Grazing yaks often face protein deficiency due to low-quality pasture, which limits milk production. This study aimed to investigate the effects of varying protein levels in concentrate supplementation on lactational performance, immune function, and rumen microbial and metabolites in grazing lactating yaks. Thirty-six lactating Qinghai Plateau yaks (172.78 ± 11.70 kg) were assigned to four treatments for 70 d (10 d adaptation + 60 d trial): grazing only (CON) or grazing plus 1.50 kg/d concentrate containing 15.09% (CP15), 17.00% (CP17), or 18.98% CP (CP19). Concentrate supplementation significantly increased average daily gain (ADG; 0.22 vs. 0.72–0.90 kg/d; p < 0.001) and milk yield (622.18 vs. 1094.25–1385.73 g/d; p < 0.001), and milk yield showed a linear increase with higher dietary protein levels (p < 0.001). Milk protein yield (29.99 vs. 56.00–68.60 g/d; p < 0.001) and milk lactose yield (40.71 vs. 79.85–93.53 g/d; p < 0.001) were also increased. Milk composition, including fat, protein, and lactose, also improved across supplementation groups, with the greatest enhancement observed at the CP17 group (p < 0.05). Rumen pH and volatile fatty acids did not differ between treatments, while microbial protein increased with supplementation (10.88 vs. 12.72–15.00 mg/dL; p = 0.041) and showed a linear response to dietary CP level (p = 0.033). Concentrate supplementation significantly altered the rumen microbial structure (ANOSIM, p = 0.036), enriching Succinivibrionaceae_UCG-002, Fibrobacter, Ruminobacter, and Succinimonas and reducing Saccharofermentans in CP17 yaks (p < 0.05). Untargeted metabolomics further indicated a marked shift in the ruminal metabolite profile. Compared with CON, CP17 yaks exhibited higher levels of calcium propionate, 2-nitrofuran, curvulalide, and 2,5-dihydroxybenzoic acid, but lower levels of 4-pyridoxic acid, L-carnitine, bitocholic acid, and taurodehydrocholic acid. Pathway enrichment analysis identified vitamin B6 metabolism as significantly enriched. Collectively, these findings suggest that moderate protein concentrate supplementation (CP17) may enhance lactation performance by modulating rumen microbiota and metabolism in lactating yaks.

Introduction:This study aimed to characterize the tissue distribution of key trace elements in fattening yaks and to establish empty body weight (EBW)-based prediction models for the net growth requirement (NRG) of copper (Cu), manganese (Mn), zinc (Zn), iron (Fe), selenium (Se), and cobalt (Co), as well as to derive their net maintenance requirement (NMR). Methods:A comparative slaughter plus graded feeding design was used. Forty approximately 4-year-old male yaks (234.20 ± 9.86 kg) were assigned to baseline slaughter (BL), midterm slaughter (M), and terminal slaughter groups stratified by intake: ad libitum (AL), 70% of ad libitum (IR70, n = 8), and 40% of ad libitum (IR40). Tissue concentrations of target elements were determined by ICP-OES and ICP-MS. Body weight and intake data were used to develop EBW-based NRG models and derive NMR. Results:Cu and Fe were primarily distributed in viscera, Mn predominantly in bone, and Zn, Se, and Co mainly in muscle. For the 230 to 320 kg body-weight range, the EBW-based NRG prediction models were: NRGCu = 2.7194 × EBW0.1827; NRGMn = 0.1302 × EBW0.3880; NRGZn = 17.1124 × EBW0.1092; NRGFe = 7.1755 × EBW0.5054; NRGSe = 0.0034 × EBW0.8043; and NRGCo = 0.0077 × EBW0.0974. The corresponding NRG values (mg/kg EBW) were Cu 7.08-7.58, Mn 0.99-1.15, Zn 30.31-31.57, Fe 101.21-122.08, Se 0.23-0.31, and Co 0.01. The NMR values (mg/d) were Cu 0.87, Mn 0.45, Zn 14.48, Fe 19.89, Se 0.11, and Co 0.01. Discussion:EBW-based models provide robust NRG and NMR parameters for Cu, Mn, Zn, Fe, Se, and Co in late-fattening yaks. These yak-specific values offer practical targets for precise mineral supplementation and ration formulation in yak production systems across Asia, helping prevent deficiency or excess and improve production efficiency.

