Correlated Responses of Blood Coagulation and Prothrombin Times to Selection for Body Weight

Abstract

Concomitant changes in unselected traits resulting from selection for a particular trait are considered correlated responses. The theory of correlated responses and computational procedures are discussed in Falconer (1960). Reported here are correlated responses of blood coagulation and plasma prothrombin times in F9 and F10 generation White Rock females selected for high and low body wieght at eight weeks of age (Siegel, 1962).Chicks, in both generations, were removed from the hatcher on the 22nd day of incubation, pedigreed, and reared in floor pens. Body weights were obtained at eight weeks of age and coagulation and prothrombin times were measured at 18 weeks by the methods of Quick (1959). Thromboplastin preparations were made from brain tissue of chickens by the acetone dehydration method (Quick, 1959).A completely randomized design was used for comparisons between lines within generations. All data for the calculation of realized genetic correlations (Falconer, 1954) were from…