Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during th...Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during the cold season.Certain stress conditions,such as environmental changes,disease,and malnutrition,can lead to a decrease in glutamine(Gln)synthesis,which fails to cover the physiological needs of the organism.Supplementation with exogenous Gln can promote nutrient digestion and improve rumen fermentation in ruminant animals under malnutrition.However,whether Gln could alleviate the barrier function injury induced by malnutrition and its mechanism is still unclear.Methods In the in vivo experiments,24 healthy yaks(31 months,265.35±25.81 kg)were randomly divided into 3 groups,namely control group(Con,free access to the basal diet),feed restriction group(FR,50% level of ad libitum feed intake),and feed restriction+Gln group(FR+Gln,50% level of ad libitum feed intake from d 1 to 30,50% level of ad libitum feed intake+1%Gln from d 31 to 60).In the in vitro experiments,the yak rumen epithelial cells(YRECs)were divided into 4 groups:Con group(complete medium),Gln group(complete medium+10 mmol/L Gln),Gln deficiency group(Gln-D,Gln-free medium),and Gln deficiency+Gln group(Gln-D+Gln,Gln-free medium+10 mmol/L Gln).Results In the in vivo experiments,FR significantly decreased the ruminal concentrations of acetate,propionate,butyrate,iso-butyrate,and total volatile fatty acid(VFA)(P<0.05).FR also reduced the m RNA expression of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase,and the concentrations of lactate,histone acetyltransferase(p300),histone deacetylase(HDAC),as well as the histone lysine lactylation level compared to Con group,while Gln supplementation alleviated them(P<0.05).In the in vitro experiments,Gln alleviated the Gln-D-induced down-regulation of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase m RNA expressions and reduction of lactate,p300,HDAC concentrations,and histone lysine lactylation level(P<0.05).Besides,p300 inhibitor abrogated Gln repair of barrier function damage in YRECs(P<0.05).Conclusions Overall,our results revealed the potential mechanism of Gln supplementation to repair malnutritioninduced damage of rumen epithelial barrier function in yaks,which might be related to histone lysine lactylation.However,because we do not have a control group receiving glutamine alone,we cannot determine the impact of Gln on the rumen epithelial function of normal yaks.展开更多
The prevalence of bacterial digestive diseases in plateau animals has caused considerable losses to the Tibetan live‑stock industry.Therefore,this study aimed to isolate safe lactic acid bacteria(LAB)with beneficial p...The prevalence of bacterial digestive diseases in plateau animals has caused considerable losses to the Tibetan live‑stock industry.Therefore,this study aimed to isolate safe lactic acid bacteria(LAB)with beneficial probiotic proper‑ties to protect yaks from intestinal diseases.After 16S rDNA matching,four strains of Lactobacillus fermentum(A4),Pediococcus pentosaceus(A3.4 and A1.2),and Pediococcus acidilactici(B1.9)were isolated from the intestinal tissues and content of healthy yaks.The results indicated that A4 was more tolerant to bile salt(0.3%),while A3.4 had better stability in an acidic(pH=3.0)environment.The results of the antibacterial activity test suggested that the isolates inhibited most pathogenic bacteria by up to 20%,except for A3.4,which inhibited Pasteurella and Staphylococcus aureus by more than 20%.Moreover,the results of the antioxidant test demonstrated that A4 and A3.4 had potent antioxidant activity.In addition,the drug sensitivity test revealed that the isolates were susceptible to commonly used antibiotics.In terms of safety,the isolates promoted growth,enhanced intestinal development,and protected the intestinal barrier without causing any adverse effects.In conclusion,LAB isolated from yak intestinal contents are potential probiotics with excellent antibacterial properties.展开更多
Coat color represents a key phenotypic trait in Sibu yak,exhibiting distinct black and brown phenotypes.To elucidate the genetic basis of the brown phenotype,genome-wide association studies and multi-omics analyses we...Coat color represents a key phenotypic trait in Sibu yak,exhibiting distinct black and brown phenotypes.To elucidate the genetic basis of the brown phenotype,genome-wide association studies and multi-omics analyses were integrated to identify loci and molecular pathways involved in pigmentation.In total,11 singlenucleotide polymorphisms(SNPs)on chromosome(chr)5displayed genome-wide significance(P-adjust<4.47×10–9),with the lead variant(chr5:g.47487664 A>G,Padjust=2.38×10–10)located within an intron of PMEL.Expression analysis revealed markedly reduced PMEL transcription in fibroblasts from brown individuals.Functional multi-omics analyses of PMEL overexpression demonstrated significant alteration of the expression of1088 genes,444 proteins,and 57 metabolites.Enrichment analyses indicated significant involvement of melanogenesis-related signaling cascades,including c AMP(e.g.,ADCY7,EDNRA,and epinephrine),PI3K-Akt(e.g.,FGF5,PIK3CG,and FGF7),and MAPK(e.g.,MAP2K6,FGFR3,and ERBB4)pathways.These findings indicate that the intronic PMEL variant modulates gene expression and pigmentation through coordinated regulation of these pathways,thereby contributing to the phenotypic divergence of Sibu yak coat color.This study provides valuable insights into the genetic mechanisms underlying Sibu yak pigmentation and identifies PMEL as a key candidate gene governing coat color differentiation in Sibu yak.展开更多
To assess the impact of N fertilization on contents of mineral elements in herbage and the effect of increased forage S on the copper metabolism of grazing yaks, study was conducted during the summer grazing season （...To assess the impact of N fertilization on contents of mineral elements in herbage and the effect of increased forage S on the copper metabolism of grazing yaks, study was conducted during the summer grazing season （2005, 2006, and 2007）. Pasture replicates （20 ha; n=3 per treatment） received the same fertilizer treatment in each growing season, consisting of i） 90 kg N ha^-1 from quickly available nitrogen, ii） 90 kg N ha^-1 from ammonium nitrate, iii） 90 kg N ha^-1 from ammonium sulfate, and iv） control （no fertilizer）. Forage sampling was collected at 60 days intervals following fertilization （10 samples per pasture） for Cu, Mo, Mn, Se, Fe, Zn, Ca, and P. To determine the effect of fertilizer treatment on mineral metabolism in grazing yaks, liver and blood samples were collected at the start and end of the study period in 2005, 2006, and 2007. Ammonium sulfate fertilization increased （P 〈 0.01） forage S concentration. Plant tissue N concentrations were increased by N fertilization, regardless of source in 2005, 2006, and 2007. Yaks grazing S fertilization pastures had lower （P〈0.05） liver and blood Cu concentrations at the end of the study period in 2005, 2006, and 2007, compared with urea, ammonium nitrate, and control. Nominal increases in forage in vitro organic matter digestibility were realized by fertilization, regardless of N source in each year.展开更多
