NUTRITION ON YAK

animal nutrition

1. NUTRITION OF YAK BY, N.ESHWAR.

2. Taxonomy : Order Artiodactyla family Bovidae Sub family Bovine genus Bos Species Grunniens and mutus . Taxonomical classification of Yak : Yaks are multipurpose ruminant animals adapted for living at high altitudes above 3000 metre mean sea level. Yak ( Bos grunniens ) was domesticated from the wild Yak ( Bos mutus ) which is still found in remote mountain of Quinghai -Tibet plateau.

3. Domestication of Yaks : The yaks were domesticated during late new stone age. The number of chromosomes in yaks is similar with cattle (2n = 60). During the last three decades yak population has declined significantly and hence it has been a great concern to the rearers and its planners. Types of Yaks in india : The yaks of world have been named on the basis of their country i.e., Indian yaks , Chinese, Nepalese, Mongolian, Bhutanese, Caucasian yaks………………….

4. Indian yaks are Himachal yaks, Arunachal, and Sikkimese yaks. Sikkimese yaks were differentiated in to “BHO” and “AHO” varieties. The National Research Center on Yak was established by the Indian Council of Agricultural Research at Dirang , Arunachal Pradesh . Research Areas of National Research Center on Yak : Studies for genetic resources,management practices , production level and problems associated with productions. Establish a small herd of pure yaks to execute observations on performances under range and semi-range systems of management.

5. Arrange for research, on improvement of yak and its products. Conduct research on nutrition, physiology , production and enterprising aspects under semi-range and confinement. Carry research on fodder and development of pasture at mid and high altitude for yaks. Provide complete health coverage through proper therapeutic and prophylactic measures. Yak population in india : There are about 65,000 yaks in the country now, a steep decline from 1,32,000 in 1977. The yak population in China is 13 million. Of the 65,000 yaks, Arunachal Pradesh alone accounted for 13,000 as per the 2003 census (NRCY).

6. Purpose of yak rearing : Production of high energy – high protein milk. Production of edible flesh of high quality protein and fat. Capability of utilizing scanty herbages for food production at high altitudes. Regular supply of dung for fuel at places where it was very difficult to obtain fire wood. Supply of long and coarse hairs for preparing ropes and carpets and utilization of soft under coat for the manufacture of fabrics for warm cloths. Availability of hides for the preparation of tents, shoes and other goods for domestic uses . heavy horn are used for manufacturing of milking pails and other articles.

7. Feeding behaviour : Very little is known about the feeding of yaks. In early summer when the pasture is covered with lush growing long grasses, tongue is more actively utilized for ingestion whereas on pasture of short grasses, lips and incisor teeth are active. During winter season, when the pasture is covered with thick layer of snow, yaks mostly use hoof, horn, head and muzzle for digging the snow layers. This is helped by sensitively developed olfactory organs. During scarcity period the yaks continue to consume even stems and leaves from the residual wilted grasses available during spring season.

8. Factors affecting the grazing behaviour : Herbage cover and season : The energy spent for grazing is higher in winter season when compared to the summer season. During hot and humid season when lush growing pasture is available they spend relatively less time to satisfy their appetite whereas in winter they are required to spend much more time in search of feed. Grazing time : The grazing time normally varies from 34 – 80 % of the total time available for grazing. The remaining time is spent in walking, resting, drinking and mastication.

9. Growing and Lactating Yaks : They spend more time in grazing due to their higher nutritional demands for supporting their active productive function. Climate change : During snowfall and hail storms yaks run over the pasture at a very high speed (about 3400 m/hour). Herd density : The number of yaks per unit of land influences the grazing time due to competition for biomass. As the no. of yaks increases, the grazing time decreases.

10. Aggressiveness of animals : Aggressive animals do not allow other to graze in their surroundings. Feed resources : During winter in Ladhak region it is a common practice of feeding ‘ oal ’ a variety of Lucerne hay as a supplementary feed for vulnerable group of young calves, pregnant animal and lactating cows. Feed of yak : The yaks grazes on alpine pastures and other herbages of high altitudes.

