R.J. Long

The yak grazing system on the Qinghai-Tibetan plateau and its status

Yaks are a multifunctional and dominant livestock species on the Qinghai-Tibetan plateau. The yak grazing system is a traditional transhumance system. Research is focussed on both understanding and improving the system. Development of local economies and the use of new knowledge from yak research and modern technology are improving the system. However, the Qinghai-Tibetan plateau ecosystem is becoming dysfunctional through adverse climate sequences, over-population and over-grazing. The Chinese Government has implemented regional projects to address these degradation problems. Several policies have recently been introduced to improve yak grazing management. This paper reviews current knowledge on the system and the options for improving and optimising the system.

The sustainable development of grassland-livestock systems on the Tibetan plateau: problems, strategies and prospects

The Tibetan plateau is the source of most of the major rivers of Asia and has a huge impact on the livelihoods of the population, who have for centuries engaged in traditional herding practices. Sustainable management of the plateau is of critical importance not only for maintaining livelihoods but also because of its vital ecological function. The major problem of sustainable development in these grassland-livestock systems is the conflict between forage and livestock production. Despite considerable investment of manpower, material resources and capital over many years, attempts to resolve the problem have not been successful. The magnitude of conflict between forage and livestock is addressed by presenting 19 resolution strategies based on numerous research data. Each of these strategies is evaluated in terms of how it can be implemented, its potential benefits for livestock production, current progress and the requirement for further research. The 19 strategies have been divided into four topic categories, namely; grassland-forage, livestock, economy and market, society-culture, which cover the basic elements of sustainable development in this pastoral region. It is argued that improved planning and implementation of the proposed strategies must be based on the background investigation of natural and social status of the pastoral region. Particular attention needs to be given to genetic resources and technology in order to ensure the successful implementation of these proposals. In addition to expanding the use of 18 currently practiced strategies, the authors propose a further novel strategy of replacing the current intensive form of ecological migration with a model incorporating two semi-permanent settlements. The objective of this novel strategy is to retain the nomadic element of pastoral husbandry while increasing the temporal and spatial scale of rotational stocking to reduce pasture degradation on the Tibetan plateau. It is argued that these proposals should be urgently incorporated into two national plans for the pastoral livestock industry, and the construction of an ecologically safe shelter zone on the Tibetan plateau, while ensuring a sustainable livelihood of its pastoral residents. Ensuring a successful implementation of these strategies in resolving the conflict between grassland and livestock, and promoting sustainable development on the Tibetan plateau, requires willing support at the level of national investment and policy commitment and from the herdsmen.

Importance of Functional Ingredients in Yak Milk-Derived Food on Health of Tibetan Nomads Living Under High-Altitude Stress: A Review

Tibetan nomads have lived since ancient times in the unique and harsh environment of the Qinghai-Tibetan Plateau with average altitudes over 4000 m. These people have been able to live and multiply healthily over numerous generations under the extreme stress of high-altitude environment, including cold, hypoxia, and strong ultraviolet radiation, and with a simple diet devoid of vegetables and fruits for most of the year. Their survival depends heavily on yak milk, and its products comprise the main portion of their daily diet. In this review, yak milk and its derived products are examined in detail and compared with milk from other ruminant species. Yak milk products seem to be particularly rich in functional and bioactive components, which may play a role in maintaining the health status of Tibetan nomads. This includes particular profiles of amino acids and fatty acids, and high levels of antioxidant vitamins, specific enzymes, and bacteria with probiotic activity (yoghurt is the main food). Based on that, it is proposed that the Tibetan nomads have developed a nutritional mechanism adapted to cope with the specific challenges posed by the environment of the worlds highest plateau. Systematic studies are required to demonstrate this in a more mechanistic way.

Rangeland governance in China: overview, impacts on Sunan County in Gansu Province and future options.

The development of the current regulatory framework for management of rangeland resources in China began in 1949. Prior to this, there were family, tribal and other traditional systems of grazing management. The emphasis in government policy since 1949 has been to increase livestock production and economic output from the rangelands. The operations of these policies and regulations in Sunan County, a typical rangeland county in Gansu Province, are examined. The existing laws, policies, and regulations related to rangeland management in Sunan County and elsewhere are identified and described. It is argued that a policy based on rational processes should lead to desired outcomes. Therefore, emphasis needs to be placed on processes that facilitate the development and implementation of policies at every level of government to promote sustainable use and management of natural resources and to secure sustainable livelihoods. It is concluded that the rangeland policies have been rarely integrated with the concept of sustainable development. This is now changing. Sustainable development philosophy needs to be further incorporated into the developmental processes for rangeland policies. Until now processes have focused predominantly on economic performance.

