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Production Performance of Artificially and Nonartificially Sired Herd-Mates in Wisconsin^{1, 2,}

Department of Dairy Science, University of Wisconsin, Madison

ABSTRACT

The production performance of AI progeny and their contemporary non-AI herd-mates was compared on an intra-herd-year-season basis. A total of 84,691 Holstein and 20,742 Guernsey 2x, 305-day, M.E. records were available for analysis. The data were divided on the basis of calving date into ten consecutive six-month periods, ranging from September, 1951, to August, 1956.

The production superiority of cows calving in the fall and winter seasons was 17 to 23 lb of fat and 413 to 581 lb of milk. Among Holstein herds, AI progeny were significantly superior to their non-AI herd-mates by approximately 13 lb of fat and 270 lb of milk. These differences were generally maintained at three levels of herd production. Significant AI vs. non-AI x herd interaction found in many of the periods indicated that these differences vary considerably from herd to herd. It appeared that the selection of AI Holstein sires in use during this time was more effective than the selection of non-AI sires in herds using both types of services. The AI progeny in Guernsey herds were not significantly superior to their non-AI herd-mates when all available records were used. These differences were in favor of the AI progeny but by only 5 lb of fat and 22 lb of milk, and varied considerably from period to period. There was general evidence that more emphasis was placed on fat test and possibly fat yield than on milk yield in the selection of AI sires for both breeds.

¹ Approved for publication by the Director of the Experiment Station, University of Wisconsin, Madison.

² Supported in part by Wisconsin's AI Cooperatives.