Yak ( Bos grunniens ) is classified as Bovine genus,they live in Qingzang Plateau with elevation more than 3500m and it's neighbor highland,where the weather is high chilly,short of oxygen and large difference o...Yak ( Bos grunniens ) is classified as Bovine genus,they live in Qingzang Plateau with elevation more than 3500m and it's neighbor highland,where the weather is high chilly,short of oxygen and large difference of temperature between day and night.But yak have adapted that circumstance after thousands of years' artificial and natural selection and has great anti adversity capacity.Yak is an important sustenance and means of production to Tibetan.China is a country with the largest number of yak,whose amount of livestock on hand accounts for 95% of the world and Tibet region takes the second place next to Qinghai in the number of yak.Tibetan yak has formed some groups for Tibetan's large area,complicated geological ecosystem conditions,geological isolation.The typical better groups are Yadong yak,Jiali yak and Sibu yak. Study about yak fell behind other animals due to the restriction of inconvenient transportation,difficult sampling and poor experimental technology.Study about the relationship between yak blood enzyme activities and milk production was little,only Jing (1992) studied correlation of milk production with serum amylase,esterase in Gansu Jiulong yak,Maiwa yak and no report was found in other groups.This study discussed six Jiali yak blood enzyme activities lactate dehydrogenase (LDH),alkaline phosphatases (AKP),acid phosphatase (ACP),catalase (CAT),amylase (Amy) and superoxide dismutase (SOD),and explored their relationship with milk production in Jiali yak,so as to supply with theoretical evidence by using blood enzyme activity as biochemical assisted selection marker in the breeding of Tibetan yak milk yield. This experiment investigated activity of six blood enzymes from 28 Tibetan yaks and explored its relationship to production performance.The results showed a extremely positive significant difference ( P <0.01) between activity of LDH and milk yield,CAT activity and length of belly hair respectively,while a positive significant difference ( P <0.05) was observed between AKP activity and body weight,Amy activity and body weight and a negative significant difference ( P <0.05) for SOD activity and body weight.Stepwise Regression Analysis showed that activity of LDH could be used for the prediction of milk yield,AKP,CAT,Amy for body weight,CAT,Amy for length of belly hair.So it is expected to use activity of LDH,AKP,CAT,Amy as biochemical genetic marker in the selection of milk yield,body weight and length of belly hair.展开更多
In the study, confinement and semi-confinement raising fattening technology of yaks in agricultural areas of tibet were analyzed. And several suggestions for improving the efficiency of yak raising were put forward. A...In the study, confinement and semi-confinement raising fattening technology of yaks in agricultural areas of tibet were analyzed. And several suggestions for improving the efficiency of yak raising were put forward. Aiming at providing the reference of healthy raising and sustainable development of yaks in the agricul- tural areas of tibet.展开更多
Yaks live in high frigid areas some 3,000-5,000 meters above sea level.In China there are 13 million yaks,making up 90 percent of the world total.They provide with transport means,meat and hide for 4.6 Tibe-tans in Ti...Yaks live in high frigid areas some 3,000-5,000 meters above sea level.In China there are 13 million yaks,making up 90 percent of the world total.They provide with transport means,meat and hide for 4.6 Tibe-tans in Tibet as well as Qinghai,Sichuan,Yunnan and Gansu prov-inces.展开更多
Objective:To evaluate the antimicrobial efficacy of berberine,a plant alkaloid.Methods:Five multi-drug resistant（MDR） STEC/EPEC and five MDR ETEC isolates from yaks with haemorrhagic diarrhoea were selected for the ...Objective:To evaluate the antimicrobial efficacy of berberine,a plant alkaloid.Methods:Five multi-drug resistant（MDR） STEC/EPEC and five MDR ETEC isolates from yaks with haemorrhagic diarrhoea were selected for the study.Antibacterial activity of berberine was evaluated by broth dilution and disc diffusion methods.The binding kinetics of berberine to DNA and protein was also enumerated.Results:For both categories of enterovirulent Escherichia coli（E.roli） isolates, berberine displayed the antibaclerial effect in a dose dependent manner.The MIC<sub>50</sub> of berberine chloride for STEC/EPEC isolates varied from 2.07μM to 3.6μM with a mean of（2.95±0.33）μM where as for ETEC strains it varied from 1.75 to 1.96μM with a mean of（1.87±0.03）μM. Berberine bind more tightly with double helix DNA with Bmax and Kd of（24.68±2.62） and（357.8±57.8）,respectively.Berberine reacted with protein in comparatively loose manner with Bmax and Kd of（18.9±3.83） and 【286.2±113.6),respectively.Conclusions:The results indicate clearly that berberine may serve as a good antibacterial against multi drug resistant E.coli.展开更多
This study was conducted to investigate the phylogenetic diversity of archaea in the rumen of adult and elderly yaks. Six domesticated female yaks, 3 adult yaks （（5.3±0.6） years old）, and 3 elderly yaks （（1...This study was conducted to investigate the phylogenetic diversity of archaea in the rumen of adult and elderly yaks. Six domesticated female yaks, 3 adult yaks （（5.3±0.6） years old）, and 3 elderly yaks （（10.7±0.6） years old）, were used for the rumen contents collection. Illumina MiSeq high-throughput sequencing technology was applied to examine the archaeal composition of rumen contents. A total of 92 901 high-quality archaeal sequences were analyzed, and these were assigned to 2 033 operational taxonomic units （OTUs）. Among these, 974 OTUs were unique to adult yaks while 846 OTUs were unique to elderly yaks; 213 OTUs were shared by both groups. At the phylum level, more than 99% of the obtained OTUs belonged to the Euryarchaeota phylum. At the genus level, the archaea could be divided into 7 archaeal genera. The 7 genera （i.e., Methanobrevibacter, Methanobacterium, Methanosphaera, Thermogymnomonas, Methanomicrobiu, Meth- animicrococcus and the unclassified genus） were shared by all yaks, and their total abundance accounted for 99% of the rumen archaea. The most abundant archaea in elderly and adult yaks were Methanobrevibacterand Thermogymnomonas, respectively. The abundance of Methanobacteria （class）, Methanobacteriales （order）, Methanobacteriaceae （family）, and Methanobrevibacter （genus） in elderly yaks was significantly higher than in adult yaks. In contrast, the abundance of Ther-mogymnomonas in elderly yaks was 34% lower than in adult yaks, though the difference was not statistically significant. The difference in abundance of other archaea was not significant between the two groups. These results suggested that the structure of archaea in the rumen of yaks changed with age. This is the first study to compare the phytogenetic differences of rumen archaeal structure and composition using the yak model.展开更多
