Yak Products Research Articles

Can the Bhutan Yak Federation Revitalize Waning Yak Herders’ Enthusiasm and Rejuvenate the Declining Yak Farming in Bhutan

Yaks, native to Bhutan and other Himalayan regions, play a crucial role in the livelihoods of highlanders, serving as a sources of milk products, meat, transportation, fiber, and even dung used as fuelwood for cooking. Concerned about the perceived decline in the country’s yak population, the Bhutan Yak Federation (BYF) was established in 2019 to support highlanders. Presently, the BYF consists of 268 males and 203 females, representing 1067 yak rearing households. Its primary objectives include advocating for policy and investment support and promoting yak farming as a vibrant and sustainable enterprise. To gain a deeper understating of BYF’s roles and functions, this study focused on the Lingshi and Sephu yak cooperatives under the Thimphu and Wangduephodrang districts, conducting phone interviews with 40 cooperative members. The study revealed that highlanders primarily generate income through the sale of cordyceps, followed by yak products, portering services, and medicinal plants collection.

CURRENT STATUS AND DEVELOPMENT PROSPECTS YAK BREEDING IN THE REPUBLIC OF ALTAI

The yak is a late-maturing animal compared to cattle. However, the yak has precious properties in terms of endurance to harsh climatic conditions, the ability to make long transitions along inconvenient rocky mountain paths and feed all year round in the pasture, including during the winter. The local population of the Altai Republic has been breeding yaks since ancient times, as evidenced by archaeologists’ finds. Although the maximum number of yaks in the Altai Republic reached in 1990 - 18468 heads and were bred in the farms of five administrative districts, at present, the number of yaks totals only 6043 heads, and they are concentrated mainly in the farms of one municipality - the Kosh-Agachsky district. The authors propose measures for the effective development of yak breeding, increasing the number and rational use of these unique animals, considering natural and climatic conditions, land resources and the existing potential of agricultural producers in the Altai Republic. It is necessary to carry out selection and breeding work to create a highly productive breed to improve the breeding and practical qualities of the Altai population of yaks. The development of gastroecological tourism is the most promising for the Altai Republic. The need for high-quality, environmentally friendly meat, including barley, is constantly growing. Therefore, it is necessary to increase the number of yaks to develop a system at the farm level that ensures the rational use of available pasture lands. One of the critical issues is the development of State Standards (GOST) for meat and all by-products of yaks. Creating a marketing and advertising system for yak products remains an urgent problem.

Characterization of Arunachali Yak: A Roadmap for Pastoral Sustainability of Yaks in India

Highland pastoralism provides economic sustainability to the tribal livelihoods and is endemic to the yak-rearing tracts of India. Transhumant pastoralists of Arunachal Pradesh (in India) have centuries-old deep socio-religious and economic connections with this unique bovine species. As a result of their conservation efforts, Arunachali was recognized as the first and is still the lone breed (to date) of yaks in the country. A survey was conducted on the pastoral production system in the region to enable the phenotypic characterization of yaks and to understand the prevailing husbandry practices. Arunachali yaks are medium-sized bovines that are predominantly black with dense and long hairs hanging down the body and are docile in temperament. They have a convex head with horizontal ears and distinctly curved horns with pointed tips. The average milk yield is 0.98–1.04 kg milk/day with 7.45% fat and 11.5% SNF and the peak milk yield/day is 1.1–1.6 kg. The average ages of clipping of coarse hairs and down fibres are 12–18 months and 12 months, respectively, with average yields of 1.5 kg and 0.5 kg/clipping/animal, respectively. Value addition of yak milk and fibre presents a unique opportunity for the economic rejuvenation of yak pastoralism. However, winter feed scarcity, inbreeding, extreme climate events and the non-availability of essential services are still major challenges for yak production in the country. Our findings acknowledge that pastoral sustainability is critical for the conservation of yaks and yak rearing. This calls for pastoralism-centric governance and research efforts in the highlands to curb the declining population and to put Indian yaks on the road to sustainability.

Average Daily Gain and Energy and Nitrogen Requirements of 4-Month-Old Female Yak Calves.

