N6-methyladenosine (m6A), a well-known post-transcriptional modification, is implicated in diverse cellular and physiological processes. However, much remains unknown regarding the precise role and mechanism of m6A modification on muscle development. In this study, we make observation that the levels of m6A and METTL3 are markedly elevated during the differentiation phase (DM) compared to the growth phase (GM) in both C2C12 and bovine myoblasts. Notably, deletion of METTL3 decreased m6A levels, and promoted myoblast proliferation, inhibited myoblast differentiation in vitro. By performing m6A sequencing in both GM and DM myoblast, we further identified that TM4SF1 is involved in m6A -regulated muscle development. Mechanistically, METTL3 increases m6A-modified TM4SF1 transcripts, and subsequently YTHDF2 promotes TM4SF1 mRNA degradation in P-body through liquid-liquid phase separation (LLPS). Additionally, the rescue experiments in vivo showed that overexpressing METTL3 could rescue the attenuated myogenesis induced by TM4SF1 overexpression during muscle regeneration in mice. Collectively, our findings shed light on a regulatory mechanism by which m6A modulates muscle development and raise a new model for m6A-mediated mRNA degradation within P-bodies.

Circular RNA (circRNA), a stable ring-shaped RNA molecule found in eukaryotic cells, plays significant roles in biological regulation, particularly by interfering with transcription factor binding or enhancing gene expression. Using transcriptomic sequencing, we identified differentially expressed circRNAs in bovine muscle at various time points. Specifically, circDYRK1A was discovered and shown to enhance differentiation while suppressing proliferation of adult myoblasts. Rescue experiments further demonstrated that circDYRK1A regulates the KLF5 gene expression by interacting with miR21-5p, thus exerting its influence at the transcriptional level. This study marks the first identification of circDYRK1A in cattle and elucidates its role in bovine myoblast development through the circDYRK1A-miR21-5p-KLF5 regulatory axis. These findings contribute novel insights into molecular breeding of cattle and advance fundamental research on beef cattle breeding and muscle development.

本试验旨在研究饲粮钙水平对夏南牛生长性能、钙磷代谢、养分利用及血液指标的影响.选用40头体重[(240.86±5.56)kg]相近、健康的夏南牛公牛,随机分为4组,每组10头.各组分别饲喂钙水平为0.45％、0.54％、0.65％和0.73％的试验饲粮.试验期100 d,分2个阶段,每个阶段50 d.结果表明:1)第1阶段,各组之间生长性能无显著差异(P＞0.05).第2阶段和全期,0.65％组平均日增重显著高于0.45％组和0.54％组(P＜0.05).2)各阶段钙采食量随饲粮钙水平升高显著升高(P＜0.05).第1阶段,0.73％组粪钙排泄量显著高于其他各组(P＜0.05),0.45％组钙表观消化率显著低于其他各组(P＜0.05),0.73％组粪磷排泄量显著高于0.54％组(P＜0.05),0.73％组磷表观消化率显著低于0.54％组(P＜0.05).第2阶段,0.45％组钙表观消化率显著低于其他各组(P＜0.05).3)第1阶段,0.65％组粗蛋白质表观消化率显著高于0.45％组(P＜0.05).第2阶段,各组之间养分表观消化率无显著差异(P＞0.05).4)各组之间各阶段血液钙、磷、骨钙素和降钙素含量均无显著差异(P＞0.05).5)第1阶段,各组之间血液铜、铁、锌、锰、镁含量无显著差异(P＞0.05).第2阶段,0.54％组血液铜含量显著低于0.45％组和0.73％组(P＜0.05),各组之间血液铁、锌、锰、镁含量无显著差异(P＞0.05).综合各项指标,在本试验条件下,推荐240～330 kg夏南牛的饲粮适宜钙水平为0.65％.

In order to compare the separation methods of bovine fibroblasts,the primary cells were isolated and cultured by tissue attachment method and tissue attachment + double enzyme digestion method(trypsin + collagenase Ⅱ)after the samples of bovine ear skin were collected and brought back to the laboratory at low temperature.The results showed that it took 6～7 days for the cells to migrate from the tissue blocks,spindle-shaped cells were visible at 10～11 days,and swirly growth halos were observed at 16 days.Tissue adhesion + double enzyme digestion method requires only 5 days for cells to migrate out of the tissue block,spindle cells can be seen on the 6th day,and the swirly growth halo can be observed on the 10th day.The comparison of the two methods shows that the tissue adhesion and double enzyme digestion method can quickly separate and obtain bovine fibroblasts,and is the best method to obtain bovine fibroblasts.

