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Simple Summary: The yak is the primary income source for millions of people in remote areas of western China and other parts of Asia, providing a basic subsistence commodity for herdsmen. Yaks depend on natural grazing, but the grass trace elements may be insufficient for the yaks' requirements. Our prior research demonstrated that the levels and sources of copper, manganese, and iodine could influence in vitro rumen fermentation for yaks. The aim of this study was to optimize yak feeding standards by examining the impact of diets containing different levels of copper, manganese, and iodine on yak growth. Results showed that diets containing 15.00 mg/kg of copper, 50.00 mg/kg of manganese, and 0.50 mg/kg of iodine had the most positive effect on the growth of growing yaks. Our study will facilitate yak diet formulation design and promote yaks' industry development. Copper, manganese, and iodine are part of a yak's required trace elements. However, knowledge about their dietary requirements is scarce. Therefore, an experiment was conducted to evaluate rumen fermentation, blood parameters, and growth performance and screen out the optimum levels of trace elements in yaks' diet. Here, 18 three-year-old castrated yaks were randomly divided into four groups, which fed with diets containing basal (CON: 4.40, 33.82, and 0 mg/kg) and low-level (LL: 10.00, 40.00, and 0.30 mg/kg), middle-level (ML: 15.00, 50.00, and 0.50 mg/kg), and high-level (HL: 20.00, 60.00, and 0.70 mg/kg) copper, manganese, and iodine for 30 days. With the increase in trace elements, yaks' daily weight gain (DWG), rumen pH, ammonia nitrogen, microbial protein (MCP), and volatile fatty acids levels and serum triglycerides and urea nitrogen levels showed firstly increasing and then decreasing trends and reached the highest values in ML, and serum ceruloplasmin and total superoxide dismutase (T-SOD) activities showed continuously increasing trends. Yaks' DWG, rumen MCP, butyrate, and valerate levels and serum triglycerides, urea nitrogen, ceruloplasmin, and T-SOD levels in ML were significantly higher than CON. Therefore, the recommended levels of copper, manganese, and iodine in growing yaks' diet are 15.00, 50.00, and 0.50 mg/kg (ML), respectively. [ABSTRACT FROM AUTHOR]

Simple Summary: The yak is a unique species found on the Tibetan plateau, adapted to the high-altitude, low-oxygen environment, providing meat, milk, and other resources to local herders, and is an indispensable means of production and livelihood for herders on the Tibetan plateau and a major source of economic income for Tibetan herders. A change in diet leads to indigestion and anorexia during the acclimatization phase, which can lead to changes in dry matter intake and daily weight gain in the early part of the housing period. The rumen microbiota will be reshaped. Ruminal fluid transplantation can reshape the rumen microbiota of the recipient animals, which can rapidly restore the microbiota to a new homeostasis. Considering the special characteristics of yaks on the Tibetan plateau, the dynamic seasonal changes in pasture and the trend of changing from natural grazing to confinement farming, this study focused on the changes in rumen flora due to dietary changes and the improvement of rumen fluid transplantation on the remodeling of yak flora and production performance when yak breeding patterns were changed. A relatively stable microbial ecological balance system in the rumen plays an important role in rumen environment stability and ruminant health maintenance. No studies have reported how rumen fluid transplantation (RFT) affects the composition of rumen microorganisms and yak growth performance. In this experiment, we transplanted fresh rumen fluid adapted to house-feeding yaks to yaks transitioned from natural pastures to house-feeding periods to investigate the effects of rumen fluid transplantation on rumen microbial community regulation and production performance. Twenty yaks were randomly divided into the control group (CON; n = 10) and the rumen fluid transplantation group (RT; n = 10). Ten yaks that had been adapted to stall fattening feed in one month were selected as the rumen fluid donor group to provide fresh rumen fluid. Ruminal fluid transplantation trials were conducted on the 1st, 3rd, and 5th. Overall, 1 L of ruminal fluid was transplanted to each yak in the RT and CON group. The formal trial then began with both groups fed the same diet. After this, growth performance was measured, rumen fluid was collected, and rumen microbial composition was compared using 16s rRNA sequencing data. The results showed that rumen fluid transplantation had no significant effect on yak total weight gain or daily weight gain (p > 0.05), and feed efficiency was higher in the RT group than in the CON group at 3 months (treatment × month: p < 0.01). Ruminal fluid transplantation significantly affected rumen alpha diversity (p < 0.05). Up to day 60, the RT group had significantly higher OTU numbers, Shannon diversity, and Simpson homogeneity than the CON group. Principal coordinate analysis showed that the rumen microbiota differed significantly on days 4 and 7 (p < 0.05). Bacteroidota, Firmicutes, Proteobacteria, and Spirochaetes were the most abundant phyla in the rumen. The relative abundances of Bacteroidota, Proteobacteria, and Spirochaetes were lower in the RT group than in the CON group, with a decrease observed in Bacteroidota in the RT group on days 7 and 28 after rumen fluid transplantation (p = 0.013), while Proteobacteria showed a decreasing trend in the CON group and an increasing trend in RT; however, this was only at day 4 (p = 0.019). The relative abundance of Firmicutes was significantly higher in the RT group than in the CON group on days 4, 7, and 28 (p = 0.001). Prevotella and Rikenellaceae_RC9_gut_group were the predominant genera. In conclusion, our findings suggest that rumen fluid transplantation improves yak growth performance and rumen microbial reshaping. The findings of this study provide new insights into yak microbial community transplantation and a reference for improving feed efficiency in the yak industry. [ABSTRACT FROM AUTHOR]

