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Length of Service Period in Relation to Productive and Reproductive Efficiency in Dairy Cows¹

University of Wisconsin

Abstract

The age of a dairy cow at first parturition and the lengths of her subsequent calving intervals are usually considered of primary importance in measuring breeding efficiency. Arbitrary values are sometimes chosen as standards of ideal efficiency and the measure of actual efficiency is judged by comparison with these standards. For example, Williams² suggested a measure of breeding efficiency in which he adopted two years as the ideal age for first calf and twelve months as the interval between subsequent calvings. By his scheme, 100 per cent efficiency would require first conception at 15 months of age and subsequent conceptions 85 days following each parturition.

The relationship of these two factors to the efficiency of production and reproduction has been studied in the records of one commercial and four Wisconsin experiment station herds. The cows in these herds are Holsteins, producing between 200 and 500 pounds of butterfat per lactation (production corrected to 2 milkings per day, mature equivalent figure).

¹ Paper from the Department of Genetics, Agricultural Experiment Station, University of Wisconsin. No. 195. Published with the approval of the Director of the Station.