秦川牛保种情况的分析(续) Ⅱ、群体留种方式与世代间隔

An Analysis on the Conservation Results of Qinchuan Cattle Ⅱ.Mating System and Average Generation Interval

根据陕西省秦川牛场秦川牛保种群30多年的记录统计,分析了该群体的世代间隔与留种方式。结果表明,该群体平均世代间隔为6.9年,采取的是对保种不利的合并留种,导致各种家系后代供量方差增大,尤其是公牛的女儿供量方差高达77.39,比平均女儿供量(5.84头)高13倍。不同始祖个体在后裔群中的血统分布也极不均匀。若能改进留种方式或设法降低选择强度,则可大大提高保种效果。

Thirty years of records from a conservation population of Qinchuan Cattle in Qinchuan Cattle Farm of Shaanxi Province were utilized to analyze the mating system and generation interval in the population.Results showed that,the average generation interval was 6.9 year,the mating system adopted was combination selection which resulted in the great increase in varances in the number of progeny from various families.The varance in the number of female progeny from male parents was especially high,which equaled 77.39 and was 13 times as much as the averge number of female progeny(5.84).Genes(blood)from different founders were rather unevenly distributed in the progeny population.The conservation results could be improved significantly by decreasing the selection intencity or by adopting proper mating systems.