Simple Summary: The purpose of this study was to investigate the effects of different source forages fed to preweaning yak calves on growth performance, pancreatic morphology, and functional development. In the experiment, we performed three different sets of experimental treatments by feeding tests, collected pancreatic tissues and recorded their organ indices at the end of the experiment, collected pancreatic tissue samples to observe morphological structures by tissue sectioning, determined the activity of main digestive enzymes and hormone levels in the pancreas by enzyme-linked immunosorbent assay, and obtained metabolic pathways and their small-molecule differential metabolites by nontargeted metabolomics techniques. The endocrine and exocrine divisions of the pancreas, which functions as a metabolic organ, are involved in the control of glucose and the organism's digestive metabolism. We discovered that feeding preweaning yak calves a combination of oat hay and alfalfa hay was better for the morphological and functional development of the pancreas than feeding either hay alone. This is essential for the early development of the pancreas in yak calves and serves as a critical resource for their healthy growth and scientific feeding. In this study, we used a combination of animal nutrition and nontargeted metabolomics to investigate the effects of feeding different sources forages rations on the morphology and function of the pancreas in preweaning yak calves, providing theoretical guidance and important references for the healthy and high-quality rearing of yak calves. At 45 days old, 21 yak calf males were divided into OP, AP, and AOP groups, with seven animals in each group, which were fed with oat hay, alfalfa hay, and mixed oat and alfalfa hay, respectively. Five calves from each group were selected randomly to slaughter after a pretest period of 21 days and the official period of 120 days, when the average daily feed intake reached 1 kg. During the test, the growth and pancreas weight of yak calves were recorded, and the morphology and function of the pancreas tissues were determined using tissue sectioning methods, enzyme-linked immunosorbent assay (ELISA) tests, and nontargeted metabolomics strategies. The results showed that the body weight and pancreatic organ index of yak calves in the AOP group were significantly higher than those of the AP and OP groups. Compared to the AP and OP groups, the AOP group had considerably lower ratios of the area of the pancreatic endocrine component and overall percentage of that section of the organ, and the AOP group increased pancreatic amylase activity and a higher concentration of growth inhibitor. The AP group had significantly higher levels of the differential metabolites L-ascorbic acid, spermidine, spermine, and dopaquinone in the glutathione, β-alanine, and tyrosine metabolic pathways than the OP group. The AOP group had significantly lower levels of the differential metabolites spermine and phenylacetylglycine in the glutathione and phenylalanine metabolic pathways than the AP group. In summary, compared to feeding oat or alfalfa hay alone, combined feeding oat hay and alfalfa hay is more beneficial to promote the morphological and functional development of the pancreas in preweaning yak calves, so as to enhance the digestion and absorption of nutrients in the diet and maintain the positive regulation of blood glucose levels. This provides an important basis for the optimized forage supply of healthy and high-quality rearing in preweaning yak calves. [ABSTRACT FROM AUTHOR]