Type I keratin 9 encoded by the KRT9 gene serves an important special function either in the mature palmar and plantar skin tissue. The changes in skin conditions and thickening of the outer layer of the skin may be affected by environmental variables. A missense mutation rs209302038 (NC_037346.1: g.41782870 G > A) was detected in KRT9, which changing the isoleucine into valine. This study aimed to identify the frequency of allele in this locus in Chinese indigenous cattle, and analyze the connection with heat stress. Our results indicated that the frequency of allele A gradually decreases from south to north, while the frequency of G allele showed the opposite pattern. Further analysis of the association of the different genotypes with three climate factors, which showed that the genotypes (GG, GA, AA) were significantly related to climatic conditions (p < 0.01). Therefore, we speculated that the mutation of the rs209302038 in Chinese indigenous cattle might be a genetic marker to detect heat stress.

Historical hybridization between southern indigenous Chinese cattle and banteng has been well-documented and has resulted in gene introgression. Bitter taste receptors were reported in indigenous cattle as a result of introgression from banteng. To determine the level of introgression of the taste 2 receptor member 16 (TAS2R16) gene from banteng into Chinese cattle, two missense mutations in the bovine TAS2R16 gene were examined. Here, we explored the prevalence of the two variants in 28 indigenous Chinese cattle and banteng breeds (comprising 750 individuals) to determine the influence of banteng introgressions on Chinese cattle based on PCR and DNA sequencing. In our study, the two mutant alleles had a higher frequency distribution in southern China with strong geographic distribution, especially in the south-central and southeast areas. In conclusion, this study examines the impact of introgression on the frequency distributions of mutations in variable regions and the subsequent adaptation of Chinese indigenous cattle to different environmental conditions.

南阳牛以体格大、役肉兼用、耐粗饲、适应性强而著称,夏南牛和"皮南牛"是以南阳牛为基础育成的肉牛品种,本文采用模型化方法对其体重生长发育及早熟性进行了研究.结果显示,夏南牛和"皮南牛"具有生长发育早熟性较好,生长强度大的特点,断奶重相对较大,12 月龄体重分别相当于其36 月龄体重的56.60%和62.21%.其中,"皮南牛"在周岁以前生长强度更大.

SLC45A2 is involved in the synthesis of melanin transporters. We investigated the association between single nucleotide polymorphisms (SNPs) of the SLC45A2 gene and humidity and hot conditions in indigenous cattle habitat. According to the Bovine Genome Variation Database and Selective Signatures (BGVD), we explored the frequency distribution of a missense mutation (NC_037347.1: c.1543A > G, p.ser515gly) in the SLC45A2 gene in Chinese indigenous cattle. This variation from serine to glycine caused a significant change in the protein modeling structure. PCR and partial DNA sequencing were used to genotype 541 individuals, including 28 Chinese indigenous cattle breeds as well as Angus and zebu. From our results, the mutant allele frequency of this SNP in Chinese native cattle increases gradually from north to south, which is consistent with the distribution of climatic conditions in China. In addition, according to association analysis of a missense mutation (NC_037347.1: c.1543A > G) (rs525805167) in Chinese cattle, it is closely related to the annual average temperature (T), relative humidity (RH), temperature and humidity index (THI) and solar radiation time (P < 0.01). Based on the statistical analysis of the data, we assumed that rs525805167 was associated with heat tolerance traits. Simple Summary: The characteristics of Chinese indigenous cattle are closely related to their climatic environment. In China, Bos taurus is mainly distributed in the northern regions; Bos indicus is mainly distributed in southern China. In addition, the average temperature is higher in the south than in the north, and there are many mixed ancestry breeds of B. taurus and B. indicus in the middle area. The SLC45A2 gene is related to melanin synthesis, which may be closely related to heat tolerance in cattle. The purpose of our study was to investigate whether the SLC45A2 gene is related to heat tolerance in Chinese indigenous cattle.