After weaning, calves undergo a critical transition from liquid milk to solid feed. During this period, the digestive system is not yet fully mature and the rumen microbial community is still being established, which can easily lead to stress responses, growth retardation and other problems. Nutritional management and microecological regulation at this stage are crucial for rumen development, maturation of immune function and subsequent growth performance. Probiotics are regarded as an important nutritional and microecological strategy to alleviate weaning stress and promote the maturation of rumen and intestinal function. Therefore, in the present study, sixteen 8-month-old weaned yaks were randomly allocated to two groups (n = 8 per group): a composite probiotic group (CP) and a control group (CK). In the CP group, a composite probiotic preparation (Bacillus subtilis, Lactobacillus acidophilus and Bacillus licheniformis; viable count ≥ 1 × 1010 CFU/g) was supplemented at 0.2

This study investigated the effects of starter feed supplementation on growth performance, immune-related parameters, intestinal microbiota, and metabolite profiles in preweaning yak calves. Twenty healthy 30-day-old male yak calves with similar body weight were randomly assigned to either a control group (A), receiving milk replacer and alfalfa hay, or a starter-supplemented group (AS), receiving milk replacer, alfalfa hay, and a concentrate-based starter feed. Growth traits, nutrient digestibility, serum immune indices, intestinal microbial communities, and metabolomic characteristics were evaluated. Compared with the A group, calves in the AS group exhibited greater total dry matter intake, final body weight, heart girth, cannon circumference, and apparent digestibility of calcium and phosphorus (p < 0.05). Average daily gain tended to increase but did not differ significantly between treatments (p > 0.05). Starter supplementation also increased serum concentrations of IgA, IL-6, TNF-α, M-CSF, and IFN-γ (p < 0.05). In contrast, jejunal TNF-α concentration was lower in the AS group than in the A group (p < 0.05). Microbial analysis demonstrated that starter supplementation modified intestinal bacterial community composition. In the jejunum, the relative abundances of Family_XIII_AD3011_group and Acetitomaculum were increased, whereas Bacteroidota and Bacteroides were enriched in the colon. Untargeted metabolomic analysis further revealed distinct metabolic profiles between groups, with differential metabolites mainly associated with amino acid metabolism, vitamin metabolism, and energy-related pathways. Overall, starter feed supplementation was associated with changes in nutrient utilization, immune-related indicators, intestinal microbial composition, and metabolic characteristics. These findings suggest that starter supplementation may facilitate dietary adaptation and support gastrointestinal function in preweaning yak calves.

Hypobaric hypoxia poses a serious threat to growth and development and can induce pronounced inflammatory responses. These effects are closely associated with the gut microbiota. However, the underlying mechanisms, particularly the role of gut microbiota in regulating hepatic metabolism under chronic hypoxic conditions, remain poorly understood. In this study, SD rats were used as recipients and assigned to three groups: a hypobaric hypoxia group (H), an antibiotic-treated group (HA), and an antibiotic-treated group receiving fecal microbiota transplantation from plateau zokors (HAM). All rats were maintained in a hypobaric hypoxia chamber simulating an altitude of 6000 m for 30 days. Subsequently, growth performance, routine hematological parameters, and multi-omics profiles were evaluated. Compared with the H group, both the HAM and HA groups showed significantly increased average daily gain (ADG) (p < 0.05), while the ADG/ADFI ratio was significantly higher in the HAM group than in the H group (p < 0.05). Monocyte count (Mon#) and monocyte percentage (Mon%) were significantly higher in the HA group than in both the H and HAM groups (p < 0.05). Microbiota analysis revealed significant enrichment of Lachnospiraceae_NK4A136_group in the HAM group, whereas Desulfovibrio was significantly enriched in the HA group (p < 0.05). Fecal metabolomics showed that ursodeoxycholic acid (UDCA) was significantly increased in the HAM group (p < 0.05). In the liver metabolome, the anti-inflammatory lipid FAHFA 18:1/20:3 was significantly elevated in the HAM group, whereas pro-inflammatory factors, including uric acid and leukotriene D4, were significantly reduced (p < 0.05). Correlation analysis further demonstrated that the abundance of Lachnospiraceae was positively correlated with FAHFA 18:1/20:3 and negatively correlated with uric acid and creatinine (p < 0.05). Collectively, these findings indicate that the gut microbiota can modulate gut-liver metabolism, alleviate inflammatory responses, and enhance the adaptation of rats to hypoxic environments. This study provides valuable insights into potential strategies for promoting sustainable animal health and adaptation under hypoxic conditions.

