Pangenome and multi-tissue gene atlas provide new insights into the domestication and highland adaptation of yaks

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.

Potential antibacterial activity of berberine against multi drug resistant enterovirulent Escherichia coli isolated from yaks(Poephagus grunniens) with haemorrhagic diarrhoea

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 MIC50 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.

牦牛MT-Ⅰ/-Ⅱ cDNA分子克隆及其蛋白质结构分析

利用基因特异引物YMTSP1和YMTSP2,通过RT-PCR从牦牛肝脏组织RNA中克隆出了牦牛 MT-Ⅰ(Genbank Accession No:AY513744)和MT-Ⅱ(Genbank Accession No:AY513745)基因编码区全 长。将牦牛MT-Ⅰ和MT-Ⅱ cDNA序列在CBI上进行同源性搜索发现,牦牛MT-Ⅰ/-Ⅱ编码区序列在 不同哺乳动物中相当保守。牦牛MT-Ⅰ和MT-Ⅱ编码的MT-Ⅰ和MT-Ⅱ蛋白分别由61个氨基酸组 成,其具有保守的短肽结构如:C-X-C,C-C-X-C-C,C-X-X-C等,其决定MT蛋白分子的整个三维结 构,在分子进化上十分保守。同时对牦牛MT的疏水性和跨膜区分析表明,牦牛MT蛋白可能不 存在跨膜区,也不存在信号肽,是1种非分泌蛋白。并通过同源比较模建,预测和构建了牦牛 MT-Ⅰ和MT-Ⅱ蛋白的分子空间结构,表明牦牛MT-Ⅰ和MT-Ⅱ由α-和β-两个结构域组成,在α-结构 域含有5个Cys短肽结构,β-结构域有4个Cys短肽结构,且2个结构域由保守的三肽序列KKS 相连。

牦牛皮胶的毒理学安全性评价

目的:评价牦牛皮胶的安全性,为其应用提供毒理学安全依据。方法:进行小鼠经口急性毒性试验、大鼠遗传毒性试验及30天喂养试验。结果:①小鼠经口急性毒性试验,雌、雄小鼠经口累计两次灌胃量达15g/kgBW(相当于人群推荐量0.133g/kgBW的113倍),属无毒级。②遗传毒性试验。小鼠骨髓微核试验及小鼠精子畸形试验结果均为阴性。③大鼠30天喂养试验。未发现其对试验大鼠的生长发育、血液学、生化、脏体比及组织病理学有明显不良影响。结论:在试验剂量3.28g/kgBW～15g/kgBW范围内。

西藏中部地区散养牦牛和绵羊细粒棘球绦虫cox1和nad1的多态性

目的分析西藏中部地区散养牦牛和绵羊细粒棘球绦虫cox1、nad1的基因多态性。方法采集西藏中部地区45份散养牦牛和绵羊细粒棘球蚴包囊,提取包囊生发层DNA,根据细粒棘球蚴线粒体cox1、nad1基因序列设计扩增的引物序列,用PCR技术扩增线粒体cox1、nad1基因片段,将扩增产物做琼脂糖凝胶电泳并测序;利用MEGA11.0软件做cox1、nad1序列特征与同源性比对,并构建系统进化树;运用DnaSP 5.0软件计算序列单倍型数量(H),分析核苷酸多样性(Pi)、单倍体型多样性(Hd)特性;利用Network软件为cox1、nad1基因的所有单倍体构建单倍体网络图,判断西藏中部地区散养牦牛和绵羊的主要单倍型。结果(1)cox1、nad1序列长度分别为925、839bp。(2)在cox1序列中,A、T、G、C碱基的平均含量分别为32.6%、33.1%、17.4%、16.9%;而nad1序列中,A、T、G、C碱基的平均含量为19.5%、47.6%、25.5%、7.4%;同源性分析结果显示,cox1序列之间的同源性为99.6%~100.0%,nad1序列之间的同源性为98.1%~100.0%;西藏中部地区散养牦牛和绵羊细粒棘球绦虫基因型为G1、G3、G6。(3)cox1、nad1单倍型个数分别为19个、7个,Hd、Pi分别为0.89600、0.56000和0.36500、0.00060。(4)单倍型网络图显示,Hc-2、Hc-12、Hn-1为西藏中部地区散养牦牛和绵羊的主要单倍型。结论西藏中部地区散养牦牛和绵羊细粒棘球绦虫基因型为G1、G3、G6,G1是主要基因型。上述结论为探明西藏中部地区细粒棘球蚴的分型和病原体遗传演化的情况提供了参考依据。

