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Factors Limiting Selection Effectiveness in Small Flocks of Columbias and Corriedales¹

University of Wyoming, Laramie

Abstract

PUREBRED breeders are constantly faced with the problem of selecting for many traits not necessarily related to productivity. Breed associations publish standards of excellence and rules for registry for their members' use. In some cases, an inspection is required before sheep can be registered. Though standards differ between breed associations, breeders in all cases have limitations on selection for productive traits; since the more traits that are considered in selection, the less the emphasis on any one trait.

Undesirable traits in some cases have been reportedly associated with lowered production, but others seemingly are unrelated to productive traits. Terrill (1949) reported that open faced ewes were more productive than woolly faced ewes, and Nordby et al. (1945) indicated that lambs with jaw inequalities were lighter and had shorter fleeces than normal lambs. However, significant relationships between brown color and weanling traits have not been found (Terrill, 1947; Keyser et al., 1958), and skin folds seemingly are not associated with lowered production (Terrill and Kyle, 1952; Shelton et al., 1953).

¹ Published with the Approval of the Director, Wyoming Agricultural Experiment Station, As Journal Paper No. 296.