Influence of feeding systems on cortisol levels, fat colour and instrumental meat quality in light lambs.

Forty-eight lambs were fed as follows: GR, lambs and dams grazed perennial pasture; GR+S, the same as GR except that lambs had access to concentrate; DRL-GRE, lambs in drylot and dams in rationed grazing; DRL, lambs with dams were stall-fed. DRL-GRE and DRL lambs were weaned at 45days of age. Lambs were slaughtered when they reached 22-24kg of live weight. Plasma cortisol concentration was determined three times before slaughter. Subcutaneous fat and meat colour, and texture were analysed. The different levels of cortisol did not affect meat quality. Both grazing systems gave yellower subcutaneous fat and redder muscles than drylot lambs. Differences between systems relating to colour and texture of the meat disappeared with ageing time, which supports the idea that grazing systems are a good alternative in order to offer similar meat to that coming from drylot systems to which consumers are accustomed. Subcutaneous fat colour was a suitable method to discriminate between grazing and drylot systems, but not within them.