Background The genetic diversity of yak,a key domestic animal on the Qinghai-Tibetan Plateau(QTP),is a vital resource for domestication and breeding efforts.This study presents the first yak pangenome obtained through...Background The genetic diversity of yak,a key domestic animal on the Qinghai-Tibetan Plateau(QTP),is a vital resource for domestication and breeding efforts.This study presents the first yak pangenome obtained through the de novo assembly of 16 yak genomes.Results We discovered 290 Mb of nonreference sequences and 504 new genes.Our pangenome-wide presence and absence variation(PAV)analysis revealed 5,120 PAV-related genes,highlighting a wide range of variety-specific genes and genes with varying frequencies across yak populations.Principal component analysis(PCA)based on binary gene PAV data classified yaks into three new groups:wild,domestic,and Jinchuan.Moreover,we pro-posed a‘two-haplotype genomic hybridization model'for understanding the hybridization patterns among breeds by integrating gene frequency,heterozygosity,and gene PAV data.A gene PAV-GWAS identified a novel gene(Bos-Gru3G009179)that may be associated with the multirib trait in Jinchuan yaks.Furthermore,an integrated transcrip-tome and pangenome analysis highlighted the significant differences in the expression of core genes and the muta-tional burden of differentially expressed genes between yaks from high and low altitudes.Transcriptome analysis across multiple species revealed that yaks have the most unique differentially expressed m RNAs and lnc RNAs(between high-and low-altitude regions),especially in the heart and lungs,when comparing high-and low-altitude adaptations.Conclusions The yak pangenome offers a comprehensive resource and new insights for functional genomic studies,supporting future biological research and breeding strategies.展开更多
Since the 1990s, yak in the Haizi area in China has been affected by an ailment characterized by pica, emaciation, dyskinesia, and anemia. To determine the cause of disease, the mineral composition of soil and forages...Since the 1990s, yak in the Haizi area in China has been affected by an ailment characterized by pica, emaciation, dyskinesia, and anemia. To determine the cause of disease, the mineral composition of soil and forages, and samples of blood, hair, and liver of yaks from the Haizi area in China were determined. The concentrations of copper in soil and forage from affected ranches and unaffected areas are within the normal ranges. The mean concentration of copper in blood and liver from the affected yaks was （0.31±0.03） and （13.7±3.1）μg·g^-1 respectively, compared with （0.98±0.16） and （95.6±11.2）μg·g^-1 for unaffected yaks. The concentrations of sulfur in soil and forage from affected ranches were （1.91±0.26） and （1.37±0.17）%, respectively, compared with （1.11±0.31） and （0.52±0.18）% （dry matter） for normal areas. The contents of sulfur in blood and liver affected animals were （7.32±1.8） and （2.54±3.1）%, respectively, compared with （4.22±0.73） and （1.31±0.33）% （in fresh and soft tissues） for healthy animals, respectively. Oral administration of tribasic copper chloride prevented and cured the disease. Thus it is reasonable to conclude that ailments of yaks in the Haizi area are probably caused by a secondary copper deficiency, mainly due to high sulfur content in soil and forage.展开更多
Female domesticated yaks were artificially inseminated with semen taken from wild yaks and the offspring used to form a nucleus breeding herd of crossbred animals. The meat production of the first generation(F1 ×...Female domesticated yaks were artificially inseminated with semen taken from wild yaks and the offspring used to form a nucleus breeding herd of crossbred animals. The meat production of the first generation(F1 × F2)from breedtng within the nucleus herd was assessed by slaughter and carcass dissection of males. One group(no. =14)was slaughtered at 6 months of age and the second(no. = 12)at 18months. Crossbred yaks were significantly heavier(P＜0.01)at 6 months(74.7(s. e. 10.41)kg v. 59.8(s.e. 10.23)kg)and at 18 months(150.5(s. e. 56.1)kg v. 117.7(s. e. 17.4)kg)than domesticated ones,The killing-out proportion(0.47)was similar at both ages and for both groups of animals. Carcass weight,meat weight and the yield of prime cuts were higher for crossbred animals than for domestic yak at both ages.展开更多
Wild yak males were crossed with domesticated female yaks to produce a breeding herd of crossbred animals. The milk production of the progeny of this herd was measured in the present study. Yaks were milked once daily...Wild yak males were crossed with domesticated female yaks to produce a breeding herd of crossbred animals. The milk production of the progeny of this herd was measured in the present study. Yaks were milked once daily after prior suckling of the calf. yaks were allowed to graze for 15 h/day on high-altitude(3200 to 3500 m) pastures. No supplementary food was given. Average daily milk yield of 1.77(s. e. 0. 16)kg and milk yield over 120 days,212.2(s. e. 20.2)kg were significantly higher(P＜0.01)than the corresponding figures for uninlproved domestic yaks(1.53(s. e. 0. 10)kg and 164. 6(s. e. 10.5)kg respectively). The fat content of milk from crossbred yaks, 52(s. e. 2. 9)g/kg, was not significantly dlfferent from that of unimproved animals, 53.5(s. e. 4. 1), g/kg.展开更多
This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that th...This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that the weight and size of testes and epidiymis was increased with the age which was hardly affected by imbalance of food supply during the cold and warm seasons. The development were similar for three kinds of yak at the same age(P＞0.05).展开更多
