Grazing improves colour and ‘stability’ in beef
Take Home Message: Finishing beef animals on grass improves the shelf life of the meat.
Meat from grazed cattle had an improved colour and lipid stability than that from concentrate-fed cattle due, to a higher deposition of vitamin E.
Just one of the findings of a study carried out by scientists to determine the influence of a forage versus a concentrate diet fed to beef cattle – and an additional treatment with a PUFA-rich lucerne-based plant extract (PX) – on the antioxidant profile of their meat, and its relationship with lipid oxidation and colour shelf life.
“While the antioxidant enzyme superoxide dismutase (SOD), did not appear to be affected by diet, or correlated with measures of oxidation, catalase activity increased when α-tocopherol concentration was low and consequently lipid oxidation was higher,” Bristol University’s Ian Richardson told delegates at this year’s British Society of Animal Science annual conference.
The oxidative stability of meat depends upon a combination of pro- and antioxidants and the degree of unsaturation of its lipid classes.
When animals graze grass the concentrations of α-tocopherol and β-carotene in meat and fat increase and decrease when they are fed concentrates. Supplementation with α-tocopherol acetate increased α-tocopherol concentration in the meat of concentrate-fed animals, less so for grass-grazed animals.
But less is known about the relationship between diet; antioxidant enzymes systems, such as SOD and catalase; and the oxidative stability of meat.
The trial involved 29 Charolais x Friesian steers that were fed one of three dietary treatments: forage (grass/white clover swards during grazing followed by grass silage in winter period); restricted barley straw and concentrate (40:60 on a DM basis); and restricted barley straw and concentrate with PX.
Liveweight was monitored every 28 days and gains were calculated for individual animals. These were then slaughtered, the carcass chilled for 48 hours and the M. longissimus thoracis was sampled.
Tocopherol analysis was performed and colour was measured daily on 10-day aged steaks kept under simulated retail display.
“And we found that the concentration of α- tocopherol was highest in the meat of grass-grazed animals and lowest in the animals fed concentrate,” said Dr Richardson.
“SOD activity in meat was not influenced by diet and catalase activity was highest in the meat of those animals fed concentrates. Catalase activity was positively correlated with change in colour,” he added.
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