Resources of yak production in Tibet and reasons for the degeneration of productive performances

J. Qiumei, B. Chong, D. Yongla, T. Degyi, D. Chyegi, Zh. Yongqing and L. Sang

Tibetan Livestock Research Institute, Lhasa 850000, Tibetan Autonomous Region, P.R. China

Summary

This paper reports about yak herd structure, growth and development, productive performance in terms of meat, milk, wool and undercoat, and reproduction in Tibetan Autonomous Region. We made recommendations to avoid further degeneration of yak production, particularly, the need to balance the number of yak and forage production, better use of the available natural pasture resources in the cold, high altitude rangelands and to protect the environment from degradation are suggested as being essential for a sustainable yak and pasture production system in the region.

Keywords: Degeneration, natural resources, productive performance, Tibet, yak

Introduction

Yak is the domestic animal species on the Tibetan Plateau. In 1998, there were 3,749,864 head of yak distributed all over Tibet (Tibetan Bureau of Agriculture and Animal Husbandry 1998). Yak have been considered as a very suitable animal to effectively convert the primary production supplied by the cold highland vegetation into various animal products: milk, meat, skin, wool and dung through their intensive growth capacity and fattening potential under situations where the season with adequate green forage is relatively short and at an altitude over 3500 metres above sea level (masl) at which other livestock species rarely adapt (Zhong 1997). In particular, yak live on the unpolluted highland pasture to produce the green, nutritional and relish-specialised products, which are advocated by the modern communities.

Due to its important position in the Tibetan daily life, yak production and its related products are the key industry of Tibetan animal husbandry which plays a key role in providing food, oil and meat to the local nomads in the region. Therefore, further investigation into the yak production resources in Tibet is essential in order to develop a sustainable yak industry.

Materials and methods

Investigation into the topographical distribution, climate, soil, pasture, productive structure and economy of the areas where the three Tibetan yak breeds are found in Tibet was conducted in a study that involved 156 households. Data collected also included herd structures in terms of species composition, sex and age of yak, and reproductive performances.

The body conformations of 225 yak from the three breeds were measured. A total of 40 hair and undercoat samples were collected for further laboratory analyses. Daily milk yield of 109 yak were recorded for 5 days in August and 17 yak were slaughtered for the assessment of carcass parameters.

Results and discussion

Yak population and geographic distribution in Tibet

There were 3,749,864 yak head in 1998, representing 16.69% of the total domestic ruminants in the region (Table 1) and represented by three breeds known to exist in Tibet: Pali, Jiali and Sibu yak.

Table 1. Distribution and number of yak in Tibet.

Prefecture or city	Naqu	Ali	Lhasa	Sigatze	Shannan	Changdu	Linzhi	Total
Ruminants	6,657,400	2,295,000	1,677,858	5,573,579	2,194,398	3,446,263	619,395	22,463,860
Yak	1,313,200	122,462	420,722	526,923	245,580	976,104	144,868	3,749,864
Percentage (%)	19.73	5.34	25.07	9.45	11.19	28.32	23.39	16.69
Source: Tibetan Bureau of Agriculture and Animal Husbandry (1998).

Yak herd structure

From the 1997–1998 survey, the species structure in areas where the three yak breeds were dominant were as follows:

Pali yak: yak–sheep and goat–cattle–horse–donkey–mule;

Jiali yak: yak–sheep–goat–horse–pig–yak crosses–chicken;

Sibu yak: yak–goat–sheep–cattle–donkey–horse–chicken–yak crosses–pig–mule.

The herd structure in terms of age and sex is shown in Table 2. For all three breeds, the sex ratio was 1:1 up to 3 years of age. From the age 4 years upward, both sexes matured and joined the breeding groups. Males aged 4–6 years were castrated for meat or draft purpose, if not selected as breeding bulls.

Within the Pali yak, the proportion of females increased from the age of 4 years upwards. The males constituted 13.35% of the herds, females 39.05%, reproductive females 45.07% and breeding bulls 1.8%. The sex ratio was 1:15.5 among the 5 year-old animals in these herds. These results indicate a sex and age structures scope increase in the population.

Table 2. Herd structure of the three yak breeds.

