Warren J H, Schalles R R, Milliken G
Growth. 1980 Sep;44(3):160-6.
Three segmented linear regression lines were fitted simultaneously to regress weight of Polled Hereford female cattle on age. Resulting parameter estimates from the procedure measure size and rates of gain. Sire and year of birth had the greatest effects on growth traits before growth rate slowed when heifers were approximately 17 months of age but had less effect in later life. Genetic correlations between weights at all ages were positive, as were genetic correlations between degrees of maturity at all ages. Animals taking longer to reach mature weights had greater mature weights. Degree of maturity and weight were positively correlated at a given age, but changed to negative as the age interval between weight and degree of maturity increased. Animals more mature at any age grew slower until they reached full maturity.
同时拟合了三条分段线性回归线，以将无角海福特母牛的体重对年龄进行回归。该过程得出的参数估计值衡量了生长规模和生长速率。在小母牛约17月龄生长速率放缓之前，父亲和出生年份对生长性状的影响最大，但在后期影响较小。所有年龄体重之间的遗传相关性均为正，所有年龄成熟度之间的遗传相关性也为正。达到成熟体重所需时间更长的动物具有更大的成熟体重。在给定年龄时，成熟度和体重呈正相关，但随着体重和成熟度之间的年龄间隔增加，相关性变为负相关。在任何年龄更成熟的动物生长较慢，直到达到完全成熟。