The experiment aimed to investigate the feasibility and accuracy of an automatic 3D point cloud-based measurement method for obtaining body size parameters of yaks under natural passage conditions, and to provide a non-contact data acquisition method for growth monitoring, group feeding, body weight estimation, and feed supply adjustment in plateau yak farms. Thirty healthy Mado yaks were selected, and a low-constraint acquisition passage equipped with top and bilateral depth cameras was constructed to synchronously collect 3D point cloud data during natural walking. To address flying point noise and blurred body contours caused by the thick coat of yaks, dual-scale voxel filtering and adaptive statistical outlier removal were used for point cloud preprocessing. To solve the problem of unclear key anatomical landmarks such as the withers and rump, anatomical prior constraints, weighted curvature analysis, and local quadratic surface RANSAC were combined for key point localization. To reduce the influence of walking posture changes on girth measurement, dynamic section projection and weighted ellipse fitting were proposed to automatically estimate chest girth, abdominal girth, and waist girth. Compared with manual measurements of six yaks, the mean absolute percentage errors of body height, body slant length, rump height, chest girth, abdominal girth, and waist girth were 2.19%, 6.30%, 4.18%, 4.88%, 3.36%, and 5.79%, respectively. The small-scale manual comparison test preliminarily showed that this method could automatically measure the main body size parameters of yaks under low-constraint natural passage conditions, providing basic data for group feeding, body condition assessment, and feed supply adjustment.

Background This study investigated the effects of rumen fluid-fermented roughage on the rumen microbiota and the growth performance of yaks. Twenty yaks with similar body conditions were randomly divided into two groups (n = 10 per group), and fed either a basal diet (CON) or 10% rumen fluid-fermented roughage. The experiment lasted 75 d, including a 15 d adaptation period and a 60 d treatment period. At the end of the experiment, serum and rumen fluid samples were collected and analyzed. The microbial communities and metabolomic profiles in the rumen fluid were analyzed using 16S rRNA sequencing and non-targeted metabolomics, respectively. Results Results showed a significant rise in serum alanine aminotransferase levels, while serum total protein and cholesterol concentrations decreased notably. Furthermore, rumen fluid ammonia nitrogen and acetic acid concentrations decreased significantly, while concentrations of yak rumen microbial protein, isovaleric acid, and valeric acid increased significantly. Rumen microbial diversity was enhanced, with decreased abundances of Firmicutes , Cyanobacteria , Klebsiella , Spirochaetota , fungi, and Pseudomonas , alongside increased populations of Anaeroplasma , Spirochaetota , Fibrobacter , and Succiniclasticum . Furthermore, the activity of the bile secretion pathway and concentrations of its metabolites—including deoxycholic acid, chenodeoxycholic acid, glycocholic acid, and glycodeoxycholic acid—were significantly elevated. Conclusions These findings indicate that rumen fluid-fermented coarse feed not only promotes yak growth but also enhances health by modulating metabolites associated with cellular proliferation, such as dUMP, adenylosuccinate, and DL-α-tocopherol. Consequently, rumen fluid-fermented coarse feed represents a beneficial dietary supplement for improving growth performance and overall health in yaks.

