EFFECT OF CHANGING MERINO RAM SOURCE ON AVERAGE HOGGET PRODUCTION ANDWOOL QUALITY LEVELS AND BETWEEN-ANIMAL VARIABILITY

Data from the Merino bloodline crossing project conducted at Trangie w ere used to study changes in performances of hogget production (fleece weight, yield and body weight) and wool quality (fibre diameter, leng th and style) traits and their variability between animals as bloodlin e substitution occurred in a commercial Merino flock. It is shown that performances in wool quality traits of first cross and backcross prog eny are fully predicted by weighted averaging of the additive bloodlin e effects of the parental bloodlines. Performances in production trait s deviate from levels expected from the additive bloodline effects thr ough significant non-additive effects. During bloodline substitution, between-animal variability of both wool quality and production traits is unaltered from variability levels of progeny of purebred bloodlines . The implications for commercial production of bloodline substitution as a means of reducing average flock fibre diameter are considered.