02065naa a2200181 a 450000100080000000500110000800800410001902400320006010000170009224500850010926000090019452015440020365000240174765000170177165000100178870000190179877300660181720755952017-09-14       1946    bl uuuu     u00u1 u    #d7 a10.2527/jas1946.54371x2DOI1 aHAZEL, L. N.  aHeritability of weanling traits in range Columbia, Corriedale and Targhee lambs.  c1946  aRecords were studied on Columbia, Corriedale and Targhee lambs at the U. S. Sheep Experiment Station, Dubois, Idaho, to obtain estimates of heritability of several weanling traits. These estimates of heritability represent the proportion of the gain which is transmitted to the offspring through selected parents. Estimates were made from half-sib correlations based on 1711 lambs by 99 sires and from regressions of offspring on dam based on 798 pairs. Estimates were not consistently higher or lower with either method of estimation or for a particular breed, but some traits were definitely more highly hereditary than others. The average estimates of heritability and their standard errors were: weaning weight, 0.17±0.05; length of staple, 0.43±0.06; body type, 0.07±0.04; condition 0.21±0.05; face covering, 0.46±0.06; and neck folds, 0.08±0.04. An increase in the incidence and size of neck folds in different breeds was found to be accompanied by an increase in variability and heritability which was consistent with genetic theory. The results indicate that face covering and staple length can be changed most rapidly by selection, followed by condition and weaning weight. Further progress toward complete elimination of neck folds will be slow but these breeds are already practically free from folds. Even the most intense selection that can be practiced and the most efficient breeding systems which can be used with sheep will not be sufficient to induce marked improvement in body type because of its low heritability.  aGenetic correlation  aHeritability  aSheep1 aTERRILL, C. E.  tJournal of Animal Sciencegv. 5, n. 4, p. 371-377, Nov. 1946.