This study examined the effects of feeding level on energy and nitrogen metabolism and gas exchange in adult yaks, and estimated their maintenance energy and protein requirements. After a 15-day adaptation period, thirty-two healthy 4-year-old male yaks with similar body weight (235.96 +/- 12.46 kg) were randomly assigned to four groups (n = 8 per group): a baseline slaughter group (BL), an ad libitum group (AL), a 70% intake-level group (IR70), and a 40% intake-level group (IR40). The BL group was slaughtered on day 0 of the main trial to obtain baseline data. During the main trial, the AL, IR70, and IR40 groups were fed at 100%, 70%, and 40% of ad libitum dry matter intake (DMI), respectively. A digestion and metabolism assessment was conducted during the final 5 d of the main trial, and a respiratory gas exchange assessment during the final 3 d; animals in AL, IR70, and IR40 were slaughtered at the end of day 90. The results showed that increasing feeding level significantly increased final body weight, shrunk body weight, empty body weight, average daily gain, and total muscle weight. Values in the AL and IR70 groups were higher than those in the IR40 group (P < 0.05). Total fat weight, total gross energy intake, metabolizable energy intake, digestible energy, DMI, carbon dioxide production, and methane emission all increased gradually with increasing feeding level (AL > IR70 > IR40; P < 0.05). The methane conversion factor averaged 5.20% (range 4.89-5.51%). With increasing restriction, total gross energy digestibility increased (IR40 > IR70 > AL; P < 0.05), and total gross energy metabolizability was higher in IR40 than in AL (P < 0.05). Within the 230-320 kg body-weight range, the net energy requirement for maintenance was 291.07kJ center dot kg(-1) W0 center dot 75 center dot d(-1) , the metabolizable energy requirement for maintenance was 434.18 kJ center dot kg(-1) W0 center dot 75 center dot d(-1) , the efficiency of metabolizable energy utilization for maintenance was 0.67, and the net protein requirement for maintenance was 2.76 g center dot kg(-1) W0 center dot 75 center dot d(-1) . These findings provide reference data for precision feeding and methane energy loss assessment in yaks under plateau conditions.

The yak is an iconic ruminant of the Qinghai-Tibet Plateau, yet segment-specific variation in its intestinal microbial functional potential and bile acid profiles under different feeding systems remains insufficiently characterized. Six healthy adult male yaks with similar body weights (320 ± 30 kg) were assigned to grazing (G) or stall-feeding (S) systems, with three animals per group, for a 90-day trial comprising a 10-day adaptation period and an 80-day formal experimental period. The individual yak was considered the experimental unit, and intestinal segments sampled from the same animal were treated as repeated observations. Liver tissue and digesta from the duodenum, ileum, cecum, and colon were analyzed using targeted bile acid metabolomics and shotgun metagenomics. Principal coordinate analysis based on Bray-Curtis dissimilarities showed segment-associated clustering of microbial communities, with PCo1 and PCo2 explaining 65.5% and 18.9% of the total variation, respectively. ANOSIM identified a significant intestinal-segment effect on microbial community composition (R = 0.2208, BH-FDR = 0.0144), whereas the overall feeding-system effect was not significant (R = 0.3747, BH-FDR = 0.1200). No statistically significant feeding-system differences were detected in Shannon, Simpson, Chao1, or ACE indices within individual intestinal segments (BH-FDR ≥ 0.800), and PERMDISP detected no significant differences in within-group dispersion (BH-FDR ≥ 0.1682). Bacillota and Bacteroidota were the dominant phyla. Descriptive functional profiling showed higher mean ileal abundances of GH2 (0.0035 vs. 0.0026), GH3 (0.0029 vs. 0.0024), and GH43 (0.0021 vs. 0.0013) in grazing yaks, whereas the starch-associated GH13 family showed its highest mean abundance in the colon of stall-fed yaks. These metagenomic patterns represent predicted genomic functional potential rather than gene expression, enzyme activity, or metabolic flux. Cecal total bile acid concentration showed a nominal between-group difference (unadjusted Welch’s p = 0.0109), but this difference did not remain significant after correction across the five anatomical sites (BH-FDR = 0.0545). In the colon, stall-fed yaks had a lower conjugated-to-unconjugated bile acid ratio and a higher secondary-to-primary bile acid ratio than grazing yaks (BH-FDR < 0.05). Feeding-system-associated descriptive patterns were observed in predicted microbial functional profiles, whereas statistically supported between-group differences were limited mainly to selected colonic bile acid ratios. Given the limited animal-level replication, these findings should be considered exploratory.