青海地区不同动物源志贺菌毒力相关基因的分布研究

为了解青海省不同动物源志贺菌相关毒力基因的分布情况,试验对分离自青海省不同地区的62株不同动物源志贺菌进行了DNA提取,将其作为模板对志贺菌的毒力基因set1B、virA、set1A、ial、ipaBCD、Sen、icsP、iutA、icsA、ipaH进行了PCR检测,并统计各毒力基因在不同动物源志贺菌中的检出率、不同动物源志贺菌毒力基因携带模式及携带毒力基因种类。结果表明:62株志贺菌毒力基因set1B、virA、set1A、ial、ipaBCD、icsP、Sen、iutA、icsA、ipaH的检出率分别为6.5%、43.5%、3.2%、25.8%、37.1%、0、12.9%、22.6%、50.0%、100%。在27株猪源志贺菌中,毒力基因ipaH、VirA、icsA、ipaBCD的检出率较高,然后依次为ial、iutA、Sen,未检出icsP。在27株鸡源志贺菌中,毒力基因ipaH、icsA、virA的检出率较高,然后依次为ipaBCD、ial、Sen、iutA,未检出set1B、set1A、icsP。在4株牦牛源志贺菌中,毒力基因ipaH、icsA、ipaBCD的检出率较高,然后依次为virA、ial、iutA,未检出set1B、set1A、Sen、icsP。在4株藏羊源志贺菌中,毒力基因ipaH、ipaBCD、iutA的检出率较高;然后依次为virA、ial,未检出set1B、set1A、Sen、icsP、icsA。在62株志贺菌中,有7株菌只检出毒力基因ipaH,55株菌携带两种及以上毒力基因,共呈现出30种携带模式,其中以virA-icsA-ipaH模式的菌株最多(11.3%,7/62),然后为ipaBCD-ipaH模式(9.7%,6/62);猪源和鸡源志贺菌毒力基因的携带模式均为18种,牦牛和藏羊源志贺菌毒力基因的携带模式均为4种。在62株志贺菌中,有18株菌携带2种毒力基因,15株菌携带3种毒力基因,13株菌携带4种毒力基因,7株菌携带5种毒力基因,2株菌携带6种毒力基因。27株猪源志贺菌中携带1,2,3,4,5,6种毒力基因菌株的占比分别为3.7%、40.7%、14.8%、18.5%、14.8%、7.4%,27株鸡源志贺菌中携带1,2,3,4,5,6种毒力基因菌株的占比分别为18.5%、18.5%、29.6%、22.2%、11.1%、0,4株牦牛源志贺菌中携带1,2,3,4,5,6种毒力基因菌株的占比分别为25.0%、0、25.0%、50.0%、0、0,4株藏羊源志贺菌中携带1,2,3,4,5,6种毒力基因菌株的占比分别为0、50.0%、50.0%、0、0、0。62株志贺菌单毒力基因携带率(11.3%,7/62)<多重毒力基因携带率(88.7%,55/62),其中猪源志贺菌的多重基因携带率最高(42.0%),然后依次为鸡源(35.5%)、藏羊源(6.4%)和牦牛源(4.8%)。说明青海地区志贺菌携带多种毒力基因,携带模式呈现多样性且因动物源不同有所差异,同时应重点加强青海地区猪志贺菌病的防治工作。

Comparison of rumen archaeal diversity in adult and elderly yaks(Bos grunniens)using 16S rRNA gene high-throughput sequencing

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.