			Percentage in total yak (%)		1 year		2 years		3 years		4 years		>5 years
Breeds	Families involved	Yak	♂	♀	♂	♀	♂	♀	♂	♀	♂	♀	♂	♀
Pali	29	2059	35.8	65.2	7.78	8.8	5.88	5.49	4.23	5.0	3.11	6.02	13.35	39.05
Sibu	39	1081	46	54	7.77	9.12	5	5.14	4.36	3.78	4.75	4.17	25.61	29.87
Jiali	34	20,952	37.2	62.8	7.22	7.74	7.12	8.37	5.74	5.74	5.31	7.0	18.98	29.88

For the Sibu yak, the male percentage was relatively high (25.61%). This was due to the use of bulls as draft animals in the transition zone in which this breed is predominantly found. The reproductive females accounted for 34.04% in the herds while breeding bulls represented only 0.58% of the herd. Sex ratio was 1:26.3 among the 5 year-old animals in these herds.

In the Jiali yak, the proportion of females was 31.88% and that of breeding bulls was 2.82% among the 5 year-olds in the herds. The sex ratio was 1:11.3.

Milk production

Peak milk production in the Tibetan yak is in August (Dou 1990) and there is a significant correlation (r = 0.993) between the observed milk yield during this period and the estimated yield during other months (Zhang 1989; Zhong 1997). On this basis, 5-day milk yield of the three breeds were recorded in August and used to estimate the milk yield from May to October in the study. The results showed that the total milk yield was different in the three breeds (Table 3).

Table 3. Estimated total and monthly milk yield of the three yak breeds.

Breeds	Milking method	Total (kg)	Monthly yield (kg)
			May	June	July	Aug.	Sept.	Oct.
Pali	Full milking	214.80	25.78	34.37	47.26	53.70	36.52	17.18
	Half milking	184.80	22.18	29.57	40.66	46.20	31.42	14.78
	Average	199.80	23.98	31.97	43.96	49.95	33.97	15.98
Jiali	Full milking	192.00	23.04	30.72	42.24	48.00	32.64	15.36
	Half milking	103.20	12.38	16.51	22.70	25.80	17.54	8.26
	Average	147.00	17.71	23.62	32.47	36.90	25.09	11.81
Sibu	Full milking	216.00	25.92	34.56	47.52	54.00	36.72	17.28
	Half milking	143.40	17.21	22.94	31.55	35.85	24.38	11.47
	Average	179.70	21.56	28.75	39.54	44.93	30.55	14.38

Meat production

The measurements of body conformation and body conformation index are shown in Tables 4 and 5. The Jiali yak had the highest body length index which is similar with what is reported for beef cattle breeds. The males also had a higher heart girth index, implying possible higher meat production. Sibu and Pali yak had a higher chest width index with the Pali females also having a higher body length index.

The data in Table 6 shows that the Jiali yak had a higher dressing percentage, net beef percentage and ratio of net beef to carcass weights than the Pali and Sibu yak. Sibu males had a lower beef productive performance but the differences between the females of the three breeds were not significant.

Hair and undercoat yield

Yak hair is harvested in July and August in Tibet. A total of 17 adult males and 9 adult females of the Jiali yak produced 0.69 kg and 0.18 kg on average, respectively. The average undercoat yield of the Jiali yak was 0.6 kg per adult animal. Pali yak produced an average of 0.15–1 kg of hair and 0.2 kg of undercoat. Yak is the only bovine species producing the undercoat with fine fibre, which has a good strengthening length and elasticity, and is now widely used in textile and has a very promising market both locally and internationally. Yak hair is used for making tents, ropes and bags, which are currently popular in Tibet and could be promoted internationally.

Reproductive performance

There was no difference, in both male and female reproduction, among the three yak breeds in Tibet. In general, Pali females come to the first oestrus at 3 years of age with a low conception rate, if serviced but improving with age to best conception at the age of 4.5 years. Sibu females show first oestrus at 2.5 years of age but are served only after 3.5 years of age. All females calve every two years, and these are usually single births as twinning rate is only 1–2%. The calving rates by natural service are 30.77, 48.38 and 45.71% for the Jiali, Pali and Sibu yak, respectively. All males are used for service only after the age of 3.5–4.5 years. However, older bulls tend to have more mating opportunities due to the ranking order in herds. Bulls aged 10 years or older may not be sexually active or could be infertile but they will keep their position in the herds. This lowers the calving rate and increased grazing pressure unnecessarily by having to keep extra unproductive males.