There is little information available on milk intake and energy and nitrogen requirements of growing yak calves. This study aimed to fill this important gap, as this information could be beneficial in designing a system to wean yak calves earlier than in natural time. We determined the average daily gain and energy and nitrogen balances and requirements of 4-month-old female yak calves (48.8 ± 2.45 kg, n = 8). The calves were allowed to suck once a day and were fed an ad libitum concentrate: hay diet at a ratio of 60:40. Milk intake averaged 540 ± 26 g/d, yielding 2.28 ± 0.112 MJ/d, which was 13% of the gross energy intake (GEI). The digestible energy intake (DEI):GEI ratio was 0.681, metabolizable energy intake (MEI):DEI was 0.913, and MEI:GEI was 0.621. The average daily gain of the calves was 433 ± 153.1 g/d, which consisted of 78.0 ± 8.99 g protein, 52.7 ± 23.74 g fat, and 302.3 ± 95.1 g water, that is, 18.0% protein, 13.0% fat and 69.8% water. There were 130.7 g of body solids and 9.06 MJ of energy in every kg of body mass gain. Of the MEI, 25.17 kJ were required for 1 g of body mass, 83.40 kJ for 1 g of body solids, and 2.62 kJ for 1 kJ of retained energy (RE), and RE was 36.6% of MEI. The maintenance energy requirement was 5.35 MJ/d, the efficiency of utilization of energy for growth (kg) was 0.72, and the heat increment of feeding for growth was 0.28 (1.55 MJ/d). Digestible nitrogen (N) was 0.685 while retained N (RN) was 0.489 of N intake. The N requirement for maintenance was 11.73 g/d or 0.61 g N/kg0.75 per day, while the biological value (BV) of N was 91.1%. The energy and N requirements for yak calves were relatively low, which could be explained, at least in part, by the high efficiency of utilization of energy and high BV of N when compared to other livestock. These findings could be beneficial in designing early weaning systems for the many Himalayan households depending on yak production for their livelihoods.

Домашний як и его гибрид в номадном стаде монголов и бурят

Goals. The article aims at characterizing a unique animal of Inner and Central Asian nomads — the domestic yak (sarlyk) and its hybrid (khainak) that have been bred by Mongols and Buryats for hundreds of years. The work provides a first ethnographic insight into statistical data on yak population dynamics in synchronous and diachronous perspectives, reviews adaptive properties of the animal instrumental in surviving in extreme conditions of highlands, its exterior, breeding and behavioral specifics, economic significance. Materials and methods. The article explores literary, field and online sources to employ the methodology of comparative analysis, in particular, the comparative-historical-genetic method. Materials about yak breeding among Turkic peoples are essentially verifying by nature. Results. When it comes to declare the five traditional types of livestock bred, Mongols and Buryats mention no yak, the latter be clustered with cattle. Mongolia’s yak population ranks second worldwide — after China. The post-Socialist era witnessed an increase in yak numbers in Mongolia paralleled by a decrease in Russia. Domestic yaks have unique adaptive properties towards low oxygen partial pressure, extreme cold, and meagre fodder resources. The incomplete domestication of animals is determined by high profitability via such extensive farming techniques. Being meat, dairy and working animals, sarlyks and khainaks were most essential to the traditional economy of nomads. In the 21st century, their products become exotic and environment friendly food items, while skin, hair, wool, undercoat and other components serve as unique raw materials for light industry, pharmacology and cosmetology. Conclusions. The 21st century Mongolia with its vast yak friendly territories witnesses a significant head increase resulting in industrial processing facilities of yak raw materials nationwide. In the 1980s, the Soviets were undertaking active purposeful efforts to develop yak breeding, while the free market period decreased both numbers of animals held by Buryats and their habitat. The situation is due to the lack of demand for yak products and the lack of infrastructure for industrial processing of raw materials. The domestic yak and its hybrid had made it possible for nomads of Inner Asia — Mongols and Buryats — to significantly extend economic boundaries of their ethnic territories and inhabit montane grasslands and shrublands.