Copper (Cu) is essential for the health of livestock, however, the optimal source and level of dietary Cu for yaks are uncertain. To fill this important gap, we designed an in vitro study to examine the effects of three Cu sources, namely Cu methionine (Met-Cu), Cu chloride (CuCl2) and tribasic Cu chloride (TBCC), at five levels, namely 5, 10, 15, 20 and 25 mg/kg DM (includes Cu in substrate), on rumen fermentation in yaks. In vitro dry matter degradability (IVDMD) and amylase activity were greater (p < 0.05) with added Met-Cu than the other two Cu sources, and ammonia nitrogen (NH3-N), microbial protein (MCP) and propionate contents were greater with Met-Cu and CuCl2 than with TBCC. Total gas production and lipase activity were greater with Met-Cu and TBCC than CuCl2 (p < 0.05), which meant that the metabolizable energy yield was greater in the two former Cu sources than the latter, but CH4 production did not differ (p = 0.92) among Cu sources. IVDMD and lipase activity were greatest (p < 0.05) at 15 mg Cu/kg DM in the substrate and MCP, isobutyrate, butyrate and isovalerate contents, and amylase and trypsin activities were greatest or second greatest at 10 and 15 mg Cu/kg DM. It was concluded that Met-Cu was the best source of Cu and 10 to 15 mg Cu/kg DM was the optimal level for yaks, at least under in vitro conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are important for the economy and livelihood of local herders in the Tibetan Plateau and are their primary source of income. Traditionally, the production performance of ruminants is generally improved by increasing the proportion of concentrate feed in the diet. To the best of our knowledge, the optimal proportion of concentrate feed is limited in actual production and research of yak. This study fed three diets with different dietary forage-to-concentrate ratios (50:50, 65:35, and 80:20) to 36 male yaks (Bos grunniens). The changes in the distribution of fecal microorganisms were studied by 16S rRNA gene sequencing and liquid chromatography–mass spectrometry. We found that the dietary forage-to-concentrate ratio significantly impacted yak fecal microorganisms. As such, these studies help us understand the fecal microbiota of yaks, further provide more complete information on the requirements of yak diets in terms of concentrate-to-forage ratio and improve yak growth performance, and provide a theoretical basis for accurate housing of yaks. (1) Background: This study aimed to investigate the effects of different dietary concentrate to roughage ratios on growth performance and fecal microbiota composition of yaks by 16S rRNA gene sequencing. (2) Methods: In the present study, three diets with different dietary forage-to-concentrate ratios (50:50, 65:35, and 80:20) were fed to 36 housed male yaks. (3) Results: The result shows that Final BW, TWG, and ADG were higher in the C65 group than in the C50 and C80 groups, but the difference was not significant (p > 0.05). DMI in the C65 group was significantly higher than in the other two groups (p < 0.05). The DMI/ADG of the C65 group was lower than that of the other two groups, but the difference was insignificant (p > 0.05). At the phylum level, Firmicutes were the most abundant in the C65 group, and the relative abundance of Bacteroidetes was lower in the C65 group than in the other two groups. At the genus level, the relative abundances of Ruminococcaceae_UCG_005, Romboutsia, and Christensenellaceae_R-7 were higher in the C56 group than in the C50 and C80 groups. The relative abundance of Lachnospiraceae_NK3A20 and Rikenellaceaewas_RC9_gut is lower in the C65 group, but the difference was insignificant (p > 0.05). At KEGG level 2, the relative abundance of lipid metabolism and energy metabolism were lowest in the C50 group, and both showed higher relative abundance in the C65 group. (4) Conclusions: In conclusion, the structure of fecal microbiota was affected by different concentrate-to-forage ratios. We found that feeding diets with a concentrate-to-forage ratio of 65:35 improved yaks' growth and energy metabolism. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the changes in the blood metabolic profiles of grazing yaks during the cold season to reveal their physiological status and seek the nutrients needed to be supplemented. Six castrated yaks (3 years old) with 166.8 kg (standard deviation = 5.3) of liveweight grazed in the Qinghai-Tibetan Plateau were used as experimental animals without supplementary feeding. Blood samples of each animal were collected in October and December 2015, and March 2016 for the analysis of serum biochemicals and metabolome. Results showed serum indices involved in protein metabolism in grazing yaks showed greater differences during the cold season than the metabolisms of energy or minerals. Cold stress in December had minor effects on the serum metabolic profiles of yaks compared with those in October. Yaks in October and December shared seven differential serum metabolites and enrichments of the "arachidonic acid metabolism" and "glycine, serine, and threonine metabolism" pathways compared with those in March caused by the shortage of feeds. Summarily, the nutrient deficiency would be influential on the physiological status of grazing yaks during the cold season, especially on the protein metabolism, which could be improved by supplementary feeds. [ABSTRACT FROM AUTHOR]

