Genetic correlations between female fertility and postweaning growth and feed efficiency traits in multibreed beef cattle

Abstract

With selection in beef cattle now incorporating feed efficiency, knowing the relationship with other traits is needed. Genetic relationships were estimated with an animal model in ASReml with a three-generation pedigree inclusive of 2882 animals. Multibreed data from two Ontario beef research farms with fertility traits were available on 1366 females and postweaning traits, including feed efficiency on 1297 individuals. Estimates of heritability for fertility traits were low to moderate ranging from 0.03 ± 0.01 for pregnancy rate to 0.21 ± 0.02 for gestation length, and postweaning traits were moderate to high with feed conversion ratio at 0.22 ± 0.06 to mid-metabolic weight at 0.89 ± 0.01. Both dry matter intake and mid-metabolic weight were genetically correlated with most fertility traits from -0.52 to 0.34. The genetic correlation between average daily gain and days to calving was moderately negative (-0.33 ± 0.16) as was residual feed intake with days to calving (-0.34 ± 0.17). Bigger cows with more feed intake and faster growth were more fertile, and residual feed intake had an unfavorable genetic correlation with days to calving, indicating that programs to select for feed efficiency should include fertility simultaneously in a selection index.