Use of Grade Animals in Dairy Cattle Improvement: Introduction

Abstract

Breeds of US dairy cattle are stratified hierarchically into partial isolates with a largely directional gene flow from a small registered to a large grade subpopulation. Meadows (3) emphasized the long-term advantage of expanding the gene pool and proposed a method to permit genetic contributions by outstanding grade cows. Indeed, the tendency of owners and managers of tested grade herds to use sires with higher Predicted Differences for milk than their registered breeder counterparts (4) provides incentive to monitor the genetic potential of the grade population. The following papers focus on the potentials and programs to use grade animals in dairy cattle improvement. This symposium resulted from the joint efforts of two American Dairy Science Association Production Division Committees: Extension and Education and Dairy Cattle Improvement. The idea of utilizing germ plasm from the grade population is probably controversial, maybe heretical, to some breeders of registered cattle. In the past, artificial insemination threatened breeders of natural service sires by portending reduced income from sales of bulls. Now suppliers of registered cattle may be threatened economically by possible egalitarian genetic contributions to the gene pool by elite grade cows. Animal scientists should emphasize that it is a lack of revision that makes sound scientific techniques antiquated. Lerner and Donald (2) provided sage focus for the theme of this symposium: Like politics, improvement of livestock is an act of the poss ib le . . . (page 182). There are good reasons to exploit and rationalize the exchange and testing of b r e e d s . . , between countr ies . . . (page 120). It is as true now as in the 18th century that those who breed the elite and significant animals are but products of their day and generation [and]