Selection for Rapid Growth Rate in Chickens

Abstract

SINCE the advent of the broiler industry more than 20 years ago, poultry breeders have been selecting for rapid growth rate in broiler-strain chickens. They have made much progress. However, it has been difficult to separate genetic progress from that resulting from advances in nutrition for improvement of growth rate. Jaap, Smith and Goodman (1962) used a randombred control population to measure the genetic change which occurred in eight-week body weight of broilers produced commercially between 1955 and 1959. During this period the breeders were estimated to have increased the eight-week weight of broilers by approximately ½ lb. This ½ lb. was almost a 20 percent gain achieved in four generations. Naturally, poultry breeders are wondering whether they may be approaching the upper limits for rapid creases in growth rate in present day populations.The implications of genetical theory (Lerner, 1958; Falconer, 1960) are not clear. Therefore, several additionals election…