EFFECT OF TRAIT DEFINITION ON HERITABILITY OF LITTER SIZE IN SHEEP

Estimates of heritability from the literature for six litter size trai ts are reviewed. All estimates were low with large standard errors, Pr ocedures that can be used to convert heritabilities for alternate defi nitions of litter size are described. The extent that heritability cha nges with a change in definition was found to be negligible to substan tial and in either direction depending on the specific situation. Effe cts are illustrated for several cases. Pooling estimates of heritabili ty that are based on different definitions of litter size is not recom mended.