Muscle development is an important factor affecting meat yield and quality and is coordinated by a variety of the myogenic genes and signaling pathways. Recent studies reported that miRNA, a class of highly conserved small noncoding RNA, is actively involved in regulating muscle development, but many miRNAs still need to be further explored. Here, we identified that the miR-183/96/182 cluster exhibited higher expression in bovine embryonic muscle; meanwhile, it widely existed in other organizations. Functionally, the results of the RT-qPCR, EdU, CCK8 and immunofluorescence assays demonstrated that the miR-183/96/182 cluster promoted proliferation and differentiation of bovine myoblast. Next, we found that the miR-183/96/182 cluster targeted FoxO1 and restrained its expression. Meanwhile, the expression of FoxO1 had a negative correlation with the expression of the miR-183/96/182 cluster during myoblast differentiation. In a word, our findings indicated that the miR-183/96/182 cluster serves as a positive regulator in the proliferation and differentiation of bovine myoblasts through suppressing the expression of FoxO1.

[Objective] Through slaughtering analysis, the slaughter performance and meat quality of hornless Xianan cattle can be understood, which can provide information for the next selection of hornless Xianan cattle. [Method] Slaughter determination and meat quality analysis were performed on 20 24-month-old hornless Xianan fattening bulls. [Result] The slaughter rate, net meat rate, eye muscle area, meat-to-bone ratio, high-grade and high-quality meat chunk ratio, and high-grade meat chunk ratio of 20 hornless Xianan cattle were: 62.62%, 52.8%, 111.17 cm~2, 5.82∶1, 49.69 % and 28.36%; the protein content of shoulder meat, large cucumber strip, and outer ridge were: 23.60% ± 0.19%, 20.85% ± 1.21%, 21.52% ± 1.28%; fat content were 4.26% ± 1.61, 3.12%, respectively 3.122% ± 1.05%, 2.80% ± 2.49%; muscle shear force were: 4.60kg ± 1.92kg, 3.59kg ± 1.58kg, 4.49kg ± 1.44kg, respectively. [Conclusion] The breeding and improvement effect of hornless Xianan cattle is remarkable, the ability to produce high-grade meat pieces is strong, and the meat quality is good.

[目的]难产是繁殖母牛的常见疾病,危害母牛和犊牛健康,进行难产牛原因分析有助于兽医或者牛场做好接产工作,提高生产力.[方法]在万方数据服务平台、CNKI中国知网、Elsevier SD数据库和"SCI—科学引文索引"上,用关键词"难产"、"病例"、"牛"精确搜索我国相关的案例,统计筛除后的病例数,对牛难产原因进行统计和分析.本文"CI"表示置信区间.[结果]检索获得母牛难产的病例总数为753例,难产原因占比最大的是胎儿性难产有525例,占69.72％(95％CI 66.3-73.0);其次是产道异常(骨折造成骨盆畸形,子宫颈、阴道、阴门狭窄造成的产道异常)造成的难产89例,占11.82％(95％CI 9.6-14.3);阵缩及努责无力造成的难产41例,占5.44％(95％CI 3.9-7.3);子宫扭转造成的难产38例,占5.05％(95％CI 3.6-6.9);子宫颈开张不全造成的难产26例,占3.46％(95％CI 2.3-5.0);营养不良造成的难产18例,占2.39％(95％CI 1.4-3.8);双胎难产9例,占1.20％(95％CI 0.5-2.3);人为因素和其他因素造成的难产有7例,占0.93％(95％CI 0.4-1.9).[结论]引起母牛难产的最主要的因素是胎儿性难产、产道异常.兽医在实际临床中,应快速、准确确定母牛难产的病因,采取对应接产措施,减少经济损失.

