Slaughter traits of Merino sheep divergently selected for multiple rearing ability
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ABSTRACT: Carcass data of 114 19-month-old Merino sheep descended from two lines that were divergently selected for maternal multiple rearing ability (H and L lines, respectively) were used. In study A only ram progeny of the same age were slaughtered, while ewes and rams of the respective selection lines were included in study B. Study A: Mean slaughter weight of H line rams was 12% heavier than that of L line contemporaries. A corresponding difference of 13% was found for carcass weight. Carcass component weights, body measurements, retail cut weights and eye-muscle areas were higher in the H line than in the L line, barring a few exceptions. Adjustment for the higher slaughter weight resulted in most of the line differences being eliminated, but the difference in the loin retail cut remained in favour of the H line. Study B: Mean slaughter and carcass weights of H line animals were respectively 7% and 11% heavier than that of L line contemporaries. Adjustment for the higher slaughter weights of H line animals resulted in most of the differences in the retail cut weight being eliminated, but the hindquarters of H line animals remained heavier than that of L line contemporaries. Line did not affect the moisture, protein, lipid or ash content of the M. longissimus dorsi toracis in study B. The effect of gender on the retail cut weights and proximate analysis was consistent with results from the literature. Selection for multiple rearing ability did not result in any unfavourable responses in retail cut weights or meat chemical properties. Carcasses in the H line, in fact, yielded better in the highly priced loin and hindquarters areas, independently of slaughter weight.