北京黑白花牛体质外形与生产力的关系

THE RELATIONSHIP OF TYPE AND COMFORMATION WITH MILK PRODUCTION IN THE PEKING BLACK.AND-WHITE CATTLE

在近代鑑定种畜的方法中,体质外形和生产力鑑定是综合评定种畜的基础。国外报导乳牛的体质外形与生产力的相关以及它们遗传力的资料很多。过去报导关于外形与产乳力的相关都是很低的,外形总评与产乳量相关的变异范围是0.08—0.25,与乳脂量相关是0.08—0.31,与乳脂率相关是0.02—0.05。

Data collected over 5 years from the Peking Black-and-White cattle herd of the Peking Sand-River People’s Commune were analysed to study the relationship of type and conforma- tion with milk production. In calculating the correlation of type ratings with milk production in mature cows,213 animals were evaluated at 9 points:head and neck,shoulder and chest,back and loin,middle and belly,hind quarters,udder-size and quality,feet and legs,general appearance and develop- meat,and final rating. The correlations between these ratings and milk yield are all low.The correlatiobn between general appearance,final rating and milk yield ranked first(r=0.219,0.206,resp.),t-test is highly significant.Those between udder(0.181),chest(0.182),middle and belly(0.170)and milk yield ranked next,the difference is significant.The correlations between other points and milk yield are very low and not significant;those between hind quarters,back-loin,feet- legs and milk yield are negatively correlated.The measurements of rump of high and low producing cows confirmed the negative correlation between the hind quarters rating and milk yield. The milk yield and type ratings of the typical cows(being of excellant dairy character, ample body capacity,and compact constitution)are compared with dual-purpose cows and herd average;the typical cows,5136 kg and 84.5 marks;dual-purpose cows 4244 kg and 78.4 marks; and herd average,4617 kg and 77.7 marks.