Nutrition of yak milk fat – Focusing on milk fat globule membrane and fatty acids

Yak dairy is highly essential in the livelihoods of Tibetans due to abundance of yak, nutritional and non-dietary purposes in Tibet. The agitating methods in making of butter dislocate milk fat globule membrane (MFGM) resulting in its separation from the fat which then forms butter. This study summarized current discoveries in nutritional compositions of yak MFGM and butter and compared with those from cow, sheep and goat whilst highlighting their health benefits to humans. Here, we found that yak MFGM had highest sphingomyelin and cholesterol levels. Also, yak butter had highest levels of conjugated linoleic acids, monounsaturated fatty acids, vaccenic acid and n-3 LC-PUFA but lowest SFA level. Taken together, we report that these yak products are rich in nutrients which play significant roles in anticancer, anti-obesity and neurodevelopment. This review demonstrated yak MFGM and butter as functional food ingredients that could be used in supplement and infant food developments.

Fat Deposition in the Muscle of Female and Male Yak and the Correlation of Yak Meat Quality with Fat.

Simple SummaryThe type and quantity of fat are among the key factors influencing the carcass and meat quality in yak. The effect of gender to fat in yak and the correlation of meat quality with fat were studied in this paper. The meat of male yaks (MYs) is healthier from the point of nutritional value, whereas the meat of female yaks (FYs) possesses better qualities in relation to the visual impact and mouthfeel. The below results can provide a theoretical basis for the deep processing of yak meat. Yak meat quality (especially tenderness) can be improved by increasing the content of fat, C18:0, cis-C18:2, and cis-C18:1 in muscle during yak production. These genes, including SCD, PLIN5, LPL, ME1 and DBI, play a crucial role in the regulation of fat deposition in yak. Above candidate genes for fat deposition in yak can supply the theoretical basis in molecular breeding of yak with a high fat content in muscle.This study aimed to explore the differences in fat deposition between female (FYs) and male yaks (MYs). Compared with MYs, the tenderness, L*, marbling, absolute content of fat, and most fatty acids (FAs) of longissimus dorsi (LD) in FYs were higher or better (p < 0.05), whereas the relative content of polyunsaturated fatty acids (PUFAs) and n-3 PUFAs were lower (p < 0.01). The absolute content of fat, C18:0, cis-C18:2, cis-C18:1, and C24:0 were positively correlated with L*45 min, b*24 h, tenderness, and marbling score of LD in FYs and MYs (p < 0.05), respectively. LPL, FATP2, ELOVL6, HADH, HACD, and PLINS genes play a crucial role in improving the marbling score and tenderness of yak meat. The results of gene expression and protein synthesis showed the effect of gender to FA biosynthesis, FA transport, lipolysis, and FA oxidation in the adipose tissue of yak was realized by the expressions of ME1, SCD, ACSL5, LPL, FABP1, PLIN4, and PLIN2 in peroxisome proliferators-activated receptor (PPAR) signaling. This study established a theoretical basis for the improvement of the meat quality of yak and molecular breeding.

Setting the mountain ablaze? The Royal Highland Festival in Bhutan from the semi-nomads\u2019 perspective

A study was conducted to assess the effects of the Royal Highland Festival (RHF) from the perspective of yak herders in Laya, Bhutan. Sixty-six respondents were randomly selected from amongst the domicile herders who were regular visitors to the festival. A survey was carried out through a questionnaire with mixed questions. Herders’ opinions suggest good progress of RHF as reflected by improved community vitality and networking with stakeholders. Tourists, both international and domestic, were the major contributors to the income of yak herders during the festival. Livestock products were the biggest income earner, followed by homestays. Herders were encouraged to produce more quantities of livestock products and desired to diversify yak products. Animal shows were adequate and encouraged breed improvement. The grazing resources and the environment were unharmed by the presence of animals in the festival. However, yak herders expressed concerns over the lack of skills and knowledge for yak product diversification and management of festival waste. Herders felt the need to shift the festival venue to benefit highlanders in other areas of Bhutan. The study recommends authorities to consider imparting skills to Laya communities on developing diverse and value-added yak products. Homestay owners require more capacity to manage and maintain farmhouses with proper sanitation. Effective management of festival wastes calls for a farsighted plan. Finally, to inculcate a sense of pride and ownership, the communities of Laya must be empowered to self-organize the festival, while government authorities should consider shifting the festival venue to other highland areas.

