Date of this Version
A total of 19,833 records on 1,992 Thoroughbred foals out of 813 dams and by 365 sires was used to estimate heritability of weight, height at withers, and front cannon bone circumference. Measurement ages ranged from 0 to 174 days. Records were adjusted for the fixed effects of age of dam, sex of foal, and month and year of birth of the foal. Body weight, height at withers and front cannon bone circumference tended to be rather lowly heritable during the first few months but were moderately to strongly heritable by 1 year of age.