Growth Rate Inheritance in Japanese Quail

THE exposition and complete utilization of all sources of genetic variation is a major goal of geneticists. One approach for achieving this goal includes the development of lines selected for growth performance in a variety of adverse environments followed by the testing of these lines and/or line-crosses in an optimum environment. Prior to initiating the selection studies, however, it is necessary to determine which environmental conditions produce a repeatable restriction in growth rate. A preliminary report (Marks and Lepore, 1966) indicated the ineffectiveness of crowding, limiting waterei or feeder space, and temperature stress in consistently restricting 4-week body weight in Japanese quail. Coupling these results with the inherent managerial ease of conducting dietary stress experiments prompted us to investigate using adverse nutritional environments for growth rate depression. A literature search provided many possible dietary treatments which could be used, but for theoretical reasons, thiouracil supplementation and protein deficiency were chosen . . .