Rumen fermentation, intramuscular fat fatty acid profiles and related rumen bacterial populations of Holstein bulls fed diets with different energy levels

Exploring rumen fermentation and microbial populations in Dhofari goats fed a chitosan-added diet

The use of chitosan (CHI) in ruminant diets is a promising natural modifier for rumen fermentation, capable of modulating both the rumen pattern and microbial activities. The objective of this study was to explore the rumen fermentation and microbial populations in Dhofari goats fed a diet supplemented with CHI. A total of 24 Dhofari lactating goats (body weight, 27.32 ± 1.80 kg) were assigned randomly into three experimental groups (n = 8 ewes/group). Goats were fed a basal diet with either 0 (control), 180 (low), or 360 (high) mg CHI/kg of dietary dry matter (DM) for 45 days. Feeding high CHI linearly increased (p < 0.05) the propionate level and reduced the acetate, butyrate, and total protozoa count (p < 0.05). Ruminal ammonia nitrogen (NH3-N) concentrations and the acetate:propionate ratio decreased linearly when goats were fed CHI (p < 0.05). The abundances of both Spirochetes and Fibrobacteres phyla were reduced (p < 0.05) with both CHI doses relative to the control. Both low and high CHI reduced (p < 0.05) the relative abundances of Butyrivibrio hungatei, Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens, Selenomonas ruminantium and Neocallimastix californiae populations. Adding CHI significantly decreased (p < 0.05) the abundances of Ascomycota, Basidiomycota, and Bacillariophyta phyla compared to the control. Adding CHI to the diet reduces the abundance of fibrolytic-degrading bacteria, however, it increases the amylolytic-degrading bacteria. Application of 360 mg of CHI/kg DM modified the relative populations of ruminal microbes, which could enhance the rumen fermentation patterns in Dhofari goats.

Potential Role of Lauric Acid in Milk Fat Synthesis in Chinese Holstein Cows Based on Integrated Analysis of Ruminal Microbiome and Metabolome

The composition and metabolic profile of the ruminal microbiome have an impact on milk composition. To unravel the ruminal microbiome and metabolome affecting milk fat synthesis in dairy cows, 16S rRNA and internal transcribed spacer (ITS) gene sequencing, as well as ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) methods were used to investigate the significant differences in ruminal bacterial and fungal communities as well as metabolome among Chinese Holstein cows with contrasting milk fat contents under the same diet (H-MF 5.82 ± 0.41% vs. L-MF 3.60 ± 0.12%). Another objective was to culture bovine mammary epithelial cells (BMECs) to assess the effect of metabolites on lipid metabolism. Results showed that the acetate-to-propionate ratio and xylanase activity in ruminal fluid were both higher in H-MF. Microbiome sequencing identified 10 types of bacteria and four types of fungi differently abundant at the genus level. Metabolomics analysis indicated 11 different ruminal metabolites between the two groups, the majority of which were lipids and organic acids. Among these, lauric acid (LA) was enriched in fatty acid biosynthesis with its concentration in milk fat of H-MF cows being greater (217 vs. 156 mg per 100 g milk), thus, it was selected for an in vitro study with BMECs. Exogenous LA led to a marked increase in intracellular triglyceride (TG) content and lipid droplet formation, and it upregulated the mRNA abundance of fatty acid uptake and activation (CD36 and ACSL1), TG synthesis (DGAT1, DGAT2 and GPAM), and transcriptional regulation (SREBP1) genes. Taken together, the greater relative abundance of xylan-fermenting bacteria and fungi, and lower abundance of bacteria suppressing short-chain fatty acid-producing bacteria or participating in fatty acid hydrogenation altered lipids and organic acids in the rumen of dairy cows. In BMECs, LA altered the expression of genes involved in lipid metabolism in mammary cells, ultimately promoting milk fat synthesis. Thus, it appears that this fatty acid plays a key role in milk fat synthesis.

Short- and long-term effects of different forage types supplemented in preweaning dairy calves on performance and milk production into first lactation

We investigated the short- and long-term effects of different forage types supplemented in preweaning dairy calves on growth performance, blood metabolites, rumen fermentation, bacterial community, and milk production during first lactation. Sixty healthy 1-mo-old female Holstein calves were blocked by birth date and body weight and randomly assigned to one of 3 groups (n = 20): normal milk and pelleted starter feeding (CON), supplemented with chopped oat hay [75.0 g/d/calf (dry matter (DM) basis); OAH], or alfalfa hay [75.0 g/d/calf (DM basis); ALF]. The forage supplementation started when calves were 30 d old (D1 of the experimental period) and ended when they were 73 d old (D44 of the experimental period when calves were weaned. Milk and feed intakes and fecal consistency scores were recorded daily. Growth performance, rumen fluid, and blood samples were collected bi-weekly. After weaning, all the calves were integrated with the same barn and diets. After calving, the milk production was recorded daily. During the experimental period, the OAH group had greater solid feed and total DM intakes and greater rumen pH than the CON group (P ≤ 0.04), but had lower forage intake and crude protein digestibility than the ALF group (P ≤ 0.04). The ALF group had higher rumen pH and blood β-hydroxybutyrate concentration (P ≤ 0.04), lower fecal score (P = 0.02), and greater ether extract digestibility (P = 0.02) than the CON group. The ALF and OAH groups had lower concentrations of ruminal total volatile fatty acids (P = 0.01). Still, the ALF group had a greater proportion of acetate and a relative abundance of cellulose degradation-related bacteria (Lachnoclostridium_1 and Oribacterium) and a lower relative abundance of inflammation-related bacteria (Erysipelotrichaceae_UCG-009) in the rumen compared with CON. Interestingly, the average milk production from 6 to 200 d in milk (DIM) was greater in the ALF group (P < 0.01) even though no significant effects were found on the rumen fermentation parameters and blood metabolites at 200 DIM. Generally, alfalfa hay supplementation in preweaning dairy calves had positive effects in the short- and long-term in terms of rumen development, health status, and future milk production.

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.

Impact of Various Ration Energy Levels on the Slaughtering Performance, Carcass Characteristics, and Meat Qualities of Honghe Yellow Cattle

Consumers are increasing their daily demand for beef and are becoming more discerning about its nutritional quality and flavor. The present objective was to evaluate how the ration energy content (combined net energy, Nemf) impacts the slaughter performance, carcass characteristics, and meat qualities of Honghe yellow cattle raised in confinement. Fifteen male Honghe yellow cattle were divided into three groups based on a one-way design: a low-energy group (LEG, 3.72 MJ/kg), a medium-energy group (MEG, 4.52 MJ/kg), and a high-energy group (HEG, 5.32 MJ/kg). After a period of 70 days on these treatments, the animals were slaughtered and their slaughter performance was determined, and the longissimus dorsi muscle (LD) and biceps femoris (BF) muscles were gathered to evaluate meat quality and composition. Increasing the dietary energy concentration led to marked improvements (p < 0.05) in the live weight before slaughter (LWBS), weight of carcass, backfat thickness, and loin muscle area. HEG also improved the yield of high-grade commercial cuts (13.47% vs. 10.39%) (p < 0.05). However, meat quality traits were not affected by treatment except for shear force, which was affected by dietary energy. A significant improvement (p < 0.05) in the intramuscular fat (IMF) content was observed in the HEG. Little effect on the amino acid profile was observed (p > 0.05), except for a tendency (p = 0.06) to increase the histidine concentration in the BF muscle. Increasing dietary energy also reduced C22:6n-3 and saturated fatty acids (SFAs) and enhanced C18:1 cis-9 and monounsaturated fatty acids (MUFAs, p < 0.05). Those results revealed that increasing energy levels of diets could enhance slaughter traits and affect the meat quality and fatty acid composition of different muscle tissues of Honghe yellow cattle. These results contribute to the theoretical foundation to formulate nutritional standards and design feed formulas for the Honghe yellow cattle.

Effects of Cattle Breeds and Dietary Energy Density on Intake, Growth, Carcass, and Meat Quality under Thai Feedlot Management System

This study determines the effects of varying dietary metabolizable energy densities on Holstein Friesian and Charolais crossbred beef cattle in fattening phases. The research focuses on nutrient utilization, ruminal fermentation, growth performance, carcass traits, and meat quality. Thirty-six steers were used in the feeding trial that lasted for six months according to a 2 × 3 factorial arrangement in a randomized complete block design (Factor A, cattle breeds (Holstein Frisian, Charolais crossbred); B, metabolizable energy density (10.5, 11.1 and 11.8 MJ/kg DM)) with six replications. The dietary energy density had no interaction with the cattle breeds (p > 0.05). Despite fewer carcass yields, Holstein Friesian crossbreds indicate superior eating quality to Charolais crossbreds on drip loss, meat iron content, and Warner-Bratzler shear force due to increased intramuscular fat content (p < 0.05) with similar meat color (p > 0.05). Increased dietary energy density positively impacts nutrient and energy intake and rumen fermentation (p < 0.05) but did not affect growth and carcass traits (p > 0.05). This research suggests the potential of Holstein Friesian crossbreds for intensive beef production, providing valuable insights into optimal feeding strategies for achieving quality meat outcomes. On-farm feeding trials are needed to develop a practical and economical Thai beef feedlot management system.

