Behaviour of Grazing Yak in Alpine Rangeland in Warm and Cold Seasons in Tibetan Plateau

Abstract

This study was aimed to obtain fundamental data to establish the grazing system for sustainable use and ecological preservation of rangeland in Qinghai-Tibetan Plateau through investigation of yak behaviour in rotational-grazing paddocks between winter-spring (cold) and summer-autumn (warm) seasons. Behavioural observations of 3 grazing yaks were conducted in warm season paddock (WSGP) and cold season paddock (CSGP) in Yushu Tibetan-Autonomous State, Qinghai Province, China. Grazing time of yak was 590.2 min/day in July 2009 (W09) and 511.8 min/day in August 2010 (W10) in WSGP, and 468.0 min/day in April 2008 (C08) in CSGP. It was significantly shorter in CSGP than in WSGP (P<0.001). The rumination time was significantly longer in WSGP (W09: 373.5 min/day and W10: 419.8 min/day) than in CSGP (C08:195.3 min/day) (P<0.001). The chewing number per bolus in rumination was significantly different among the observation periods (p<0.001) and chewing rate was greatest in C08 among the three (P<0.001). The bite number per patch in foraging behaviour was not significantly different among the observation periods (p>0.05). Bite rate in a patch and number of steps between patches were significantly greater in WSGP (W09 and W10) than that in CSGP (C8) (p<0.001). Number of feeding station (FS) per patch was greater in C08 than in W09 and foraging time per FS was greater in C08 than in W09, but bite number per FS was smaller in C08 than in W10 (p<0.05). It was considered that the differences of vegetation and biomass influenced on grazing and rumination in yak behaviour and that new grazing system should be investigated.