Circular RNA (circRNA) is endogenous noncoding RNA found throughout the eukaryotic genome. It regulates several biological activities at the transcription or post-transcription level. However, the underlying function of circRNA in bovine skeletal muscle development remains unknown. Here, we identified a novel circRNA, circNDST1, and investigated its function and mechanism on the proliferation and differentiation of bovine myoblasts. At the molecular and cellular levels, circNDST1 could promote bovine myoblasts proliferation and inhibit differentiation. Mechanistically, circNDST1 is expressed in the cytoplasmic of myoblast and was enriched by protein Ago2. circNDST1 acts as a competing endogenous RNA that sponges miR-411a and alleviates the inhibitory effect on its target gene, Smad4. miR-411a and Smad4 were also involved in regulating bovine myoblast proliferation and differentiation. These findings suggest that circNDST1 functions as a competing endogenous RNA and regulates bovine myoblast proliferation and differentiation through the miR-411a/Smad4 axis.

[目的]探索胚胎移植前供体牛与受体牛血浆外泌体miRNA的表达差异,以明确血浆外泌体miRNA在牛早期妊娠中的作用及其调控机制.[方法]以3～6岁、体重480～600 kg的夏南牛作为研究对象,选取10头供体牛进行同期发情、超数排卵和人工授精,23头受体牛只做同期发情处理.在人工授精后第7天,冲洗供体牛子宫以获取囊胚,选取3头囊胚数相近的供体牛及3头与供体牛体重和年龄均相近的受体牛,颈静脉采血,进行血浆外泌体的分离与鉴定;然后提取血浆外泌体miRNA,并检测其表达量;采用R语言中的DESeq差异算法计算P值,并筛选出P＜0.05的miRNA,对差异表达的miRNA进行靶基因预测、GO功能富集分析和KEGG信号通路分析.[结果]6个样本的囊泡粒径均在135 nm左右,符合外泌体的特征.与供体牛相比,受体牛中有9个miRNAs表达显著上调(P＜0.05),13个miRNAs显著下调(P＜0.05);22个差异表达的miRNAs中,有15个miRNAs预测出无重复的靶基因 2990个.GO功能富集分析和KEGG信号通路分析的结果表明,这些靶基因主要富集在与生物黏附(biological adhesion)、定位(localization)、细胞连接(cell junction)功能有关的通路上,显著富集的信号通路与黏着斑(focal adhesion)、黏着连接(adherens junction)有关,提示血浆外泌体miRNA可能参与调控胚胎着床.[结论]研究结果可为筛选和探究影响胚胎着床的血浆外泌体miRNA提供参考,并为进一步阐明血浆外泌体miRNA在母牛早期妊娠调控中的作用提供依据.

为探讨单舍单犊饲养模式对犊牛成活率、腹泻发生率和死亡率的影响,采用回顾性队列研究方法,对两个饲养条件类似牛场2013—2018年的犊牛腹泻资料进行统计学分析.结果显示:采用单舍单犊饲养模式的A场与对照B场的犊牛成活率分别为98.11％(468/477)、70.83％(306/432),OR=0.047(95％CI,0.023～0.093),P=0;犊牛腹泻发病率分别是37.32％(178/477)和50.93％(220/432),OR=1.743(95％CI,1.338～2.271),P=0;腹泻犊牛死亡率分别是1.68％(8/477)和12.73％(55/432),OR=8.553(95％CI,4.024～18.178),P=0;腹泻犊牛病死率分别为4.49％(8/178)和25.00％(55/220),OR=7.083(95％CI,3.273～15.328),P=0.结果表明,单舍单犊饲养模式可显著提高总犊牛成活率,显著降低腹泻发病率、死亡率和病死率(P≤0.01).本研究为牧场采取相应管理措施提高犊牛成活率提供了依据,也拓宽了牧场的分析性工作方法,从而促进牧场的整体管理,提高经济效益.

[目的]探究郏县红牛的mtDNA D-loop遗传多样性与母系起源.[方法]采用生物信息学方法.[结果]在46头郏县红牛mtDNA D-loop区全序列共检测到60个变异位点,定义20种mtDNA D-loop单倍型,平均单倍型多样度(Hd)为0.8530,平均核苷酸多样度(Pi)为0.0254,表明郏县红牛有丰富的母系遗传多样性.构建的IQ系统发育树表明郏县红牛具有瘤牛和普通牛两个母系支系.[结论]郏县红牛具有丰富的母系遗传多样性,有普通牛和瘤牛两个母系起源.

