Age and weight were highly correlated in nine growing bulls. The correlation of age and weight dropped from +.989 for the period up to two years of age to +.642 after two years. Regressions of weight on age were essentially linear for the two growth periods, before and after two years of age. Up to two years, the regression of weight in pounds (Y) on age in weeks (X) was Ŷ = 59 + 14.23X. Beyond two years the regression was Ŷ = 792 + 6.86X. The logarithms of weight in pounds were essentially linear with respect to heart girth below and above 47 in. of girth. Linear regressions of the logarithms of the weight in pounds (Y) on the heart girth in inches (X) were Ŷ = .7572 + .03783X for the range below 47 in. and Ŷ = 1.7983 + .01686X for the range above 47 in. Correlations of the logarithm of weight with heart girth were +.967 and +.959 for the ranges below and above 47 in. of girth. Sperm numbers per ejaculation were highly significantly correlated with age (+.514) and with weight (+.533). The regression of sperm numbers per ejaculation in millions (Y) on age in weeks (X) was Ŷ = 55.03X − 1601. The regression of sperm numbers per ejaculation in millions (Y) on weight in lb. (X) was Ŷ = 4.374X − 2335.