Yak Breeds Research Articles

Politiques pastorales et transformations de l’élevage des yaks sur le plateau tibétain : l’intégration au marché peut-elle apporter une solution à la dégradation continue de la steppe ?

The Western Region, a new area for development in China, faces tremendous environmental, economic and social challenges. During the last six decades, a succession of policies has transformed the production systems and had a profound impact on the environment of the region, and has resulted in a huge diversity of local situations. Yak breeding on the Qinghai-Tibet Plateau has been chosen to illustrate this diversity and the different perspectives that emerging markets are opening to this very fragile pastoral area. Based on documentation, field inquiries carried out in herders’families and interviews with consumers in supermarkets in major cities, the article analyses the evolution of yak livestock production systems. In the discussion of the results, cooperation between stakeholders appears to be indispensible for building sustainable development. However, asymmetries between actors limites the extent of participation, a situation that threatens the sustainability of the current development trends.

Association of novel single-nucleotide polymorphisms of the vascular endothelial growth factor-A gene with high-altitude adaptation in yak (Bos grunniens)

Vascular endothelial growth factor-A gene (VEGF-A) is a key regulator of angiogenesis and an endothelial cell mitogen that plays an important role in high-altitude adaptation. In this study, we detected 2 novel single-nucleotide polymorphisms (SNPs) of VEGF-A by screening for genetic variation in 700 individuals of 3 domestic Chinese yak breeds--namely Gannan (GN), Datong (DT), and Tianzhu white (TZW)--using polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing techniques. GN and DT yaks live at high altitude and TZW yaks live at low altitude on the Qinghai-Tibetan Plateau. SNP g.8430T>C is located in intron 4 of VEGF-A. SNP g.14853G>A is located in the 3' untranslated region of VEGF-A. Frequencies of the GA and AA genotypes and the A allele of SNP g.14853G>A observed in GN and DT yaks were significantly higher than that in TZW yaks (P < 0.01). No significant difference among the breeds was observed for SNP g.8430T>C. The frequency of haplotype TA was significantly higher (P < 0.01), whereas the frequency of TG (P < 0.01) was significantly lower in GN and DT yaks compared with that in TZW yaks. The 2 SNPs were in moderate linkage disequilibrium in GN and DT yaks, but not in TZW yaks. The fixation index (FST) pairwise value was significantly different among the breeds studied. The neutral test result indicated that the region between the 2 SNPs may have been subjected to positive or balancing selection, and the high-altitude hypoxia environment might be the main determinant for selection. These results suggest that VEGF-A might contribute to the high-altitude adaptability of yak.

Maternal Phylogeny of a Newly-Found Yak Population in China

The Jinchuan yak is a new yak population identified in Sichuan, China. This population has a special anatomical characteristic: an additional pair of ribs compared with other yak breeds. The genetic structure of this population is unknown. In the present study, we investigated the maternal phylogeny of this special yak population using the mitochondrial DNA variation. A total of 23 Jinchuan yaks were sequenced for a 823-bp fragment of D-loop control region and three individuals were sequenced for the whole mtDNA genome with a length of 16,371-bp. To compare with the data from other yaks, we extracted sequence data from Genebank, including D-loop of 398 yaks (from 12 breeds) and 55 wild yaks, and whole mitochondrial genomes of 53 yaks (from 12 breeds) and 21 wild yaks. A total of 127 haplotypes were defined, based on the D-loop data. Thirteen haplotypes were defined from 23 mtDNA D-loop sequences of Jinchuan yaks, six of which were shared only by Jinchuan, and one was shared by Jinchuan and wild yaks. The Jinquan yaks were found to carry clades A and B from lineage I and clade C of lineage II, respectively. It was also suggested that the Jinchuan population has no distinct different phylogenetic relationship in maternal inheritance with other breeds of yak. The highly haplotype diversity of the Pali breed, Jinchuan population, Maiwa breed and Jiulong breed suggested that the yak was first domesticated from wild yaks in the middle Himalayan region and the northern Hengduan Mountains. The special anatomic characteristic that we found in the Jinchuan population needs further studies based on nuclear data.