Effect of Nitrogenous Fertilizer Treatment on Mineral Metabolism in Grazing Yaks

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.

Sulfur-Induced Copper Deficiency in the Yaks

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.

基于转录组数据挖掘牦牛皱胃发育代谢的关键候选基因

旨在比较不同年龄段牦牛皱胃指数测定、转录组表达谱的变化,挖掘影响牦牛皱胃发育代谢的信号通路和关键基因,为进一步探讨牦牛皱胃发育机制提供理论基础。本研究对1日龄、20日龄、60日龄、15月龄与3岁的牦牛皱胃组织进行转录组测序,对转录组数据进行质控、比对、差异表达基因筛选,并对差异表达基因进行GO功能注释和KEGG富集分析。为进一步验证测序数据的可靠性,随机选取5个差异表达基因进行qRT-PCR验证。结果显示,在发育过程中,瘤胃重的增长最快,其次是瓣胃、网胃和皱胃。转录组结果显示,以1日龄组为对照,在20日龄、60日龄、15月龄和3岁组中分别鉴定到1310、1715、1931和2199个差异表达基因,4个组共有基因565个;以前一个时间点为对照,20日龄、60日龄、15月龄和3岁组分别鉴定到1310、861、569和597个差异表达基因,4个对比组共有基因9个。GO功能注释发现,以1日龄组为对照,20日龄、60日龄、15月龄和3岁组分别富集到1191、2578、1117和2835条显著条目,不同年龄组的前10条显著性GO条目中有共有的,也有各年龄阶段特有的条目。KEGG富集分析结果显示,20日龄、60日龄、15月龄和3岁4个年龄段的前30条显著通路中特有信号通路分别为4、1、3和4条,包括ECM受体相互作用、细胞色素P450对外源性物质的代谢和药物代谢-细胞色素P450等与皱胃发育相关的通路。qRT-PCR结果与测序结果基本一致,表明测序结果可靠。通过对牦牛不同发育阶段皱胃组织的转录组测序及生物信息学分析,筛选到与皱胃发育相关的差异表达候选基因,这些基因主要参与胃粘膜上皮细胞增殖分化、细胞分化和免疫调控等过程,其中GKN1、CXCL17、SCNN 1B、SCNN 1G、CCL 5和IGF 2BP3等基因可能在牦牛皱胃发育过程中起着重要作用;进一步筛选到参与皱胃葡萄糖代谢、葡萄糖转运、脂肪酸转运、肽转运等过程相关的信号通路和候选基因,其中GANAB、GBA2、SLC 2A1、SLC 2A3、SLC 2A4、CPT 1B、SLC 15A1等是与牦牛皱胃组织营养代谢和吸收相关的重要候选基因。

Supplementation with yak (Bos grunniens) bone collagen hydrolysate altered the structure of gut microbiota and elevated short-chain fatty acid production in mice

In this study, yak bone collagen hydrolysate(YBCH)was produced by mixed proteases and provided to standard-diet mice at a different dose(low dose(LD), medium dose(MD), and high dose(HD))to investigate its effects on the composition of gut microbiota and short-chain fatty acids(SCFA)production. It was found that YBCH was mainly composed of small molecular peptides whose molecular weight below 2 000 Da. Notably, supplementation with different doses of YBCH could significantly downregulate the ratio of Firmicutes to Bacteroidetes in the fecal microbiota. At the family level, the Lachnospiraceae abundance was significantly reduced in the YBCH gavage groups(mean reduction ratio 41.7 %, 35.2%, and 36.4% for LD, MD, and HD group, respectively). The predicted functions of gut microbes in the MD group were significantly increased at “lipid metabolism” and “glycan biosynthesis and metabolism”. Moreover, the SCFA production in the YBCH groups was elevated. Especially, the concentration of acetic acid, propionic acid, and butyric acid in the MD group was separately increased 79.7%, 89.2%, and 78.8% than that in the NC group. These results indicated that YBCH might be applied in the development of functional food for intestinal microecological regulation.