Introduction:Echinococcosis is a zoonotic parasitic disease caused by the larval stage of Echinococcus,prevalent in northwestern China.It poses a serious threat to human health and causes significant economic losses i...Introduction:Echinococcosis is a zoonotic parasitic disease caused by the larval stage of Echinococcus,prevalent in northwestern China.It poses a serious threat to human health and causes significant economic losses in the livestock industry.This study aims to investigate the infection and development of Echinococcus in livestock in northwestern China,providing scientific basis for precise prevention and control of echinococcosis.Methods:This study utilized a combination of slaughterhouse and household investigations.Liver and lungs from slaughtered livestock in Sichuan Province,Qinghai Province,Xizang Autonomous Region,and Xinjiang Uygur Autonomous Region were examined through visual inspection and palpation,and Echinococcus cysts were collected.The cyst fertility was analyzed via microscopic examination.Metacestode DNA was extracted for PCR amplification of the mitochondrial Cox1 gene.Sequence alignment with the GenBank database was conducted to identify the genotypes of Echinococcus.Phylogenetic tree was constructed using MEGA 7.0 software.Haplotypes were analyzed using DnaSP 6,and a haplotype network was constructed using PopART 1.7.Data analysis was performed using SAS 9.4,and P<0.05 indicates statistical significance.Results:Between October and December 2023,400 yaks and 808 sheep were surveyed in Qinghai,Xizang,and Xinjiang.The infection rate of Echinococcus in yaks was 16.5%,significantly higher than that in sheep(9.41%,χ^(2)=12.9802,P<0.001).The fertility rate of Echinococcus cysts in sheep was 71.79%,significantly higher than that in yaks(15.57%,χ^(2)=64.1670,P<0.0001).The cysts were mainly parasitizes in the liver of sheep(82.89%)and the lungs of yaks(63.89%).A total of 169 Cox1 sequences were successfully amplified,of which 98.82%(167/169)corresponded to E.granulosus sensu stricto(s.s.)G1/G3,while one sequence was identified as E.canadensis G6,and one from E.multilocularis.A total of 48 haplotypes were detected,with H3 being the predominant haplotype.Conclusions:In the four survey provincial-level administrative divisions(PLADs)of China,the infection rate in yaks(16.5%)was significantly higher than in sheep(9.41%).Echinococcus was found preferably infect sheep liver and yak lungs,with a higher cyst fertility rate in sheep compared to yaks.Livestock infections are mainly caused by E.granulosus G1/G3,and this study,for the first time,identified E.multilocularis infection in yaks from Xizang.The findings provide a crucial foundation for further research into the molecular epidemiology,genetic evolution,and the development of precise prevention and control strategies for Echinococcus in the regions.展开更多
The study investigated the metabolic responses of yaks to dietary net energy for gain(NEg)and metabolizable protein(MP),and explored potential biomarkers for average daily gain(ADG)in serum metabolites.A total of 40 t...The study investigated the metabolic responses of yaks to dietary net energy for gain(NEg)and metabolizable protein(MP),and explored potential biomarkers for average daily gain(ADG)in serum metabolites.A total of 40 three-year-old yaks(initial body weight=255±8.04 kg)were assigned to a 2×2 factorial treatment arrangement based on dietary NEg(4.18 vs 4.81 MJ/kg DM;low NEg[LE]vs high NEg[HE])and MP(72.0 vs 82.8 g/kg DM;low MP[LP]vs high MP[HP]),comprising 4 treatments with 10 replicates each(1 yak per replicate).The yaks were fed these diets for 55 days including a 15-day adaptation period.Yaks on HP diets had greater ADG(P=0.013)and a reduced feed-to-gain ratio(P=0.019)compared to those on the LP diet,and those on the LE diet had greater dry matter intake(P<0.001)but unaffected ADG compared to those on the HE diet(P>0.05).Dietary NEg interacted with MP in relation to the apparent digestibility of dry matter(P=0.028)and crude protein(P<0.001).The apparent digestibility of gross energy(GE),organic matter,and neutral detergent fiber in yaks on the HE diet was greater than those in yaks on the LE diet(P<0.05).The digestibility of GE in yaks on the HP diet was lower than those on the LP diet(P=0.011).An significant interaction between dietary NEg level and MP level was observed on serum total bilirubin concentration,catalase concentration,and superoxide dismutase concentration(P<0.05).Yaks fed HE diets exhibited higher serum glutathione peroxidase protein concentration(P<0.001),but lower serum triglyceride concentration(P=0.012)compared to those fed LE diets.Serum level of alanine transaminase was higher in yaks on the HP diet compared to those on the LP diet(P=0.038).Untargeted metabolomics identified novel biomarkers linked to dietary NEg and MP levels,revealing that the HE diet enhanced adenosine triphosphate production through acetyl-CoA synthesis and affected amino acid,fat,and carbohydrate pathways(P<0.05).The HP diet altered the synthesis of aromatic amino acids and vitamins(P<0.05).Additionally,random forest analysis identified N-(9-oxodecyl)acetamide and biliverdin,as biomarkers for predicting ADG.These findings provide a theoretical foundation for the effective feeding and nutritional management of yaks.展开更多
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 Qi...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 BW0.75).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 ofβ-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.展开更多
The yak(Bos grunniens),an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level,is closely linked to more than 40 ethnic communities and plays a vital role in the ecological stability,live...The yak(Bos grunniens),an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level,is closely linked to more than 40 ethnic communities and plays a vital role in the ecological stability,livelihood security,socio-economic development,and ethnic cultural traditions in the Asian highlands.They provide the highlanders with meat,milk,fibres,leather and dung(fuel).They are also used as pack animals to transport goods,for travel and ploughing,and are important in many religious and traditional ceremonies.The Asian highlands are known for an extremely,harsh environment,namely low air temperature and oxygen content and high ultraviolet light and winds.Pasture availability fluctuates greatly,with sparse pasture of poor quality over the long seven-month cold winter.After longterm natural and artificial selections,yaks have adapted excellently to the harsh conditions:1)by genomics,with positively selected genes involved in hypoxia