COLLAGEN CROSS-LINKS IN LONGISSIMUS MUSCLE FROM LAMBS EXPRESSING THE CALLIPYGE GENE

The objective of this study was to determine whether increased amounts of collagen and(ori hydroxylysylpyridinoline crosslinks in longissimu s muscle are partially responsible for decreased tenderness when calli pyge lambs are compared to normal lambs. The longissimus muscle was us ed because we believe tenderness is a greater problem in loin chops of callipyge lambs than it is in other cuts. Ten normal and 10 half-sibl ing lambs expressing the callipyge gene were compared. Lambs were slau ghtered at approximately 8 mo of age when they reached a target weight of 59 kg. Dressing percentages were higher for the leaner callipyge l ambs that exhibited larger longissimus muscle areas and heavier leg we ights (P <.01). Warner-Bratzler shear values for longissimus muscle fr om callipyge lambs mere higher (P <.01) than those from normal lambs. The higher shear values were not explained by amount of muscle collage n or by hydroxylysylpyridinoline crosslink concentration because both collagen percentage (P <.09) and crosslink concentration (P <.04) were lower in callipyge lambs. Therefore, attempts to modify shear values and make loin chops from callipyge lambs more acceptable to consumers should focus on the myofibrillar fraction of muscle.