English

A total of three family farms including Village No. 9 in Nima township, Nerong Naqu County (NQA); Village No. 11 in Nima township, Nerong Naqu County (NQB); and Yare township, Gegi County, Ali District (GJ) from three ecology yak populations (EYP) were selected for this study to identify the most optimized mode of exogenous male adult yak introduction (EMI) within EYP for solving the inbreeding problem caused by the small-scale yak husbandry system. Exogenous adult male yaks from the same EYP with different proportions (100% to NQA, 50% to NQB, and 0% to GJ) were introduced, and 10 microsatellites were used to detect the genetic diversity of these populations before (in 2017) and after (in 2019) the introduction of exogenous adult male yaks (EMI). Results showed that the divergence between the observed and the expected heterozygosity of the NQA and NQB populations was reduced in 2019, while the number of markers significantly deviating from Hardy–Weinberg equilibrium (P&lt;0.05) and FIS (inbreeding coefficient) within populations decreased compared with that in 2017. In contrast, the FIS of GJ population without EMI continued to increase (from 0.011 to 0.033) over the years 2017 to 2019. Moreover, genetic differences between the populations (Pairwise Fixation index, FST) showed that EMI increased the genetic divergence between populations. Overall, this study shows that the introduction of exogenous male adult yaks not only effectively reduces the degree of population deviation from equilibrium but also decreases the inbreeding level within the population within a few generations. This study also provides a valuable management model for stable yak production on small sized family farms

Phenotypic and genotypic characterisation of lactic acid bacteria isolated from exotic naturally fermented milk (cow and yak) products of Arunachal Pradesh, India

Exotic naturally fermented milk of cow and yak products of Arunachal Pradesh in India such as mar, chhurpi and churkam were analysed for identification of lactic acid bacteria (LAB). The pH of samples was 5.32 ± 0.01 to 6.62 ± 0.01 with viable LAB count of 6.27 ± 0.01 to 6.49 ± 0.02 log cfu g−1. A total of 307 LAB isolates were isolated from 30 samples, and out of which 76 isolates were randomly grouped on the basis phenotypic characteristics, and were identified using 16S rRNA gene sequence analysis into 9 species of LAB from cow-milk products, and 5 LAB species from yak-milk products, respectively. Enterococcus durans was the predominant species along with Leuconostoc mesenteroides subsp. mesenteroides, Lactococcus lactis subsp. lactis, Lc. lactis subsp. cremoris, Lc. lactis subsp. hordniae, Lacticaseibacillus paracasei subsp. tolerans, Levilactobacillus brevis, Loigolactobacillus coryniformis subsp. torquens and Lentilactobacillus parabuchneri. Chhurpi (cow-milk) showed the higher species richness and diversity among the products.

Effects of Premating Calcium and Phosphorus Supplementation on Reproduction Efficiency of Grazing Yak Heifers.