A novel single nucleotide polymorphism in exon 7 of LPL gene and its association with carcass traits and visceral fat deposition in yak (Bos grunniens) steers

Lipoprotein lipase (LPL) is considered as a key enzyme in the lipid deposition and metabolism in tissues. It is assumed to be a major candidate gene for genetic markers in lipid deposition. Therefore, the polymorphisms of the LPL gene and associations with carcass traits and viscera fat content were examined in 398 individuals from five yak (Bos grunniens) breeds using PCR-SSCP analysis and DNA sequencing. A novel nucleotide polymorphism (SNP)-C→T (nt19913) was identified located in exon 7 in the coding region of the LPL gene, which replacement was responsible for a Phe-to-Ser substitution at amino acid. Two alleles (A and B) and three genotypes designed as AA, AB and BB were detected in the PCR products. The frequencies of allele A were 0.7928, 0.7421, 0.7357, 0.6900 and 0.7083 for Tianzhu white yak (WY), Gannan yak (GY), Qinghai-Plateau yak (PY), Xinjiang yak (XY) and Datong yak (DY), respectively. The SNP loci was in Hardy-Weinberg equilibrium in five yak populations (P>0.05). Polymorphism of LPL gene was shown to be associated with carcass traits and lipid deposition. Least squares analysis revealed that there was a significant effect on live-weight (LW) (P<0.01), average daily weight gain (ADG) and carcass weight (P<0.05). Individuals with genotype BB had lower mean values than those with genotype AA and AB for loin eye area and viscera fat weight (% of LW) in 25-36 months (P<0.05). The results indicated that LPL gene is a strong candidate gene that affects carcass traits and fat deposition in yak.

Milk fat chemical composition of yak breeds in China

The present study was undertaken to evaluate the fatty acid composition, conjugated linoleic acid (CLA) and cholesterol contents in the milk from three yak breeds, Maiwa yak ( n = 24), Zhongdian yak ( n = 16) and Gannan yak ( n = 16) and two yak crossbreeds, Maiwa yak × yellow cattle ( n = 16) and Gannan yak × yellow cattle ( n = 16). Statistically significant differences ( P < 0.05) in the proportions of individual milk fatty acids were observed among the three yak breeds. The proportion of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) did not differ statistically ( P > 0.05) among the three yak breeds. However, the percentage of total polyunsaturated fatty acids (PUFAs) in Zhongdian yak milk (4.82%) was significantly higher ( P < 0.01) than in Maiwa (3.99%) and Gannan (3.68%) yak milks. The contents of α-linolenic acid (C18:3) and cis-9, trans-11 conjugated linoleic acid (CLA) were significantly different ( P < 0.05) among the three yak breeds. The total SFAs, MUFAs and PUFAs were not significantly different ( P > 0.05%) between the two yak crossbreeds. The cholesterol contents in milk samples from yak breeds and yak crossbreeds were found to be in the range 12.32–16.17 mg/100 g. Cholesterol contents in milk samples from yak breeds and yak crossbreeds were positively correlated with their fat contents.

A novel single nucleotide polymorphism (SNP) of the &amp;lt;i&amp;gt;IGF1R&amp;lt;/i&amp;gt; gene and the association with growth traits in yak (Brief Report)

Abstract. The insulin-like growth factor-I (IGF1) is a peptide growth factor that exerts mitogenic and metabolic activities, which are regulators of growth, survival and cell differentiation in a number of cell and tissue types. To elicit its effects, IGF1 must bind its receptors. The insulinlike growth factor 1 receptor (IGF1R) is similar to insulin receptor (INSR) and it mediates the growth-promoting effect of IGF1. The IGF1R gene, therefore, was selected as a biological candidate gene for growth, body composition, metabolic, and skeletal traits in animals (Rothschild et al. 1997). By now, no polymorphism of yak (Bos grunniensL) IGF1R gene is reported. In the present paper, the partial exon 1 region of IGF1R was screened to detect the SNPs in Chinese yak breeds. Associations of SNP of IGF1R with growth traits were analysed.

