公牛家系泌乳曲线的研究

A Study on the Lactation Curves of Bull Families

本文根据北京黑白花奶牛22个公牛家系的女儿泌乳期资料，利用Wood模型估计了各公牛家系的泌乳曲线参数，并且按照家系内女儿的不同胎次、所在牧场和产犊年份分组作了更加深入的研究。所考虑的曲线参数为规模因子a、产奶量上升率b和下降率c；次极参数包括305天实际产奶量（MY）、305天估计产奶量（EMY）、高峰月份（MPY）、高峰月产奶量（PY）和泌乳持久力。结果表明，与低产公牛家系相比，高产公牛家系的泌乳曲线通常具有较高的初始产奶量、参数a、b和PY，但往往伴随着较低的持久力。此结果预示着一条通过改善公牛对其女儿泌乳曲线波型的遗传贡献，从而提高群体泌乳水平的育种新途径。

In this paper an estimation was made on the lactation curve parameter of each of the 22 bull families after the Wood Model on the basis of the milking stage records of the daughters. And a further study was made in different groups divided according to different births of the daughters inside the family,the animal farms and calving years. The curve parameters considered were scope factor A,increase rate of milk yield B and decrease rate C. The secondary parameters considered were estimated milk yield(EMY)within 305 days,real milk yield(MY),peak yield month (PYM),peak yield in a month (PY) and lactation persistency. The result shows that,compared with low -yielding bull families,the lactation curves of high-yielding often shows a higher initial level,parameter A and B,and PY,but sometimes with lower persistency. This result predicts a new breeding way to increase group milk yield by improving bulls' genetic contribution to their daughters' lactation curve waves.