Profiling and functional analysis of circular RNAs in yaks intramuscular fat

Circular RNAs (circRNAs) are a new class of endogenous RNA regulating gene expression. However, the regulatory mechanisms of lipid metabolism in yaks involved in circRNAs remain poorly understood. The IMF plays a crucial role in the quality of yak meat, to greatly improve the meat quality. In this study, the fatty acid profiles of yak IMF were determined and circRNAs were sequenced. The results showed that the total of polyunsaturated fatty acid (PUFA) content of adult yak muscle was significantly higher than that in yak calves (p < 0.05). A total of 29,021 circRNAs were identified in IMF tissue, notably, 99 differentially expressed (DE) circRNAs were identified, to be associated with fat deposition, the most significant of which were circ_12686, circ_6918, circ_3582, ci_106 and ci_123 (A circRNA composed of exons is labelled 'circRNA' and a circRNA composed of introns is labelled 'ciRNA'). KEGG pathway enrichment analysis showed that the differential circRNAs were enriched in four pathways associated with fat deposition (e.g., the peroxisome proliferator-activated receptor signalling, fatty acid degradation, sphingolipid metabolism and sphingolipid signalling pathways). We also constructed co-expression networks of DE circRNA-miRNA using high-throughput sequencing in IMF deposition, from which revealed that ci_106 target binding of bta-miR-130b, bta-miR-148a, bta-miR-15a, bta-miR-34a, bta-miR-130a, bta-miR-17-5p and ci_123 target binding of bta-miR-150 were involved in adipogenesis. The study revealed the role of the circRNAs in the IMF deposition in yak and its influence on meat quality the findings demonstrated the circRNA differences in the development of IMF with the increase of age, thus providing a theoretical basis for further research on the molecular mechanism of IMF deposition in yaks.

Assessing the impact of three feeding stages on rumen bacterial community and physiological characteristics of Japanese Black cattle

In Japan, Japanese Black cattle, known for their exceptional meat quality owing to their abundant intramuscular fat, undergo a unique three-stage feeding system with varying concentrate ratios. There is limited research on physiological and rumen microbial changes in Japanese Black cattle during these stages. Therefore, this study aimed to examine Japanese Black steers in these three stages: early (T1, 12-14 months), middle (T2, 15-22 months), and late (T3, 23-30 months). The rumen bacteria of 21 cattle per phase was analyzed using 16S rRNA gene sequencing. Rumen bacterial diversity was significantly higher in T1, with a distinct distribution, than in T2 and T3. Specific phyla and genera were exclusive to each stage, reflecting the shifts in feed composition. Certain genera dominated each stage: T1 had Flexilinea, Streptococcus, Butyrivibrio, Selenomonas, and Kandleria; T2 had Bifidobacterium, Shuttleworthia, and Sharpea; and T3 had Acetitomaculum, Mycoplasma, Atopobium, and Howardella. Correlation analysis revealed significant associations between certain microbial populations and physiological parameters. These findings indicate that changes in energy content and feed composition are associated with physiological and ruminal alterations. This study may guide strategies to improve rumen health and productivity in Japanese Black cattle by modifying diets to specific fattening stages.

Do microbial-gut-muscle mediated by SCFAs, microbial-gut-brain axis mediated by insulin simultaneously regulate yak IMF deposition?

Ruminant rumen plays an important role in the digestibility of cellulose, hemicellulose, starch and fat. In this study, the yaks under graze and stall feeding were chosen as the models of different rumen bacteria and intramuscular fat (IMF). The characteristics of IMF deposition, serum indexes in yaks were detected; the bacteria, metabolites in rumen was explored by 16S rRNA sequencing technology, untargeted metabolomics based on liquid chromatography-mass spectrometer and gas chromatography, respectively; the transcriptome of longissimus thoracis was identified by RNA-Sequencing analysis. Based on above results, a hypothesis that yak IMF deposition is regulated by the combined action of microbiome-gut-brain and muscle axis was proposed. The short-chain fatty acids (SCFAs) and neurotransmitters precursors like acetylcholine produced in yak rumen promoted insulin secretion via central nervous system. These insulin resulted in the high expression of SREBF1 gene by gut-brain axis; SCFAs can directly arrive to muscular tissue via blood circulation system, then activated the expression of PPARγ gene by gut-muscle axis. The expression of lipogenesis gene SCD, FABP3, CPT1, FASN and ACC2 was accordingly up-regulated. This study firstly introduce the theory of microbiome-gut-brain/muscle axis into the study of ruminant, and comprehensively expounded the regulatory mechanism of yak IMF deposition.

- Invited Review - Translational gut microbiome research for strategies to improve beef cattle production sustainability and meat quality

Advanced and innovative breeding and management of meat-producing animals are needed to address the global food security and sustainability challenges. Beef production is an important industry for securing animal protein resources in the world and meat quality significantly contributes to the economic values and human needs. Improvement of cattle feed efficiency has become an urgent task as it can lower the environmental burden of methane gas emissions and the reduce the consumption of human edible cereal grains. Cattle depend on their symbiotic microbiome and its activity in the rumen and gut to maintain growth and health. Recent developments in high-throughput omics analysis (metagenome, metatranscriptome, metabolome, metaproteome and so on) have made it possible to comprehensively analyze microbiome, hosts and their interactions and to define their roles in affecting cattle biology. In this review, we focus on the relationships among gut microbiome and beef meat quality, feed efficiency, methane emission as well as host genetics in beef cattle, aiming to determine the current knowledge gaps for the development of the strategies to improve the sustainability of beef production.

Integrated rumen microbiome and serum metabolome analysis responses to feed type that contribution to meat quality in lambs

BACKGROUND

Lifestyle factors, such as diet, are known to be a driver on the meat quality, rumen microbiome and serum metabolites. Rumen microbiome metabolites may be important for host health, the correlation between rumen microbiome and production of rumen metabolites are reported, while the impact of rumen microbiome on the serum metabolome and fatty acid of meat are still unclear. This study was designed to explore the rumen microbiome, serum metabolome and fatty acid of meat in response to the grass diet and concentrate diet to lambs, and the relationship of which also investigated.

METHODS

In the present study, 12 lambs were randomly divided into two groups: a grass diet (G) and a concentrate diet (C). Here, multiple physicochemical analyses combined with 16S rRNA gene sequences and metabolome analysis was performed to reveal the changes that in response to feed types.

RESULTS

The concentrate diet could improve the growth performance of lambs compared to that fed with the grass diet. The microbiome composition was highly individual, compared to the concentrate group, the abundance of Rikenellaceae_RC9_gut_group, F082_unclassified, Muribaculaceae_unclassified, Ruminococcaceae_NK4A214_group, Bacteroidetes_unclassified, and Bacteroidales_UCG-001_unclassified were significantly (P < 0.05) lower in the grass group, while, the abundance of Succinivibrio, Succinivibrionaceae_UCG-002, Fibrobacter and Christensenellaceae_R-7_group were significantly (P < 0.05) higher in the grass group. Serum metabolomics analysis combined with enrichment analysis revealed that serum metabolites were influenced by feed type as well as the metabolic pathway, and significantly affected serum metabolites involved in amino acids, peptides, and analogues, bile acids, alcohols and derivatives, linoleic acids derivatives, fatty acids and conjugates. Most of the amino acids, peptides, and analogues metabolites were positively associated with the fatty acid contents. Among the bile acids, alcohols and derivatives metabolites, glycocholic was positively associated with all fatty acid contents, except C18:0, while 25-Hydroxycholesterol and lithocholic acid metabolites were negatively associated with most of the fatty acid contents.

CONCLUSION

Correlation analysis of the association of microbiome with metabolite features, metabolite features with fatty acid provides us with comprehensive understanding of the composition and function of microbial communities. Associations between utilization or production were widely identified among affected microbiome, metabolites and fatty acid, and these findings will contribute to the direction of future research in lamb.

Gut Microbiome Profiling of the Endangered Southern Greater Glider (Petauroides volans) after the 2019-2020 Australian Megafire

Studying the gut microbiome can provide valuable insights into animal health and inform the conservation management of threatened wildlife. Gut microbiota play important roles in regulating mammalian host physiology, including digestion, energy metabolism and immunity. Dysbiosis can impair such physiological processes and compromise host health, so it is essential that the gut microbiome be considered in conservation planning. The southern greater glider (Petauroides volans) is an endangered arboreal marsupial that faced widespread habitat fragmentation and population declines following the 2019-2020 Australian bushfire season. This study details baseline data on the gut microbiome of this species. The V3-V4 region of the 16S rRNA gene was amplified from scats collected from individuals inhabiting burnt and unburnt sites across southeastern Australia and sequenced to determine bacterial community composition. Southern greater glider gut microbiomes were characterised by high relative abundances of Firmicutes and Bacteroidota, which is consistent with that reported for other marsupial herbivores. Significant differences in gut microbial diversity and community structure were detected among individuals from different geographic locations. Certain microbiota and functional orthologues were also found to be significantly differentially abundant between locations. The role of wildfire in shaping southern greater glider gut microbiomes was shown, with some significant differences in the diversity and abundance of microbiota detected between burnt and unburnt sites. Overall, this study details the first data on greater glider (Petauroides) gut microbiomes, laying the foundation for future studies to further explore relationships between microbial community structure, environmental stressors and host health.

Effects of replacing hybrid giant napier with sugarcane bagasse and fermented sugarcane bagasse on growth performance, nutrient digestibility, rumen fermentation characteristics, and rumen microorganisms of Simmental crossbred cattle

This study investigated the effects of replacing hybrid giant napiers with sugarcane bagasse and fermented sugarcane bagasse on the growth performance, apparent nutrient digestibility, rumen fermentation characteristics, and rumen microorganisms of Simmental crossbred cattle. Twenty-one Simmental crossbred cattle with similar initial body weight (363.42 ± 8.67 kg) were randomly divided into three groups: Group CON (20% hybrid giant napier +45% distillers grains +35% concentrate mixture), Group SB (20% sugarcane bagasse +45% distillers grains +35% concentrate mixture), and Group FSB (20% fermented sugarcane bagasse +45% distillers grains +35% concentrate mixture). The average daily weight gain in the SB group was lower than in the CON group, no significant difference was found between the CON and FSB groups. The feed conversion ratio of the CON and FSB groups was lower compared to the SB group. The apparent digestibility of neutral detergent fiber and acid detergent fiber in the SB group was lower than in the CON group, no significant difference was found between the CON and FSB groups. The levels of NH3-N, microbial protein, acetate, propionate, butyrate, isobutyrate, and total volatile fatty acids were higher in the CON and FSB groups than in the SB group, no significant difference was found between the CON and FSB groups. The relative abundances of Christensenellaceae_R-7_group, Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-003, Saccharofermentans, and Eubacteriumcoprostanoligenes_group were lower in the CON and FSB groups compared to the SB group. The relative abundance of Succiniclasticum was highest in the FSB group, followed by the CON group and then the SB group. Correlation analysis showed that the relative abundance of Succiniclasticum was positively correlated with propionate and NH3-N content, while the relative abundance of Rikenellaceae_RC9_gut_group was inversely correlated with NH3-N content. Gene function prediction indicated that fermented sugarcane bagasse promoted rumen microbial amino acid metabolism. In conclusion, replacing hybrid giant napiers with 20% sugarcane bagasse negatively affected the growth performance of Simmental crossbred cattle, while the addition of 20% fermented sugarcane bagasse had no adverse effects on growth performance and rumen fermentation characteristics, and did not alter the abundance of the rumen core flora in Simmental crossbred cattle.