OBJECTIVE:The study investigated how varying protein levels in low-energy diets affected the microbiota, meat quality, and metabolomics of the longissimus dorsi muscle in yaks. The aim was to determine the optimal yak diet for growth and meat quality under low-energy conditions. METHODS:Twenty-four adult male yaks were divided into two groups of 12: the low-energy, medium-protein (LM) group and the low-energy, high-protein (LH) group. The study analysed rumen microbiota and longissimus dorsi muscle metabolites using 16S rDNA gene sequencing and untargeted metabolomic analysis. The effects of the diets on growth performance, meat quality and microbial community composition were evaluated. RESULTS:There were no significant differences in growth performance between the LH and LM groups. However, the LH group had a lower pH value at 45 minutes after death and was better for meat colour and tenderness. There were no significant differences in average daily gain, cooking loss, hardness, elasticity, adhesiveness, chewiness, or the pH at 24 hours after death in the longissimus dorsi muscle between the groups. Microbial community analysis revealed no significant differences in diversity indices; however, it did indicate distinct bacterial composition between the groups. Predictions of function suggested the LM group had a higher level of enrichment and a greater number of unique operational taxonomic units compared to the LH group. Metabolomic analysis revealed differences in muscle metabolites and metabolic pathways, with the LM group having a higher capacity for fatty acid and selenocompound metabolism, implying greater energy utilisation efficiency and antioxidant function. CONCLUSION:The study suggests that a diet with 14% protein, as part of low-energy diets, is best for increasing yak fattening. This is because it improves energy use and antioxidant function, without affecting growth.

IntroductionThe nutritional level of the diet plays a crucial role in maintaining the balance of the yak rumen microbiota. To explore the relationship between dietary nutritional levels, the rumen microbiota, and muscle metabolites, we examined the characteristics of the yak rumen microbiota and muscle metabolome under different dietary nutritional levels.MethodsRandomly divide 24 yaks with similar body weights, [235.96 ± 12.46 kg], into three groups. These groups were subjected to three nutritional feeding levels: ad libitum feeding (AL), 70% of ad libitum intake (IR70), and 40% of ad libitum intake (IR40). When the yaks in the AL group gained 70 kg in body weight, they were slaughtered.ResultsThe results indicated that the ad libitum feeding group (AL) demonstrated superior edible meat quality in terms of Chroma L*, Chroma a*, and shear force, compared to the 70% intake group (IR70) and the 40% intake group (IR40). At the phylum level, the abundance of Patescibacteria was notably greater in the IR40 group compared to both the AL group and the IR70 group. At the genus level, the relative abundance of Succinimonas was higher in the AL group than in both the IR70 and IR40 groups. Untargeted metabolomics analysis revealed that the levels of metabolites such as 5-Methylcytosine, Cytosine, and Thymine were upregulated in the longissimus dorsi muscle of the AL group, which contributed to the enhancement of meat flavor. Furthermore, Spearman's correlation analysis revealed a notable relationship between the rumen microbiota and both meat quality and metabolite levels. pH45min is positively correlated with trans-Cinnamic acid. Methanobrevibacter exhibited a positive correlation with the concentration of 4-(Diethylamino)benzaldehyde, while Candidatus_Saccharimonas showed a positive correlation with the concentration of phenylacetylglycine.DiscussionThis study provides scientific evidence for understanding the impact of different nutritional feeding conditions on yak meat quality, rumen microbiota, and related muscle metabolomic pathways. It also reveals the potential impact of these factors on meat flavor. These findings offer important reference information for optimizing yak husbandry management, improving the formation of beef flavor compounds, and understanding their regulatory mechanisms.