Background: Tenderness is the main quality of meat products. However, the meat tenderness formation is a complex biological process, and pathways and proteins that affect the tenderness of yak meat are unknown. Methods: Label‐free proteomics method was used to explore the effects of differentially expressed proteins on the tenderness of yak skeletal muscle (tenderloin) during post‐mortem storage (0, 3, and 7 days) at 3 ± 1°C. Results: The tenderness of yak skeletal muscle improved significantly during storage. A total of 91 differentially expressed proteins of yak skeletal muscle during post‐mortem storage were identified by the following comparisons: day 3 versus 0, day 7 versus 0, and day 7 versus 3. NDUFS6, CYCS, COX6A2, LDB3, HSPB7, TPM4, TAGLN, COL1A1, LUM, MYH11, ACTC1, and MYOZ1 proteins showed a significant difference during yak skeletal muscle post‐mortem storage. Furthermore, bioinformatics analyses revealed that the identified proteins were related to carbon metabolism, citrate cycle, glycolysis, oxidative phosphorylation, and RNA degradation. Conclusion: The results of the present study could provide proteomic insights into changes in yak skeletal muscle tenderness during storage and may be a valuable resource for future investigations. [ABSTRACT FROM AUTHOR]

Simple Summary: Yaks are an important for the economy and livelihood of local herders in the Tibetan Plateau and are their main source of income. They are mainly fed on natural pastures, especially during the warm season. Information on the effects of concentrate supplementation on the growth performance, rumen fermentation, and bacterial community composition of grazing yaks during the warm season is limited. Our study showed that concentrate supplementation increased the relative abundances of Firmicutes, Succiniclasticum, Prevotellaceae_UCG_003, Prevotellaceae_UCG_005, and Ruminococcus_1. Supplementation increased the average daily gain (ADG) and serum concentrations of glucose (GLU), total protein (TP), and aspartate aminotransferase (AST). Furthermore, the concentrations of ruminal ammonia-N (NH3-N), microbial protein (MCP), and volatile fatty acids (VFAs) increased in the supplement group. We concluded that supplementary feed improved ruminal fermentation, and altered the bacterial community composition in yaks during the warm season, thereby improving growth performance. This study aimed to evaluate the effects of concentrate supplementation on the growth performance, serum biochemical parameters, rumen fermentation, and bacterial community composition of grazing yaks during the warm season. Eight male yaks (body weight, 123.96 ± 7.43 kg; 3-years) were randomly allocated to two treatments groups: grazing (n = 4, GY) and concentrate supplement group (n = 4, GYS). Concentrate supplementation increased the average daily gain (ADG) (p < 0.05). Glucose (GLU), total protein (TP), and aspartate aminotransferase (AST) serum concentrations were significantly higher in the GYS group than in the GY group (p < 0.05). Ammonia-N, MCP: microbial protein, and total volatile fatty acid concentrations were significantly higher in the GYS group than in the GY group (p < 0.01), whereas the pH and acetate: propionate values were significantly decreased (p < 0.01). The relative abundance of Firmicutes in the rumen fluid was significantly higher in the GYS group than in the GY group (p < 0.01). At the genus level, the relative abundances of Succiniclasticum, Prevotellaceae_UCG_003, Prevotellaceae_UCG_005, and Ruminococcus_1 were significantly greater in the GY group than in the GYS group (p < 0.01). In conclusion, concentrate supplementation improved yaks' growth potential during the warm season, improved ruminal fermentation, and altered core bacteria abundance. [ABSTRACT FROM AUTHOR]

