1380 Guernsey, 13614 Holstein, and 804 Jersey Dairy Herd Improvement yearly herd averages collected in eight Eastern and Southeastern states between 1965 and 1970 were analyzed to determine their value as management tools, identify recent trends in the dairy industry, and identify short term effects of changing herd size. Objective measures such as percent days in milk, milk production, and milk and grain price were found to be reliable estimates of true values. More subjective measures such as succulents, pasture and especially dry forage showed high coefficients of variation and appeared to be less reliable.

Least Squares multiple regression techniques were employed to identify management variables which influence milk production and income over feed cost. Of nine measures analyzed, concentrate level, percent days in milk, other feed costs, and grain costs had the most significant affects on milk production. Twelve variables were found to significantly influence herd average income over feed cost in one or more of the three breeds studied. Curvilinear relationships were observed in many of the variables, but added little value to the final prediction equation.

Differences between herd average variables for consecutive years were calculated, and when averaged, they represented yearly trends in dairying. Results for all three breeds were similar in magnitude with increases of 54 to 56 kgs. of milk per year, and 23 to 26 cents per cwt. per year in milk price. Using these differences, the affects of changing herd size were studied, and it was noted that as herd size increases rapidly, production per cow drops.