Dairy Herd Improvement Association Yearly Herd Averages. I. Sources of Variation and Relations Among Measurements

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Abstract
Yearly herd average records from 1,801 Holstein hexds on test continuously during 1960-1964 in the northeastern United States were studied. All herds fed both concentrates and hay, but stone did not provide silage or pasture. Grain price, milk price, and feed cost per hundredweight of milk exhibited the largest degree of vari- ation among states. Milk yield (62%) and income over feed cost (62%) had the largest variance among herds. Yalue of product (.77) and income over feed cost (.72) were most repeatable from year to year in the same herd. Milk yield a~counted for about one-half the total variation in income over feed cost. The amount of concentrates fed was the only feed measure closely related to income over feed cost. The amount of hay fed had little influence on production and income over feed cost. It was concluded that estimates of feed costs other than concentrates were of little usefulness. The DHIA program provides data to aid the dairyman in attaining two specific objectives: a) selection among cows and b) evaluation of herd management variables. Most of the re- search on the use of DHIA information has dealt with a). Insufficient attention has been given to the study of the effectiveness of DHIA data as a tool for management decisions. This is the first of a series of papers dealing with this aspect of the DHIA program. The assessment of costs and returns in the DHIA program has customarily been limited to those directly associated with the milking herd. Costs of labor, equipment, and other factors have not been considered. Further, efforts have been made to divorce returns associated with the cropping system from those directly asso- elated with the dairy herd. Usually, DHIA feed costs are estimated on the basis of the prices that would be paid to obtain feedstuffs comparable to home-grown grain and forage.