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The present study aims to evaluate the effects of different early weaning paradigms, which supplied with extra alfalfa hay, or starter feeding, or both alfalfa hay and starter feeding, along with the milk replacer, on the gastrointestinal microbial community, growth, and immune performance of yak calves. Twenty 30-day-old male yak calves were randomly assigned to four groups, including the control (CON), alfalfa hay (A), starter feeding (S), and starter plus alfalfa hay (SA) groups. The gastrointestinal microbial colonization, the gastrointestinal development and function, and the growth and immune performance of all the yak calves were separately measured. Supplementation with alfalfa and starter feeding during the pre-weaning period significantly increased body weight, body height, body length, and chest girth. The significantly improved rumen fermentation and promoted intestinal digestion-absorption function in alfalfa and starter feeding groups, including the identified significantly increased concentrations of ruminal total volatile fatty acid (VFA); the significantly increased concentrations and proportions of acetate, butyrate, and isovalerate; the increased α-amylase activities in the duodenum, jejunum, and ileum; the increased papillae length and width of rumen epithelium and rumen wall thickness; and the increased villus height and crypt depth of the duodenum, jejunum, and ileum, could all contribute to promote the growth of calves. These significant improvements on rumen fermentation and intestinal digestion-absorption function could be further attributed to the increased proliferation of starch-decomposing, and cellulose- or hemicellulose-decomposing bacteria identified in the rumen, jejunum, and ileum. Furthermore, based on the expression of intestinal inflammatory cytokines and the rumen epithelial RNA sequencing results, alfalfa supplementation reduced the occurrence of ruminal and intestinal inflammation, whereas starter feeding supplementation was mainly beneficial to the differentiation of immune cells and the improved immune function. Meanwhile, the significantly altered relative abundances of genera in the SA group, including increased relative abundance of Limnobacter , Escherichia / Shigella , and Aquabacterium in the rumen and increased relative abundance of Coprococcus, Pseudobutyrivibrio , Flavonifractor , Synergistes , and Sutterella in jejunum, were able to reduce gastrointestinal inflammation and enhance the immune function, which enhanced the immune function of the yak calves fed with alfalfa and starter feeding. Overall, milk replacer supplemented with alfalfa and starter feeding during the pre-weaning period could alter gastrointestinal microbiota and then benefit the gastrointestinal development, digestion-absorption function, growth, and immune performance of the yak calves. [ABSTRACT FROM AUTHOR]

Understanding the altered gastrointestinal microbiota is important to illuminate effects of maternal grazing (MG: maternally nursed and grazed) and barn feeding (BF: supplied milk replacer, starter feed, and alfalfa hay) on the performance and immune function of yak calves. Compared with the MG group, the significantly increased body weight, body height, body length, chest girth, and organ development of liver, spleen, and thymus were identified in the BF group, which were resulted from the significantly increased dry matter intake, increased concentrations of propionate, butyrate, isobutyrate, and valerate, increased ruminal pectinase, duodenal α-amylase, jejunal α-amylase and trypsin, and ileal trypsin, and promoted gastrointestinal epithelial development. Furthermore, genera of Sharpea , Sphingomonas , Atopobium , Syntrophococcus , Clostridium _ XIVb , Acinetobacter , Oscillibacter , Dialister , Desulfovibrio , Bacteroides , Lachnospiracea _ incertae _ sedis , and Clostridium _ sensu _ stricto , which were involved in utilization of non-fibrous carbohydrate and further beneficial to improve the gastrointestinal digestion, development, and immune functions, were significantly increased in the BF group. Meanwhile, the significantly enhanced ruminal epithelial immune functions and intestinal immune functions based on enhanced ruminal immune related pathway, duodenal IL-1β, jejunal IL-1β, IL-2, TNF-α, and IFN-γ, and ileal IL-1β were identified in the BF group, which also may induced by the increased abundance of gastrointestinal microbiota. Overall, barn feeding significantly increased the diversity of species and abundance of microbes which used different carbohydrates and further benefit to the growth and immune function of yak calves. [ABSTRACT FROM AUTHOR]

Heat‐treated rapeseed was supplemented to indoor fed yaks in winter to test the effect on dry matter intake (DMI), body mass change, and meat quality. Sixteen 3‐year‐old yak steers (124 ± 15.3 kg) were divided randomly into two groups and were offered either heat‐treated rapeseed (HTR) or rapeseed meal (CONT). The yaks were allowed 14 days for adjustment and measurements were made over 120 d. There was no difference in DMI between groups (p = 0.67), but average daily gain tended to be higher (p < 0.056) and feed to gain ratio tended to be lower (p = 0.050) in HTR than in CONT yaks. Meat from HTR yaks was more tender (p = 0.006), had higher intramuscular fat (p = 0.013), and had lower cholesterol content (p = 0.009) than from CONT yaks. In addition, the atherogenic index was lower (0.37 vs. 0.43; p = 0.049), the PUFA:SFA ratio was higher (0.55 vs. 0.37; p = 0.049), and the n‐6:n‐3 (n‐6 PUFA to n‐3 PUFA) ratio was lower (2.76 vs. 4.78; p = 0.003) in HTR than in CONT yaks, which all favoured the HTR yaks. Meat from HTR yaks met human health standards of a PUFA:SFA ratio of above 0.4 and n‐6:n‐3 ratio of less than 4, whereas meat from CONT yaks just missed these standards. [ABSTRACT FROM AUTHOR]