This experiment aimed to explore the effects of nutritional intervention on the composition and content of routine nutrients, amino acids, and fatty acids in the colostrum of lactating yaks. Twenty yaks in the late pregnancy stage with the same parity and similar body conditions were selected as and randomly divided into two groups (n = 10). The control group were allowed to graze freely from 8:00 to 18:00, and treatment (TR) group, yaks were supplemented with 3.0 kg of oat hay and 1.0 kg of concentrate feed per day. The experimental period lasted for 28 days, including 21 days before parturition and 7 days after parturition. From 1u20137 days after parturition, colostrum was collected daily to determine the routine nutrients, amino acids, and fatty acids profile of colostrum. The results showed that the colostrum protein, non-fat colostrum solids, and lactose contents were extremely significantly higher (P u0026lt; 0.01) in the TR group. The lysine content in the TR group increased significantly (P u0026lt; 0.05), additionally the prolongation of lactation time, the ratio of essential to non-essential amino acids increased significantly (P u0026lt; 0.05) higher in colostrum of lactating yaks. The C18:1 n-9t, C18:3 n-3, and polyunsaturated fatty acids (PUFA) contents extremely significantly increased (P u0026lt; 0.01) with supplementation in the TR group. Compared to day 1, the contents of C6:0 and C10:0 increased extremely significantly on day 7 (P u0026lt; 0.01). In contrast, the contents of C14:1, C18:2 n-6c, and PUFA decreased significantly (P u0026lt; 0.05), and the content of C16:1 decreased extremely significantly (P u0026lt; 0.01). Colostrum protein content was significantly positively correlated with methionine content (P u0026lt; 0.05), and lactose content was significantly negatively correlated (P u0026lt; 0.05) with C4:0 and C18:0 contents. The non-fat colostrum solids content was extremely significantly negatively correlated with C4:0 and C18:0 contents (P u0026lt; 0.01), while colostrum fat content was significantly positively correlated (P u0026lt; 0.05) with C18:0 content, additionally the colostrum fat content was extremely significantly positively correlated (P u0026lt; 0.01) with histidine content. Perinatal supplementation with oat hay and concentrate significantly improved yak colostrum quality by increasing protein, non-fat colostrum solids, lactose, lysine, and beneficial fatty acids (C18:1 n-9t, C18:3 n-3, PUFA) contents. Key correlations (protein-methionine, fat-C18:0/histidine) suggest nutrient interventions regulate fatty acid and amino acid metabolism to enhance colostrum synthesis. This study demonstrates the importance of targeted perinatal nutrition for optimizing neonatal yak health and livestock productivity in high-altitude pastoral systems, and offering a sustainable strategy to address nutritional challenges in grazing-based management.

The study aimed to investigate the impact of the feed concentrate to roughage ratio transition on the microbial distribution and functions in yak feces. Twenty-four healthy male yaks at three years old with similar weight were fed a diet of 30∶70 for 1~60 days (Group C30 ), and converted to a diet of 70∶30 for 61~120 days (Group C70 ). The pre-test period was 15 days, and the formal test period was 120 days. Fecal samples were collected using the rectal fecal sampling method from six randomly selected yaks on day 60 and day 120 after feeding for 3~4 hours. The samples were sequenced using 16S rRNA gene sequencing technology to compare and analyze the fecal microbial community, and functional predictions were made using PICRUSt2. The results showed no significant differences in lineage diversity and diversity indices between the two groups (P>0.05). PCoA analysis revealed a significant difference in the composition of fecal microbial communities between the two groups (P<0.05). At the phylum level, the relative abundance of Actinobacteriota in Group C70 was significantly higher than in Group C30 (P<0.05). At the genus level, the relative abundance of unidentified taxa in Group C70 was extremely higher than in Group C30 (P<0.01), and the relative abundance of uncultured bacterium and Roseburia was significantly higher in Group C70 than in Group C30 (P<0.05), while the relative abundance of Lachnospiraceae_NK3A20_group, Olsenella, and Paeniclostridium was significantly higher in Group C30 than in Group C70 (P<0.05). At the KEGG level 2, the expression levels of functions such as energy metabolism, terpenoid and polyketide metabolism, interspecies biodegradation, and metabolism were lower in Group C70 compared to Group C30. The study indicates that the transition of feed concentrate to roughage ratio affects the richness and diversity of fecal microbial communities, significantly influencing the composition of microbial communities in yak feces. Transitioning from a low concentrate to roughage ratio to a high ratio reduces the relative abundance of fiber-degrading bacteria in the hindgut, promotes the proliferation of acid-producing bacteria, increases the proportion of Paeniclostridium.

