U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



1980 Poultry Science 59:1155-1166


U.S. Government Work


The growth and laying performance of two strains (6 and 8) after two generations of close inbreeding (44%) were compared with that of their reciprocal crosses ( 6 X 8 and 8X6) under two levels (17% and 13%) of dietary protein and a corresponding 19% reduction in daily protein intake.

Inbreeding effects were large for most traits measured, including body weights, components of egg production, and egg quality.

Reduced dietary protein had adverse effects upon viability, egg mass, age at first egg, and body weight late in the laying period. However, this dietary modification improved egg mass produced per kilogram of protein intake and had no effects upon egg quality.

The tendency for inbreeding depression to be greater under the low (13%) protein diet for viability, sexual maturity, and egg production was too slight for statistical significance. Inbreeding did not change feed or protein conversion response to low protein because inbreds increased their intake of the low protein diet less than the crosses.