Effect of pre-slaughter rations of forage and/or concentrates on the composition and quality of retail packaged beef

Continental Limousin and Charolais crossbred steers (n=66) were assigned to one of six diets: (1) high herbage allowance (18 kg grass dry matter), zero concentrate (HH0C), (2) high herbage allowance and 2.5 kg concentrate (HHLC), (3) high herbage allowance and 5 kg concentrate (HHHC), (4) low herbage allowance (6 kg grass DM) and 5 kg concentrate (LHHC), (5) medium herbage allowance (12 kg grass DM) and 2.5 kg concentrate (MHLC) or (6) concentrates ad-libitum+1 kg straw (CON). Colour was assessed in steaks (n=5) chosen at random from each dietary group and held in overwrapped and/or modified atmosphere packaging (MAP) (80 O2:20 CO2) under simulated retail display conditions for 17 days. When the HH0C and the CON groups were compared, there was no significant difference in colour under overwrapped conditions, however under MAP, surface redness was significantly (P<0.01) higher (greatest Hunter “a” values) in the HH0C group. When the other four diets were compared to the HH0C and CON groups, there was no significant difference in colour under both forms of packaging. Lipid oxidation was highest for the dietary group CON compared to all other dietary groups examined. There was no significant difference in vitamin E levels between the six dietary groups, levels ranged from 1.7 to 2.5 μg/g meat.