Milk protein polymorphisms in cattle (Bos indicus), mithun (Bos frontalis) and yak (Bos grunniens) breeds and their hybrids indigenous to Bhutan

In the current study, milk protein variation was examined in cattle (Bos indicus), mithun (Bos frontalis), yak (Bos grunniens) and their hybrid populations in Bhutan to estimate genetic variability, conduct genetic characterization and assess the possibility of gene flow between mithun and cattle. Isoelectric focusing of 372 milk samples from 11 populations detected four molecular types of β-lactoglobulin (A, B, E and M), five molecular types of α(S1) -casein (A, B, C, E and X) and three molecular types of k-casein (A, B and X). Mithun and yak shared alleles but were found to exhibit different allele frequencies for the proteins studied. The degree of genetic variability within populations was measured by average heterozygosity and ranged from 24-40% in cattle, 26% for yak and 33% for mithun. We also resolved the traditional mithun and cattle hybridization system via principal component analysis. Our results suggested secondary introgression of mithun genes to the village Thrabum population, and a close genetic relationship between Bhutanese indigenous cattle and Indian cattle.

Characterization of fat globules and milk fat globule membrane proteins in milk of different yak breeds

The objective of this work was to characterize the fat globule and milk fat globule membrane (MFGM) proteins in Maiwa (n = 6), Gannan (n = 4) and Zhongdian yak whole milks (n = 4). Fat globule size distribution and specific fat surface area of whole yak milk were determined using a laser diffraction particle size analyzer. The average specific fat surface area of Gannan yak milk (2.05 m2 ·mg−1 ) and Zhongdian yak milk (2.01 m2 ·mg−1 ) was higher (P ·mg−1 ). The total protein content of MFGM and surface protein coverage of fat globule in Maiwa yak milk (11.12 mg·g−1 fat and 5.67 mg·m−2 , respectively) and Gannan yak milk (12.24 mg·g−1 fat and 5.97 mg·m−2 , respectively) were higher (P fat and 4.81 mg·m−2 , respectively). Protein components in the MFGM of yak milk were analyzed using an Ultrascan XL laser densitometer and an LKB 2400 GelScanXL software program. No major differences (P > 0.05%) in the protein patterns on the SDS gel were observed among the MFGM of Maiwa yak, Gannan yak and Zhongdian yak, with the exception of mucin 1 and butyrophilin which were significantly lower (P < 0.05) in the MFGM of Zhongdian yak milk.

A Single Nucleotide Polymorphism and Sequence Analysis of CSN1S1 Gene Promoter Region in Chinese BOS Grunniens (YAK)

The aim of this study was to investigate the polymorphism of the CSN1S1 gene promoter region in 4 Chinese yak breeds, and compare the yak CSN1S1 gene promoter region sequences with other ruminants. A Polymerase Chain Reaction-Single Strand Conformation Polymorphism protocol was developed for rapid genotyping of the yak CSN1S1 gene. One hundred fifty-eight animals from 4 Chinese yak breeds were genotyped at the CSN1S1 locus using the protocol developed. A single nucleotide polymorphism of the CSN1S1 gene promoter region has been identified in all yak breeds investigated. The polymorphism consists of a single nucleotide substitution G→A at position 386 of the CSN1S1 gene promoter region, resulting in two alleles named, respectively, G386 and A386, based on the nucleotide at position 386. The allele G386 was found to be more common in the animals investigated. The corresponding nucleotide sequences in GenBank of yak (having the same nucleotides as allele G386 in this study), bovine, water buffalo, sheep, and goat had similarity of 99.68%, 99.35%, 97.42%, 95.14%, and 94.19%, respectively, with the yak allele A386.

