF in the AF−SS mixed silages was increased. In conclusion, the best beneficial effect on the physiological status of the blood and rumen, DM intake, and rumen microbiota in lambs came from those that consumed the diet containing the AF−SS mixed silage with 60% AF.

365 Towards the Integration of Microbial Genomic Information Into Mechanistic Models of the Rumen Microbiome: A Theoretical Study

The objective of this work was to develop a mathematical framework enabling the integration of microbial genomic information (i.e., 16S rDNA) into mechanistic models of the rumen microbiome. Mechanistic modelling provides promising tools to enhance our system-level understanding of the rumen ecosystem. Existing mechanistic models of rumen fermentation consider an aggregated representation of the rumen microbiota and its metabolic function. However, none of these models integrate microbial genomic knowledge and are thus limited to capitalize on the rich information of microbial genomic sequencing. In this work, we investigated theoretically, how microbial time series of the rumen microbiota determined by 16S rDNA can be integrated into a mechanistic fermentation model of the rumen microbiome. Our study used a previously developed model of in vitro rumen fermentation that represents the microbiota by three microbial functional groups, namely sugar utilisers, amino acid utilisers, and methanogens 1. The model was extended to represent the fermentation under continuous operation (i.e. chemostat). We considered a hypothetical scenario where 16S rumen microbial time series are available. Our rationale is that the microbial species can be categorized into the macroscopic functions of the mechanistic model by using tools such as CowPI 2. In a simulation case study, we used the theory of state observers to integrate the mechanistic model and the microbial data to provide estimations of the dynamics of the volatile fatty acids (VFA) acetate, butyrate, and propionate. The estimated VFA converge towards the real VFA dynamics demonstrating the promising potential of our approach. The next step we are currently working is the validation of our approach using in vitro experimental data. 1 Muñoz-Tamayo, R. et al. Anim. Feed Sci. Technol. 220, 1–21 (2016)2 Wilkinson, T. J. et al. Front. Microbiol. 9, 1095 (2018)

The effects of fermented pineapple residue on growth performance, meat quality, and rumen microbiota of fattening Simmental bull

In this study, silage Pennisetum sinese Roxb-based diet was replaced with fermented pineapple residue (FPR) at the replacement ratio of 0% (CON), 25% (T25), and 50% (T50) in fattening Simmental bulls for 30 days to evaluate the effects of FPR on growth performance, serum indexes, and ruminal characteristics. A total of 30 Simmental bulls (546 ± 44 kg initial BW) were allocated to three groups according to a completely randomized design. On day 30, the slaughter performance and meat quality were determined. Rumen fluids were collected for analyzing the rumen fermentation parameters and microbiota composition on day 30. The results showed that the average daily weight gain increased (P < 0.05) as the proportion of FPR rose. Within treatments, the T25 group reached more profit (5.34 RMB per day per bull) than CON while T50 was 3.69. The content of crude fat, cysteine, and proline in the muscle of T50 increased significantly (P < 0.05). The amounts of tyrosine, proline, and phenylalanine were significantly increased in the T25 (P < 0.05). The beta diversity analysis showed significant differences among the rumen bacterial flora of each group (P < 0.05). In the T25 group, the relative abundance of Spirochaetes decreased significantly (P < 0.05). The relative abundance of Lachnospiraceae_bacterium_RM44 was significantly lower (P < 0.05). Thus, FPR could improve the growth performance, economic benefits, and meat quality without adverse effects on ruminal characteristics.

Coevolution of Rumen Epithelial circRNAs with Their Microbiota and Metabolites in Response to Cold-Season Nutritional Stress in Tibetan Sheep

This study explores the effects of the coevolution of the host genome (the first genome) and gut microbiome (the second genome) on nutrition stress in Tibetan sheep during the cold season. The rumen epithelial tissue of six Tibetan sheep (Oula-type) was collected as experimental samples during the cold and warm seasons and the study lasted for half a year. The cDNA library was constructed and subjected to high-throughput sequencing. The circRNAs with significant differential expression were identified through bioinformatics analysis and functional prediction, and verified by real-time quantitative PCR (qRT-PCR). The results showed that a total of 56 differentially expressed (DE) circRNAs of rumen epithelial tissue were identified using RNA-seq technology, among which 29 were significantly upregulated in the cold season. The circRNA-miRNA regulatory network showed that DE circRNAs promoted the adaptation of Tibetan sheep in the cold season by targeting miR-150 and oar-miR-370-3p. The results of correlation analysis among circRNAs, microbiota, and metabolites showed that the circRNA NC_040275.1:28680890|28683112 had a very significant positive correlation with acetate, propionate, butyrate, and total volatile fatty acid (VFA) (p < 0.01), and had a significant positive correlation with Ruminococcus-1 (p < 0.05). In addition, circRNA NC_040256.1:78451819|78454934 and metabolites were enriched in the same KEGG pathway biosynthesis of amino acids (ko01230). In conclusion, the host genome and rumen microbiome of Tibetan sheep co-encoded a certain glycoside hydrolase (β-glucosidase) and coevolved efficient VFA transport functions and amino acid anabolic processes; thus, helping Tibetan sheep adapt to nutrient stress in the cold season in high-altitude areas.