Effect of dietary inclusion of tea residue and tea leaves on ruminal fermentation characteristics and methane production

The aim of this study was to compare the differences of dietary tea leaves (TL) and tea residue (TR) inclusion on rumen fermentation characteristics and to explore whether TR could be an alternative feedstuff of ruminants. For these purposes, seven treatments consisted of two inclusion types (TL vs. TR) and three inclusion levels (g/g of dry matter basis) of 10% (TL10/TR10), 20% (TL20/TR20), and 30% (TL30/TR30) in each inclusion type, plus control group with inclusion of 0% (CON) were designed, with four replicates in each group, to conduct an in vitro ruminal fermentation test. Results showed that the contents of crude protein, neutral detergent fiber, and acid detergent fiber were higher in TR than TL, while TL contained more ether extract and crude ash than TR. Interaction effects between inclusion type and inclusion level were observed in concentrations of isobutyrate and microbial crude protein (MCP), as well as in gas production and digestibility of organic matter. Fermentation characteristics were significantly influenced by TL and TR depending on the inclusion level, except for the concentration of total branched-chain volatile fatty acid. These significant differences of fermentation characteristics due to inclusion level mainly focused on CON and tea inclusion, with higher values in CON than TR or TL groups. The total gas production during the 48-h incubation showed no differences among CON, TL10, and TR10. The inclusion of TR and TL decreased the production of methane. The concentration of MCP in CON, TR10 and TR30 was lower than TR20 and all TL groups. In conclusion, dietary inclusion of TR and TL possessed equivalent effect on rumen fermentation characteristics and methane production, substituting diet with TR or TL for over 10% would inhibit rumen fermentation despite positive effects in TR20 and all TL groups regarding more MCP and less methane production. This study indicates that special attention should be paid to the inclusion level of TR and TL when considering them as alternative feedstuffs of ruminants. Further in vivo study is needed to evaluate the applicability of tea residue as a feedstuff for production of ruminants.

Glycolysis characteristics of intracellular polysaccharides from Agaricus bitorquis (Quél.) sacc. Chaidam and its effects on intestinal flora from different altitudes of mice in vitro fermentation

The glycolysis characteristics and effects on intestinal flora of polysaccharides from Agaricus bitorquis (Quél.) Sacc. Chaidam (ABIPs) in vitro fermentation by different altitudes of mice feces was examined, including low, medium, and high altitudes groups (LG, MG, and HG). In vitro, fermentation of ABIPs forty-eight hours resulted in a remarkable decrease in total sugar content and improvement of short-chain fatty acids (SCFAs) (mainly acetate, propionate, and butyrate), which simultaneously induced the composition of monose and uronic acids and SCFAs continuously change. Besides, ABIPs influenced the abundance and composition of the intestinal flora, generally increasing the abundance of probiotic bacteria (such as Bifidobacterium and Faecalibacterium) and decreasing the abundance of harmful bacteria (such as Phenylobacterium and Streptococcus) in all groups, with the highland biology core genus Blautia significantly enriched in LG and MG groups. It was also found that ABIPs enhanced pathways associated with biosynthesis and metabolism. In addition, correlation analysis speculated that the metabolism of SCFAs by ABIPs may be associated with genera such as Anaerostipes, Roseburia, and Weissella. ABIPs may protect organismal health by regulating hypoxic intestinal flora composition and metabolic function, and more superior fermentation performance was observed in MG compared to other groups.

Dynamic changes of rumen bacteria and their fermentative ability in high-producing dairy cows during the late perinatal period

Background

High-producing dairy cows face varying degrees of metabolic stress and challenges during the late perinatal period, resulting in ruminal bacteria abundance and their fermentative ability occurring as a series of changes. However, the dynamic changes are still not clear.

Aims/methods

Ten healthy, high-producing Holstein dairy cows with similar body conditions and the same parity were selected, and ruminal fluid from the dairy cows at postpartum 0, 7, 14, and 21 d was collected before morning feeding. 16S rRNA high-throughput sequencing, GC-MS/MS targeted metabolomics, and UPLC-MS/MS untargeted metabolomics were applied in the study to investigate the dynamic changes within 21 d postpartum.

Results

The results displayed that the structures of ruminal bacteria were significantly altered from 0 to 7 d postpartum (R = 0.486, P = 0.002), reflecting the significantly declining abundances of Euryarchaeota and Chloroflexi phyla and Christensenellaceae, Methanobrevibacter, and Flexilinea genera (P < 0.05) and the obviously ascending abundances of Ruminococcaceae, Moryella, Pseudobutyrivibrio, and Prevotellaceae genera at 7 d postpartum (P < 0.05). The structures of ruminal bacteria also varied significantly from 7 to 14 d postpartum (R = 0.125, P = 0.022), reflecting the reducing abundances of Christensenellaceae, Ruminococcaceae, and Moryella genera (P < 0.05), and the elevating abundances of Sharpea and Olsenella genera at 14 d postpartum (P < 0.05). The metabolic profiles of ruminal SCFAs were obviously varied from 0 to 7 d postpartum, resulting in higher levels of propionic acid, butyric acid, and valeric acid at 7 d postpartum (P < 0.05); the metabolic profiles of other ruminal metabolites were significantly shifted from 0 to 7 d postpartum, with 27 significantly elevated metabolites and 35 apparently reduced metabolites (P < 0.05). The correlation analysis indicated that propionic acid was positively correlated with Prevotellaceae and Ruminococcaceae (P < 0.05), negatively correlated with Methanobrevibacter (P < 0.01); butyric acid was positively associated with Prevotellaceae, Ruminococcaceae, and Pseudobutyrivibrio (P < 0.05), negatively associated with Christensenellaceae (P < 0.01); valeric acid was positively linked with Prevotellaceae and Ruminococcaceae (P < 0.05); pyridoxal was positively correlated with Flexilinea and Methanobrevibacter (P < 0.05) and negatively correlated with Ruminococcaceae (P < 0.01); tyramine was negatively linked with Ruminococcaceae (P < 0.01).

Conclusion

The findings contribute to the decision of nutritional management and prevention of metabolic diseases in high-producing dairy cows during the late perinatal period.

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.

Exploring the rumen microbiota of Hu lambs in response to diet with paper mulberry

Paper mulberry (Broussonetia papyrifera), as a new woody forage with high-protein characteristic, is being widely used in ruminant feeding. However, little is known about the comprehensive microbiota picture of whole ruminal niches (liquid, solid, and epithelium) under paper mulberry diet. To gain a better understanding of feeding paper mulberry on the rumen microbiota, the effects of fresh paper mulberry, paper mulberry silage, or a conventional high-protein alfalfa silage on rumen fermentation products and microbiota in rumen niches of Hu lambs were studied. Forty-five Hu lambs were randomly divided into 3 treatments with 15 replicates in each treatment. No significant difference was observed among treatments in the average daily gain (ADG). The fresh paper mulberry treatment had lower (P < 0.05) pH and higher (P < 0.05) total volatile fatty acids (TVFA) compared with silage treatments, but the fermentation parameters did not show significant differences between paper mulberry silage and alfalfa silage treatments. The Shannon index did not show a significant difference (P < 0.05) among treatments except between fresh paper mulberry and alfalfa silage treatment in rumen epithelial niches. Butyrivibrio and Treponema were the predominant genera in the rumen epithelial fraction, while Prevotella and Rikenellaceae_RC9 dominated in both rumen liquid and solid fractions. These results indicated the paper mulberry supplement did not have distinct impact on the microbial diversity and growth performance compared with alfalfa silage, especially for paper mulberry silage, which might help us develop an alternative animal feeding strategy of replacing alfalfa with paper mulberry. KEY POINTS: • Feeding paper mulberry silage did not show significant impact on the growth performance compared with alfalfa silage treatment. • Feeding fresh paper mulberry reduced rumen pH value and increased total volatile fatty acid. • The microbial diversity did not show significant difference among treatments.

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.

Recent advances in feed and nutrition of beef cattle in China - A review

The beef cattle industry in China has advanced remarkably since its reform and opening up; consequently, China has become the world's third-largest beef cattle producer. China is also one of the countries with the most substantial research input and output in the field of beef cattle feed and nutrition. The progress and innovation by China in the research field of beef cattle feed and nutrition have undoubtedly promoted the development of the domestic beef cattle industry. This review summarizes recent advances in feed resource development, nutrient requirements, and nutritional regulation of beef cattle in China. Limitations in current research and perspectives on future work are also discussed.

Rumen microbial-driven metabolite from grazing lambs potentially regulates body fatty acid metabolism by lipid-related genes in liver

BACKGROUND

Lipid metabolism differs significantly between grazing and stall-feeding lambs, affecting the quality of livestock products. As two critical organs of lipid metabolism, the differences between feeding patterns on rumen and liver metabolism remain unclear. In this study, 16S rRNA, metagenomics, transcriptomics, and untargeted metabolomics were utilized to investigate the key rumen microorganisms and metabolites, as well as liver genes and metabolites associated with fatty acid metabolism under indoor feeding (F) and grazing (G).

