The objectives of this research were to: 1) express variation in DHIA herd performance measures by means of a limited number of factors; 2) determine the relationship of DHIA performance measures to profit score and their sensitivity to market price changes; and 3) identify which herd performance measures changes were associated with profit score changes over a five-year horizon. For the variability in DHIA herd performance measures, large variation among herds would indicate notable opportunity for changing management strategy. It was concluded that three independent factors offer the greatest opportunity for improvement within most production subsets. Notably, the reproductive measures of calving interval, days open, and percent cows bred> 3 times accounted for a large portion of variability among herds. Also, considerable variation among herds for percent cows with SCS 4-5 and cows with SCS> 5 suggests that management practices or their successful implementation at preventing mastitis differ greatly from farm to farm. Simple regression was used for determining the relationship of DHIA performance measures to profit score and the sensitivity of performance measures to market price changes. It was determined that 1) several measures were related to profit score by quadratic effects; 2) for measures with quadratic relationship to profit score, resulting changes in score for herds are dependent on the current herd performance for the respective measure, and 3) milk yield was not the only measure that significantly impacted profit score. Sensitivity analysis indicated that several of the performance measures were sensitive to milk price changes. These price sensitivities suggest that producers need to consider economic conditions when assessing the importance of different management changes. Lastly, herds which differed in realized changes for profit score over a five-year horizon were identified, characterized for performance measures, and performance changes that were associated with profit score changes were determined. Changes in milk yield were not associated with changes in profit score for herds that either significantly or consistently increase profit over time. Rather, it was shown that average annual changes in reproductive measures had a more important effect on changes in profit score for herds that were less profitable.

"Nearly 50 years ago a few progressive dairy farmers in Michigan organized the first cow-testing association in the United States. They wanted to improve the profitableness of their herds. They hired a tester to weigh and test the milk of each cow and keep a record of her food cost and income. They wanted that information so the could cull the low producers from their herds and feed the rest more economically. In the first 4 years of their pioneer effort these Michigan dairy farmers doubled the average profit per sow. since then thousands of other dairy farmers have followed their example with equally striking results. The cow-testing movement grew and eventually expanded into the present-day dairy-herd-improvement-association program. Members of these associations now use their records not only to test the cows but to prove the bulls. The improvement they have brought about in their herds is one of the outstanding 'success' stories in agriculture. No herd is so good that it cannot be made better by effective culling, good feeding, and the use of production-tested breeding stock. Breeding records and records of production, feed cost, and income are essential for carrying on such an improvement program. Membership in a dairy-herd improvement association is one of the best and most economical ways for any dairy farmer to obtain the necessary records."--Page ii.

"Nearly 50 years ago a few progressive dairy farmers in Michigan organized the first cow-testing association in the United States. They wanted to improve the profitableness of their herds. They hired a tester to weigh and test the milk of each cow and keep a record of her food cost and income. They wanted that information so the could cull the low producers from their herds and feed the rest more economically. In the first 4 years of their pioneer effort these Michigan dairy farmers doubled the average profit per sow. since then thousands of other dairy farmers have followed their example with equally striking results. The cow-testing movement grew and eventually expanded into the present-day dairy-herd-improvement-association program. Members of these associations now use their records not only to test the cows but to prove the bulls. The improvement they have brought about in their herds is one of the outstanding 'success' stories in agriculture. No herd is so good that it cannot be made better by effective culling, good feeding, and the use of production-tested breeding stock. Breeding records and records of production, feed cost, and income are essential for carrying on such an improvement program. Membership in a dairy-herd improvement association is one of the best and most economical ways for any dairy farmer to obtain the necessary records."--Page ii.