Abstract
In an attempt to estimate the number of gene-loci controlling the racing performance and the effect of the genes concerned, an analysis was carried out on the racing results of some Thoroughbreds. These horses were born by foreign sires during a period from 1970 to 1978 and ran on good conditions at the age of three years for 1200m, 1400m, 1600m, and 1800m on the turf or dirt-course. If it is allowed to take a portion where the probability of the chi-square distribution is high, it will be presumed that the number of gene-loci controlling the racing performance may be in the neighborhood of N=7-10 (average, 7.9) and that the effect of the genes may be α=0.8-1.4s (average, 1.02s). Another method of estimation of the number of genetic factors was worked out by Furusho. Then the number of gene-loci controlling the racing performance and the effect of the genes concerned were estimated to be N=9-24 (average, 14.2) and α=0.3-0.8s (average, 0.52s), respectively. Taking these two N-values and two α-values into consideration, it was presumed that the number of gene-loci controlling the racing performance and the effect of the genes concerned might be in the neighborhood of N=7-24 (average, 11.5) and α=0.3-1.4s (average, 0.73s), respectively.
