Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China

	Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China
	Xue, B ; Zhao, XQ ; Zhang, YS
刊名	journal of animal science
	2005-08-01
卷号	83 期号:8 页码:1908-1913
关键词	body composition body weight grassland live weight seasonal dynamics yak
合作状况	其它
中文摘要	forty-five male yaks (born april 2001) were studied to determine how seasonal changes on the qinghai-tibetan plateau affected bw and body composition. thirty yaks were weighed monthly from birth to 26 mo of age to determine seasonal changes in bw. the remaining 15 yaks were allocated randomly to five groups (three yaks per group), designated for slaughter at 13, 15, 18, 22, and 25 mo to measure seasonal effects on body chemical composition. all yaks were grazed on the alpine-meadow grassland of the plateau without any supplementation. all bw and body composition data were calculated on an individual basis. body weight and body composition data were both compared across seven growth periods spanning 2 yr and defined by season. from april (birth) to december 2001 of the first growing season, yak bw increased (p < 0.01); however, during the subsequent cold season (december 2001 to may 2002), bw decreased (p < 0.01). the second growing season ran from may 2002 (13 mo of age) to october 2002 (18 mo of age), and the second live weight-loss season ran from october 2002 until may 2003. the weight loss experienced by yaks during the first weight loss season was 25.64% of the total weight gain in the first growing season. the weight loss experienced by yaks during the second weight-loss season was 29.73% of the total weight gain in the second growing season. energy retention in the second growing season was 291.07 mj, 50.8% of which was consumed during the subsequent cold season. energy accumulation in the summer (from may to july) and fall (from july to october) of the second growing season did not differ (5.01 and 6.30 mj/kg of ebw gain, respectively; p = 0.63). the energy mobilized during the second winter (from october 2002 to february 2003) was 16.49 mj/kg of ebw, and in the second spring (from february to may 2003), it was 9.06 mj/kg of ebw. these data suggest that the decrease in grazing yak bw during the first cold season is much less than during the second cold season, and that the energy content per unit of bw mobilized is greater (p = 0.02) in winter than in spring. results from this study demonstrate highly efficient compensatory growth in grazing yaks following the first weight loss period during the first cold season. this benefit could be exploited by herders to improve yak production. yaks may have developed a type of self-protection mechanism to overcome the long cold seasons in the qinghai-tibetan plateau.
英文摘要	forty-five male yaks (born april 2001) were studied to determine how seasonal changes on the qinghai-tibetan plateau affected bw and body composition. thirty yaks were weighed monthly from birth to 26 mo of age to determine seasonal changes in bw. the remaining 15 yaks were allocated randomly to five groups (three yaks per group), designated for slaughter at 13, 15, 18, 22, and 25 mo to measure seasonal effects on body chemical composition. all yaks were grazed on the alpine-meadow grassland of the plateau without any supplementation. all bw and body composition data were calculated on an individual basis. body weight and body composition data were both compared across seven growth periods spanning 2 yr and defined by season. from april (birth) to december 2001 of the first growing season, yak bw increased (p < 0.01); however, during the subsequent cold season (december 2001 to may 2002), bw decreased (p < 0.01). the second growing season ran from may 2002 (13 mo of age) to october 2002 (18 mo of age), and the second live weight-loss season ran from october 2002 until may 2003. the weight loss experienced by yaks during the first weight loss season was 25.64% of the total weight gain in the first growing season. the weight loss experienced by yaks during the second weight-loss season was 29.73% of the total weight gain in the second growing season. energy retention in the second growing season was 291.07 mj, 50.8% of which was consumed during the subsequent cold season. energy accumulation in the summer (from may to july) and fall (from july to october) of the second growing season did not differ (5.01 and 6.30 mj/kg of ebw gain, respectively; p = 0.63). the energy mobilized during the second winter (from october 2002 to february 2003) was 16.49 mj/kg of ebw, and in the second spring (from february to may 2003), it was 9.06 mj/kg of ebw. these data suggest that the decrease in grazing yak bw during the first cold season is much less than during the second cold season, and that the energy content per unit of bw mobilized is greater (p = 0.02) in winter than in spring. results from this study demonstrate highly efficient compensatory growth in grazing yaks following the first weight loss period during the first cold season. this benefit could be exploited by herders to improve yak production. yaks may have developed a type of self-protection mechanism to overcome the long cold seasons in the qinghai-tibetan plateau.
学科主题	动物学
WOS标题词	science & technology ; life sciences & biomedicine
类目[WOS]	agriculture, dairy & animal science
研究领域[WOS]	agriculture
关键词[WOS]	compensatory growth ; performance ; cattle
收录类别	SCI
语种	英语
WOS记录号	WOS:000235847700019
公开日期	2009-12-08
内容类型	期刊论文
源URL	[http://ir.nwipb.ac.cn/handle/363003/1339]
专题	西北高原生物研究所_中国科学院西北高原生物研究所
作者单位	1.Chinese Acad Sci, NW Inst Plateau Biol, Xining 810001, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing 100003, Peoples R China 3.Qinghai Acad Anim Sci & Vet Med, Xining 810003, Qinghai, Peoples R China
推荐引用方式 GB/T 7714	Xue, B,Zhao, XQ,Zhang, YS. Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China[J]. journal of animal science,2005,83(8):1908-1913.
APA	Xue, B,Zhao, XQ,&Zhang, YS.(2005).Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China.journal of animal science,83(8),1908-1913.
MLA	Xue, B,et al."Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China".journal of animal science 83.8(2005):1908-1913.