Effect of snow disasters on livestock farming in some rangeland regions of China and mitigation strategies – a review

Severe snowfall events, termed snow disasters, lead to losses of livestock, preventing sustainable development of livestock systems, in the rangelands of northern China. In order to reduce losses under snow disasters, a review of the factors contributing to these losses was used to indicate the most appropriate strategy. It is proposed that governments and herders should implement a holistic strategy using a multi-disciplinary approach to ensure sustainable development in these rangelands. The possibility of seeing snow disasters as a natural restraint on livestock numbers and allowing losses to take place during these events is not considered as acceptable as part of a holistic strategy. The aim of the strategy is to improve animal nutrition, health and disease control rather than simply mounting rescue missions to save threatened livestock. It is suggested that central and local governments should encourage permanent solutions through a combination of education, the provision of materials for animal housing and the creation of reserve banks sufficient to ensure adequate feeding and survival of livestock through the winter, whether threatened by snow disasters or not. The economic return from the marketing of animal products should be enhanced through a combination of government and herder initiatives to promote a higher turnover rate of livestock and to encourage the sale of high-quality products. Regeneration of degraded grassland by herders should be encouraged by enhancing vegetation cover and forage plant height, thereby reducing the effect of snow cover on forage accessibility. Since current stocking rates on many rangelands are too high, their reduction should be an absolute priority in order to prevent irreversible degradation of rangelands. Only by improving herders’ confidence in their economic survival, through the adoption of such changes, will they be persuaded to reduce grazing livestock numbers, thereby helping to ensure, not only the short-term survival of livestock through snow disasters, but the long-term survival of their rangeland pastures upon which their livelihood depends.

Aspects of lipid oxidation of meat from free-range broilers consuming a diet containing grasshoppers on alpine steppe of the Tibetan Plateau

The objective of this study was to evaluate the characteristics of lipid oxidation in the meat of free-range broilers feeding on grasshoppers in alpine rangeland on the Tibetan Plateau. Eighty 28-d-old Qinjiaoma male broilers were introduced into a rangeland where there was a dense population of grasshoppers (PB). Control birds were reared under intensive conditions and given a maize-soybean diet. At 91 d of age, 24 birds from each treatment were slaughtered. Fresh breast and thigh meats were packaged and refrigerated for determination. The results indicate that rearing conditions, which included a diet rich in grasshoppers for PB broilers, significantly (P < 0.05) affected α-tocopherol content, total iron, heme iron, and nonheme iron content in the muscle of both the breast and leg. Rearing system and diet also had an important effect on antioxidant activity and lipid oxidation during refrigerated storage. This influence changed with storage time between different tissues. The activities of glutathione peroxidase and superoxide dismutase in the muscle of chicken breasts or legs from PB broilers were significantly (P < 0.05) higher than those from the controls, but no significant (P > 0.05) differences were found for the activities of catalase between the PB broilers and the controls. In conclusion, the meat in free-range broilers feeding on grasshoppers has more antioxidative potential and longer storage life.

A comparative study on urinary purine derivative excretion of yak (Bos grunniens), cattle (Bos taurus), and crossbred (Bos taurus X Bos grunniens) in the Qinghai-Tibetan plateau, China

Two experiments were conducted to determine the urinary purine derivative (PD) excretion rates and to analyze potential variations in PD excretions between yak, Tibetan indigenous cattle, and their crossbreds under similar ecological environment, and to develop prediction equations based on PD excretion for estimating rumen microbial protein supply. Three Tibetan castrated male yaks, and similar numbers of indigenous cattle and their crossbreds, were used in a fasting trial followed by a feeding trial, using three 3 x 3 Latin squares (1 for each breedtype), to measure responses of PD excretion to different feeding levels. The results showed that i) daily endogenous PD excretion for yak, indigenous cattle, and their crossbreds was 134, 163, and 138 micromol/kg of BW(0.75) (P = 0.38), respectively; and ii) crossbreds have greater PD excretion rate per unit digestible OM intake than indigenous cattle (P = 0.03). However, there were no significant differences between yaks and the crossbreds (P = 0.24) or between yaks and the indigenous cattle (P = 0.25). The proportion of allantoin to total PD in urine ranged from 0.83 to 0.88, with the crossbreds having greater values compared with the 2 parents (P = 0.03). Daily glomerular filtration rate, calculated using endogenous creatinine as an internal marker, for the above animals was 3.85, 4.23, and 3.61 L/kg of BW(0.75), respectively, in fasting trial (P = 0.59). The alpine animals may develop special regulating mechanisms in the kidney in terms of glomerular filtration rate and PD excretion, which would help the animals in adapting to the harsh environment of the Qinghai-Tibetan plateau.