IntroductionThe dietary protein level plays a crucial role in maintaining the equilibrium of rumen microbiota in yaks. To explore the association between dietary protein levels, rumen microbiota, and muscle metabolites, we examined the rumen microbiome and muscle metabolome characteristics in yaks subjected to varying dietary protein levels.MethodsIn this study, 36 yaks were randomly assigned to three groups (n = 12 per group): low dietary protein group (LP, 12% protein concentration), medium dietary protein group (MP, 14% protein concentration), and high dietary protein group (HP, 16% protein concentration).Results16S rDNA sequencing revealed that the HP group exhibited the highest Chao1 and Observed_species indices, while the LP group demonstrated the lowest. Shannon and Simpson indices were significantly elevated in the MP group relative to the LP group (P < 0.05). At the genus level, the relative abundance of Christensenellaceae_R-7_group in the HP group was notably greater than that in the LP and MP groups (P < 0.05). Conversely, the relative abundance of Rikenellaceae_RC9_gut_group displayed an increasing tendency with escalating feed protein levels. Muscle metabolism analysis revealed that the content of the metabolite Uric acid was significantly higher in the LP group compared to the MP group (P < 0.05). The content of the metabolite L-(+)-Arabinose was significantly increased in the MP group compared to the HP group (P < 0.05), while the content of D-(-)-Glutamine and L-arginine was significantly reduced in the LP group (P < 0.05). The levels of metabolites 13-HPODE, Decanoylcarnitine, Lauric acid, L-(+)-Arabinose, and Uric acid were significantly elevated in the LP group relative to the HP group (P < 0.05). Furthermore, our observations disclosed correlations between rumen microbes and muscle metabolites. The relative abundance of NK4A214_group was negatively correlated with Orlistat concentration; the relative abundance of Christensenellaceae_R-7_group was positively correlated with D-(-)-Glutamine and L-arginine concentrations.DiscussionOur findings offer a foundation for comprehending the rumen microbiome of yaks subjected to different dietary protein levels and the intimately associated metabolic pathways of the yak muscle metabolome. Elucidating the rumen microbiome and muscle metabolome of yaks may facilitate the determination of dietary protein levels.

本试验旨在研究不同精粗比对牦牛粪便菌群结构的影响.选取24头体重相近、健康的3岁公牦牛,随机分成2组,分别饲喂低精粗比饲粮(35∶65,C35组)和高精粗比饲粮(65∶35,C65组).预试期为15 d,试验期为90 d.运用16S rDNA高通量测序技术对粪便菌群结构变化进行分析.结果表明:1)2组共检测出1702个操作分类单元(OTU),其中两组共有的OTU数目为1273个,占总OTU数目的74.79％;C35组的物种数、Chao1指数与Shannon指数显著高于C65组(P<0.05).2)在门水平下,C35组牦牛粪便中髌细菌门和蓝藻菌门极显著高于C65组(P<0.01),放线菌门显著高于C65组(P<0.05);C65组牦牛粪便中拟杆菌门、螺旋体门显著高于C35组(P<0.05).3)C35组牦牛粪便中瘤胃球菌属极显著高于C65组(P<0.01),毛螺菌科_NK3A20显著高于C65组(P<0.05);C65组牦牛粪便中未培养的属极显著高于C35组(P<0.01),未培养细菌属、拟普雷沃氏菌属、密螺旋体属显著高于C35组(P<0.05).4)利用PICRUSt预测粪便微生物的代谢途径和功能,在KEGG2水平,C65组复制和修复、翻译、核苷酸代谢、其他次生代谢物的合成、细胞生长和死亡的基因家族相对丰度极显著高于C35组(P<0.01).综上,饲粮精粗比显著影响了牦牛粪便菌群的多样性与丰富度.且饲喂高精粗比饲粮(65:35)促进了牦牛粪便中非纤维降解菌的增殖,提高了拟普雷沃氏菌属的丰度值,但抑制了毛螺菌科的生长,研究结果丰富了对牦牛粪便菌群结构的认识.

