AbstractThree weaning treatments (weaning at 45 days of age, at 65 days of age, unweaned) and two slaughter weights (24 and 28 kg) were compared in lambs raised at pasture, and their effect on carcass and meat traits were studied. Unweaned lambs displayed a greater growth rate, lower concentrate consumption, greater dorsal fat thickness, more kidney knob and channel fat and greater total fat levels, measured through dissection of the hind limb. Total collagen concentration was lower in unweaned lambs and the intramuscular fat of these same animals exhibited a greater proportion of saturated fatty acids and a lower n-6/n-3 fatty acid ratio. Slaughter weight influenced scored carcass fatness, which was greater in heavier lambs, meat colour, which displayed greater lightness in lower-weight lambs, and water-holding capacity, which was lower in lambs with the lower slaughter weight. The heavier lambs displayed lower soluble collagen values, and the intramuscular fat of thelongissimus dorsimuscle of these same lambs contained higher levels of monounsaturated and lower levels of polyunsaturated fatty acids.