The effect of a diet containing grasshoppers and access to free-range on carcase and meat physicochemical and sensory characteristics in broilers

1. Research was conducted to evaluate the impact of a diet containing grasshoppers on the carcase, physicochemical and sensory characteristics in a free-range, grassland-based broiler production system. 2. A total of 80, 28-d-old male broilers were reared on grassland containing a large population of grasshoppers (treatment PB). Control birds were reared intensively on a maize-soybean diet (treatment CB). At 91 d of age, 24 birds from each treatment were slaughtered to evaluate carcase, meat and sensory characteristics. 3. Treatment PB produced birds with significantly lower live weights, breast, wing, thigh and drum weights, and higher dressing percentage and breast percentage of carcase, compared with CB. Treatment PB produced breast meat with significantly higher redness values, shear force and protein content, and lower pH values, cooking loss, moisture and fat content compared with CB. Sensory panel results for breast and thigh meats showed no treatment effect on colour and juiciness, but significantly higher scores for chewiness, flavour, aroma and overall appreciation, and lower scores for tenderness from treatment PB compared with CB. 4. Rearing chickens on rangeland may provide an alternative way to produce poultry meat which is considered superior by modern consumers.

Nitrogen metabolism and recycling in yaks (Bos grunniens) offered a forage-concentrate diet differing in N concentration

An experiment was conducted to characterise N use efficiency and quantify urea fluxes in yaks offered four levels of dietary N (1.43%, 1.97%, 2.45% and 2.90% of diet DM) in a 4 × 4 Latin square design. The incremental increase in N intake linearly increased N retention (P = 0.003) and the excretion of urinary N (P 0.05) in faecal N excretion was observed in growing yaks fed any of the four diets. Microbial N production had quadratic (P < 0.001) responses to dietary N, characterised by the highest microbial N production occurring in the 1.97% N diet (P < 0.05). As the N content of the diet increased, the urinary excretion of urea increased from 13% to 27% of urea entry rate (quadratic, P < 0.001), whereas gastrointestinal entry urea returned to ornithine cycling decreased from 46% to 40% (linear, P < 0.001), and the gastrointestinal entry urea used for anabolism increased from 50% to 56% (linear, P < 0.001). Gastrointestinal entry urea incorporated into bacterial N decreased linearly (P < 0.001) with incremental increase in N intake, and the greatest concentration (23.5%) of bacterial N originating from plasma urea N was in yaks fed the 1.43% N diet. As much as 87% of the urea synthesised in the liver was returned to the gastrointestinal tract when the yaks were fed a diet with 1.43% N (1.1 times the maintenance N level). Moreover, constantly greater urea production than the intake of digestible N, and the gastrointestinal-urea clearance than the kidney-urea clearance were observed, respectively, in the growing yaks, regardless of the level of N intake. These results suggest that yaks might be more efficient at utilising N under harsh environment than are cattle.

Effects of plant enzyme inactivation or sterilization on lipolysis and proteolysis in alfalfa silage

This experiment studied the contribution of plant enzymes and microbial activity on lipolysis and proteolysis in ensiled alfalfa. Before ensiling, the wilted alfalfa was treated with plant enzyme inactivation by autoclaving or with sterilization by γ-ray irradiation. The treated alfalfa was then inoculated with commercial lactic acid bacteria inoculants and ensiled for 40 d. Alfalfa without treatment was ensiled as the control. The content of total fatty acid (FA) after ensiling decreased 43% in the control silage and 28% in the γ-ray-treated silage, but did not change in the autoclave-treated silage. Among the major FA (C16:0, C18:2n-6, C18:3n-3), a considerable increase was observed in proportion of C16:0 in the control silage as compared with fresh alfalfa; conversely, decreases in proportions of C18:2n-6 and C18:3n-3 occurred during ensilage. Silage treated with γ-ray radiation at ensiling had a smaller proportion of C16:0 and greater proportions of C18:2n-6 and C18:3n-3 than control silage. Autoclave treatment further decreased proportions of C16:0 and most of the other FA, and increased C18:2n-6 and C18:3n-3 proportions in comparison with γ-ray treatment. Proportions of C16:0, C18:2n-6, C18:3n-3 and other detected FA (except for the proportion of C15:0) did not differ between fresh forage and autoclave-treated silage. Remarkably, smaller nonprotein nitrogen content was observed in the autoclave-treated silage compared with the γ ray-treated silage or the control silage. These results indicated that an extensive lipolysis occurred during ensiling of alfalfa, and plant enzymes played a major role in lipolysis and proteolysis.