Current knowledge about the relationships between ruminal bacterial communities and metabolite profiles in the yak rumen is limited. This is due to differences in the nutritional and metabolic features between yak and other ordinary cattle combined with difficulties associated with farm-based research and a lack of technical guidance. A comprehensive analysis of the composition and alterations in ruminal metabolites is required to advance the development of modern yak husbandry. In the current study, we characterized the effect of feed type on the ruminal fluid microbiota and metabolites in yak using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS). Bacteroidetes and Firmicutes were the predominant bacterial phyla in the yak rumen. At the genus level, the relative abundance of Bacteroidales BS11 gut group, Prevotellaceae UCG-003, Ruminococcaceae UCG-011, Bacteroidales RF16 group and Ruminococcaceae UCG-010 was significantly (P < 0.01) higher in the forage group compared to that in the concentrate group, while the concentrate group harbored higher proportions of Bacteroidales S24-7 group, Ruminococcaceae NK4A214, Succiniclasticum and Ruminococcus 2. Yak rumen metabolomics analysis combined with enrichment analysis revealed that feed type altered the concentrations of ruminal metabolites as well as the metabolic pattern, and significantly (P < 0.01) affected the concentrations of ruminal metabolites involved in protein digestion and absorption (e.g., L-arginine, ornithine, L-threonine, L-proline and β-alanine), purine metabolism (e.g., xanthine, hypoxanthine, deoxyadenosine and deoxyadenosine monophosphate) and fatty acid biosynthesis (e.g., stearic acid, myristic acid and arachidonic acid). Correlation analysis of the association of microorganisms with metabolite features provides us with a comprehensive understanding of the composition and function of microbial communities. Associations between utilization or production were widely identified between affected microbiota and certain metabolites, and these findings will contribute to the direction of future research in yak. [ABSTRACT FROM AUTHOR]

Physical tenderization technologies for beef have been of particular interest to the meat industry. Here a novel tenderization technology by mechanical resonance vibration was proposed. The fundamental natural frequency (NF f) of the yak longissimus thoracis et lumborum (LTL) was obtained through a hammer impacting on the muscle, and was reported to be 24.89 Hz. The tensile stress and Warner–Bratzler shear force of the yak meat were decreased by using the obtained NF f as the frequency of resonance vibration (RV), and only linear elastic deformation was found in stress-strain behavior of the vibrated meat. The variation of mechanical properties in post-rigor meat is responsible for the disappearance of the M-bands, shortening of the A-bands, and lengthening change in I-bands, rather than of the sarcomere length. The research demonstrated that RV treatment resulted in the M-band disappearance, the extensively detachment of endomysium from the myofibers, and the destruction of the linkages between α-actinin and thin filaments as well as other linkages. • The natural frequency of yak meat was accurately determined by hammer excitation. • The effect of the components of yak meat on mechanical properties was revealed. • The myofibril detached and the collagen fibers decomposed by resonance vibration. • Resonance vibration resulted in the disappearance of M-bands in sarcomeres. [ABSTRACT FROM AUTHOR]

Contrasting Y-chromosomal lineage distributions in Chinese domestic yak Yak ( I Bos grunniens i ) is a valuable bovine species that lives in the central Asian highlands with more than 15 million animals living in China.[1] Previous Y-SNP markers analyses revealed two yak paternal lineages, Y1 and Y2, in the Gaoyuan, Datong, Huanhu and Tianzhu breeds.[[2]] Here, we present a comprehensive survey of the lineage distributions in the 12 recognized Chinese domestic yak breeds. The differential distributions of the yak lineages Y1 and Y2 reveal a clear phylogeographical structure among Chinese domestic yak breeds, in clear contrast to nuclear microsatellite and mitochondrial analyses on domestic yak.[[4]]. [Extracted from the article]