response and energy metabolism;2)anatomically,including a short tongue with a weak sense of taste,and large lung and heart;3)physiologically,by insensitivity to hypoxic pulmonary vasoconstriction,maintaining foetal haemoglobin throughout life,and low heart rate and heat production in the cold season;4)behaviourlly,by efficient grazing and selecting forbs with high nutritional contents;5)by low nitrogen and energy requirements for maintenance and low methane emission and nitrogen excretion,namely,‘Low-Carbon’and‘Nitrogen-Saving’traits;6)by harboring unique rumen microbiota with a distinct maturation pattern,that has coevolved with host metabolism.This review aims to provide an overview of the comprehensive adaptive strategies of the yak to the severe conditions of the highlands.A better understanding of these strategies that yaks employ to adapt to the harsh environment could be used in improving their production,breeding and management,and gaining benefits in ecosystem service and a more resilient livelihood to climate change in the Asian highlands.展开更多
基金the National Natural Science Foundation of China(NSFC),Grant/Award Number:32272909Discipline Construction Program in Sichuan Agricultural University(2221993012)China Agriculture(Beef Cattle/Yak)Research System of MOF and MARA(CARS-37)。
文摘Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during the cold season.Certain stress conditions,such as environmental changes,disease,and malnutrition,can lead to a decrease in glutamine(Gln)synthesis,which fails to cover the physiological needs of the organism.Supplementation with exogenous Gln can promote nutrient digestion and improve rumen fermentation in ruminant animals under malnutrition.However,whether Gln could alleviate the barrier function injury induced by malnutrition and its mechanism is still unclear.Methods In the in vivo experiments,24 healthy yaks(31 months,265.35±25.81 kg)were randomly divided into 3 groups,namely control group(Con,free access to the basal diet),feed restriction group(FR,50% level of ad libitum feed intake),and feed restriction+Gln group(FR+Gln,50% level of ad libitum feed intake from d 1 to 30,50% level of ad libitum feed intake+1%Gln from d 31 to 60).In the in vitro experiments,the yak rumen epithelial cells(YRECs)were divided into 4 groups:Con group(complete medium),Gln group(complete medium+10 mmol/L Gln),Gln deficiency group(Gln-D,Gln-free medium),and Gln deficiency+Gln group(Gln-D+Gln,Gln-free medium+10 mmol/L Gln).Results In the in vivo experiments,FR significantly decreased the ruminal concentrations of acetate,propionate,butyrate,iso-butyrate,and total volatile fatty acid(VFA)(P<0.05).FR also reduced the m RNA expression of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase,and the concentrations of lactate,histone acetyltransferase(p300),histone deacetylase(HDAC),as well as the histone lysine lactylation level compared to Con group,while Gln supplementation alleviated them(P<0.05).In the in vitro experiments,Gln alleviated the Gln-D-induced down-regulation of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase m RNA expressions and reduction of lactate,p300,HDAC concentrations,and histone lysine lactylation level(P<0.05).Besides,p300 inhibitor abrogated Gln repair of barrier function damage in YRECs(P<0.05).Conclusions Overall,our results revealed the potential mechanism of Gln supplementation to repair malnutritioninduced damage of rumen epithelial barrier function in yaks,which might be related to histone lysine lactylation.However,because we do not have a control group receiving glutamine alone,we cannot determine the impact of Gln on the rumen epithelial function of normal yaks.
基金supported by the Key Project of Tibet Autonomous Region(XZ202001ZY0044NXZ202101ZD0002N-05).
文摘The prevalence of bacterial digestive diseases in plateau animals has caused considerable losses to the Tibetan live‑stock industry.Therefore,this study aimed to isolate safe lactic acid bacteria(LAB)with beneficial probiotic proper‑ties to protect yaks from intestinal diseases.After 16S rDNA matching,four strains of Lactobacillus fermentum(A4),Pediococcus pentosaceus(A3.4 and A1.2),and Pediococcus acidilactici(B1.9)were isolated from the intestinal tissues and content of healthy yaks.The results indicated that A4 was more tolerant to bile salt(0.3%),while A3.4 had better stability in an acidic(pH=3.0)environment.The results of the antibacterial activity test suggested that the isolates inhibited most pathogenic bacteria by up to 20%,except for A3.4,which inhibited Pasteurella and Staphylococcus aureus by more than 20%.Moreover,the results of the antioxidant test demonstrated that A4 and A3.4 had potent antioxidant activity.In addition,the drug sensitivity test revealed that the isolates were susceptible to commonly used antibiotics.In terms of safety,the isolates promoted growth,enhanced intestinal development,and protected the intestinal barrier without causing any adverse effects.In conclusion,LAB isolated from yak intestinal contents are potential probiotics with excellent antibacterial properties.
基金supported by the Research and Integrated Demonstration of Efficient Breeding Technology for Yaks(XZ202101ZD0002N-02)Fundamental Research Funds for the Central University(SWU-XDJH202301)。
文摘Coat color represents a key phenotypic trait in Sibu yak,exhibiting distinct black and brown phenotypes.To elucidate the genetic basis of the brown phenotype,genome-wide association studies and multi-omics analyses were integrated to identify loci and molecular pathways involved in pigmentation.In total,11 singlenucleotide polymorphisms(SNPs)on chromosome(chr)5displayed genome-wide significance(P-adjust<4.47×10–9),with the lead variant(chr5:g.47487664 A>G,Padjust=2.38×10–10)located within an intron of PMEL.Expression analysis revealed markedly reduced PMEL transcription in fibroblasts from brown individuals.Functional multi-omics analyses of PMEL overexpression demonstrated significant alteration of the expression of1088 genes,444 proteins,and 57 metabolites.Enrichment analyses indicated significant involvement of melanogenesis-related signaling cascades,including c AMP(e.g.,ADCY7,EDNRA,and epinephrine),PI3K-Akt(e.g.,FGF5,PIK3CG,and FGF7),and MAPK(e.g.,MAP2K6,FGFR3,and ERBB4)pathways.These findings indicate that the intronic PMEL variant modulates gene expression and pigmentation through coordinated regulation of these pathways,thereby contributing to the phenotypic divergence of Sibu yak coat color.This study provides valuable insights into the genetic mechanisms underlying Sibu yak pigmentation and identifies PMEL as a key candidate gene governing coat color differentiation in Sibu yak.
