Comparison of different magnesium sources on lamb muscle quality

Wether lambs (n=20) were used to compare the effect of dietary magnesium oxide (MgO), unweathered Magnesium Mica® (UMM) and weathered Magnesium Mica® (WMM) on muscle quality. Lambs were fed a corn-based, control diet (Ctrl), or the Ctrl supplemented with either MgO, UMM, or WMM for 95 days before harvest. Following a 24-h chill, carcasses were fabricated, and L*, a* and b* values were determined on the triceps brachii (TB), longissimus thoracis (LT), semimembranosus (SM), and semitendinosus (ST) muscles. Supplemental magnesium had no (P > 0.10) effect on live and carcass weights, fat thickness, loin eye area, and USDA yield grade. Carcasses from lambs supplemented with MgO had higher (P < 0.10) flank streaking scores and USDA quality grades than those from lambs fed diets containing UMM. Although magnesium-supplementation had no (P > 0.10) effect on marbling scores, the LT from Ctrl-fed lambs had more (P < 0.05) intramuscular lipid than lambs fed diets containing UMM or WMM. Lambs supplemented with UMM had greater (P < 0.05) LT shear force values than lambs fed MgO or WMM. Magnesium-supplementation had no (P > 0.10) effect on muscle color; however, supplementing finishing diets with UMM may result in less palatable lamb.