Milk from yaks, also called "liquid gold", is reputed to be very healthy for people, but the yield is relatively low. The intake of energy and amino acids, especially lysine and methionine, of grazing, lactating yaks are often below requirements and this could explain, at least in part, the low milk yield. We hypothesized that grazing, lactating yaks, supplemented with energy and/or amino acids, would improve their performance and the average daily gain (ADG) of their calves. Twenty-four multiparous yaks (218 ± 5.3 kg), blocked by bodyweight, were offered one of four dietary treatments (n = 6 yaks per treatments) as: 1) no supplement (CON); 2) 15.0 g/d rumen-protected lysine plus 5.0 g/d rumen-protected methionine (SA); 3) 1.20 kg/d concentrate (SC); and 4) both SA and SC (SAC). The ADG was greater (P < 0.001) in yaks with than without supplementary concentrate, whereas the greatest ADG for calves was in the SAC group (interaction, P = 0.034). The concentration of ruminal total volatile fatty acids (VFAs) and of butyrate increased (P < 0.01) in yaks with supplementary concentrate, whereas iso-VFAs increased (P < 0.01) in yaks with supplementary rumen-protected lysine plus methionine (RPLM). The relative abundances of the ruminal bacteria Prevotella brevis and Ruminococcus albus increased (P < 0.01) in yaks with supplementary concentrate or RPLM, with the greatest abundance (interaction, P < 0.05) in the SAC group. Milk yield from hand-milking, and the concentrations of fat, protein, total solids and urea were not affected by dietary supplements, but lactose concentration increased (P = 0.021) with concentrate supplementation, whereas somatic cell count decreased (P < 0.01) when yaks received either supplementary concentrate or RPLM. Milk lysine and methionine, as proportions of total amino acids (TAAs), and concentration of TAAs increased with supplementary concentrate or RPLM. The milk concentrations of C16:1, C18:2n-6c and C18:3n-6 increased (P < 0.05) in yaks supplemented with concentrate, whereas, the concentrations of saturated, monounsaturated, and polyunsaturated fatty acids were not affected (P > 0.05) by treatments. These results indicated that the ADG of calves improved, whereas the rumen fermentation capacity of the lactating yaks was enhanced with supplementary concentrate and RPLM. It was concluded that dietary supplements could be an effective management option to improve performance in grazing, lactating yaks and the ADG of their calves raised on the Qinghai-Tibetan Plateau. • Supplements improved average daily gain in lactating yaks and calves. • Concentration of volatile fatty acids increased with supplementary concentrates. • Somatic cell count declined with supplementary concentrate or lysine + methionine. • Lysine and methionine in yak milk increased with supplements. [ABSTRACT FROM AUTHOR]

Many prediction equations are available for enteric methane (CH 4) emission in cattle; however, these are not suitable for yaks, as CH 4 emission differs between these species. To our knowledge, no equation has been generated for yaks and, consequently, the aim of this study, at least in part, is to fill this gap. Feed and energy intakes, dry matter digestibility, and CH 4 emissions were measured in 16 yak calves (8 males and 8 females) at 8, 12, and 16 months of age. Concentrate (C) and forage (F) were offered the calves at a ratio of 60:40. There was no difference (P = 0.92) in body mass (m b) between sexes, but there was a difference (P < 0.001) among ages. Significant differences (P < 0.001) were observed in the dry matter intake (DMI), organic matter intake (OMI), neutral detergent fiber intake (NDFI), acid detergent fiber intake (ADFI), gross energy intake (GEI), digestive energy intake (DEI), and metabolizable energy intake (MEI) among ages and between sexes. The CH 4 emission (g/d) and the energy equivalent of CH 4 emission (MJ/d) increased (P < 0.005) with increasing age, and they were higher (P < 0.005) in males than in females. There was no difference (P = 0.22) in CH 4 emission between sexes in g CH 4 /kg DMI. Using simple linear regressions, DMI, OMI, and NDFI each explained 49–50% of the variation in CH 4 emission; whereas, GEI explained 49% of the energy loss due to CH 4 emission. In multiple regressions, NDFI and either m b or ADFI explained 49–50% of the variation in CH 4 emission. It was concluded that CH 4 emission in yaks: (1) tended to be lower than emissions reported in the literature for cattle and Murrah buffalo calves fed diets of similar C:F ratios; and, (2) as in cattle, can be predicted by dry matter intake. • Prediction equations of enteric methane emission for yaks were generated. • Dry matter intake explained 50% of the variation in methane emission. • Methane emission was lower in yak than cattle and Murrah buffalo calves. • Methane emission for yaks was lower than predicted for ruminant of its mass. [ABSTRACT FROM AUTHOR]