RESULTS

Compared with grazing, indoor feeding increased ruminal propionate content. Using metagenome sequencing in combination with 16S rRNA amplicon sequencing, the results showed that the abundance of propionate-producing Succiniclasticum and hydrogenating bacteria Tenericutes was enriched in the F group. For rumen metabolism, grazing caused up-regulation of EPA, DHA and oleic acid and down-regulation of decanoic acid, as well as, screening for 2-ketobutyric acid as a vital differential metabolite, which was enriched in the propionate metabolism pathway. In the liver, indoor feeding increased 3-hydroxypropanoate and citric acid content, causing changes in propionate metabolism and citrate cycle, while decreasing the ETA content. Then, the liver transcriptome revealed that 11 lipid-related genes were differentially expressed in the two feeding patterns. Correlation analysis showed that the expression of CYP4A6, FADS1, FADS2, ALDH6A1 and CYP2C23 was significantly associated with the propionate metabolism process, suggesting that propionate metabolism may be an important factor mediating the hepatic lipid metabolism. Besides, the unsaturated fatty acids in muscle, rumen and liver also had a close correlation.

CONCLUSIONS

Overall, our data demonstrated that rumen microbial-driven metabolite from grazing lambs potentially regulates multiple hepatic lipid-related genes, ultimately affecting body fatty acid metabolism.

The relationship between shifts in the rhizosphere microbial community and root rot disease in a continuous cropping American ginseng system

The root rot disease causes a great economic loss, and the disease severity usually increases as ginseng ages. However, it is still unclear whether the disease severity is related to changes in microorganisms during the entire growing stage of American ginseng. The present study examined the microbial community in the rhizosphere and the chemical properties of the soil in 1-4-year-old ginseng plants grown in different seasons at two different sites. Additionally, the study investigated ginseng plants' root rot disease index (DI). The results showed that the DI of ginseng increased 2.2 times in one sampling site and 4.7 times in another during the 4 years. With respect to the microbial community, the bacterial diversity increased with the seasons in the first, third, and fourth years but remained steady in the second year. The seasonal changing of relative abundances of bacteria and fungi showed the same trend in the first, third, and fourth years but not in the second year. Linear models revealed that the relative abundances of Blastococcus, Symbiobacterium, Goffeauzyma, Entoloma, Staphylotrichum, Gymnomyces, Hirsutella, Penicillium and Suillus spp. were negatively correlated with DI, while the relative abundance of Pandoraea, Rhizomicrobium, Hebeloma, Elaphomyces, Pseudeurotium, Fusarium, Geomyces, Polyscytalum, Remersonia, Rhizopus, Acremonium, Paraphaeosphaeria, Mortierella, and Metarhizium spp. were positively correlated with DI (P < 0.05). The Mantel test showed that soil chemical properties, including available nitrogen, phosphorus, potassium, calcium, magnesium, organic matter, and pH, were significantly correlated to microbial composition. The contents of available potassium and nitrogen were positively correlated with DI, while pH and organic matter were negatively correlated with DI. In summary, we can deduce that the second year is the key period for the shift of the American ginseng rhizosphere microbial community. Disease aggravation after the third year is related to the deterioration of the rhizosphere microecosystem.

High-energy diet modify rumen microbial composition and microbial energy metabolism pattern in fattening sheep

Higher dietary energy is often used to achieve better animal performance in mutton sheep production. Notably, changing the diet formula affects rumen fermentation and the microbiota of ruminants. In this study, we investigated the effect of dietary energy on rumen fermentation and ruminal microbiota in fattening sheep. Fifteen 2-month-old white-headed Suffolk sheep (♂) × Hu sheep (♀) crossbred lambs were randomly divided into three treatments based on the dietary energy of the feeds fed: 8.67 MJ/kg (Low energy (LE); n = 5), 10.38 MJ/kg (standard energy (CON); n = 5), and 12.31 MJ/kg (high energy (HE); n = 5) groups. After 70 days of feeding, sheep were slaughtered and the ruminal fluids were collected and analyzed to determine fermentation parameters. Microbiota was determined using metagenomics sequencing. Notably, the microbial cell protein (MCP) and butyric acid concentrations were significantly high in the HE group. Metagenomic sequencing revealed that ACE and Chao indexes of the HE group were significantly decreased. Four genera among the major classified taxa across all the kingdoms differed in relative abundance in the three dietary energy levels. The relative abundances of Prevotella_brevis, Succiniclasticum_ruminis, Prevotellace-ae_bacterium, and Lachnospiraceae_bacterium were significantly correlated with rumen fermentation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis further revealed that a high-energy diet increased lipid metabolism of microbiota. The Carbohydrate Active enzymes (CAZy) gene, which participates in energy metabolism, was upregulated, while genes regulating plant cell wall degradation were downregulated in the HE group. These results suggest that a high-energy diet had minimal influence on the rumen fermentation pattern but altered the composition of the rumen microbiota, enhancing microbial lipid metabolism and limiting crude fiber metabolism. The findings of this study provide scientific evidence of the effect of dietary energy on ruminant fermentation and fattening sheep production.

"The Yak"-A remarkable animal living in a harsh environment: An overview of its feeding, growth, production performance, and contribution to food security

Yaks play an important role in the livelihood of the people of the Qinghai-Tibet Plateau (QTP) and contribute significantly to the economy of the different countries in the region. Yaks are commonly raised at high altitudes of ~ 3,000-5,400 m above sea level. They provide many important products, namely, milk, meat, fur, and manure, as well as social status, etc. Yaks were domesticated from wild yaks and are present in the remote mountains of the QTP region. In the summer season, when a higher quantity of pasture is available in the mountain region, yaks use their long tongues to graze the pasture and spend ~ 30-80% of their daytime grazing. The remaining time is spent walking, resting, and doing other activities. In the winter season, due to heavy snowfall in the mountains, pasture is scarce, and yaks face feeding issues due to pasture scarcity. Hence, the normal body weight of yaks is affected and growth retardation occurs, which consequently affects their production performance. In this review article, we have discussed the domestication of yaks, the feeding pattern of yaks, the difference between the normal and growth-retarded yaks, and also their microbial community and their influences. In addition, blood biochemistry, the compositions of the yaks' milk and meat, and reproduction are reported herein. Evidence suggested that yaks play an important role in the daily life of the people living on the QTP, who consume milk, meat, fur, use manure for fuel and land fertilizer purposes, and use the animals for transportation. Yaks' close association with the people's well-being and livelihood has been significant.

Lipid Characteristics of the Muscle and Perirenal Fat in Young Tudanca Bulls Fed on Different Levels of Grass Silage

Beef derived from grass-fed cattle is a specific quality criterion. The effect of grass silage intake on quality characteristics, i.e., fatty acids, fat-soluble vitamins, and lipid-derived volatile composition of intramuscular and perirenal fat from fattening bull weaners were studied. Visible (VIS) and near-infrared (NIR) spectra were also obtained from perirenal fat. Perirenal fat analysis was performed for feeding differentiation purposes. A total of 22 Tudanca breed 11-month-aged bulls were finished on three different diets: grass silage and a commercial concentrate ad libitum (GS-AC), grass silage ad libitum and the commercial concentrate restricted to half of the intake of the GS-AC group (GS-LC), and barley straw and concentrate ad libitum (Str-AC). Feeding had a significant effect (p < 0.05) on γ-linolenic acid and the ratio n-6/n-3 fatty acids. Furthermore, β-carotene content was greater in beef from silage groups than in the Str-AC group. Feeding also affected the perirenal fat composition. Beef from silage-fed bulls and straw-fed bulls could be differentiated by fatty acid percentages, especially 18:0, t-18:1, and c9-18:1, β-carotene content, b* colour value, and carotenoid colour index. However, the VIS or NIR spectra data showed poor differentiating performance, and the volatile composition did not have appreciable differentiation power.

Influence of dietary oils rich in omega-6 or omega-3 fatty acids on rumen microbiome of dairy cows

The objective of this study was to compare the effect of supplementing dairy cow diets with contrasting sources of omega-6 (soybean oil) and omega-3 (fish oil) PUFA on rumen microbiome. For 63 d, 15 mid-lactating cows were fed a control diet (n = 5 cows; no fat supplement) or control diet supplemented with 2.9% dry matter (DM) of either soybean oil (SO; n = 5 cows) or fish oil (FO; n = 5 cows). Ruminal contents were collected on days 0, 21, 42, and 63 for 16S rRNA gene sequencing. Beta diversity and Shannon, Simpson and Chao1 diversity indices were not affected by dietary treatments. In terms of core microbiome, Succiniclasticum, Prevotella, Rikenellaceae_RC9_gut_group, and NK4A214_group were the most prevalent taxa regardless of treatments. Bifidobacterium was absent in SO diet, Acetitomaculum was absent in FO, and Sharpea was only detected in SO. Overall, results showed that at 2.9% DM supplementation of either SO or FO over 63 days in dairy cow diets does not cause major impact on bacterial community composition and thus is recommended as feeding practice.