Simple SummaryThis study was realized to explore the effects of calcium chloride (CaCl) and monocalcium phosphate (MCP) supplementation on the reproductive efficiency of grazing yak heifers. The body weight, serum markers of bone metabolism, and conception and calving rate of grazing yaks in control group and supplementary feeding groups were compared. The results revealed that supplementation with MCP but not CaCl could significantly improve the reproductive performance, possibly due to the improvement in body weight and bone phosphorus storage providing better estrous physiological conditions for grazing yak heifers. The findings of this study may be helpful and instructional to improve the reproductive efficiency of yaks on the Qinghai Tibet Plateau.Reproductive efficiency is the main factor limiting yak production on the Tibet Plateau. The purpose of this study was to investigate the effect of supplementation with calcium chloride (CaCl) and monocalcium phosphate (MCP) for 30 days before breeding on body weight (BW) change, serum bone metabolism biomarkers, conception rate, and calving rate of grazing yaks. Ninety 3 year old yak heifers (153.05 ± 6.56 kg BW) were assigned to three treatments (n = 30 per treatment): grazing without supplementation (CONT), grazing plus calcium chloride supplementation (CaCl), and grazing plus monocalcium phosphate supplementation (MCP). Compared with the CONT group, supplementation with CaCl increased the serum concentrations of osteocalcin and decreased the alkaline phosphatase (ALP) levels (p < 0.05); supplementation with MCP increased the average daily gain (ADG), serum concentrations of phosphorus (P) and osteocalcin, conception rate, and calving rate (p < 0.05), whereas it decreased the serum concentrations of hydroxyproline, ALP, and calcitonin (p < 0.05). Both CaCl and MCP supplementation had no effect on serum calcium (Ca) concentration. The ADG, conception rate, and calving rate were higher in the MCP group than in the CaCl group (p < 0.05), while the serum concentrations of hydroxyproline and calcitonin were lower (p < 0.05). It could be concluded that premating supplementation with MCP increased the body weight gain and subsequent conception and calving rate of grazing yaks. Supplementation with MCP had a positive effect on body condition and bone metabolism, thus providing a better estrous condition for grazing yak heifers, which could contribute to enhancing reproduction efficiency.

Livestock Movement in Gaurisankhar Valley, Dolakha, Nepal

Animals are an integral part of subsistence farming system. They are considered as assets and are the source of food and manure. In mountains of Nepal, transhumance ruminant production system is practiced this practice of herding of cattle like Yak (Nak, Chauri)/ sheep has been practiced for generation in the mountains of Nepal. This study is based on household questionnaire survey, FGD and interview in Gaurishankar gaupalika shows the movement of sheep ranged from 1,200m to 4,500m elevation and the movement of Yak ranged from 2,000m to 3,500masl. The agricultural fields around the settlements are cultivated when the herds remained in high mountain pasture. After returning to the village, they are tied to the field and their waste is used for manuring the agricultural lands. The types and size of livestock has also undergone a significant change. The number of sheep and buffalo have decreased due to lack of market while the Yak farming has been gaining popularity because of increase in national and international demand for Yak products.

Shrub cover impacts on yak growth performance and herbaceous forage quality on the Qinghai-Tibet Plateau, China

Shrub cover in alpine meadows around the world has experienced significant changes during the past 20 yr. An increase in shrub cover has often been associated with large influences in ecosystem functions. The objectives of the present study were to investigate the impact of shrub cover on herbaceous forage quality and yak grazing efficiency on the Qinghai-Tibetan Plateau, China. Forty-eight yak steers were randomly assigned to four grazing pastures with different shrub cover rates (control, low, middle, and high). The whole grazing period was categorized as vegetative stage (June to July), bloom stage (August to October), and senescent stage (November to December). Herbaceous forage chemical composition and body weight of yaks were measured, and serum and rumen samples were analyzed. Although shrub cover had no effect on herbaceous forage chemical composition and serum biochemical parameters of yaks, total herbaceous forage production in pastures and crude protein intake of yaks decreased with increasing shrub cover. Such changes decreased average daily gain of yaks. As expected, increasing the herbaceous forage maturation significantly decreased crude protein content while increased dry matter, neutral detergent fiber and acid detergent fiber contents, consequently, reduced herbaceous forage crude protein and organic matter intakes and average daily gain of yaks. The rumen of yaks has higher ammonia nitrogen and total volatile fatty acid concentrations and butyrate proportion in the bloom stage of forage compared with those of the senescent stage. The results indicate that shrub cover on the Qinghai-Tibetan Plateau needs a certain level of control for the sustainable grazing yak production, although it has little negative effect on blood health and rumen fermentation. Additionally, it is vital to select the optimum time to market livestock or supplement feed with yaks during the cold season on the Qinghai-Tibetan Plateau.

