Weaning Weights of Hereford Calves as Affected by Inbreeding, Sex, and Age

Abstract

A set of descriptive constants was developed, whereby the variations in weaning weight caused by inbreeding, age and sex could be estimated in a herd of Hereford beef cattle. These constants were developed to increase effectiveness of selection for weaning weights among calves to be considered for replacements and their dams. The variables considered were years, age of dam, sex of calf, inbreeding of calf and dam, and age of calf at weaning; all were significant in their effect at the 0.05 or 0.01 level. Effect in pounds as deviations from the average weaning weight were: Years: 1946, +6.; 1947, −24; 1948, −2; 1949, +2; 1950, −1; 1951, +20. Age of dam: 2 years, −15; 3 to 5 years; +5; 6 to 8, +21; 9 and over, −10. Sex: steer, −6; bull, +14; heifer, −8. Per one percent inbreeding of calf: −1.75. Per one percent inbreeding of dam: −1.15. Per increase in age of calf of one day: +1.67.