Different feeding patterns affect meat quality of Tibetan pigs associated with intestinal microbiota alterations

This study aimed to investigate the effects of different feeding patterns on meat quality, gut microbiota and its metabolites of Tibetan pigs. Tibetan pigs with similar body weight were fed the high energy diets (HEP, 20 pigs) and the regular diets (RFP, 20 pigs), and free-ranging Tibetan pigs (FRP, 20 pigs) were selected as the reference. After 6 weeks of experiment, meat quality indexes of semitendinosus muscle (SM) and cecal microbiota were measured. The results of meat quality demonstrated that the shear force of pig SM in FRP group was higher than that in HEP and RFP groups (p < 0.001); the pH-value of SM in HEP pigs was higher at 45 min (p < 0.05) and lower at 24 h (p < 0.01) after slaughter than that in FRP and RFP groups; the SM lightness (L* value) of FRP pigs increased compared with RFP and HEP groups (p < 0.001), while the SM redness (a* value) of FRP pigs was higher than that of RFP group (p < 0.05). The free fatty acid (FA) profile exhibited that the total FAs and unsaturated FAs of pig SM in HEP and RFP groups were higher than those in FRP group (p < 0.05); the RFP pigs had more reasonable FA composition with higher n-3 polyunsaturated FAs (PUFAs) and lower n-6/n-3 PUFA ratio than HEP pigs (p < 0.05). Based on that, we observed that Tibetan pigs fed high energy diets (HEP) had lower microbial α-diversity in cecum (p < 0.05), and distinct feeding patterns exhibited a different microbial cluster. Simultaneously, the short-chain FA levels in cecum of FRP and RFP pigs were higher compared with HEP pigs (p < 0.05). A total of 11 genera related to muscle lipid metabolism or meat quality, including Alistipes, Anaerovibrio, Acetitomaculun, etc., were identified under different feeding patterns (p < 0.05). Spearman correlation analysis demonstrated that alterations of free FAs in SM were affected by the genera Prevotellaceae_NK3B31_group, Prevotellaceae UCG-003 and Christensenellaceae_R-7_group (p < 0.05). Taken together, distinct feeding patterns affected meat quality of Tibetan pigs related to gut microbiota alterations.

In Situ Rumen Degradation Characteristics and Bacterial Colonization of Corn Silages Differing in Ferulic and p-Coumaric Acid Contents

In plant cell wall, ferulic acid (FA) and p-coumaric acid (pCA) are commonly linked with arabinoxylans and lignin through ester and ether bonds. These linkages were deemed to hinder the access of rumen microbes to cell wall polysaccharides. The attachment of rumen microbes to plant cell wall was believed to have profound effects on the rate and the extent of forage digestion in rumen. The objective of this study was to evaluate the effect of bound phenolic acid content and their composition in corn silages on the nutrient degradability, and the composition of the attached bacteria. Following an in situ rumen degradation method, eight representative corn silages with different FA and pCA contents were placed into nylon bags and incubated in the rumens of three matured lactating Holstein cows for 0, 6, 12, 24, 36, 48, and 72 h, respectively. Corn silage digestibility was assessed by in situ degradation methods. As a result, the effective degradability of dry matter, neutral detergent fibre, and acid detergent fibre were negatively related to the ether-linked FA and pCA, and their ratio in corn silages, suggesting that not only the content and but also the composition of phenolic acids significantly affected the degradation characteristics of corn silages. After 24 h rumen fermentation, Firmicutes, Actinobacteria, and Bacteroidota were observed as the dominant phyla in the bacterial communities attached to the corn silages. After 72 h rumen fermentation, the rumen degradation of ester-linked FA was much greater than that of ester-linked pCA. The correlation analysis noted that Erysipelotrichaceae_UCG-002, Olsenella, Ruminococcus_gauvreauii_group, Acetitomaculum, and Bifidobacterium were negatively related to the initial ether-linked FA content while Prevotella was positively related to the ether-linked FA content and the ratio of pCA to FA. In summary, the present results suggested that the content of ether-linked phenolic acids in plant cell walls exhibited a more profound effect on the pattern of microbial colonization than the fibre content.

Effect of Lipids in Yak Muscle under Different Feeding Systems on Meat Quality Based on Untargeted Lipidomics

Simple Summary

With the development of living standards, consumers are paying more and more attention to meat quality and flavor. When consumers choose meat, they directly pay attention to meat quality and flavor, so the meat quality and flavor directly decide meat price and sales volume. Better meat quality and flavor are the crucial factors that increase the additional value of meat. Because of its special nutritional value and taste, yak meat is popular with consumers. The intramuscular lipids can greatly affect the meat quality and flavor, but there is no report on the effect of lipids in yak muscle on the meat quality and flavor. In this study, we studied the characterization of lipids in yak muscle under different feeding systems and further explored the key lipids affecting yak meat quality and flavor. This study can provide new insight into the improvement of yak meat quality and flavor.

Abstract

The effect of lipids on yak meat quality and volatile flavor compounds in yak meat under graze feeding (GF) and stall feeding (SF) was explored using untargeted lipidomics based on liquid chromatography–mass spectrometry (LC-MS) in this study. First, the volatile flavor compounds in longissimus dorsi (LD) of SF and GF yaks were detected by gas chromatography–mass spectrometry (GC-MS). In total 49 and 39 volatile flavor substances were detected in the LD of GF and SF yaks, respectively. The contents of pelargonic aldehyde, 3-hydroxy-2-butanone and 1-octen-3-ol in the LD of both GF and SF yaks were the highest among all detected volatile flavor compounds, and the leading volatile flavor substances in yak LD were aldehydes, alcohols and ketones. In total, 596 lipids were simultaneously identified in the LD of SF and GF yaks, and the leading lipids in the LD of both GF and SF yaks were sphingolipids (SPs), glycerolipids (GLs) and glycerophospholipids (GPs). Seventy-five significantly different lipids (SDLs) between GF and SF yaks were identified in the LD. The high content of TG(16:1/18:1/18:1), TG(16:0/17:1/18:1) and TG(16:0/16:1/18:1), PE(18:0/22:4) and PC(18:2/18:0) can improve the a* (redness) and tenderness of yak muscle. The changes in volatile flavor compounds in yak muscle were mainly caused by TG(18:1/18:1/18:2), TG(18:0/18:1/18:1), TG(16:0/17:1/18:1), TG(16:0/16:1/18:1), PC(18:2/18:0), TG(16:1/18:1/18:1), PI(18:0/20:4), TG(16:1/16:1-/18:1) and TG(17:0/18:1/18:1). The above results provide a theoretical basis for improving yak meat quality from the perspective of intramuscular lipids.

Cysteamine-supplemented diet for cashmere goats: A potential strategy to inhibit rumen biohydrogenation and enhance plasma antioxidant capacity

Cysteamine (CS), as a feed supplement, can increase the level of growth hormone (GH) in the blood, promote animal growth. However, little attention has been paid to the effects of CS on the rumen microbiome and metabolic profile in cashmere goats. This study aimed to assess the effects of rumen microbiota, metabolites, and plasma antioxidative capacity induced by CS supplementation in cashmere goats. We selected 30 Inner Mongolia white cashmere goat ewes (aged 18 months), and randomly separate the goats into three groups (n = 10 per group) to experiment for 40 days. Oral 0 (control group, CON), 60 (low CS, LCS), or 120 mg/kg BW^-1 (high CS, HCS) coated CS hydrochloride every day. Using 16S and internal transcribed spacer (ITS) rRNA gene amplicon sequencing, we identified 12 bacterial and 3 fungal genera with significant changes among the groups, respectively. We found a significant increase in rumen NH₃-N and total volatile fatty acid (TVFA) concentrations in the LCS and HCS groups compared with the CON. With untargeted LC-MS/MS metabolomics, we screened 59 rumen differential metabolites. Among the screened metabolites, many unsaturated and saturated fatty acids increased and decreased with CS treatment, respectively. CS supplementation increased the levels of plasma total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), GH, and insulin-like growth factor-1(IGF-1). Spearman correlation analysis revealed that the abundance of U29-B03, Lactococcus, and Brochothrix were positively associated with the levels of δ2-THA, TVFA and antioxidant capacity. In conclusion, CS significantly affected rumen microbiota and fermentation parameters, and ultimately inhibited the biohydrogenation of rumen metabolites, enhanced plasma antioxidant capacity, and regulated some hormones of the GH-IGF-1 axis. This study provides an overall view into the CS application as a strategy to improve health production in cashmere goats.

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

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

Tannic acid reduced apparent protein digestibility and induced oxidative stress and inflammatory response without altering growth performance and ruminal microbiota diversity of Xiangdong black goats

The present study was performed to evaluate the impacts of tannic acid (TA) supplementation at different levels on the growth performance, physiological, oxidative and immunological metrics, and ruminal microflora of Xiangdong black goats. Twenty-four goats were randomly assigned to four dietary treatments: the control (CON, basal diet), the low-dose TA group [TAL, 0.3 % of dry matter (DM)], the mid-dose TA group (TAM, 0.6 % of DM), and the high-dose TA group (TAH, 0.9 % of DM). Results showed that the growth performance was unaffected (P > 0.05) by adding TA, whilst the 0.3 % and 0.6 % TA supplementation significantly decreased (P < 0.05) the apparent digestibility of crude protein (CP) and ruminal NH3-N concentration, and raised (P < 0.05) the level of total volatile fatty acid (TVFA) in rumen. The increments of alanine aminotransferase (ALT), triglyceride (TG), cortisol (CORT), total antioxidant capacity (T-AOC), interleukin (IL)-1β, IL-6, and serumamyloid A (SAA), and decrements of globulin (GLB), immunoglobulin G (IgG), cholinesterase (CHE), glutathione reductase (GR), creatinine (CRE), growth hormone (GH), high-density lipoprotein cholesterol (HDLC), and insulin-like growth factor 1 (IGF-1) to different extents by TA addition were observed. Although the Alpha and Beta diversity of rumen bacterial community remained unchanged by supplementing TA, the relative abundance of the predominant genus Prevotella_1 was significantly enriched (P < 0.05) in TAL. It could hence be concluded that the TA supplementation in the present trial generally decreased CP digestion and caused oxidative stress and inflammatory response without influencing growth performance and ruminal microbiota diversity. More research is needed to explore the premium dosage and mechanisms of effects for TA addition in the diet of goats.

Comparison of rumen bacterial communities between yaks (Bos grunniens) and Qaidam cattle (Bos taurus) fed a low protein diet with different energy levels

The yak (Bos grunniens), an indigenous bovine on the Qinghai-Tibetan plateau (QTP), is reported to digest low quality forage to a greater extent and to require less protein and energy for maintenance than the introduced Qaidam cattle (Bos taurus). Ruminal bacteria play a major role in feed degradation, and therefore, we hypothesized that ruminal bacteria composition would differ between yaks and cattle, and confer an advantage to yaks for poor quality diets. To test our hypothesis, we determined the ruminal bacteria profiles, rumen fermentation parameters, and enzyme activities in these bovine species consuming a low-protein diet differing in energy level. Six castrated yaks (155 ± 5.8 kg) and 6 castrated Qaidam cattle (154 ± 8.0 kg) were used in two concurrent 4 × 4 Latin square designs with 2 additional animals of each species in each period. The animals were offered a low-protein diet of 70.4 g/kg dry matter (DM) and one of four metabolizable energy levels, namely 6.62, 8.02, 9.42, and 10.80 MJ/kg. Ruminal pH, concentrations of ammonia-N and total volatile fatty acids (VFAs), the molar proportion of acetate, and the ratio of acetate to propionate (A:P) were greater (P < 0.05), whereas the molar proportion of propionate was lesser (P = 0.043) in yaks than in cattle. With increasing dietary energy level, ruminal pH, the molar proportion of acetate and the ratio of A:P decreased linearly (P < 0.05), whereas, the concentration of total VFAs, molar proportions of propionate, butyrate, iso-butyrate, and iso-valerate and concentration of ammonia-N increased linearly (P < 0.05). The relative abundance (RA) of Firmicutes increased linearly (P < 0.01), whereas, the RA of Bacteroidetes decreased linearly (P < 0.001) with increasing energy level in both bovine species. The RAs of Prevotella and Rikenellaceae_RC9_gut_group decreased linearly (P < 0.05) with increasing energy level in both yaks and cattle. The RAs of fibrolytic (e.g., Rikenellaceae_RC9_gut_group), and H₂-incorporating (e.g., Quinella) bacteria were greater (P < 0.05) in yaks than in cattle. We concluded that the two bovines differ in ruminal bacterial profiles and rumen fermentation parameters, and confer an advantage to yaks over cattle in consuming a low protein diet with differing energy level.

A comparison of average daily gain, apparent digestibilities, energy balance, rumen fermentation parameters, and serum metabolites between yaks (Bos grunniens) and Qaidam cattle (Bos taurus) consuming diets differing in energy level

Yaks (Bos grunniens), indigenous to the harsh Qinghai-Tibetan Plateau, are well adapted to the severe conditions, and graze natural pasture without supplements all year round. Qaidam cattle (Bos taurus), introduced to the Qinghai-Tibetan Plateau 1,700 years ago, are raised at a lower altitude than yaks, provided with shelter at night and offered supplements in winter. Based on their different backgrounds, we hypothesized that yaks have lower energy requirements for maintenance than cattle. To test this hypothesis, we measured average daily gain (ADG), apparent digestibilities, energy balance, rumen fermentation parameters, and serum metabolites in growing yaks and cattle offered diets differing in metabolizable energy (ME) levels (6.62, 8.02, 9.42 and 10.80 MJ/kg), but with the same crude protein concentration. Six castrated yaks (155 ± 5.8 kg) and 6 castrated Qaidam cattle (154 ± 8.0 kg), all 2.5 years old, were used in 2 concurrent 4 × 4 Latin square designs. Neutral and acid detergent fiber digestibilities were greater (P < 0.05) in yaks than in cattle, and decreased linearly (P < 0.05) with increasing dietary energy level; whereas, digestibilities of dry matter, organic matter, crude protein and ether extract increased (P < 0.05) linearly with increasing energy level. The ADG was greater (P < 0.001) in yaks than in cattle, and increased (P < 0.05) linearly with increasing energy levels. From the regressions of ADG on ME intake, the estimated ME requirement for maintenance was lower (P < 0.05) in yaks than in cattle (0.43 vs. 0.57 MJ/kg BW^0.75). The ratios of digestible energy (DE):gross energy and ME:DE were higher (P < 0.05) in yaks than in cattle, and increased (P < 0.05) linearly with increasing dietary energy level. Ruminal pH decreased (P < 0.05), whereas concentrations of total volatile fatty acids (VFAs) and ammonia increased (P < 0.01) with increasing dietary energy level, and all were greater (P < 0.05) in yaks than in cattle. Concentrations of ruminal acetate and iso-VFAs were greater (P < 0.05), whereas propionate was lower (P < 0.05) in yaks than in cattle; acetate decreased (P < 0.001), whereas butyrate and propionate increased (P < 0.001) linearly with increasing dietary energy level. Serum concentrations of β-hydroxybutyrate were lower (interaction, P < 0.001) in yaks than in cattle fed diets of 9.42 and 10.80 MJ/kg, whereas non-esterified fatty acids were greater (interaction, P < 0.01) in yaks than in cattle fed diets of 6.62 and 8.02 MJ/kg. Concentrations of serum leptin and growth hormone were greater in yaks than in cattle and serum insulin and growth hormone increased (P < 0.01) linearly with increasing dietary energy level. Our hypothesis that yaks have lower energy requirements for maintenance than cattle was supported. This lower requirement confers an advantage to yaks over Qaidam cattle in consuming low energy diets during the long winter on the Qinghai-Tibetan Plateau.

Gut microbiota and meat quality

Sustainable meat production is important to providing safe and quality protein sources for humans worldwide. Intensive artificial selection and high energy input into the diet of many commercial animals for the last decade has significantly increased the daily gain of body weight and shortened the raising period, but unexpectedly decreased the meat quality. The gastrointestinal tract of animals harbors a diverse and complex microbial community that plays a vital role in the digestion and absorption of nutrients, immune system development, pathogen exclusion, and meat quality. Fatty acid composition and oxidative stress in adipose and muscle tissue influences meat quality in livestock and poultry. Recent studies showed that nutraceuticals are receiving increased attention, which could alter the intestinal microbiota and regulate the fat deposition and immunity of hosts to improve their meat quality. Understanding the microbiota composition, the functions of key bacteria, and the host-microbiota interaction is crucial for the development of knowledge-based strategies to improve both animal meat quality and host health. This paper reviews the microorganisms that affect the meat quality of livestock and poultry. A greater understanding of microbial changes that accompany beneficial dietary changes will lead to novel strategies to improve livestock and poultry meat product quality.

Metabolomics Analysis Across Multiple Biofluids Reveals the Metabolic Responses of Lactating Holstein Dairy Cows to Fermented Soybean Meal Replacement

This experiment was performed to reveal the metabolic responses of dairy cows to the replacement of soybean meal (SBM) with fermented soybean meal (FSBM). Twenty-four lactating Chinese Holstein dairy cattle were assigned to either the SBM group [the basal total mixed ration (TMR) diet containing 5.77% SBM] or the FSBM group (the experimental TMR diet containing 5.55% FSBM), in a completely randomized design. The entire period of this trial consisted of 14 days for the adjustment and 40 days for data and sample collection, and sampling for rumen liquid, blood, milk, and urine was conducted on the 34th and 54th day, respectively. When SBM was completely replaced by FSBM, the levels of several medium-chain FA in milk (i.e., C13:0, C14:1, and C16:0) rose significantly (p < 0.05), while the concentrations of a few milk long-chain FA (i.e., C17:0, C18:0, C18:1n9c, and C20:0) declined significantly (p < 0.05). Besides, the densities of urea nitrogen and lactic acid were significantly (p < 0.05) higher, while the glucose concentration was significantly (p < 0.05) lower in the blood of the FSBM-fed cows than in the SBM-fed cows. Based on the metabolomics analysis simultaneously targeting the rumen liquid, plasma, milk, and urine, it was noticed that substituting FSBM for SBM altered the metabolic profiles of all the four biofluids. According to the identified significantly different metabolites, 3 and 2 amino acid-relevant metabolic pathways were identified as the significantly different pathways between the two treatments in the rumen fluid and urine, respectively. Furthermore, glycine, serine, and threonine metabolism, valine, leucine, and isoleucine biosynthesis, and cysteine and methionine metabolism were the three key integrated different pathways identified in this study. Results mainly implied that the FSBM replacement could enhance nitrogen utilization and possibly influence the inflammatory reactions and antioxidative functions of dairy cattle. The differential metabolites and relevant pathways discovered in this experiment could serve as biomarkers for the alterations in protein feed and nitrogen utilization efficiency of dairy cows, and further investigations are needed to elucidate the definite roles and correlations of the differential metabolites and pathways.

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

The objective of this study was to evaluate the effects of isopropyl ester of 2-hydroxy-4-(methylthio)-butyrate acid (HMBi) on ruminal and cecal fermentation, microbial composition, nutrient digestibility, plasma biochemical parameters, and growth performance in finishing beef cattle. The experiment was conducted for 120 days by a complete randomized block design. Sixty 24-month-old Angus steers (723.9 ± 11.6 kg) were randomly assigned to one of the flowing three treatments: basal diet (the concentrate: 7.6 kg/head·d-1, the rice straw: ad libitum) supplemented with 0 g/d MetaSmart® (H0), a basal diet supplemented with 15 g/d of MetaSmart® (H15), and a basal diet supplemented with 30 g/d of MetaSmart® (H30). Results showed that the average daily gain (ADG) increased linearly (P = 0.004) and the feed conversion ratio (FCR) decreased linearly (P < 0.01) with the increasing HMBi supplementation. Blood urea nitrogen (BUN) concentration significantly decreased in the H30 group (P < 0.05) compared with H0 or H15. The ruminal pH value tended to increase linearly (P = 0.086) on day 56 with the increased HMBi supplementation. The concentrations of ammonia-nitrogen (NH3-N), propionate, isobutyrate, butyrate, isovalerate, valerate, and total volatile fatty acid (VFA) were linearly decreased in the cecum (P < 0.05). The results of Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed that the abundance of most pathways with a significant difference was higher in the rumen and lower in the cecum in the H30 group compared to the H0 group, and those pathways were mainly related to the metabolism of amino acids, carbohydrates, and lipids. Correlation analysis showed that ADG was positively associated with the ratio of firmicutes/bacteroidetes both in the rumen and cecum. Additionally, the abundance of Lachnospiraceae, Saccharofermentans, Lachnospiraceae_XPB1014_group, and Ruminococcus_1 was positively correlated with ADG and negatively correlated with FCR and BUN in the rumen. In the cecum, ADG was positively correlated with the abundances of Peptostreptococcaceae, Romboutsia, Ruminococcaceae_UCG-013, and Paeniclostridium, and negatively correlated with the abundances of Bacteroidaceae and Bacteroides. Overall, these results indicated that dietary supplementation of HMBi can improve the growth performance and the feed efficiency of finishing beef cattle by potentially changing bacterial community and fermentation patterns of rumen and cecum.

