Heritability of treadmill running endurance in rats.
Treadmill running was evaluated as a phenotype for selective breeding for high- and low-endurance performance from a starting population of 18 male and 24 female outbred Sprague-Dawley rats. Each rat was exercised to exhaustion once per day for 5 consecutive days. The treadmill was set at a constant 15 degrees slope, and the initial velocity of 10 m/min was increased by 1 m/min every 2 min. The total distance run on the single best day out of the five trials was taken as the measure of endurance performance. The original population (males and females combined, n = 42) ran on average for 396 m. The two lowest-performing pairs and two highest-performing pairs were selectively bred through three successive generations. After three generations of selection, performance of the offspring from the high selected line averaged 659 +/- 36 m (n = 20), whereas low-performance offspring (n = 13) averaged 388 +/- 28 m. The narrow-sense heritability, calculated as the regression of individual offspring performance on midparental value for each family, was 0.39 across the three generations. This implies that 39% of the variation in running endurance performance between the low and high selected lines was determined by heritable factors.
Koch
L G
LG
Department of Physiology and Molecular Medicine, Medical College of Ohio, Toledo, Ohio 43614-5804, USA.
Meredith
T A
TA
Fraker
T D
TD
Metting
P J
PJ
Britton
S L
SL
D000818:Animals; D001947:Breeding; D005260:Female; D008297:Male; D010641:Phenotype; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley