Feeding behaviour of yaks on spring, transitional, summer and winter pasture in the alpine region of the Qinghai–Tibetan plateau

doi:10.1016/j.applanim.2007.06.008

Applied Animal Behaviour Science

Volume 111, Issues 3–4, June 2008, Pages 373-390

https://doi.org/10.1016/j.applanim.2007.06.008 Get rights and content

Abstract

Of the present estimated world population of 14.2 million yaks, approximately 13.3 million occur within Chinese territories (Food and Agriculture Organization of the United Nations, 2003). Although there is an extensive bibliography covering the species, few studies have been conducted in the area of foraging behaviour. The present study was conducted at pasture during the spring, transitional, summer and winter seasons to determine the daily temporal patterns of grazing and ruminating behaviour by yaks. During each study period, two 24 h recordings were undertaken with each of six mature dairy yaks. One study period was conducted on each of the transitional, summer and winter pastures, whereas, due to the considerable changes occurring in the morphology of the spring pasture, three separate studies were completed during March, April and May. During the second of these studies (April), the effect of level of concentrate supplementation on grazing and ruminating behaviour was also examined. Behaviour recordings were made using solid-state behaviour recorders. Short-term intake rates (IR, g min⁻¹) were calculated by weighing yaks before and after approximately 1 h of grazing, retaining the faeces and urine excreted and applying a correction for insensible weight loss. Yaks spent less time grazing during the dry season (the early period on the spring pasture) compared with the later green swards (the later period on the spring pasture, the transitional pasture and the summer pasture) (P < 0.05). When the forage quality improved, but there was still insufficient mass (the later period on the spring pasture), the yaks extended their grazing time at the expense of other activities. During the early periods on the spring pasture, the short-term IR by yaks was up to 53 g DM min⁻¹, significantly higher than at other times (P < 0.05). The level of concentrate offered had little or no effect on grazing or ruminating time. The total eating time of the yaks offered 0.5 or 1.0 kg concentrate was 2.9 and 4.5 h day⁻¹, respectively, significantly lower than unsupplemented yaks (6.8 h) (P < 0.05). In general, yaks can regulate their foraging behaviour according to the changes of sward conditions in order to achieve optimal grazing strategies.

Introduction

On the Qinghai–Tibetan plateau, China, yaks (Bos grunniens) are essential for providing meat, milk, skins, transport and fuel (faeces), and fulfill various socio-cultural functions within the pastoral society. However, due to their relatively restricted worldwide distribution and population number of 14.2 million, yaks have been the subject of considerably less research than the ubiquitous and more numerous common domesticated cattle (Bos taurus; 1291 million).

Grazing systems represent approximately 20% of the total land area of the earth's surface (Hodgson and Illius, 1996). Herbivore utilization of grass swards is limited by the quality and quantity of forage ingested (Fryxell, 1991, Ungar, 1996), and the interaction between the grazing animal and sward has important implications for the development of both. Therefore, quantifying diet selection, herbage intake and modification of the forage resource by the grazing animal will help to define limits to sustainable grazing systems on the Qinghai–Tibetan plateau, rather than present practices which have led to serious degradation of the pastures. High stocking rates and the over-utilization of these alpine grasslands are the main cause of this grassland degradation.

Behaviour studies have played an important role in the improvement of grazing management throughout much of the world (Goldson, 1962). Grazing behaviour is important because of the immediate effect on the animal's productivity and because of its consequences for future grazing opportunities, composition of pasture and productivity (Coates and Penning, 2000).

The yak is a specialized species that has adapted to living in harsh and high altitude environments. The majority of the world population of yak occurs on the high plateau of western China in alpine and sub-alpine regions with a cold and semi-humid climate. The centre of the yak's distribution is the Qinghai–Tibetan plateau. The objectives of this work were to assess the feeding behaviour of yak grazing on Qinghai–Tibetan rangeland on spring, transitional, summer and winter pastures. In addition, the effect of providing a concentrate supplement during the spring season on yak foraging behaviour, when herbage was depleted, was examined.

Section snippets

Location

Qinghai Lake grassland is typical of the alpine grassland of the Qinghai–Tibetan plateau. It is an important pasturing area for yak and sheep production, with a seasonal migration between different grazing areas. Typically, four pasture types are utilized over the year: spring, transitional, summer, autumn and winter pasture, with spring and winter pastures belong to one type, but divided by fences as different seasonal pastures. Before moving from spring pasture to summer pasture, the yaks are

Herbage mass, sward height and chemical composition

The herbage mass in period 1 (March), period 2 (April) and period 3 (May) on spring pasture, transitional pasture, summer pasture and winter pasture are shown in Table 1. The herbage mass was significantly higher in the dry periods (periods 1 and 2 on spring season, winter season) than in green periods (period 3 on spring season, transitional and summer seasons) (P < 0.05). The height of the dominant species in the four pastures during the different periods is shown in Table 1. The height of A.

Grazing and ruminating behaviour

Grazing activity occurred mainly, though not exclusively, during the hours of daylight (range: 06:00–19:00 h, in spring and winter seasons, respectively). At night, yaks avoid grazing and tend to gather in groups in order to reduce body heat loss, because of the cold night temperatures, and as a defense mechanism against attack by predators. However, with the growth of new green herbage in May (period 3) on the spring pasture, and subsequently on the transitional and summer pastures, the yaks

Conclusion

The results show that yaks adapted their foraging behaviour in response to changes in sward conditions. In the dry periods or seasons, the yaks did not extend their grazing time because of the low quality of forage. In the germinating season (period 3 of spring pasture), the yaks increased their bite rate and TGT as a response to reduced bite mass. This research on yak foraging behaviour is a valuable aid to the improvement of the management of grazing livestock under alpine grassland on the

Acknowledgements

We thank the staff of San Jiao Cheng Sheep Breeding Farm for assistance with the fieldwork. We also wish to thank M.D. Qin for making this research possible. We express our gratitude to Malcolm Gibb (formerly of the Institute of Grassland and Environmental Research, North Wyke, EX20 2SB, UK, E-mail: [email protected]) for his assistance in revising this manuscript. This paper is a contribution to project Ministry of Education/China/20040733004: ‘Evaluation of Germplasm Source of

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Citation Excerpt :
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Feeding behaviour of yaks on spring, transitional, summer and winter pasture in the alpine region of the Qinghai–Tibetan plateau

Abstract

Introduction

Section snippets

Location

Herbage mass, sward height and chemical composition

Grazing and ruminating behaviour

Conclusion

Acknowledgements

Appl. Anim. Behav. Sci.

Appl. Anim. Behav. Sci.

J. Dairy Sci.

Measuring animal performance

Forage quality and aggregation by large herbivores

Am. Nat.

Forage quality and camel feeding patterns in central Baringo, Kenya

Livest. Prod. Sci.

The Yak

Effect of sward height on intake and behaviour by lactating British Friesian cows

Grass Forage Sci.

Effect of time of day on grazing behaviour by lactating dairy cows

Grass Forage Sci.

Effects of concentrate supplementation on grazing behaviour and performance by lactating dairy cows grazing continuously stocked grass swards

Anim. Sci.