Table 4. Measurements of body conformation of the three yak breeds in Tibet.¹

Breeds

Sex

No.

Head Length

Head width

Height

Length

Chest height

chest width

Heart girth

Rump width

Height at rump

Cannon bone

Body weight (kg)

Pali

♂

2

46.00 ± 2.83

24.25 ±3.18

112.00 ±6.63

131.50 ±13.44

61.5   ±0.00

32.50 ±2.83

157.50 ±2.12

34.50 ±0.00

112.50 ±0.00

18.50    ±2.83

236.64 ±31.11

♀

21

39.60 ±3.17

19.14 ±0.84

110.21 ±4.26

120.57 ±9.50

60.55 ±2.57

32.83 ±2.55

154.10 ±4.32

31.28 ±1.93

105.69 ±4.22

15.62 ±0.89

200.85 ±22.13

Jiali

♂

18

48.03 ±12.24

25.03 ±3.43

127.47 ±9.26

151.83 ±14.00

73.53 ±6.99

41.22 ±4.36

186.78 ±18.12

39.83 ±3.43

117.47 ±7.03

20.13 ±2.25

368.02 ±90.96

♀

31

40.23 ±1.65

18.90 ±0.80

108.18 ±3.46

120.19 ±6.19

58.05 ±6.77

33.63 ±4.51

147.77 ±5.99

31.13 ±1.69

103.31 ±3.47

14.92 ±0.83

189.66 ±20.62

Sibu

♂

8

46.25 ±4.40

20.19 ±2.03

111.5 ±2.5

121.75 ±9.71

59.06 ±6.26

33.31 ±3.69

152.13 ±14.10

32.31 ±3.03

105.75 ±6.32

16.28 ±1.42

204.42 ±54.69

♀

41

42.78 ±1.72

17.70 ±0.85

105.30 ± 4.19

116.80 ±5.27

57.01 ± 2.91

33.26 ±2.16

145.85 ±5.74

29.57 ±1.68

100.49 ±3.42

14.96 ±0.73

172.87 ±87.00

1. Units of measurement: cm for all except the body weight in kg

Table 5. Body conformation index of the three yak breeds in Tibet (%).

Breeds	Sex	Limb length	Body length	Heart girth	Chest width	Height at rump	Cannon bone
Pali	♂	45.06	109.40	139.82	54.22	95.90	14.17
	♀	46.54	114.29	131.05	54.94	96.50	15.82
Jiali	♂	42.32	115.54	146.53	56.06	92.16	15.79
	♀	45.06	111.10	136.60	57.93	95.50	13.77
Sibu	♂	45.06	110.92	138.50	58.34	95.43	14.11
	♀	41.03	109.19	136.44	56.40	94.84	14.60

Table 6. Beef productive performances of the three yak breeds in Tibet.

Breeds	Sex	No.	Live weight (kg)	Carcass weight (kg)	Net beef (kg)	Dressing percentage (%)	Net beef (%)	Net beef/ carcass (%)	Bone/beef
Jiali	♂	2	314.45	157.89	140.89	50.38	44.97	89.24	1:4.16
	♀	3	203.45	103.21	83.54	50.79	41.06	80.94	1:4.25
Pali	♂	3	332.74	164.58	137.15	50.84	42.40	83.17	1:4.96
	♀	3	221.59	106.58	85.75	48.10	39.08	80.50	1:4.16
Sibu	♂	3	254.65	114.13	88.67	44.76	34.82	77.69	1:3.48
	♀	3	205.94	101.29	82.62	49.18	39.98	81.55	1:4.43

Evidences for the degeneration of yak production in Tibet

A comparison of the results from this study with previous reports indicates that performance has been decreasing over the years in terms of both beef and milk production among all the three yak breeds in Tibet. For example, the milk yield of the Jiali yak averaged 202.24 kg in 1980 (Dorji 1995b) but dropped to 147.6 kg in the present study. The average dressing percentage in males and females dropped by 15.78 and 5.9% in Sibu yak, 8.4 and 3.2% in Jiali yak, and 10.81 and 10.86% in Pali yak, respectively.

