To strengthen protection and improvement for Tianzhu White Yak, opening conservation and breeding system has been constructed based on principle, one farm plus three districts plus one station. After running for 20 years, a plenty of conservation and breeding data has been collected. Up to 2006, 39 400 White Yaks survived in this areas, which accounted for 44% of total yaks in Tianzhu County. Comparing with beginning of the system construction in 1987, the number of white yak increased for 16 percent. Among them, the nucleus group increased for 10 groups, which included 560 yaks, the improved group increased for 64 groups, which were 3300 yaks. The first and the second class yaks increased by 14 and 16 percent, respectively. The proportion of white-hair individuals increased for 4 percent. Average body height, chest girth and body weight of adult bulls increased by 4.11cm, 15.37cm and 13.05 kg, respectively. Average hair and beef yield of adult yak bulls and cows increased by 0.28 kg and 5.58 kg, respectively. The system framework and construction accorded with the practice in protecting areas. The technical route was advanced and rational. The function was obvious.%为加强本种的保护与选育提高,逐步构架建立以"一场三区一站"为核心的开放保种繁育体系,经对该体系运行二十多年的保种选育资料分析, 截止2006年,保种区存栏天祝白牦牛3.94万头,占牦牛的44%,比体系建立初的1987年增加16个百分点.其中:核心群增加10群560头,选育群增加64群3 300头,一、二级牛比例分别增加14、16个百分点,白色被毛比例增加4个百分点.主要体尺、体重与生产性能,成年公牛平均体高、胸围和体重分别增加4.11 cm、15.37 cm和13.05 kg;成年公、母牛平均产毛绒、产肉量提高0.28 kg和 5.58 kg.体系构架、建立符合保种区实际,技术路线先进、合理,运行效果显著.
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