Genotyping of the polymorphism within exon 1 of &amp;lt;i&amp;gt;Hormone Sensitive Lipase (LIPE)&amp;lt;/i&amp;gt; Gene in three Chinese Yak (&amp;lt;i&amp;gt;Bos grunniens&amp;lt;/i&amp;gt;) breeds by PCR-RFLP (Brief Report)

Abstract. The yak (Bos grunniens), a herbivore living on the Qinghai-Tibetan Plateau and its adjacent territories, is one of world’s most remarkable domestic animals. Over the past decades, research has been done on properties of yak meat at physiological and biochemical levels. In recent years, some candidate genes associating with meat quality and lipid metabolism in yak have been studied (MA et al. 2007, ZHONG et al. 2007). The Hormone Sensitive Lipase (LIPE) gene has been regarded as a candidate gene associating with lipid metabolism and meat quality. Several studies have reported the genetic variations in the LIPE genes of human and pig (TALMUD et al. 1998, KNOLL et al. 1998, WU et al. 1998, HARBITZ et al. 1999), whereas the yak LIPE gene polymorphism has not been investigated and no information is available. The aim of this study was to identify and characterize the genetic variation in Chinese yak LIPE at the DNA sequence level and genotyping of the polymorphism within LIPE in different yak breeds.

Sequence Characterization of the MC1R Gene in Yak (Poephagus grunniens) Breeds with Different Coat Colors

Melanocortin 1 receptor (MC1R) gene plays a key role in determining coat color in several species, including the cattle. However, up to now there is no report regarding the MC1R gene and the potential association of its mutations with coat colors in yak (Poephagus grunniens). In this study, we sequenced the encoding region of the MC1R gene in three yak breeds with completely white (Tianzhu breed) or black coat color (Jiulong and Maiwa breeds). The predicted coding region of the yak MC1R gene resulted of 954 bp, the same to that of the wild-type cattle sequence, with >99% identity. None of the mutation events reported in cattle was found. Comparing the yak obtained sequences, five nucleotide substitutions were detected, which defined three haplotypes (EY1, EY2, and EY3). Of the five mutations, two, characterizing the EY1 haplotype, were nonsynonymous substitutions (c.340C>A and c.871G>A) causing amino acid changes located in the first extracellular loop (p.Q114K) and in the seventh transmembrane region (p.A291T). In silico prediction might indicate a functional effect of the latter substitution. However, all three haplotypes were present in the three yak breeds with relatively consistent frequency distribution, despite of their distinguished coat colors, which suggested that there was no across-breed association between haplotypes or genotypes and black/white phenotypes, at least in the investigated breeds. Other genes may be involved in affecting coat color in the analyzed yaks.

Analysis of genetic diversity and population structure of Chinese yak breeds ( Bos grunniens) using microsatellite markers

Nine Chinese yak breeds (Maiwa, Tianzhu White, Qinghai Plateau, Sibu, Zhongdian, Pali, Tibetan High Mountain, Jiulong, and Xinjiang) and Gayal were analyzed by means of 16 microsatellite markers to determine the level of genetic variation within populations, genetic relationship between populations, and population structure for each breed. A total of 206 microsatellite alleles were observed. Mean F-statistics (0.056) for 9 yak breeds indicated that 94.4% of the genetic variation was observed within yak breeds and 5.6% of the genetic variation existed amongst breeds. The Neighbor-Joining phylogenetic tree was constructed based on Nei's standard genetic distances and two clusters were obtained. The Gayal separated from the yaks far away and formed one cluster and 9 yak breeds were grouped together. The analysis of population structure for 9 yak breeds and the Gayal showed that they resulted in four clusters; one cluster includes yaks from Tibet Autonomous Region and Qinghai Province, one cluster combines Zhongdian, Maiwa, and Tianzhu White, and Jiulong and Xinjiang come into the third cluster. Pali was mainly in the first cluster (90%), Jiulong was mainly in the second cluster (87.1%), Zhongdian was primarily in the third cluster (83%), and the other yak breeds were distributed in two to three clusters. The Gayal was positively left in the fourth cluster (99.3%).