Issues for future actions

1. Cull bulls aged 10 years and older and exchange breeding males among herds and villages. The optimum service age of breeding bulls should be 4 to 10 years. However, most herders have over-age animals, including those up to 15–17 years of age. This was found to be common in Sibu yak herds. Such bulls cause reduction in conception rates. Furthermore, inbreeding, which significantly affects beef production, is common due to a limited number of breeding bulls kept and used for extended periods in the herds by smallholders after the formulation of a livestock tenure policy 20 years ago in Tibet.
2. Optimise species and herd structures. Although the yak is the predominant species in the areas inhabited by the three yak breeds, this study also found that there are many horses (4.76% of the large domestic ruminants) in the Jiali yak producing area. Because the horse is no longer used for transportation since 1990 due to extensive use of motor vehicles, their numbers should be reduced in these herds, as they do not make significant economic contribution to the herders. There were also many goats with low cashmere and meat production in Pali and Sibu yak producing areas. These should also be reduced due to their negative effect on the pasture ecology.

Pali and Sibu yak herders had many over-age females, including those aged 18–22 years in Sibu herds. A high proportion of unconfined yak (up to 5% in some areas) by the local Tibetan religious custom also increases pressure on grazing land. In particular, the male to female ratio of Sibu yak of 1:26.3 is too high compared with the normal 1:15–20.

3. There is strong need to secure winter pasture and to preserve hay and crop by-products for use in the long, cold season. Overgrazing and irrational grazing are common in Tibetan herding system, which reduces the reserved winter pasture area and storage. There is also a severe shortage of supplementary feeds in the cold season. These result into severe degeneration of pasture and subsequent difficulty to attain full recovery of yak body weight loss during and after the long, cold season in Tibet.
4. There is also need to strengthen selection and breeding system to improve the genetic potential of the yak herds in the area. All the three yak breeds identified in Tibet are indigenous to Tibet. However, there has never been a well-planned selection and breeding strategy. This, plus the poor feeding, may be responsible for the degeneration of yak growth and development. In setting up a breeding programme, the indigenous breeding practices and goals of the herders need to be taken into account.
5. The study has also identified a need to improve feeding and management in order to increase individual animal output. The natural herding and management system has been a very effective practice in yak production. However, extraction of increasing amounts of milk as the market demand has been increasing is significantly affecting the growth and development of the newborns and cows as well. In addition, the traditional link between number of heads of livestock and wealth as perceived by local nomads is also negative and inconsistent with increases in individual animal productivity.
6. Encourage more input for pasture protection and reconstruction. There was almost no individual responsibility and investment to protect communal pasture from overgrazing and irrational use after the livestock tenure policy. The pasture tenure policy, which has been adopted in other Provinces bordering Tibet in China, is recommended so that enthusiasm and collective sense of duty by all local herders could be used to ensure responsible pasture management. To ensure sustainable yak production and environmental conservation, the Government also need to provide both financial assistance and policy support for pasture rehabilitation and management.

Special remarks

Increasing human population pressure in the rural area

Average annual birth rate in Tibet has been 23.52% since 1990 (Dorji 1995a). The consequent increase in human population pressure has necessitated keeping more livestock, creating severe shortages of pasture. Family planning should be considered to mitigate this pressure to available resources from the increase in both human and yak populations.

Influence by global climate change

The global climate change is already evidently significantly affecting the microclimate in Tibet in recent years. The increase in temperatures is causing increased evaporation and decreased humidity. These changes will, in turn, result in reduced milk yield and conception rate of yak in this hot and dry environment.

Acknowledgements

The authors acknowledge the technical support from the Jiali Bureau of Animal Husbandry, Jiali Animal Breeding Station, Pali Township, Yadong Veterinary Service Station, Kangbu Township in Yadong County, Mezhugongka County Government, Mezhugongka Farm, Southwestern Nationality College, Sichuan Sanitation and Prevention Station, Sichuan Livestock Research Institute, and Tibet First People's Hospital.

References

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