Abstract
Average daily feed consumption (ADFC) and feed efficiency (FE, gain/feed) from 21 to 42 days of age were measured in three groups of mice during generations 11 through 14 of a study designed to measure responses to selection for increased growth. One group was selected for increased 21-day weight (WWL), another group was selected for rapid gain between 21 and 42 days of age (ADGL), and a third group served as an unselected control (CL). Comparisons of FE and ADFC among WWL, ADGL and CL were very consistent over the four generations studied. As a result of the selection pressure applied, WWL and ADGL exceeded (P<.001) CL in 21-day weight by an average of 26.4% and 17.2%, respectively, and in 21 to 42-day ADG by 14.1% and 53.1%, respectively. The WWL and ADGL exceeded (P<.001) CL in ADFC by 17.4% and 26.9%, respectively. There was a 21.6% improvement (P<.001) in FE in ADGL over CL; however, WWL were 2.4% (P<.05)less efficient than CL. Analyses of variance and covariance in CL provided estimates of genetic correlations between 21-day weight and ADFC of .37 ± .26, between 21-day weight and FE of −.48 ± .38, between 21 to 42-day ADG and ADFC of .55 ± .18 and between 21 to 42-day ADG and FE of .63 ± .16. Copyright © 1975. American Society of Animal Science. Copyright 1975 by American Society of Animal Science.