Metagenomic Characterization and Volatile Compounds Determination in Rumen from Saanen Goat Kids Fed Olive Leaves

The accumulation and disposal of by-products deriving from the agro-food industry represents a problem both from an economic and environmental point of view. The use of these matrices in zootechnical nutrition could represent a feasible solution. The aim of the study was to examine the effect of a diet containing olive leaves (OL), a by-product of the olive industry, on the ruminal microbial community of Saanen goat kids and on volatile organic compounds (VOCs) produced during the digestion. Twenty goat kids were randomly divided into two groups of ten goat kids each. The control group (CTR) was fed with a standard diet, while the experimental group (OL+) received a custom-formulated diet containing 10 % OL on a dry matter (DM) basis. After 30 days of trial, genomic DNA was extracted from the rumen liquor and prepared for 16S rRNA-gene sequencing to characterize the rumen microbiota; furthermore, rumen VOCs were also characterized by solid-phase microextraction coupled with gas chromatography-mass spectrometry. The Shannon’s alpha index was not significantly different between the two groups, on the contrary, Bray-Curtis (p < 0.01) and Jaccard (p < 0.01) distances evidenced that feed affected microbial community. Eleven genera were influenced by OL supplementation, with a significant increase (p < 0.05) in Paludibacter, Fibrobacter, Sphaerochaeta Christensenella, Rikenella, Oligosphaera, Candidatus Endomicrobium, Anaerovorax, and Atopobium was observed, while the percentages of Bacteroides and Selenomonas were reduced (p < 0.05). Differences were also observed between the two groups at the family level (p < 0.004). Fibrobacteriaceae, Christensenellaceae, Coriobacteriaceae, Oligosphaeraceae, Candidatus Endomicrobium, and Planctomycetaceae were significantly higher (p < 0.05) in goat kids fed OL diet compared to CTR, while the levels of other identified families, Succinivibrionaceae and Bifidobacteriaceae, were opposite (p < 0.05). Finally, results showed that the main phyla in both groups were Bacteroidetes and Firmicutes; however, no significant differences in the relative abundance of any phyla were observed between the two groups. In addition to what has been reported, the analysis of VOCs at the rumen level showed the ability of the OL integration to induce an increase in hexanoic acid and a parallel decrease in decanal. Furthermore, only in OL+ samples there was the accumulation of α-terpineol to which a wide range of interesting biological properties is attributed. The presence of VOCs associated with health status suggests a favorable role of OL in preserving and improving animal welfare.

Metabolomics approach reveals high energy diet improves the quality and enhances the flavor of black Tibetan sheep meat by altering the composition of rumen microbiota

This study aims to determine the impact of dietary energy levels on rumen microbial composition and its relationship to the quality of Black Tibetan sheep meat by applying metabolomics and Pearson's correlation analyses. For this purpose, UHPLC-QTOF-MS was used to identify the metabolome, whereas 16S rDNA sequencing was used to detect the rumen microbiota. Eventually, we observed that the high energy diet group (HS) improved the carcass quality of Black Tibetan sheep and fat deposition in the longissimus lumborum (LL) compared to the medium energy diet group (MS). However, HS considerably increased the texture, water holding capacity (WHC), and volatile flavor of the LL when compared to that of MS and the low energy diet group (LS). Metabolomics and correlation analyses revealed that dietary energy levels mainly affected the metabolism of carbohydrates and lipids of the LL, which consequently influenced the content of volatile flavor compounds (VOCs) and fats. Furthermore, HS increased the abundance of Quinella, Ruminococcus 2, (Eubacterium) coprostanoligenes, and Succinivibrionaceae UCG-001, all of which participate in the carbohydrate metabolism in rumen and thus influence the metabolite levels (stachyose, isomaltose, etc.) in the LL. Overall, a high-energy diet is desirable for the production of Black Tibetan sheep mutton because it improves the mouthfeel and flavor of meat by altering the composition of rumen microbiota, which influences the metabolism in the LL.