Herders and livestock professionals’ experiences and perceptions on developments and challenges in yak farming in Bhutan

Context The yak-based transhumant system is influenced by socioeconomic developments, regulations and environmental changes. Little is known about the impact of this on yak farming practices among different regions in Bhutan. Aim and methods The experienced changes in yak farming practices over the years and perceptions on developments were assessed through interviews with yak herders in three regions (west, n = 22; central, n = 20; east, n = 25) and with livestock extensionists (n = 28). Key results At present, forage shortage in the rangeland, yak mortality mainly due to (endangered) wild predators and, to a lesser extent, labour availability are the main concerns in all yak farming regions. These concerns have increased due to socioeconomic developments (e.g. education and other sources of income) and strong conservation policy, which affects the living environment of the yaks. Overall, the market to sell yak products and livestock extension services has improved, but forage shortage and yak mortality has increased over the years. However, some factors causing forage shortage are more specific to certain regions, e.g. competition with the horse population (west), cattle and cattle–yak hybrids (east), cordyceps collection (west and central) and prohibited burning of rangelands (central and east). Family labour available to herd yaks has slightly decreased, and the number of young family members (successors) to take over yak farming has decreased over the years. Conclusions On the basis of the experiences and perceptions of yak herders and extensionists, we conclude that increasing forage shortage in the rangelands, decreasing numbers of successors, and increasing yak predation by wild animals are the major threats to yak farming. Implications This study demonstrates that yak farming in Bhutan experiences an increasing pressure to sustain. Differences between regions make clear that a one blanket-policy will not be effective to preserve yak farming for the future.

Effects of climate change on yak production at high altitude

Yak is considered the life-line of highland pastoral nomads who raise them on high altitude ranges under transhumance. Yak production at high-altitude alpine ranges may be affected due to the gradual increase of environmental temperature as a result of impending climate change. The mean environmental temperature of yak habitat at 3,000 m above mean sea level in Northeastern Indian Himalaya, varying from 1.2 to 11.1°C and 7.9 to 19.7°C during winter and summer seasons, respectively, evidencing the heat stress to the yaks in summer with THI more than 52. When environmental temperature exceeds 13°C, adaptive mechanisms of body accelerate respiration rate and heart rate to cope with heat stress in yaks. It was reported that the climate change is already witnessed at high altitude with average rise of environmental temperature 0.01 to 0.04°C/year and the expected increase of 2– 3°C have potentially catastrophic for high-altitude animals and ecosystem. The alpine pasture decreased in vegetative above ground biomass and composition which results in starvation or loss of body condition appeared to be manifested as reduced fertility in yak with low milk yield. Further, climate change may result in increase of pests and diseases at the lower permanent settlements of sub-alpine region thereby making these areas incompatible for yaks. Mitigation of heat stress in yak possibly can be done through three means by physical modification of the environment, improved nutritional management and genetic development of strains that would be less sensitive to heat stress.

DNA barcoding reveals mislabeling of game meat species on the U.S. commercial market

Game meats represent a valuable specialty market in the United States that has high economic incentives associated with mislabeling. However, there is limited information on this topic. The purpose of this study was to conduct a market survey of game meats sold within the United States and identify instances of mislabeling using DNA barcoding. Products were also examined for the presence of threatened or endangered species. Fifty-four samples of whole-cut game meats were collected from online distributors in the United States and sequenced across a 658 base-pair region of the cytochrome c oxidase subunit I (COI) gene. The resulting DNA sequences were identified based on top species matches in the Barcode of Life Database (BOLD) and GenBank. The results showed that 18.5% of samples were potentially mislabeled and 9.3% of samples legally contained a near-threatened or vulnerable species and were correctly labeled. The samples appeared to have been mislabeled due to reasons such as economic gain and product mishandling. However, cross-species hybridization could also have contributed to the potential mislabeling of bison and yak products. Although near threatened (bison) and vulnerable (lion) species were identified, the products were correctly labeled and legally sold, as bison populations are managed and the identified lion species is not protected by the Endangered Species Act (ESA). Overall, the results of this study revealed the occurrence of game meat mislabeling in the United States and suggest the need for further evaluation of this practice.