11. Name of the forage Crude protein Ether extract Crude fibre Total Ash Barhar 13.74 1.70 27.58 12.72 Dudhilo 9.98 1.06 16.68 11.20 Gineri 16.01 1.64 32.40 8.98 Kabra 14.89 2.68 49.84 8.76 Kamli 16.54 1.36 36.82 14.96 Bat 11.90 2.16 40.66 11.10 Chiple 19.43 2.64 44.50 14.71 Khasre 16.80 1.22 21.86 16.60 Katush 11.83 3.14 43.90 6.22 Gayo 11.99 1.02 24.00 10.47 Proximate composition of some top feed of high altitude for yak :

12. They generally avoid poisonous or thorny plants. But during lean period due to acute shortage of green they graze on poisonous weeds and suffer from poisoning. In india , yaks loose 25-30 % of their body wt. during winter due to inadequate fodder. Concentrate and urea block supplements are effective in improving the productivity of grazing yak and maintaining the body weight of animals in winter : : PERFORMANCE OF YAK : MEAT: The most economically important product from the Yak is its juicy, flavorful, and healthy meat. The flavor can be compared to sweet beef flavor. extremely low in palmitic acid that is bad for our health (30% less than beef as a percentage of fats and 120% less than beef as a percentage of meat).

13. Yak meat is also much lower in calories, saturated fats, cholesterol, and triglycerides. Yak meat is much higher in stearic and oleic acids that are good for us (35% higher than beef as a percentage of fats). Yak meat is also higher in protein and solids (less water) than beef. Milk : In China, Yak x Holstein or Yak x Hereford cross cows are milked for their very rich milk which is used primarily for production of butter and cheese. yak milk is rich in carotene, the butter is of yellowish colour . high protein content leads to the high acidity of yak milk.

14. Among the fatty acids of yak milk, the saturated and unsaturated types constitute 22% and 55.2% of the total, respectively.

15. Wool : Wool of yak has some special characters like warmth, odour resistance, breathability, softness, strength, resistance to static.

16. Feed intake : Generally, yak consume less feed than other cattle, probably because of their smaller rumen capacity. Yak prefer fresh, high-quality forages, and both housing and high temperature can reduce feed intakes. voluntary intake (VI) of the yak varies with the season and sward heights, from 18 to 25 kg of fresh forage in summer to 6 to 8 kg per day , or even much less, of wilted grass in cold-season grazing conditions. Dry matter intake (DMI, kg per day) of the growing yak under indoor feeding can be estimated as DMI = 0.0165 W + 0.0486 The lactating yak :- DMI = 0.008W 0.52 + 1.369Y (W 0.52 is metabolic body weight, Y is milk yield, kg per day).

17. Outflow rate of rumen fluid ranges from 3.1 to 3.5 litre per hour, hence lower than in cattle. Total volatile fatty acid (VFA) production in the yak rumen increases with the animal's age. The proportions of propionic acid and butyric acid to total VFA in the yak are higher than those in other ruminants. The concentration of NH 3 -N in the yak rumen varies with the diet composition and feeding behavior. Mature forages can promote lower NH 3 -N concentrations in grazing yak than can young forages. Ruminal digestion and metabolism : The rumen of the yak is far smaller than that of other cattle.

18. Non-protein nitrogen metabolism Non-protein nitrogen (NPN) has been used as an extra source of nitrogen for microbial protein synthesis in dairy and beef production but not so in yak. Xie et al. (1989) found a higher concentration of NH 3 -N in the rumen of growing yak fed with ammonia-treated straw than in animals fed with untreated straw . Also pH, VFA production and the density of ciliated protozoa in the yak rumen increased correspondingly with NPN ingestion. Clearly, as a ruminant, the yak can use NPN as efficiently as other ruminants. Chai et al . (1996) indicated that when a basal diet (containing 4.2 percent of CP) was supplemented with urea (to give a diet containing 7.3 percent of CP), there was a great increase in the concentration of NH 3 -N in the yak rumen that, in turn, improved the microbial protein production (Table 14.12). This shows that the utilization of dietary nitrogen can be improved by adding a source of NPN (such as urea).