Genetic diversity of five native Chinese yak breeds based on microsatellite DNA markers

Genetic diversity of five native Chinese yak breeds based on microsatellite DNA markers

Mitochondrial DNA sequence diversity and origin of Chinese domestic yak

In order to clarify the origin and genetic diversity of yak in China, we analysed mitochondrial DNA (mtDNA) control region sequences (approximately 891 bp) in 52 individuals from four domestic yak (Poephagus grunniens) breeds, as well as from a hybrid between yak and cattle (Pianniu). Twenty-five samples were further selected for partial (420 bp) cytochrome b sequencing based on control region sequence information. Two yak samples shared sequences with Chinese cattle (Bos taurus); the remaining yak mtDNAs converged into two major clades in the phylogenetic analysis. Genetic diversity varied substantially among the breeds, with the hybrid Pianniu yak demonstrating the highest diversity. Our results suggest that the Chinese yak was domesticated from two distinct matrilineal sources or from a heterogeneous pool containing both divergent lineages, with occasional gene introgression from cattle.

Genetic polymorphisms of milk epithelial mucin of yaks

Abstract Milk epithelial mucin (MUCI) of yaks was separated by SDS–polyacrylamide gel electrophoresis. Atotal of nine types of MUCI were revealed in 427 yaks from five yak breeds including Maiwa yak, Jiulong yak, Tianzhu white yak, Qinghai yak and Tibetan yak. The molecular weights of MUCI are from 163 kD to 208 kD, most of which are larger than those of bovine. Population genetic analysis shows that the gene frequency and genotype frequency of yak MUCI differ among breeds, with relatively high gene heterozygosity. The five yak breeds studied fall into two groups according to their milk MUCI gene frequency, suggesting that milk MUCI exhibits specificities for local yak groups. * Supported by National Natural Science Foundation of China MUCI and New Century Excellent Talents in University (NCET–04–0135)

Classification of ecological types of the Chinese yak

To investigate the genetic resources and to clarify the classification status of the Chinese yak, the Maiwa yak, Jiulong yak, Datong yak, and Tianzhu White yak were intensively studied using microsatellite DNA, RAPD (random amplified polymorphic DNA), and AFLP (Amplified Fragment Length Polymorphism) DNA markers on the basis of the previous study work of the authors' on chromosomes and blood protein polymorphisms of the Chinese yak. The overall results showed that: (1) the genetic distance based on allele frequencies at the microsatellite loci between the Maiwa yak and Jiulong yak was the largest (1.506), and as expected, the two populations of the Maiwa yak had the smallest genetic distance (1.062). The four yak breeds were clustered into two groups: the first group comprised the Jiulong yak, and the second group comprised the remaining three breeds; (2) the genetic distance between the Datong yak and Tianzhu White yak was the smallest (0.0336), whereas the genetic distance between the Jiulong yak and Maiwa yak was the largest (0.0414) based on the data from the RAPD and RFLP analyses. The four yak breeds were again clustered into two groups with the Datong yak and Tianzhu White yak grouped together first, followed by the Maiwa yak; (3) analyses of the chromosomes and blood protein polymorphisms showed a similar pattern of relationship among the breeds. Therefore, it was concluded that the Chinese yak could be considered to be of two types with the Jiulong yak and Maiwa yak as their representatives, respectively. This conclusion was in accordance with the classification proposed later by professor Cai L and his colleagues, according to which the Chinese yak was classified into two types, the ‘Qinghai-Tibetan Plateau yak’ and the ‘Hengduan Mountain Alpine yak’, although this conclusion differed from the other classifications. Considering the geographic distribution, ecological factors, history and development of the Chinese yak, it was believed that this classification is reasonable.

Meal to pellet intervals in 14 species of captive raptors

In order to clarify the origin and genetic diversity of yak in China, we analysed mitochondrial DNA (mtDNA) control region sequences (approximately 891 bp) in 52 individuals from four domestic yak (Poephagus grunniens) breeds, as well as from a hybrid between yak and cattle (Pianniu). Twenty-five samples were further selected for partial (420 bp) cytochrome b sequencing based on control region sequence information. Two yak samples shared sequences with Chinese cattle (Bos taurus); the remaining yak mtDNAs converged into two major clades in the phylogenetic analysis. Genetic diversity varied substantially among the breeds, with the hybrid Pianniu yak demonstrating the highest diversity. Our results suggest that the Chinese yak was domesticated from two distinct matrilineal sources or from a heterogeneous pool containing both divergent lineages, with occasional gene introgression from cattle.