The Effects of Breed and Residual Feed Intake Divergence on the Abundance and Active Population of Rumen Microbiota in Beef Cattle

To assess the effects of residual feed intake (RFI) and breed on rumen microbiota, the abundance (DNA) and active population (RNA) of the total bacteria, archaea, protozoa, and fungi in the rumen of 96 beef steers from three different breeds (Angus (AN), Charolais (CH), and Kinsella Composite (KC)), and divergent RFIs (High vs Low), were estimated by measuring their respective maker gene copies using qRT-PCR. All experimental animals were kept under the same feedlot condition and fed with the same high-energy finishing diet. Rumen content samples were collected at slaughter and used for the extraction of genetic material (DNA and RNA) and further analysis. There was a significant difference (p < 0.01) between the marker gene copies detected for abundance and active populations for all four microbial groups. AN steers had a higher abundance of bacteria (p < 0.05) and a lower abundance of eukaryotes (protozoa and fungi, p < 0.05) compared to KC steers, while the abundance of protozoa (p < 0.05) in the AN cattle and fungi (p < 0.05) in the KC cattle were lower and higher, respectively, than those in the CH steers. Meanwhile, the active populations of bacteria, archaea, and protozoa in the KC steers were significantly lower than those in the AN and CH animals (p < 0.01). This work demonstrates that cattle breed can affect rumen microbiota at both the abundance and activity level. The revealed highly active protozoal populations indicate their important role in rumen microbial fermentation under a feedlot diet, which warrants further study.

The Role of Rumen Microbiota and Its Metabolites in Subacute Ruminal Acidosis (SARA)-Induced Inflammatory Diseases of Ruminants

Subacute ruminal acidosis (SARA) is a common metabolic disease in ruminants. In the early stage of SARA, ruminants do not exhibit obvious clinical symptoms. However, SARA often leads to local inflammatory diseases such as laminitis, mastitis, endometritis and hepatitis. The mechanism by which SARA leads to inflammatory diseases is largely unknown. The gut microbiota is the totality of bacteria, viruses and fungi inhabiting the gastrointestinal tract. Studies have found that the gut microbiota is not only crucial to gastrointestinal health but also involved in a variety of disease processes, including metabolic diseases, autoimmune diseases, tumors and inflammatory diseases. Studies have shown that intestinal bacteria and their metabolites can migrate to extraintestinal distal organs, such as the lung, liver and brain, through endogenous pathways, leading to related diseases. Combined with the literature, we believe that the dysbiosis of the rumen microbiota, the destruction of the rumen barrier and the dysbiosis of liver function in the pathogenesis of SARA lead to the entry of rumen bacteria and/or metabolites into the body through blood or lymphatic circulation and place the body in the “chronic low-grade” inflammatory state. Meanwhile, rumen bacteria and/or their metabolites can also migrate to the mammary gland, uterus and other organs, leading to the occurrence of related inflammatory diseases. The aim of this review is to describe the mechanism by which SARA causes inflammatory diseases to obtain a more comprehensive and profound understanding of SARA and its related inflammatory diseases. Meanwhile, it is also of great significance for the joint prevention and control of diseases.

An Age Effect of Rumen Microbiome in Dairy Buffaloes Revealed by Metagenomics

Age is an important factor in shaping the gut microbiome. However, the age effect on the rumen microbial community for dairy buffaloes remains less explored. Using metagenomics, we examined the microbial composition and functions of rumen microbiota in dairy Murrah buffaloes of different ages: Y (1 year old), M (3−5 years old), E (6−8 years old), and O (>9 years old). We found that Bacteroidetes and Firmicutes were the predominant phyla, with Prevotella accounting for the highest abundance at the genus level. The proportion of Bacteroides and Methanobrevibacter significantly increased with age, while the abundance of genus Lactobacillus significantly decreased with age (LDA > 3, p < 0.05). Most differed COG and KEGG pathways were enriched in Y with carbohydrate metabolism, while older buffaloes enriched more functions of protein metabolism and the processing of replication and repair (LDA > 2, p < 0.05). Additionally, the functional contribution analysis revealed that the genera Prevotella and Lactobacillus of Y with more functions of CAZymes encoded genes of glycoside hydrolases and carbohydrate esterases for their roles of capable of metabolizing starch and sucrose-associated oligosaccharide enzyme, hemicellulase, and cellulase activities than the other three groups (LDA > 2, p < 0.05), thus affecting the 1-year-old dairy buffalo rumen carbohydrate metabolism. This study provides comprehensive dairy buffalo rumen metagenome data and assists in manipulating the rumen microbiome for improved dairy buffalo production.

