NONGENETIC FACTORS INFLUENCING EARLY GROWTH TRAITS IN THE ELSENBURG DORMER SHEEP STUD

Records of the Elsenburg stud where the Dormer sheep breed originated in 1941, were analysed from 1941 to 1990 to investigate non-genetic fa ctors contributing to early growth traits. The fixed effects, identifi ed as having a significant (P < 0.01) effect on birth weight, weaning weight, average daily gain and Kleiber ratio, were year-season, age of dam, sex, birth status and level of inbreeding. Although some signifi cant interactions were found, they were subsequently ignored owing to their very small effects. A model best describing the data, which can be used for further analyses, is constructed and discussed. It is advo cated that the uniqueness of each population and situation necessitate s such an analysis in each specific case.