studies on the genetics of trotting performance in dutch trotters. i. – the heritability of trotting performance研究遗传学的快步在荷兰猪、羊蹄的表现。.pdf

STUDIES ON THE GENETICS OF TROTTING PERFORMANCE IN DUTCH TROTTERS 1)( 1. -THE HERITABILITY OF TROTTING PERFORMANCE D. MINKEMA Research Institute for Animal Husbandry « Schoonoord a, Driebergseweg 10d, Zeist (Netherlands) SUMMARY The heritability of trotting performance in 2 867Dutch trotters, born between 2i99and 8,95r was studied using a within-sire regression of progeny on dams. Performance criteria chosen were earnings and time records. Earnings were corrected for economic fluctuations by means of multi- plication factors, based on the average amount of money each year available per trotter starting. Time records were corrected for time trends by taking the deviations of individual time records from annual trend values, derived from a smooth curve fitted to yearly running means. Heritability estimates of earnings and time records increased with increasing length of trot- ting career. For lifetime performances the estimates of heritability were. 26 for total earnings and 36.for the best time record. A square root transformation, applied to earnings, increa- sed the estimate of the heritability for total earnings to 40.. Also the precocity for trotting performance was studied by expressing the earnings, won as 2- and -year-old3trotter, as a percentage of the total earnings won during the whole trotting career. The heritability estimate of this criterion was 20,.increasing to 27.after applying a logit- transformation to the percentages calculated. Flying- and staying-ability of trotters were studied by expressing the amount of money won by each horse over each of three distance classes (short, medium and long) as percentages of its total earnings, won in trots over all distance classes. Little or no additive genetic variation was fo