19. Energy requirement : Lactating yak cows have better utilization of dietary energy than dry yak cows. An increased feeding level leads to the decreased digestibility of dietary energy in dry cows. The fasting heat production (FHP) of the growing yak can be estimated as FHP = 916 kJ per kgW 0.52 per day. The metabolizable energy requirement for maintenance ( ME m ) in growing yak is around 460 kJ per kg W 0.75 per day. Metabolizable energy requirement in the growing yak can be estimated as: ME (MJ per day)= 0.45W 0.75 + (8.73 + 0.091 W) DG (DG is kg per day).

20. protein requirement : Yak has evolved a mechanism to recycle more nitrogen to the rumen than ordinary cattle. Yak excretes 316 mg per kg W 0.75 per day Yak can use non-protein nitrogen as efficiently as other ruminants. Rumen degradable crude protein requirement for maintenance ( RDCP m , g per day) in growing yak is around 6.09W 0.52 g per day. The crude protein requirements for daily gain (DG RDCP g g per day) in growing yak can be estimated as RDCP g = (1.16/DG + 0.05/W 0.52 ) -1 . Thus the total crude protein requirement of growing yak could be calculated as RDCP (g per day) = 6.09W 0.52 + (1.16/DG + 0.05/W 0.52 ) -1 .

21. CP intake & requirement for growing calf: Parameters May-June (Budding) July-Sept (Green) Oct-Nov (Yellow) Dec-April (Dry) Body WT(kg) 122.60 115.34 125.96 120.11 Body mass(g/ m.sq ) 49.18 80.69 57.92 43.55 CP intake(g/head/day) 732.77 258.38 159.97 50.98 Requirement for maint . (g/head/day) 92.85 89.94 64.16 91.86 Growth(g/day) 100 79.50 78.82 79.79 79.27 200 125.64 123.96 126.38 125.08 300 155.78 153.20 156.91 154.91 400 176.99 173.68 178.47 175.88 500 192.75 188.83 194.50 191.43

22. Mineral requirement : existing information suggests that mineral deficiencies may occur, varying from one yak-raising area to another. Seasonal deficiency of specific elements could be a common issue throughout the Plateau owing to an uneven seasonal supply of feeds. Mineral and trace element deficiencies can cause some problems to yak, but appropriate supplementation will generally improve the conditions. Carotene utilization : The conversion of carotenes into vitamin A activity is less efficient in yaks as in cattle. So, high yellow pigmentation of butter fat in the yak milk is seen.

23. Salt feeding : Yaks have great craving for salt. This habit has been used to attract the animal and they return from the pasture to obtain their salt on the fixed day and time. Salt is fed at weekly or fortnightly intervals. Water intake : Yaks normally drink stream river water and in the absence of water in winter they lick snow. Daily water intake of a 9-10 month old calf is recorded as 9.02 litres by Tiwari et al.(1991).

24. Feeding of yak calf : Composition of milk replacer in calves :

25. Colostrum The newborn calf should be fed maternal colostrum (first mothers milk) in the first 24 hours. This will help provide protection against future infections, particularly if the colostrum is fed before 12 hours. If the mother’s colostrum is not available, the second option is to use cow’s colostrum . Starter ration, water, forage and weaning : If a starter ration is available, offer small quantities daily. Offer good quality roughage (leafy material) and/or pasture on a free choice basis.

26. BIBLIOGRAPHY :- Animal nutrition advances and developments - Usha Rani Mehra , Putan Singh, A.K.Verma . Animal nutrition advancements in feeds and feeding of livestock. - Lokesh Gupta and K.K.Singhal . Nutritional requirements of Yak and Mithun , ICAR, New Delhi The Yak (second edition). -FAO of United Nations and Regional Office for Asia. National Research Center on Yak at Dirang , Arunachal Pradesh .