Lamb meat oxidative stability as affected by the length of concentrate-based finishing diet

This study was designed to assess the effect of the duration of feeding lambs with concentrates in stall after a period of pasture feeding on meat oxidative stability. Thirty-eight Italian Merino lambs were divided into 4 groups at 60 days of age. Over 89 days, 10 lambs (S group) were fed concentrates in stall, while 9 animals (P group) grazed herbage at pasture. Ten lambs (P-S37 group) and 9 lambs (P-S14 group) initially grazed together with animals in the P group, but were housed in stall and fed as the S group for 37 and 14 days before slaughtering, respectively. Lipid oxidation was measured as TBARS (mg of malonaldehyde / kg of meat) on slices of raw muscle Longissimus dorsi and on cooked minced muscle over 8 and 2 days of storage at 4°C, respectively. After 8 days of storage, lower TBARS values were found in raw muscle from lambs in the P group (0.70) compared to the S, PS14 and P-S37 groups (2.32, 2.13 and 3.09, respectively; P <0.0005), while meat from lambs in the P-S37 group displayed higher TBARS values compared to S and P-S14 groups (P < 0.05). After 2 days of storage, TBARS values in cooked meat from S, PS14 and P-S37 groups (2.48, 2.03 and 2.41, respectively) did not differ, but were higher compared to the P group (1.47; P < 0.05). These results suggest that possible modifications of the balance between pro-oxidant and antioxidant components in muscle may be responsible for a different lipid stability between meat from lambs fed exclusively herbage at pasture and meat from animals fed exclusively concentrates or finished on concentrates after a period of pasture feeding.