基金the National Natural Science Foundation of China (90202009) for financial support
文摘To assess the impact of N fertilization on contents of mineral elements in herbage and the effect of increased forage S on the copper metabolism of grazing yaks, study was conducted during the summer grazing season （2005, 2006, and 2007）. Pasture replicates （20 ha; n=3 per treatment） received the same fertilizer treatment in each growing season, consisting of i） 90 kg N ha^-1 from quickly available nitrogen, ii） 90 kg N ha^-1 from ammonium nitrate, iii） 90 kg N ha^-1 from ammonium sulfate, and iv） control （no fertilizer）. Forage sampling was collected at 60 days intervals following fertilization （10 samples per pasture） for Cu, Mo, Mn, Se, Fe, Zn, Ca, and P. To determine the effect of fertilizer treatment on mineral metabolism in grazing yaks, liver and blood samples were collected at the start and end of the study period in 2005, 2006, and 2007. Ammonium sulfate fertilization increased （P 〈 0.01） forage S concentration. Plant tissue N concentrations were increased by N fertilization, regardless of source in 2005, 2006, and 2007. Yaks grazing S fertilization pastures had lower （P〈0.05） liver and blood Cu concentrations at the end of the study period in 2005, 2006, and 2007, compared with urea, ammonium nitrate, and control. Nominal increases in forage in vitro organic matter digestibility were realized by fertilization, regardless of N source in each year.
文摘Yak ( Bos grunniens ) is classified as Bovine genus,they live in Qingzang Plateau with elevation more than 3500m and it's neighbor highland,where the weather is high chilly,short of oxygen and large difference of temperature between day and night.But yak have adapted that circumstance after thousands of years' artificial and natural selection and has great anti adversity capacity.Yak is an important sustenance and means of production to Tibetan.China is a country with the largest number of yak,whose amount of livestock on hand accounts for 95% of the world and Tibet region takes the second place next to Qinghai in the number of yak.Tibetan yak has formed some groups for Tibetan's large area,complicated geological ecosystem conditions,geological isolation.The typical better groups are Yadong yak,Jiali yak and Sibu yak. Study about yak fell behind other animals due to the restriction of inconvenient transportation,difficult sampling and poor experimental technology.Study about the relationship between yak blood enzyme activities and milk production was little,only Jing (1992) studied correlation of milk production with serum amylase,esterase in Gansu Jiulong yak,Maiwa yak and no report was found in other groups.This study discussed six Jiali yak blood enzyme activities lactate dehydrogenase (LDH),alkaline phosphatases (AKP),acid phosphatase (ACP),catalase (CAT),amylase (Amy) and superoxide dismutase (SOD),and explored their relationship with milk production in Jiali yak,so as to supply with theoretical evidence by using blood enzyme activity as biochemical assisted selection marker in the breeding of Tibetan yak milk yield. This experiment investigated activity of six blood enzymes from 28 Tibetan yaks and explored its relationship to production performance.The results showed a extremely positive significant difference ( P <0.01) between activity of LDH and milk yield,CAT activity and length of belly hair respectively,while a positive significant difference ( P <0.05) was observed between AKP activity and body weight,Amy activity and body weight and a negative significant difference ( P <0.05) for SOD activity and body weight.Stepwise Regression Analysis showed that activity of LDH could be used for the prediction of milk yield,AKP,CAT,Amy for body weight,CAT,Amy for length of belly hair.So it is expected to use activity of LDH,AKP,CAT,Amy as biochemical genetic marker in the selection of milk yield,body weight and length of belly hair.
基金Supported by the State "Twelfth Five-year" Science and Technology Support Project(2012BAD12D04)
文摘In the study, confinement and semi-confinement raising fattening technology of yaks in agricultural areas of tibet were analyzed. And several suggestions for improving the efficiency of yak raising were put forward. Aiming at providing the reference of healthy raising and sustainable development of yaks in the agricul- tural areas of tibet.
文摘Yaks live in high frigid areas some 3,000-5,000 meters above sea level.In China there are 13 million yaks,making up 90 percent of the world total.They provide with transport means,meat and hide for 4.6 Tibe-tans in Tibet as well as Qinghai,Sichuan,Yunnan and Gansu prov-inces.
文摘Objective:To evaluate the antimicrobial efficacy of berberine,a plant alkaloid.Methods:Five multi-drug resistant（MDR） STEC/EPEC and five MDR ETEC isolates from yaks with haemorrhagic diarrhoea were selected for the study.Antibacterial activity of berberine was evaluated by broth dilution and disc diffusion methods.The binding kinetics of berberine to DNA and protein was also enumerated.Results:For both categories of enterovirulent Escherichia coli（E.roli） isolates, berberine displayed the antibaclerial effect in a dose dependent manner.The MIC<sub>50</sub> of berberine chloride for STEC/EPEC isolates varied from 2.07μM to 3.6μM with a mean of（2.95±0.33）μM where as for ETEC strains it varied from 1.75 to 1.96μM with a mean of（1.87±0.03）μM. Berberine bind more tightly with double helix DNA with Bmax and Kd of（24.68±2.62） and（357.8±57.8）,respectively.Berberine reacted with protein in comparatively loose manner with Bmax and Kd of（18.9±3.83） and 【286.2±113.6),respectively.Conclusions:The results indicate clearly that berberine may serve as a good antibacterial against multi drug resistant E.coli.
基金the International Cooperation Project of the Ministry of Sciences and Technology of China(2014DFA32860)the National Natural Science Foundation of China(31402104)for their financial support
文摘This study was conducted to investigate the phylogenetic diversity of archaea in the rumen of adult and elderly yaks. Six domesticated female yaks, 3 adult yaks （（5.3±0.6） years old）, and 3 elderly yaks （（10.7±0.6） years old）, were used for the rumen contents collection. Illumina MiSeq high-throughput sequencing technology was applied to examine the archaeal composition of rumen contents. A total of 92 901 high-quality archaeal sequences were analyzed, and these were assigned to 2 033 operational taxonomic units （OTUs）. Among these, 974 OTUs were unique to adult yaks while 846 OTUs were unique to elderly yaks; 213 OTUs were shared by both groups. At the phylum level, more than 99% of the obtained OTUs belonged to the Euryarchaeota phylum. At the genus level, the archaea could be divided into 7 archaeal genera. The 7 genera （i.e., Methanobrevibacter, Methanobacterium, Methanosphaera, Thermogymnomonas, Methanomicrobiu, Meth- animicrococcus and the unclassified genus） were shared by all yaks, and their total abundance accounted for 99% of the rumen archaea. The most abundant archaea in elderly and adult yaks were Methanobrevibacterand Thermogymnomonas, respectively. The abundance of Methanobacteria （class）, Methanobacteriales （order）, Methanobacteriaceae （family）, and Methanobrevibacter （genus） in elderly yaks was significantly higher than in adult yaks. In contrast, the abundance of Ther-mogymnomonas in elderly yaks was 34% lower than in adult yaks, though the difference was not statistically significant. The difference in abundance of other archaea was not significant between the two groups. These results suggested that the structure of archaea in the rumen of yaks changed with age. This is the first study to compare the phytogenetic differences of rumen archaeal structure and composition using the yak model.