[目的]为了分析河南三种肉牛超数排卵效果.[方法]分别选择夏南牛、郏县红牛、南阳牛作为试验母牛,采用两次PG+促卵泡素(FSH)的方法对试验母牛进行超数排卵,观测试验母牛获得总胚胎数、可用胚数分析超数排卵效果.[结果]结果显示,夏南牛可用胚9.86枚/头,南阳牛可用胚7.71枚/头,郏县红牛为6.75枚/头,可用胚中夏南牛最高与郏县红牛和南阳牛有显著性差异.可用胚率郏县红牛最高79.41％,显著高于夏南牛和南阳牛.[结论]结果表明,PG+FSH法可以用于夏南牛、郏县红牛和南阳牛的超数排卵.

Bovine leukocyte antigen, class II, DO beta (BoLA-DOB) is related to antigen presentation, which can triggered by multicul factors. And the condition of immune function determines how much cattle load to heat stress. To evaluate the relationship between heat-resistance and single nucleotide polymorphisms (SNPs) in BoLA-DOB gene, our study has taken further analysis in Chinese indigenous cattle for the first time. A missense single nucleotide polymorphism (rs464874590) was detected in BoLA-DOB gene. We directly sequenced rs464874590 (NM_001013600.1 g.7122762 A G) in BoLA-DOB gene of 522 individuals of 26 cattle breeds. The frequency of allele G gradually decreases from south to north with distinct climatic distribution characteristics. Further association analysis was carried out between different genotypes and environmental parameters, including annual mean temperature (T), relative humidity (RH), and temperature-humidity index (THI). The result showed that three genotypes were significantly correlated with T, H, and THI (P < 0.01), indicating that GG genotype was distributed in areas with hot and moist conditions. Therefore, our results suggested that the rs464874590 could be applied as a genetic marker to detect the heat-resistance of Chinese indigenous cattle.

蜱虫病是被蜱虫叮咬而感染,造成牛充血、水肿和继发性病症;锥虫病是感染锥虫后引起牛贫血、黄疸、高热、体表浮肿等.由于牛的品种不同以及生活环境的差异,导致牛对蜱虫病和锥虫病的抗性不同,加大了防治和研究的难度.寄生虫寄生于畜体中,就会和宿主产生一定的互作关系,引起机体代谢、信号转导、基因表达等发生变化.因此,从分子机制入手可以更深入了解致病原因和抗病机理.该文主要从牛蜱虫病与锥虫病概况、牛对蜱虫病与锥虫病的抗虫性能、牛抗蜱虫病与抗锥虫病的分子机制3个方面进行综述,以期为牛寄生虫病防治和培育优良牛品种提供理论基础.

自2019年12月我国暴发新冠肺炎疫情以来,全国31个省市启动重大突发公共卫生事件一级响应预案.为了有效隔离,一段时间内各地采取了封城、封区、封镇等措施阻止疫情扩散,取得了阶段性成果.但是封锁、隔离和限制移动给养殖业等基础行业带来严重影响.鉴于此,国家肉牛牦牛产业技术体系疾病控制研究室岗位专家联合国家肉牛牦牛产业技术体系遗传育种研究室张杨岗位专家及其团队成员于2月1日,对全国43个养殖场进行了电话调研,了解封锁和移动控制的强制实施措施下各养殖场的情况及其面临的挑战.

Association studies have indicated profound effects of copy number variations (CNVs) on various phenotypes in different species. In this study, we identified the CNV distributions and expression levels of guanylate-binding protein 6 (GBP6) associated with the growth traits of Chinese cattle. The results showed that the phenotypic values of body size and weight of Xianan (XN) cattle were higher than those of Nanyang (NY) cattle. The medium CNV types were mostly identified in the XN and NY breeds, but their CNV distributions were significantly different (adjusted p < 0.05). The association analysis revealed that the body weight, cannon circumference and chest circumference of XN cattle had significantly different values in different CNV types (p < 0.05), with CNV gain types (Log22−ΔΔCt > 0.5) displaying superior phenotypic values. We also found that transcription levels varied in different tissues (p < 0.001) and the CNV gain types showed the highest relative gene expression levels in the muscle tissue, consistent with the highest phenotypic values of body weight and cannon circumference among the three CNV types. Consequently, our results suggested that CNV gain types of GBP6 could be used as the candidate markers in the cattle-breeding program for growth traits.