Study on the Correlation between Blood Enzyme Activity and Production Performance in Tibetan Yaks

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.

西藏部分县域牦牛球虫寄生现状调查

为了调查西藏部分地区牦牛球虫病感染率、寄生球虫种类特征,采用饱和食盐水漂浮法检查西藏日喀则市(萨嘎县、亚东县)、那曲市(嘉黎县、聂荣县)和阿里地区(改则县)245份牦牛粪便样本内球虫。研究结果显示,各调查县域牦牛球虫感染率较高,平均感染率为71.43%,萨嘎县、亚东县、聂荣县、嘉黎县、改则县牦牛球虫感染率分别为82.61%(38/46)、80.25%(65/81)、68.97%(20/29)、68.18%(30/44)和48.89%(22/45);感染强度最高可达15000(OPG);牦牛球虫病呈现以混合感染为主的特点,阳性病例中混合感染率达100.00%,80.57%的患病牦牛同时寄生3种以上球虫;经鉴定,在样本中共发现6种球虫病病原,分别为邱氏艾美耳球虫(E.zuernii)、牛艾美耳球虫(E.bovis)、怀俄明艾美耳球虫(E.wyomingensis)、阿拉巴艾美耳球虫(E.alabamensis)、柱状艾美耳球虫(E.cylindrica)、拨克朗艾美耳球虫(E.bukidnonensis)。调查地区牦牛球虫感染率高,均呈现混合感染,且在调查区域内发现致病力很强的邱氏艾美耳球虫(E.zuernii)、牛艾美耳球虫(E.bovis),其对当地牦牛的危害值得深入研究。

不同蛋白质、能量水平饲粮对舍饲育肥牦牛生长性能、养分表观消化率及血清生化指标的影响

本试验旨在研究不同蛋白质、能量水平饲粮对舍饲育肥牦牛生长性能、养分表观消化率和血清生化指标的影响。选取年龄相近、体况良好、体重[(180.00±11.67)kg]相近的公牦牛90头,随机分为9组,每组10头。采用2因素3水平随机区组进行设计,即低(12.5%)、中(15.5%)、高(18.5%)3个蛋白质水平和低(6.5 MJ/kg)、中(7.5 MJ/kg)、高(8.5 MJ/kg)3个综合净能水平,按3×3(蛋白质水平×综合净能水平)设计9种不同蛋白质和能量水平的全混合日粮(TMR),每个试验组饲喂1种,预试期20 d,正试期90 d。结果表明:1)饲粮蛋白质水平对所测各生长性能指标影响均不显著(P>0.05);饲粮综合净能水平对总增重(TWG)和平均日增重(ADG)影响显著(P<0.05),对料重比(F/G)影响极显著(P<0.01);饲粮蛋白质水平和综合净能水平两者交互对TWG、ADG和F/G影响极显著(P<0.01)。2)饲粮蛋白质水平对粗蛋白质(CP)和粗灰分(Ash)表观消化率影响极显著(P<0.01),对酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)和粗纤维(CF)表观消化率影响显著(P<0.05);饲粮综合净能水平对Ash表观消化率影响显著(P<0.05);饲粮蛋白质水平和综合净能水平两者交互对干物质(DM)和Ash表观消化率影响显著(P<0.05)。3)饲粮蛋白质水平对血清尿素氮(UN)含量影响极显著(P<0.01),对磷(P)含量影响显著(P<0.05);饲粮综合净能水平对血清总蛋白(TP)、白蛋白(ALB)、UN、甘油三酯(TG)和总胆固醇(TC)含量影响极显著(P<0.01),对总胆汁酸(TBA)含量影响显著(P<0.05);饲粮蛋白质水平和综合净能水平两者交互对血清碱性磷酸酶(ALP)活性和UN含量影响极显著(P<0.01),对肌酐(CRE)和P含量影响显著(P<0.05)。由此得出,在本试验条件下,饲粮综合净能水平对牦牛生长性能的影响大于蛋白质水平的影响;饲粮蛋白质水平对牦牛养分表观消化率的影响大于综合净能水平对其的影响;饲粮中综合净能水平为8.5 MJ/kg、蛋白质水平为15.5%时,舍饲育肥牦牛生长性能最佳。

