Effects of age on chemical composition and tenderness of muscle Longissimus thoracis of Martina Franca donkey breed.

The aim of this study was to determine the effects of age on chemical composition and tenderness of donkey meat. These characteristics were determined on Longissimus thoracis samples taken from 40 entire donkey males of Martina Franca breed slaughtered at 12 (Group 1, n = 20) and at 18 months (Group 2, n = 20) of age. Tenderness was evaluated at two and seven days post slaughter using a Warner-Bratzler shear force device. The chemical composition showed a signifycant increase in protein content (P < 0.05) in the meat of donkeys slaughtered at 18 months of age (22.3 g/100g) compared to the meat of younger animals (21.4 g/100g). Intramuscular fat content was significantly lower (P < 0.05) in Group 1 (2.41 g/100g) compared to Group 2 (3.71 g/100g). Shear force values at seven days post slaughter were significantly (P < 0.01) lower ((5.15 ± 0.31) kg/cm2) in Group 1 compared with the results obtained at two days post slaughter ((6.25 ± 0.53) kg/cm2). In Group 2 shear force values obtained seven days post mortem were higher ((5.88 ± 0.23) kg/cm2) compared with Group 1 after the same ageing period but significantly (P < 0.05) lower if compared with those ((6.53 ± 0.23) kg/cm2) determined in the same animals two days post slaugher.