Repeatability of Net Economic Effeciency in Dairy Cattle and Role of Some Economic Variables as Its Predictors1,2,3

Abstract

This investigation was to explore the possibility of improving net profitability in dairy cattle. Net profitability was measured as: 1) total profit; 2) profit per day of herd life; and 3) profit per unit of investment. Repeatabilities were estimated by three methods from two data sets consisting of 202 observations on 78 Holstein cows up to the end of their third calving interval. Repeatabilities of cumulative measures ranged from .6 to .8. Repeatabilities of noncumulative measures of profitability were approximately .4 for total profit and .3 for the other two measures. Correlations between economic variables in first lactation and the three measures of lifetime net profitability show that first lactation total income (correlations .41 to .64), value of product (.42 to .65), value of fat (.37 to .59), value of protein (.46 to .65), feed cost (.3 3 to .57), mastitis cost (−.20 to −.44), and services cost (−.15 to −.36) were significant predictors of the lifetime traits. Value of calves, salvage value, total expense, and initial inventory cost were of little predictive value. Correlations of most economic variables with herd life were low. Correlations of heifer body weight at different ages and age at first calving with all the different lifetime measures of economic efficiency were near zero. Number of services and days open had low negative associations with measures of economic efficiency.