高寒草甸功能群组成及营养品质对不同放牧强度的响应

为了探究高寒草甸对牦牛长期放牧活动的响应,选择青藏高原高寒草甸为对象,调查不同放牧强度对高寒草甸植物群落生物量、功能群组成变化和牧草品质的影响,探讨植被功能群组成变化及牧草品质之间的互作关系。结果表明:1)禁牧处理下的植物群落生物量最高,但植物群落生物量在有放牧的样地随放牧强度的增加呈下降趋势;2)物种丰富度和多样性随放牧强度的增加基本呈单峰变化,中度放牧下群落多样性指数、物种丰富度和均匀度指数均高于轻牧和重牧;3)植物粗蛋白与粗灰分含量随放牧强度增加而上升;4)放牧强度增加,豆科、毛茛科和杂类草比例无显著变化(P>0.05),禾本科占比降低,禾本科与莎草科呈此消彼长的关系;5)功能群组成变化与牧草营养之间有显著相关关系,其中粗蛋白含量随禾本科比例下降而下降,但与豆科、毛茛科及菊科占比呈负相关关系,莎草科占比与中性洗涤纤维呈显著正相关关系。综上所述,不同放牧强度下植物群落特征及营养品质发生不同程度的变化,对比禁牧,轻度放牧对地上和地下生物量有最优的促进作用,中度放牧有助于群落物种多样性的增加。适度放牧可以保持草地植物群落稳定,促进草地生态系统可持续发展。

脑源性神经营养因子在牦牛与黄牛端脑不同区域的表达与分布

目的探讨高原牦牛与平原黄牛端脑中脑源性神经营养因子(BDNF)表达与分布,探讨BDNF功能发挥与高原低氧适应性之间的关联。方法选取牦牛和黄牛各5只,应用Real-time PCR、Western blotting及免疫组织化学技术对BDNF在牦牛和黄牛端脑的额叶、颞叶、顶叶、枕叶、大脑白质以及海马中的含量与分布进行了定量与定性分析。结果Real-time PCR结果表明,在牦牛与黄牛端脑中,BDNF mRNA均在颞叶皮质中的表达量最高,海马次之,其后依序为顶叶皮质,枕叶皮质和额叶皮质,在大脑白质中的表达量最低。Western blotting结果表明,BDNF蛋白在牦牛颞叶皮质中含量最高,海马次之,其他组织含量由高到低依次为顶叶皮质、额叶皮质、大脑白质,枕叶皮质中含量最低。BDNF蛋白在黄牛端脑颞叶皮质中含量最高,海马次之,其余组织含量由高及低依次为顶叶皮质、枕叶皮质、额叶皮质,大脑白质中蛋白含量最低。免疫组织化学结果表明,BDNF蛋白在牦牛和黄牛端脑中的阳性表达情况基本相似,主要分布在额叶皮质、颞叶皮质、顶叶皮质、枕叶皮质的颗粒细胞和神经胶质细胞,大脑白质的神经胶质细胞以及海马的锥体细胞层和多形细胞层,在端脑皮质区的马丁诺提细胞和海马的分子细胞层中有少量分布。结论BDNF mRNA和蛋白在牦牛和黄牛端脑不同区域中均有表达,但表达量存在差异,推测与端脑不同分区的特定功能密切相关。牦牛端脑中的表达水平除枕叶皮质外,均高于黄牛,推测与其生存的高原低氧环境有关,BDNF在动物机体适应低氧环境过程中可能发挥着增强低氧耐受性和保护机体内环境稳态等重要功能。

