The effect of the change from a herbage to a concentrate-based diet on the oxidative stability of raw and cooked lamb meat

Over 89 days, 10 lambs (S) were fed concentrates and hay in stall, while 9 lambs (P) grazedat pasture. Two groups of 9 animals grazed at pasture until switching to a concentrate-based diet for14 or 37 days before slaughter (P-S14 and P-S37). The fat content oflongissimus dorsimuscle(LM) increased with increasing duration of concentrate feeding (P =0.05). As a consequence, theconcentration of polyunsaturated fatty acids (PUFA) and of the highly peroxidisable (HP) PUFA inthe polar lipids was similar between treatments. Lipid oxidation in fresh LM over 8 days of storagewas affected by the diet (P <0.0005) with the P-S37 and P treatments producing, respectively, thehighest and the lowest TBARS values. The P treatment reduced TBARS in cooked minced LM over2 days of storage and no difference was found between the P-S14, P-S37 and S treatments. Colourstability of fresh LM was not noticeably affected by the dietary treatment.