Association of dietary patterns with gut microbiota in kidney stone and non-kidney stone individuals

The dietary patterns are closely associated with gut microbiota, which has been proved associated with kidney stones. To assess the association among the dietary patterns, gut microbiota, and kidney stones, patients with calcium oxalate stones and participants without kidney stones were recruited in West China Hospital and were divided into the low nephrolithiasis risk (LNR) and high nephrolithiasis risk (HNR) dietary pattern group based on the results of food frequency questionnaires. The genomic DNA of the fecal samples were extracted for 16S ribosomal RNA gene sequencing. The non-kidney stone (NS) group comprised 39 LNR and 45 HNR individuals, while the kidney stone (KS) group consisted of 19 LNR and 50 HNR individuals. The distribution of oxalate in urine (p < 0.01) but not calcium (p = 0.741) was significantly varied among the four groups. Significant difference was found in the dietary patterns of people with KS and NS controls (X² = 5.744, p = 0.017). Forty-six discriminative bacteria were found among different dietary patterns groups in KS patients and NS controls. Not only gut bacteria such as Pseudomonas, Sphingomonas, Hydrogenoanaerobacterium, Faecalitalea, etc., but also metabolic pathways associated with inflammation, lipid, and mineral metabolism were found more abundant in KS patients with HNR dietary pattern. It is noteworthy that g__Prevotellaceae_UCG_001, g__hgcI_clade, and g__Bradyrhizobium were negatively related to water intake but instead had a positive correlation with salt and meat intake. Our study revealed that gut microbiota with significantly different abundance existed in the HNR dietary patterns compared to the LNR counterparts in both calcium oxalate KS and NS individuals. The dietary patterns may affect the prevention and management of calcium oxalate stones by regulating the homeostasis of gut microbiota.

A comparative analysis of carcass and meat traits, and rumen bacteria between Chinese Mongolian sheep and Dorper × Chinese Mongolian crossbred sheep

Mutton is one of the most widely consumed meats globally. The Chinese Mongolian sheep (MS) breed is an indigenous breed of sheep characterised by high-quality meat and strong adaptability. Dorper × Chinese Mongolian crossbred sheep (DS) is an improved breed with a rapid growth rate and high mutton yield found in parts of China. The rumen microbiota is known to play a key role in shaping host nutrition and health. However, the carcass traits and meat nutritional qualities of DS and MS remain poorly defined, as does how rumen microbes affect these characteristics. The objective of this study was to compare carcass profiles, rumen bacterial communities, and meat nutritional qualities between MS and DS and clarify the associations between rumen microbiota and meat nutritional composition. We found that DS had a faster growth rate and better carcass traits than MS, including BW, carcass weight, meat weight, and loin-eye area. We further found that metabolite and rumen bacterial community composition differed between the two sheep breeds. First, compared with MS, DS had lower contents of some sweet amino acids, monounsaturated fatty acids, n-3 polyunsaturated fatty acids, and beneficial metabolites. Secondly, MS and DS had distinct rumen bacterial compositions, and these differential bacteria were related to carcass traits as well as to contents of meat amino acids, free fatty acids, and other metabolites. Taken together, our data showed that DS had better carcass characteristics but lower meat nutritional quality, parameters that were associated with differences in rumen bacterial community composition. These findings may benefit future breeding strategies aimed at improving sheep carcass performance and meat quality worldwide.

Serum Biochemical Parameters, Rumen Fermentation, and Rumen Bacterial Communities Are Partly Driven by the Breed and Sex of Cattle When Fed High-Grain Diet

Hybridization in bovines is practiced with the main aim of improving production performance, which may imply the microbial variations in the rumen from the parental breed cross to their progeny. Besides, the interactions of offspring breed with sex in terms of rumen bacteria are not clear. This study aims to evaluate the variations in rumen bacterial communities in different breeds and sexes, and the correlations among fattening performance, serum biochemical parameters, and rumen fermentation. Forty-two 19.2 ± 0.67-month-old beef cattle (390 ± 95 kg of initial body weight) comprising two genetic lines (Yiling and Angus × Yiling) and two sexes (heifers and steers) were raised under the same high-grain diet for 120 d. On the last two days, blood samples were collected from each animal via the jugular vein before morning feeding for analyzing serum biochemical parameters; rumen fluid samples were obtained via esophageal intubation 2 h after morning feeding for analyzing rumen fermentation parameters and bacterial communities. The results show that both breed and sex had a certain impact on fattening performance, serum biochemical parameters, and rumen fermentation. No differences in the diversity and structure of rumen bacterial communities were observed. Significant interactions (p < 0.05) of breed and sex were observed for Succinivibrionaceae UCG-002 and Prevotellaceae UCG-001. The relative abundances of the Rikenellaceae RC9 gut group, Prevotellaceae UCG-003, and Succinivibrio were different (p < 0.05) between breeds. Heifers had a higher (p = 0.008) relative abundance of the Rikenellaceae RC9 gut group than steers. Correlation analysis showed a significant relationship (p < 0.05) of rumen bacteria with serum biochemical parameters, rumen pH, and rumen fermentation patterns. Additionally, only two genera, Prevotellaceae UCG-003 and Prevotellaceae UCG-001, had positive correlations with feed efficiency. In conclusion, serum biochemical parameters, rumen fermentation, and rumen bacterial communities are partly driven by the breed and sex of cattle fed a high-grain diet.

Comprehensive functional core microbiome comparison in genetically obese and lean hosts under the same environment

Our study provides an exhaustive comparison of the microbiome core functionalities (captured by 3,936 microbial gene abundances) between hosts with divergent genotypes for intramuscular lipid deposition. After 10 generations of divergent selection for intramuscular fat in rabbits and 4.14 phenotypic standard deviations (SD) of selection response, we applied a combination of compositional and multivariate statistical techniques to identify 122 cecum microbial genes with differential abundances between the lines (ranging from -0.75 to +0.73 SD). This work elucidates that microbial biosynthesis lipopolysaccharides, peptidoglycans, lipoproteins, mucin components, and NADH reductases, amongst others, are influenced by the host genetic determination for lipid accretion in muscle. We also differentiated between host-genetically influenced microbial mechanisms regulating lipid deposition in body or intramuscular reservoirs, with only 28 out of 122 MGs commonly contributing to both. Importantly, the results of this study are of relevant interest for the efficient development of strategies fighting obesity.

Dietary Energy Levels Affect Carbohydrate Metabolism-Related Bacteria and Improve Meat Quality in the Longissimus Thoracis Muscle of Yak (Bos grunniens)

The effects of different dietary energy levels on the ruminal bacterial population, selected meat quality indices, and their relationship in yak longissimus thoracis (LT) muscle were assessed in this study. A total of 15 castrated yaks were randomly assigned to three groups with low- (NEg: 5.5 MJ/Kg, LE), medium- (NEg: 6.2 MJ/Kg, ME), and high- (NEg: 6.9 MJ/Kg, HE) dietary energy levels and occurred in the cold season (March to May). All yaks from each treatment group were humanely slaughtered and sampled on the day of completion of their feeding treatment. The results showed that the water content and crude fat levels of the LT muscle were markedly elevated in the HE group (P < 0.05), while the shear force was drastically reduced (P = 0.001). Methionine, aspartic acid, and glycine levels in the LT muscle were higher in the LE group compared with the ME and HE groups (P < 0.05). The glutamic acid level in the ME group was greater in comparison to the LE and HE groups (P < 0.05), while the histidine level in the ME group was higher than that in the HE group (P < 0.05). Additionally, the HE diet significantly elevated (P < 0.05) the abundance of carbohydrate metabolism-associated bacteria including Prevotella_1, Lachnospiraceae_NK4A136_group, U29_B03, Ruminiclostridium_6, and Ruminococcaceae_UCG_013 in the rumen. The results of the Spearman's rank correlation analysis showed that the abundance of uncultured_bacterium_f_vadinBE97 and uncultured_bacterium_f_Lachnospiraceae showed a significant influence on the indicator of IMF and SF. In conclusion, a high dietary energy level improved the meat quality in the LT muscle of yak mainly by increasing the relative abundance of ruminal amylolytic bacteria to provide substrates for fatty acid synthesis.

Multi-Omics Analysis Reveals a Dependent Relationship Between Rumen Bacteria and Diet of Grass- and Grain-Fed Yaks

Current information on the differences between rumen bacteria and metabolites of the grass-fed and grain-fed yaks is limited. Understanding the composition and alterations of rumen microbial metabolites is important to clarify its potential role in grass-fed and grain-fed systems. The aim of this research was to explore the influence of different production systems on the functional attributes and metabolites in the rumen microbiota of yak using genomics (Illumina MiSeq sequencing of the 16S rRNA gene) and untargeted metabolomics (UHPLC-QTOF-MS). Rumen samples were obtained from grass-fed (C), grain-fed for 3-month (G3), and grain-fed for 6-month yaks (G6). Results showed that the grain-fed yaks presented a lower rumen bacterial richness and diversity when compared to grass-fed yaks. Bacteroidota, Firmicutes, and Fibrobacterota were the main bacterial phyla. At the phylum and genus level, the grass-fed yaks significantly increased the abundance of Fibrobacterota and Fibrobacter (p < 0.05), respectively. The metabolomics analysis revealed that the metabolite profiles differed among the three groups. Compared with the grass-fed group, grain feeding significantly increased azelaic acid, hypoxanthine, uridine, L-phenylalanine, anserine, and decreased alpha-linolenic acid, adenine. Pathway enrichment analysis showed significant differences in metabolic pathways among all comparison groups, but the glycerophospholipid metabolism and alpha-linolenic acid metabolism pathway were common key metabolic pathways. This study showed that the combined analysis of microbiota and metabolites could distinguish different production systems and the fattening time of yaks, providing novel insights for us to understand the function of the rumen bacteria.

