The Influence of Genetic Increases in Egg Production and Body Weight on Egg Mass Production and Biological Efficiency of Turkey Hens

Abstract

Changes in total egg mass (average egg weight × total egg production) and biological efficiency (ratio of egg mass to metabolic body weight) were measured in Generations 11 to 24 of a line (E) of turkeys selected for increased egg production and in Generations 1 to 18 of a turkey line (F) selected for increased 16-week body weight. Total egg mass increased (.27 kg/generation, P<.01) in the E line even though egg weight decreased (.25 g/generation, P<.01). Egg production increased greatly (3.9 eggs/generation, P<.01) in the E line. Biological efficiency increased in the E line at a rate slightly lower than the increase observed in total egg production (.143σ vs. .128σ/generation, both P<.01) when expressed in standard deviation units. In the F line, egg weight increased (.37 g/generation, P<.01), egg production decreased (1.04 eggs/generation, P<.05), while egg mass production did not change significantly (−.074 kg/generation). Biological efficiency of egg production decreased in the F line. In both the E and F lines, a change in egg production of one egg resulted in a similar change in biological efficiency (.016 kg/kg.75), even though there was a large difference in average body weight (7.2 kg in E and 13.65 kg in F) and egg weight (74 g in E and 95 g in F) in the last generation studied.