基金supported by the National Key R&D Program of China(2021YFD1600200)Program of National Beef Cattle and Yak Industrial Technol-ogy System(NO.CARS-37)+1 种基金Natural Science Foundation of Sichuan Province(General Program)(24NSFSC0581)the Scientific and Technological Innovation Team for Qinghai-Tibetan Plateau Research in Southwest Minzu University(Grant No.2024CXTD02)。
文摘Background The genetic diversity of yak,a key domestic animal on the Qinghai-Tibetan Plateau(QTP),is a vital resource for domestication and breeding efforts.This study presents the first yak pangenome obtained through the de novo assembly of 16 yak genomes.Results We discovered 290 Mb of nonreference sequences and 504 new genes.Our pangenome-wide presence and absence variation(PAV)analysis revealed 5,120 PAV-related genes,highlighting a wide range of variety-specific genes and genes with varying frequencies across yak populations.Principal component analysis(PCA)based on binary gene PAV data classified yaks into three new groups:wild,domestic,and Jinchuan.Moreover,we pro-posed a‘two-haplotype genomic hybridization model'for understanding the hybridization patterns among breeds by integrating gene frequency,heterozygosity,and gene PAV data.A gene PAV-GWAS identified a novel gene(Bos-Gru3G009179)that may be associated with the multirib trait in Jinchuan yaks.Furthermore,an integrated transcrip-tome and pangenome analysis highlighted the significant differences in the expression of core genes and the muta-tional burden of differentially expressed genes between yaks from high and low altitudes.Transcriptome analysis across multiple species revealed that yaks have the most unique differentially expressed m RNAs and lnc RNAs(between high-and low-altitude regions),especially in the heart and lungs,when comparing high-and low-altitude adaptations.Conclusions The yak pangenome offers a comprehensive resource and new insights for functional genomic studies,supporting future biological research and breeding strategies.
基金supported financially by the National Natural Science Foundation of China(90202009)
文摘Since the 1990s, yak in the Haizi area in China has been affected by an ailment characterized by pica, emaciation, dyskinesia, and anemia. To determine the cause of disease, the mineral composition of soil and forages, and samples of blood, hair, and liver of yaks from the Haizi area in China were determined. The concentrations of copper in soil and forage from affected ranches and unaffected areas are within the normal ranges. The mean concentration of copper in blood and liver from the affected yaks was （0.31±0.03） and （13.7±3.1）μg·g^-1 respectively, compared with （0.98±0.16） and （95.6±11.2）μg·g^-1 for unaffected yaks. The concentrations of sulfur in soil and forage from affected ranches were （1.91±0.26） and （1.37±0.17）%, respectively, compared with （1.11±0.31） and （0.52±0.18）% （dry matter） for normal areas. The contents of sulfur in blood and liver affected animals were （7.32±1.8） and （2.54±3.1）%, respectively, compared with （4.22±0.73） and （1.31±0.33）% （in fresh and soft tissues） for healthy animals, respectively. Oral administration of tribasic copper chloride prevented and cured the disease. Thus it is reasonable to conclude that ailments of yaks in the Haizi area are probably caused by a secondary copper deficiency, mainly due to high sulfur content in soil and forage.
文摘Female domesticated yaks were artificially inseminated with semen taken from wild yaks and the offspring used to form a nucleus breeding herd of crossbred animals. The meat production of the first generation(F1 × F2)from breedtng within the nucleus herd was assessed by slaughter and carcass dissection of males. One group(no. =14)was slaughtered at 6 months of age and the second(no. = 12)at 18months. Crossbred yaks were significantly heavier(P＜0.01)at 6 months(74.7(s. e. 10.41)kg v. 59.8(s.e. 10.23)kg)and at 18 months(150.5(s. e. 56.1)kg v. 117.7(s. e. 17.4)kg)than domesticated ones,The killing-out proportion(0.47)was similar at both ages and for both groups of animals. Carcass weight,meat weight and the yield of prime cuts were higher for crossbred animals than for domestic yak at both ages.
文摘Wild yak males were crossed with domesticated female yaks to produce a breeding herd of crossbred animals. The milk production of the progeny of this herd was measured in the present study. Yaks were milked once daily after prior suckling of the calf. yaks were allowed to graze for 15 h/day on high-altitude(3200 to 3500 m) pastures. No supplementary food was given. Average daily milk yield of 1.77(s. e. 0. 16)kg and milk yield over 120 days,212.2(s. e. 20.2)kg were significantly higher(P＜0.01)than the corresponding figures for uninlproved domestic yaks(1.53(s. e. 0. 10)kg and 164. 6(s. e. 10.5)kg respectively). The fat content of milk from crossbred yaks, 52(s. e. 2. 9)g/kg, was not significantly dlfferent from that of unimproved animals, 53.5(s. e. 4. 1), g/kg.
文摘This paper was carried out on the morphological character of the test and epididymis of three types of yak bull age 6,12,18,24 months old (1/2 wild yak, cross 1/2 wild yak and domestic yak). The results showed that the weight and size of testes and epidiymis was increased with the age which was hardly affected by imbalance of food supply during the cold and warm seasons. The development were similar for three kinds of yak at the same age(P＞0.05).
基金supported by the National Key Research and Development Program of China(No.2021YFC2300800,2021YFC2300803)State Key Laboratory for Reproductive Regulation and Breeding of Grassland Livestock(No.2021KF0301)+1 种基金NHC Key Laboratory of Echinococcosis Prevention and Control(No.2022WZK1006)The National Parasitic Resources Center,the Ministry of Science and Technology fund(NPRC-2019-194-30).