暖季补饲对高寒牧区天然草地放牧泌乳牦牛产乳性能的效应

青藏高原高寒草甸草地牧草营养品质虽高,但产量极低,尤其缺乏蛋白饲草且草地呈现不同程度退化,导致泌乳牦牛(Bos grunniens)营养不良,乳产量和品质呈下降趋势。另外,多汁饲料因富含维生素、水分等,通常作为提高奶牛产乳性能的重要饲料种类,但其对泌乳牦牛产乳性能的影响尚不明确。由于青藏高原牧区大多相对干旱,天然草地植物水分含量相对较少,因此预测补给多汁饲料,可能也会提高泌乳期牦牛维生素以及水分的摄取,提高泌乳性能。本研究于2021年暖季(7月-10月)在西藏那曲高寒牧区筛选了体重、年龄、胎次相近的带犊泌乳牦牛24头,随机分4组,在天然草地传统放牧基础上分别设蛋白质饲料[苜蓿(Medicago sativa):1 kg·(d·head)^(-1)]、多汁饲料[萝卜(Raphanus sativus):1 kg·(d·head)^(-1)]、蛋白质加多汁饲料[萝卜和苜蓿各0.5 kg·(d·head)^(-1)]补给和不补给饲料(对照)处理,探讨暖季补给蛋白质和多汁饲料对青藏高原高寒牧区天然草地放牧泌乳期牦牛乳产量和品质(乳脂率、蛋白质率、非脂乳固体率、乳糖率、灰分率、密度、冰点)的影响。结果表明:与对照比较,蛋白质饲料补给显著提高了天然草地放牧泌乳牦牛日产乳量(P<0.05),提高率达22%,延缓了泌乳期牦牛产乳量随时间下降的趋势;多汁饲料补给显著降低了天然草地放牧泌乳牦牛日产乳量,降低率为6%(P<0.05)。与对照比较,单独补给蛋白质饲料或蛋白质加多汁饲料均显著提高了天然草地放牧泌乳牦牛的乳蛋白质率、非脂肪固体率、乳糖率、乳灰分以及乳密度,显著降低了乳冰点,同时补给蛋白质加多汁饲料显著降低了乳脂率。另外,与对照比较,仅补给多汁饲料显著提高了乳脂率、蛋白质率、非脂肪固体率和灰分率,显著降低了乳冰点。但3种补饲处理对泌乳牦牛和犊牛体重均无显著影响(P>0.05)。综上,即使在牧草生长旺盛的暖季,天然草地仍无法满足泌乳牦牛营养需求。且补给蛋白质和多汁饲料均有效提高泌乳牦牛产乳潜能。因此对缓解草畜矛盾,加速当地畜牧业发展以改善当地生活状况具有重要意义。

Complete Sequence of Yak Mitochondrial D-loop Region and Its Taxonomic Status in Bovinae

Primers based upon the mitochondrial genome sequences of Bos taurus were used to amplify and sequence the complete mitochondrial D-loop region of Jiulong yak(Poephagus grunniens).The results showed that the length of D-loop was 893 bp,with 87.4%homology to the Bos taurus D-loop sequence;there were 17 bp deletion.Using Ovis aries as an outgroup,the phylogeny of representative species of Bovinae(P.grunniens,P.mutus,Bos taurus,Bos indicus,Bison bison,Bison bonasus,and Bubalus bubalis)was analyzed.Among Bovinae,the sequence divergence between P.grunniens,P.mutus and American bison(Bison bison)was 6.2%-6.8%,which was less than that of Bos taurus and Bos indicus within Bos(10.0%-11.3%).Phylogenetic analysis found that P.grunniens,P.mutus and Bison bison clustered first of all,indicating there was higher genetic comparability among them than to that of Bos.Combining data from paleontology,morphology,and molecular biology,the present analysis supports the argument that Poephagus grunniens and Poephagus mutus should be classified as a distinct genus in Bovinae,that is Poephagus.