Effects of whole corn high-grain diet feeding on ruminal bacterial community and epithelial gene expression related to VFA absorption and metabolism in fattening lambs

The objective of this study was to investigate the effects of whole corn high-grain diet feeding on growth performance, ruminal bacterial community, and epithelial morphology and gene expression related to VFA absorption and metabolism in fattening lambs. Fourteen male (castrated) lambs were randomly assigned to either a group fed a ground corn high-grain diet (50.4% grain; HGC, n = 7) or a group fed a whole corn high-grain diet (50.4% grain; HWC, n = 7). After 7 wk of feeding, HWC group increased the average daily gain (ADG) (P = 0.036) and decreased the feed: gain value (P = 0.010) significantly. HWC group had a greater crude protein apparent digestibility (P = 0.028) in the third week and dry matter and neutral detergent fiber apparent digestibility (P < 0.05) in the seventh week. Pyrosequencing of the 16S ribosomal RNA gene revealed that HWC feeding increased the relative abundance of genera Anaerovibrio, Schwartzia and Unclassified Veillonellaceae in the rumen content and Howardella, Schwartzia and Unclassified Veillonellaceae in the rumen epithelia (P<0.05), while decreased the proportion of Lachnospira and Unclassified Synergistaceae in the rumen content and Anaerovorax, Papillibacter, Ruminococcus, Fibrobacter, Unclassified Lachnospiraceae, Unclassified Bacteroidales and Unclassified Prevotellaceae in the rumen epithelia (P < 0.05). HWC group increased the rumen papilla length (P = 0.001) and surface area (P = 0.002). Furthermore, HWC diet feeding up-regulated the relative mRNA expression of putative anion transporter isoform 1 (PAT1) (P = 0.032) in the rumen epithelia. In summary, compared with ground corn high-grain diet feeding, whole corn high-grain diet feeding improved animal performance, changed ruminal bacterial composition and diversity, and increased VFA absorption of epithelial papilla in fattening lambs. These findings provided theoretical guidance for the actual application of whole corn high-grain diet in ruminants.

The Rumen Microbiota Contributes to the Development of Mastitis in Dairy Cows

Mastitis, a highly prevalent disease in dairy cows, is commonly caused by local infection of the mammary gland. Our previous studies have suggested that the gut microbiota plays an important role in the development of mastitis in mice. However, the effects of rumen microbiota on bovine mastitis and the related mechanisms remain unclear. In this study, we assessed the effects and mechanisms of rumen microbiota on bovine mastitis based on the subacute rumen acidosis (SARA) model induced by feeding Holstein Frisian cows a high-concentrate diet for 8 weeks. Then, the inflammatory responses in the mammary gland and the bacterial communities of rumen fluid, feces, and milk were analyzed. The results showed that SARA induced mastitis symptoms in the mammary gland; activated a systemic inflammatory response; and increased the permeability of the blood-milk barrier, gut barrier, and rumen barrier. Further research showed that lipopolysaccharides (LPS), derived from the gut of SARA cows, translocated into the blood and accumulated in the mammary glands. Furthermore, the abundance of Stenotrophomonas was increased in the rumen of SARA cows, and mastitis was induced by oral administration of Stenotrophomonas in lactating mice. In conclusion, our findings suggested that mastitis is induced by exogenous pathogenic microorganisms as well as by endogenous pathogenic factors. Specifically, the elevated abundance of Stenotrophomonas in the rumen and LPS translocation from the rumen to the mammary gland were important endogenous factors that induced mastitis. Our study provides a foundation for novel therapeutic strategies that target the rumen microbiota in cow mastitis. IMPORTANCE Mastitis is a common and frequently occurring disease of humans and animals, especially in dairy farming, which has caused huge economic losses and brought harmful substance residues, drug-resistant bacteria, and other public health risks. The traditional viewpoint indicates that mastitis is mainly caused by exogenous pathogenic bacteria infecting the mammary gland. Our study found that the occurrence of mastitis was induced by the endogenous pathway. Evidence has shown that rumen-derived LPS enters the mammary gland through blood circulation, damaging the blood-milk barrier and then inducing inflammation of the mammary gland in cows. In addition, a higher abundance of Stenotrophomonas in the rumen was closely associated with the development of mastitis. This study provides a basis for novel therapeutic strategies that exploit the rumen microbiota against mastitis in cows.