文摘Introduction:Echinococcosis is a zoonotic parasitic disease caused by the larval stage of Echinococcus,prevalent in northwestern China.It poses a serious threat to human health and causes significant economic losses in the livestock industry.This study aims to investigate the infection and development of Echinococcus in livestock in northwestern China,providing scientific basis for precise prevention and control of echinococcosis.Methods:This study utilized a combination of slaughterhouse and household investigations.Liver and lungs from slaughtered livestock in Sichuan Province,Qinghai Province,Xizang Autonomous Region,and Xinjiang Uygur Autonomous Region were examined through visual inspection and palpation,and Echinococcus cysts were collected.The cyst fertility was analyzed via microscopic examination.Metacestode DNA was extracted for PCR amplification of the mitochondrial Cox1 gene.Sequence alignment with the GenBank database was conducted to identify the genotypes of Echinococcus.Phylogenetic tree was constructed using MEGA 7.0 software.Haplotypes were analyzed using DnaSP 6,and a haplotype network was constructed using PopART 1.7.Data analysis was performed using SAS 9.4,and P<0.05 indicates statistical significance.Results:Between October and December 2023,400 yaks and 808 sheep were surveyed in Qinghai,Xizang,and Xinjiang.The infection rate of Echinococcus in yaks was 16.5%,significantly higher than that in sheep(9.41%,χ^(2)=12.9802,P<0.001).The fertility rate of Echinococcus cysts in sheep was 71.79%,significantly higher than that in yaks(15.57%,χ^(2)=64.1670,P<0.0001).The cysts were mainly parasitizes in the liver of sheep(82.89%)and the lungs of yaks(63.89%).A total of 169 Cox1 sequences were successfully amplified,of which 98.82%(167/169)corresponded to E.granulosus sensu stricto(s.s.)G1/G3,while one sequence was identified as E.canadensis G6,and one from E.multilocularis.A total of 48 haplotypes were detected,with H3 being the predominant haplotype.Conclusions:In the four survey provincial-level administrative divisions(PLADs)of China,the infection rate in yaks(16.5%)was significantly higher than in sheep(9.41%).Echinococcus was found preferably infect sheep liver and yak lungs,with a higher cyst fertility rate in sheep compared to yaks.Livestock infections are mainly caused by E.granulosus G1/G3,and this study,for the first time,identified E.multilocularis infection in yaks from Xizang.The findings provide a crucial foundation for further research into the molecular epidemiology,genetic evolution,and the development of precise prevention and control strategies for Echinococcus in the regions.
基金support was received for the research,authorship,and/or publication of this article.This study was supported by the National Key R&D Program of China(grant no:2021YFD1600202).
文摘The study investigated the metabolic responses of yaks to dietary net energy for gain(NEg)and metabolizable protein(MP),and explored potential biomarkers for average daily gain(ADG)in serum metabolites.A total of 40 three-year-old yaks(initial body weight=255±8.04 kg)were assigned to a 2×2 factorial treatment arrangement based on dietary NEg(4.18 vs 4.81 MJ/kg DM;low NEg[LE]vs high NEg[HE])and MP(72.0 vs 82.8 g/kg DM;low MP[LP]vs high MP[HP]),comprising 4 treatments with 10 replicates each(1 yak per replicate).The yaks were fed these diets for 55 days including a 15-day adaptation period.Yaks on HP diets had greater ADG(P=0.013)and a reduced feed-to-gain ratio(P=0.019)compared to those on the LP diet,and those on the LE diet had greater dry matter intake(P<0.001)but unaffected ADG compared to those on the HE diet(P>0.05).Dietary NEg interacted with MP in relation to the apparent digestibility of dry matter(P=0.028)and crude protein(P<0.001).The apparent digestibility of gross energy(GE),organic matter,and neutral detergent fiber in yaks on the HE diet was greater than those in yaks on the LE diet(P<0.05).The digestibility of GE in yaks on the HP diet was lower than those on the LP diet(P=0.011).An significant interaction between dietary NEg level and MP level was observed on serum total bilirubin concentration,catalase concentration,and superoxide dismutase concentration(P<0.05).Yaks fed HE diets exhibited higher serum glutathione peroxidase protein concentration(P<0.001),but lower serum triglyceride concentration(P=0.012)compared to those fed LE diets.Serum level of alanine transaminase was higher in yaks on the HP diet compared to those on the LP diet(P=0.038).Untargeted metabolomics identified novel biomarkers linked to dietary NEg and MP levels,revealing that the HE diet enhanced adenosine triphosphate production through acetyl-CoA synthesis and affected amino acid,fat,and carbohydrate pathways(P<0.05).The HP diet altered the synthesis of aromatic amino acids and vitamins(P<0.05).Additionally,random forest analysis identified N-(9-oxodecyl)acetamide and biliverdin,as biomarkers for predicting ADG.These findings provide a theoretical foundation for the effective feeding and nutritional management of yaks.
基金This work was supported by the National Natural Science Foundation of China(32072757,U21A20250)the Key Research and Development Program for International Cooperation of Gansu Province,China(21YF5WA117)Key Research and Development and Conversion Program of Qinghai Province,China(2018-SF-145).
文摘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 BW0.75).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 ofβ-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.
基金the National Natural Science Foundation of China(32072757 and U21A20250).
文摘The yak(Bos grunniens),an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level,is closely linked to more than 40 ethnic communities and plays a vital role in the ecological stability,livelihood security,socio-economic development,and ethnic cultural traditions in the Asian highlands.They provide the highlanders with meat,milk,fibres,leather and dung(fuel).They are also used as pack animals to transport goods,for travel and ploughing,and are important in many religious and traditional ceremonies.The Asian highlands are known for an extremely,harsh environment,namely low air temperature and oxygen content and high ultraviolet light and winds.Pasture availability fluctuates greatly,with sparse pasture of poor quality over the long seven-month cold winter.After longterm natural and artificial selections,yaks have adapted excellently to the harsh conditions:1)by genomics,with positively selected genes involved in hypoxia response and energy metabolism;2)anatomically,including a short tongue with a weak sense of taste,and large lung and heart;3)physiologically,by insensitivity to hypoxic pulmonary vasoconstriction,maintaining foetal haemoglobin throughout life,and low heart rate and heat production in the cold season;4)behaviourlly,by efficient grazing and selecting forbs with high nutritional contents;5)by low nitrogen and energy requirements for maintenance and low methane emission and nitrogen excretion,namely,‘Low-Carbon’and‘Nitrogen-Saving’traits;6)by harboring unique rumen microbiota with a distinct maturation pattern,that has coevolved with host metabolism.This review aims to provide an overview of the comprehensive adaptive strategies of the yak to the severe conditions of the highlands.A better understanding of these strategies that yaks employ to adapt to the harsh environment could be used in improving their production,breeding and management,and gaining benefits in ecosystem service and a more resilient livelihood to climate change in the Asian highlands.