Marketing of Yak Products and Substitution of Yak Products with other available Products: A Field Study on Tawang District of Arunachal Pradesh

Tawang district of Arunachal Pradesh is well known for variety of Yak products. Basically, it includes both food and non-food based items. It is important to note that food items are valued more. However, non-food items made from yak is on constant decrease in the study area. Substitution is the main factor responsible for such decrease in non-food products made from yak. But demand of food items like chur (local cheese) is still high due to non-availability of its close substitutes. Also, the herders use traditional equipment instead of modern machinery in producing the products. Again, Brokpas (Yak herders) have opted for traditional technique over modern technique due to taste and quality preference. During the study it is found that majority of consumers of yak products are forced or compelled to substitute due to unavailability of yak products in the Tawang region. Declining numbers of yak herd and herdsman to take up yak rearing have been found to be the reasons for shortages in supply of yak products.

Molecular investigation of bovine viral diarrhea virus infection in yaks (Bos gruniens) from Qinghai, China

BackgroundBovine viral diarrhea virus (BVDV) is a pestivirus which infects both domestic animals and wildlife species worldwide. In China, cattle are often infected with BVDV of different genotypes, but there is very limited knowledge regarding BVDV infection in Chinese yaks and the genetic diversity of the virus. The objectives of this study were to detect viral infection in yaks in Qinghai, China and to determine the genotypes of BVDV based on analysis of the 5′untranslated region (5′UTR) and N-terminal protease (Npro) region.ResultsBetween 2010 and 2012, 407 blood samples were collected from yaks with or without clinical signs in six counties of Qinghai Province. Ninety-eight samples (24%) were found to be positive by reverse transcription polymerase chain reaction (RT-PCR) targeting a conserved region of BVDV-1 and BVDV-2. The nucleotide sequences of the 5′UTR and complete Npro region were determined for 16 positive samples. Phylogenetic reconstructions demonstrated that all 16 samples belong to subgenotypes BVDV-1b, BVDV-1d and BVDV-1q.ConclusionsThis study provides, for the first time, molecular evidence for BVDV infection in yaks in Qinghai involving multiple subgenotypes of BVDV-1. This may have occurred under three possible scenarios: interspecies transmission, natural infection, and the use of vaccines contaminated with BVDV. The results have important implications for yak production and management in China, and specifically indicate that unscientific vaccination practices should be stopped and bio-security increased.

The yak, an essential element of the high altitude regions of Central Asia

The yak is critical for the life and economic activity of the people on the vast and inhospitable Qinghai-Tibetan plateau and on the surrounding mountainous areas. This article gives an overview of the domestication, the geographical distribution, the herding practices, the production and the products of the yak. Its breeding and hybridization management, as well as its reproduction and its special adaptation attributes are reviewed. Concluding thoughts about the role of the research and the role of social changes - driven from within or imposed from above - on the future of yak production systems are outlined.

Enzymatic characterization of transglutaminase from Streptomyces mobaraensis DSM 40587 in high salt and effect of enzymatic cross-linking of yak milk proteins on functional properties of stirred yogurt

Streptomyces transglutaminase (TGase) purified from high-salt medium was characterized and applied into yak yogurts. The purified enzyme presented a Michaelis constant of 40.47mmol and a maximum velocity of 44.44U/mg of protein for N-carboxybenzoyl-l-glutaminyl-glycine in the hydroxamate procedure. The purified TGase exhibited optimum activity at 55°C and pH 6.0. The enzyme was not stable above 50°C and was stable within a pH range of 5.0 to 10.0 at 4°C for 12h and pH 5.0 to 9.0 at 37°C for 30min. The TGase activity was not affected by Ca2+, K+, Ba2+, or Na+, but slightly inhibited by Fe2+, Mg2+, and Mn2+, and strongly by Cu2+ and Zn2+. To explore yak milk products, it was used to produce yogurt and TGase was used. It was found that TGase-catalyzed cross-linking was effective in improving functional properties of stirred yak yogurt. Treated yogurt produced a strong acid gel, higher consistency, cohesiveness, index of viscosity, and creamier mouth feel than the untreated product. Furthermore, yak yogurt treated with TGase presented lower wet yak hair or sweat odor, or both. Therefore, TGase can be used to pave the way for exploration of novel yak products to overcome the issues of peculiar wet yak hair or sweat odor, or both.