本试验旨在研究饲粮不同蛋白质水平对舍饲牦牛生长性能、瘤胃发酵参数及菌群结构和功能的影响.试验选取36头体重为(200±20)kg、健康状况良好的成年公牦牛,随机分为3组,每组3个重复,每个重复4头牦牛.在饲粮代谢能(10.6 MJ/kg)一致的前提下,分别配制低蛋白质水平饲粮(12％,LP组)、中蛋白质水平饲粮(14％,MP组)、高蛋白质水平饲粮(16％,HP组).预试期15 d,正试期90 d.结果表明:1)MP组牦牛平均 日增重显著高于LP组和HP组(P＜0.05);LP组干物质采食量显著高于HP组(P＜0.05);LP组料重比显著高于MP组和HP组(P＜0.05).2)LP组微生物蛋白浓度显著低于HP组(P＜0.05);MP组丙酸浓度显著低于HP组(P＜0.05).3)3个试验组共鉴定出11 989种瘤胃液特征序列,共有1 165种瘤胃液特征序列(ASVs),占总数的9.72％,LP组、MP组和HP组的ASVs数量分别为3 437、4 184和3 903种,其独占种数分别为1 351、1 978和1 790种;LP组Shannon指数显著低于MP组和HP组(P＜0.05);LP组Simpson指数显著低于MP组(P＜0.05).4)在门水平上,MP组螺旋体门(Spiro-chaetota)相对丰度显著高于其他2组(P＜0.05);LP组广古菌门(Euryarchaeota)相对丰度显著低于其他2组(P＜0.05);在属水平上,LP组与MP组克里斯藤森菌科_R-7(Christensenellaceae_R-7)相对丰度均显著低于HP组(P＜0.05).5)利用PICRUSt2来预测瘤胃细菌的代谢途径及功能,在KEGG2水平上,氨基酸代谢、能量代谢、辅助因子和维生素的代谢在HP组显著富集(P＜0.05);碳水化合物代谢、脂质代谢在LP组显著富集(P＜0.05);LP组其他氨基酸代谢显著低于HP组(P＜0.05).综上所述,饲喂相同代谢能不同蛋白质水平饲粮对舍饲牦牛生长性能、瘤胃发酵类型、瘤胃细菌丰富度、瘤胃菌群结构和瘤胃细菌代谢功能途径均会产生影响.饲喂14％蛋白质水平饲粮的舍饲牦牛具有较高的平均日增重、较低的料重比与较高的养殖效益,瘤胃微生物蛋白浓度较高,瘤胃菌群丰富度和多样性较高,且具有相对较高的蛋白质消化代谢及能量转化利用能力.综合考虑,当饲粮代谢能为10.6 MJ/kg时,推荐舍饲牦牛饲粮蛋白质水平为 14％.

Fermented feed is rich in probiotics, organic acids and other components, which is easy to digest and absorb by animals, and has high nutritional value. The palatability of the fermented feed is good, with a low content of anti-nutrient factors. It can improve the digestibility and utilization rate of animal feed, stabilize the structure of animal intestinal microorganisms, and enhance the immunity of the body. The paper mainly elaborates the concept and action mechanism of the fermented feed, reviews the effects of the fermented feed on the intestinal health, feed utilization rate, feeding cost and animal production performance, analyzes the problems existing in the application of the fermented feed in animal production, and prospects the future application of the fermented feed, in order to provide reference for the efficient utilization of fermented feed in animal breeding.

Under the background of domestic feed end prohibition, it has become a hot research direction to search for high-quality feeds that can improve animal performance and immunity and reduce feed to gain ratio. Compared with conventional feed, fermented feed can improve the performance and immunity of animals, reduce feed to gain ratio, and regulate the balance of rumen flora. In the paper, the types, mechanism, nutritional value of fermented feed and its application in ruminant breeding are reviewed, in order to provide reference for the development of fermented feed and its application in yak breeding in Qinghai-Tibet region.

目的 探究粪菌移植对低海拔动物的高原适应性的影响.方法 将30只雄性SD大鼠随机分为3组,每组10只,即模拟高原环境组(H组)、模拟高原环境+抗生素预处理组(HA组)及模拟高原环境+抗生素预处理+高原鼢鼠粪菌组(HAM组).粪菌移植结束,持续饲养3周后,将所有组大鼠转移至模拟海拔6 000 m环境低压氧舱饲养30 d.测定粪菌移植对SD大鼠体质量、血常规指标及肠道菌群的影响.结果 HAM组、HA组和H组3组大鼠间平均日采食量比较差异无统计学意义(F=2.928,P＞0.05),H组大鼠平均日增重显著低于HA组、HAM组(F=3.951,P＜0.05);HA组大鼠中性粒细胞数量较H组、HAM组分别上升7.85％和51.27％,HA组大鼠单核细胞数、单核细胞百分比显著高于H组、HAM组(F=5.131、4.325,均P＜0.05);HAM组、HA组和H组大鼠肠道菌群的优势菌门以拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)为主.HAM组大鼠肠道菌群的毛螺菌科(Lachnospiraceae)的相对丰度显著高于HA组、H 组(F=8.545,P＜0.01),毛螺菌科 NK4A136 属(Lachnospiraceae_NK4A136_group)的相对丰度显著高于HA组、H组(F=3.926,P＜0.05).LEfSe分析显示,HAM组大鼠肠道菌群中对群落结构影响较大的物种有乳螺目(Lachnospirales)、毛螺菌科.结论 通过粪菌移植能够提高进入高原环境的低海拔动物的高原适应性.