冷季不同饲养管理模式和粗精比饲粮对牦牛瘤胃菌群结构和功能的影响

为探究饲养管理模式和不同粗精比饲粮对冷季牦牛瘤胃菌群丰度和多样性的影响,并预测菌群功能。选取2岁龄(24月龄),体重相近、体况良好的公牦牛(Bos grunmiens)24头随机分为4组,RCG1组在冬季放牧场自然放牧,RCC90、RCC70和RCC50组分别饲喂粗精料比为90∶10、70∶30和50∶50的饲粮。试验结束屠宰后采集各组牦牛瘤胃液,利用16S rDNA高通量测序检测其菌群结构。结果表明,24份样品共检测到20696个ASVs,有4966、3069、3680和3536个ASVs分别在RCG1、RCC90、RCC70和RCC50组4组样品特异性表达。在门和属水平上,4组样品的共同优势菌为厚壁菌门、拟杆菌门、变形菌门,以及理研菌科RC9属、普雷沃菌属和克里斯滕森菌科_R-7菌群。RCG1组和补饲组牦牛瘤胃菌群区系和丰度差异显著(P<0.05)。各补饲组厚壁菌门/拟杆菌门相对丰度(F/B)比值显著高于RCG1组(P<0.05)。与RCG1相比,理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)、产生乙酸相关细菌(Anaerovorax)和毛螺科菌_UCG-009(Lachnospiraceae_UCG-009)分别在RCC50、RCC70和RCC90组中显著下调(P<0.05),普雷沃菌属(Prevotella)、赤芍铁杆菌(Ferruginibacter)和梭菌属_UCG-014(Clostridia_UCG-014)分别在RCC50、RCC70和RCC90组中显著上调(P<0.05)。此外,4组牦牛瘤胃菌群功能差异不显著(P>0.05),均注释到营养代谢和复制与修复等生物过程。饲养管理模式和不同粗精比饲粮对牦牛瘤胃菌群结构影响显著(P<0.05),菌群功能影响不显著(P>0.05),冷季补饲10%精料可显著提高瘤胃菌群丰度和多样性(P<0.05),补饲30%高蛋白水平精料时瘤胃菌群对饲草料消化吸收最佳。本研究结果为青藏高原牦牛的合理饲养提供了数据支撑,也为研发适宜于青藏高原牦牛养殖业的管理模式,减轻放牧场压力,解决草地退化、草畜失衡及保持牦牛养殖业的健康良性发展等问题提供了理论支持。

干式熟成时间对牦牛肉品质的影响

为探究牦牛肉在不同干式熟成时间(7、14、21、28和35 d)下品质的变化,本研究采用感官评价、质构和气相色谱-离子迁移谱(Gas Chromatography-Ion Mobility Spectrometry,GC-IMS)技术分析了不同干式熟成时间牦牛肉的质构变化和风味差异,并结合偏最小二乘法分析(Partial Least Squares-Discrimination Analysis,PLSDA)筛选出其特征性风味物质。结果表明,干式熟成35 d样品综合得分最高,其触感柔软组织结构完好,香气整体可接受度较好;干式熟成时间对牦牛肉硬度、咀嚼性、胶黏性和内聚性具有显著影响(P<0.05)并随熟成时间延长呈逐步下降趋势;共检测出50种挥发性化合物,主要包括醇类14种、醛类11种、酯类12种、烯烃类3种、酮类2种和酸类2种(包括单双聚体),其中醛类、醇类和酯类等化合物相对含量随熟成时间延长呈增长趋势,酮类和烯烃类化合物相对含量呈下降趋势。不同熟成时间牦牛肉整体风味存在差异,0 d和35 d整体风味差异较大;筛选出17种关键挥发性化合物,包括3-羟基-2-丁酮(D)、正己醇(M)和正己醛(D)等。该研究揭示了干式熟成时间对牦牛肉质构和风味的影响,为干式熟成牦牛肉风味形成和产品开发提供了一定的理论依据。