Rumen Fermentation Characteristics Require More Time to Stabilize When Diet Shifts

Simple Summary

Previous study revealed that the rumen bacterial community was in temporal dynamics, even after an adaptation of three months when diet shifted, while the dynamic rumen bacterial community is not necessarily in accord with varied rumen fermentation characteristics. Thus, no proper time for practical sampling frequency is available for conducting basal nutritional research in the long-term fattening stage of steers. This study aimed to evaluate the proper time for nutrient apparent digestibility, serum metabolic parameters, and rumen fermentation characteristics to stabilize when diet shifts. Results showed that nutrient apparent digestibility and serum metabolic parameters were stable across each collection month, while most rumen fermentation characteristics were affected by the interaction effects between collection period and dietary density. These results indicate that rumen fermentation characteristics require more time to stabilize when diet shifts, and it is recommended to collect ruminal digesta monthly to evaluate rumen fermentation characteristics.

Abstract

This study was conducted to explore the proper time required to achieve stabilization in digestibility, serum metabolism, and rumen fermentation characteristics when different diets shift, thus providing decision-making of practical sampling frequency for basal nutritional research. For these purposes, 12 Holstein steers (body weight 467 ± 34 kg, age 14 ± 0.5 months) were equally assigned to two dietary treatments: high-density (metabolizable energy (ME) = 2.53 Mcal/kg and crude protein (CP) = 119 g/kg; both ME and CP were expressed on a dry matter basis) or low-density (ME = 2.35 Mcal/kg and CP = 105 g/kg). The samples of feces, serum, and rumen contents were collected with a 30-day interval. All data involved in this study were analyzed using the repeated measures in mixed model of SPSS. Results showed that nutrient apparent digestibility and serum metabolic parameters were stable across each monthly collection, while most rumen fermentation characteristics, namely concentrations of acetate, propionate, isobutyrate, and valerate, were affected by the interaction effects between collection period and dietary density. These findings indicate that rumen fermentation characteristics require more time to stabilize when diet shifts. It is recommended to collect ruminal digesta monthly to evaluate rumen fermentation characteristics, while unnecessary to sample monthly for digestion trials and blood tests in the long-term fattening of Holstein steers. This study may provide insights into exploring the associations between detected parameters and stabilization time, and between diet type and stabilization time when diet shifts.

Fat Deposition in the Muscle of Female and Male Yak and the Correlation of Yak Meat Quality with Fat

This study aimed to explore the differences in fat deposition between female (FYs) and male yaks (MYs). Compared with MYs, the tenderness, L*, marbling, absolute content of fat, and most fatty acids (FAs) of longissimus dorsi (LD) in FYs were higher or better (p < 0.05), whereas the relative content of polyunsaturated fatty acids (PUFAs) and n-3 PUFAs were lower (p < 0.01). The absolute content of fat, C18:0, cis-C18:2, cis-C18:1, and C24:0 were positively correlated with L*_{45 min}, b*_{24 h}, tenderness, and marbling score of LD in FYs and MYs (p < 0.05), respectively. LPL, FATP2, ELOVL6, HADH, HACD, and PLINS genes play a crucial role in improving the marbling score and tenderness of yak meat. The results of gene expression and protein synthesis showed the effect of gender to FA biosynthesis, FA transport, lipolysis, and FA oxidation in the adipose tissue of yak was realized by the expressions of ME1, SCD, ACSL5, LPL, FABP1, PLIN4, and PLIN2 in peroxisome proliferators-activated receptor (PPAR) signaling. This study established a theoretical basis for the improvement of the meat quality of yak and molecular breeding.

Effects of Age and Rice Straw Inclusion Levels in the Diet of Yiling Cull Cows on Growth Performance, Meat Quality, and Antioxidant Status of Tissues

Simple Summary

Several negative attributes are associated with carcass and meat from cull cows, including lower carcass weights, inferior tenderness, etc. These undesirable characteristics are normally more distinct with increasing age. In addition, there are no recommended standards for forage levels in the diet of Chinese local cattle to produce high marbled beef. In the current study, we evaluated the effects of age and forage levels on the finishing performance of Yiling cull cows under high-energy ration conditions, and also investigated their antioxidant status related to age and diet. We found that younger age and adequate forage had better growth performance and carcass traits. Our findings highlight the importance of selecting according to age and providing adequate forage feed for Yiling cull cows. Moreover, our study also demonstrated the excellent capability of producing high marbled beef for Yiling cattle.

Abstract

The objectives of this study were to investigate the effects of age and dietary straw levels on growth performance, carcass and meat traits, as well as tissue antioxidant status of Yiling cull cows. Twenty-four Yiling cull cows were arranged in a 2 × 2 factorial design: two age classes consisting of younger cull cows (YCC; appearing with three or four pairs of permanent teeth) and older cull cows (OCC; worn out teeth); two dietary treatments consisting of lower and higher rice straw levels (LRS and HRS; providing 0.7 kg/d and 1.2 kg/d rice straw per head based on air-dry basis, respectively). Cows were fed twice a day. Straw was offered at half of the predetermined weight each meal; concentrate was separately supplied ad libitum. After 300 d of feeding, final body weight (BW), total BW gain, average daily gain and gain:feed intake were higher (p < 0.01) in the YCC group than in the OCC group. Total dry matter intake was higher (p = 0.03) in the HRS group than in the LRS group, but neutral detergent fiber apparent digestibility was negatively affected (p = 0.01) by increased straw levels. Decreased C15:0, C17:0, C20:5n3c, and saturated fatty acids (SFAs) proportion as well as increased C18:1n9c and monounsaturated fatty acids (MUFAs) proportion in meat from YCC with HRS diet were observed as compared to that in meat from YCC with LRS diet (p < 0.05). Meat from HRS group had higher (p = 0.04) C18:3n3c proportion than meat from LRS group. No significant differences (p > 0.05) were found for meat quality attributes except for cooking loss, which was higher (p = 0.02) in the HRS group than in the LRS group. Both YCC group and HRS group had higher (p < 0.05) cold carcass weight compared to OCC group and LRS group. Moreover, catalase activity of liver tissue was higher (p = 0.045) in YCC than in OCC, while superoxide dismutase activity of muscle tissue was higher (p = 0.01) in LRS than in HRS. Based on results, we concluded that younger age and feeding high-level straw can improve the finishing performance of Yiling cull cows.

Characterization of growth phenotypes and gastrointestinal tract microbiota in sheep fed with caragana

AIMS

Using high-protein caragana as an unconventional feed supplement has promising application potential in livestock feeding programmes, and verifying its function is of great importance to guide efficient dietary management of livestock.

METHODS AND RESULTS

This study investigated the resulting changes in the growth, slaughter performance, serum physiological index, physical and chemical characteristics of meat, ruminal and intestine morphology and gastrointestinal tract microbiota in sheep fed with caragana (CAR), corn straw (COR) and alfalfa (ALF) diets. The CAR group showed an increased abundance of Christensenellaceae R-7 group, Marvinbryantia, Ruminococcaceae NK4A214, Lachnospiraceae UCG-002 and Desulfuromonas in the rumen compared with ALF, and CAR group mainly enhanced starch and sucrose metabolism, fructose and mannose metabolism, photosynthesis and d-alanine metabolism in the rumen compared with ALF.

CONCLUSIONS

CAR diet positively changed the fatty acid profile of longissimus dorsi muscle and significantly altered the composition and function of the microbiota in the rumen, ileum and cecum.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study systematically demonstrated the feasibility of CAR as an alternative to ALF for animal fattening in a complete formula granulated feed and provided a fundamental basis for further research and development of CAR as an unconventional feed source for ruminants.

Fermented Soybean Meal Replacement in the Diet of Lactating Holstein Dairy Cows: Modulated Rumen Fermentation and Ruminal Microflora

This study was conducted to examine the influences of replacing soybean meal (SBM) with fermented soybean meal (FSBM) in the diet of lactating Holstein cattle on rumen fermentation and ruminal bacterial microbiome. Twenty-four lactating Chinese Holstein dairy cattle were assigned to each of the two treatments in a completely randomized design: the SBM group [the basal total mixed ration (TMR) diet containing 5.77% SBM] and the FSBM group (the experimental TMR diet containing 5.55% FSBM). This trial lasted for 54 days (14 days for adjustment and 40 days for data and sample collection), and samples of rumen liquid were collected on 34 d and 54 d, respectively. The results showed that replacing SBM with FSBM significantly increased the molar percentages of propionate (P < 0.01) and valerate (P < 0.05), but reduced the total volatile fatty acid (TVFA) concentration (P < 0.05), butyrate molar proportion (P < 0.05), and the acetate to propionate ratio (P < 0.01). The copy numbers of total bacteria (P < 0.05), Fibrobacter succinogenes (P < 0.01), Selenomonas ruminantium (P < 0.01), and Prevotella spp. (P < 0.05) in the FSBM group were greater, while the density of Prevotella ruminicola (P < 0.05) was lower than those in the SBM treatment. Additionally, Succiniclasticum ruminis and Saccharofermentans acetigenes were significantly enriched (P < 0.05) in the rumen fluid of FSBM-fed cows, despite the fact that there was no remarkable difference in the Alpha diversity indexes, structure and KEGG pathway abundances of the bacterial community across the two treatments. It could hence be concluded that the substitution of FSBM for SBM modulated rumen fermentation and rumen bacterial microbiota in lactating Holstein dairy cows. Further research is required to elucidate the relevant mechanisms of FSBM, and provide more insights into the application of FSBM in dairy cattle.