Relationships Between Sire Evaluations at Different Herdmate Levels

Abstract

Relationships between independent measures of a bull's breeding value at different levels of herd production were investigated. The data consisted of the 2 times, 305-day, mature equivalent (ME) first lactation records of the artificially inseminated (AI) progeny of 40 Holstein sires. Each bull had 1,000 or more daughters. Progeny were classified into one of four groups, based on milk yield level of herdmates 442 kg;349 kg; III= 6,256 kg; and IV = 7,164 kg). Daughter averages rose with increases in herdmate level, while the magnitude of the Predicted Difference measure of a sire's breeding value decreased 289 kg (103, 47, --39, and --186 kg, respectively) from low (I) to high (I) herdmate levels.