A further study of the inheritance of racing performance in thoroughbred horses.
In an analysis of handicap ratings of 1158 3-year-old thoroughbred racehorses, estimates were obtained for the effects of sex differences, the correlation between mates, the effectiveness of selection in males and females, and the heritability of racing performance. The results agreed closely with those of a previous study, and indicated a heritability of about 0.35 to 0.40, some assortative mating, and highly effective selection for performance.