ABSTRACT
Response in the selected and the correlated traits from five generations of index selection (I.D.S. method) for egg production to 40 weeks of age in four White Leghorn populations have been presented. The correlated traits measured included: Age at first egg, egg weight, body weight and also derived traits such as egg mass, survivors' rate of lay, efficiency index and ratio of egg weight to body weight. Response realized for the selected trait was significant in three out of the four selected lines. Predicted and realized genetic gains were comparable in magnitude for most of the traits studied. The significance of these findings in selection experiments is discussed.
ABSTRACT
Responses from four generations of index selection for egg production to 280 days of age in four White Leghorn populations have been presented. A pedigreed randombred population derived from one of the lines was reared with the selected lines to measure the environmental trend. The magnitude of total as well as average response although varying from population to population was positive in all the lines studied. Close correspondence between predicted and realized gains indicated that natural selection, genotype environmental interactions and environmental fluctuations were unimportant during the course of selection. Realized heritabilities agreed fairly well with the estimated heritabilities in at least three out of four populations studied. Probable reasons for variable and insufficient response were investigated.
