STUDIES ON WESTERN-AUSTRALIAN MERINO SHEEP .3. GENETIC AND PHENOTYPICPARAMETER ESTIMATES FOR SUBJECTIVELY ASSESSED AND OBJECTIVELY MEASURED TRAITS IN EWE HOGGETS

Between 1440 and 2084 Merino hoggets were scored for visual traits, wi th the number of records differing according to the traits. Eight wool traits and seven body traits were subjectively assessed, while four w ool traits and five serial liveweights were measured. Heritabilities f or all subjective traits were estimated, with sire models using restri cted maximum likelihood, as were genetic and phenotypic correlations b etween subjective and objective traits. Heritability estimates for bac k wool, lock thickness, wool character, underline, condition, wool col our, hock shape, feet shape, face cover score, neck wrinkle, breech wr inkle and side wrinkle were moderate (0.1 to 0.3), while those for vis ual fineness and wool handle were high (0.34 and 0.41), and overall sc ore, low (0.06). Correlations between these traits and objective trait s having economic value (wool weight, average fibre diameter and livew eight) were low or negligible, indicating that it may be more efficien t if classing traits are not used to the exclusion of objectively meas ured traits. However, under some circumstances, they may have potentia l for increasing selection efficiency or used as an inexpensive first step in a two-stage selection procedure.