Abstract

Lifetime records on 344 purebred Hereford (HE) and 517 multibreed Beef Synthetic #1 (SY1) cows bom
 from 1966 to 1975 were analysed to provide estimates of genetic parameters for growth traits measured early in
 life and measures of longevity and lifetime production. The cows were managed under a stringent culling policy where a heifer or cow failing to wean a calf each year was culled. Estimates of direct heritability were higher than maternal heritability for all traits, except weaning weight for which die pattern was reversed Estimates of direct heritability for growth traits (except weaning weight, with low estimates) were moderate to high (0.23 - 0.68), while those for lifetime production traits were moderate (0.22 - 0.37). Total heritability for the lifrtimp
 production traits were low, ranging from 0.04 to 0.17. Estimates of direct and total heritabilities were higher in
 die multibreed SY1 than the purebred HE breed group for all die traits studied Estimates of genetic correlation between direct and maternal effects were nagative for all traits in both breed groups except for yearling weight of HE cows which was dose to zero.
 

Paul F Arthur, M. F Liu, M. Makarechian

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 17. Genetics and breeding of dairy and beef cattle, swine and horses, , 225–228, 1994