The Istrian Milk sheep is an endangered breed of the Pramenka group raised in the North-Adriatic Karst region. Carcass and meat characteristics of 46 suckling, 6- to 14- week-old intact male light lambs from two feeding systems were analysed. Thirty-two lambs were raised in a flock fed only with forage (hay supplied in stall during winter or fresh herbage directly grazed during the other seasons). The lambs had free access to the forage supplied to their dams (feeding system: milk and forage; MF). The other fourteen suckling ovine were grown on a farm with a feeding system incorporating a concentrated supply of the forage base. The lambs were stabled and creep fed on a concentrate (20% CP) at a daily rate of 100 g/head, in addition to the suckled milk (feeding system: milk and concentrate; MC). The carcasses were divided into three categories of weight, following the Community scale of light lambs classification: A (≤7 kg, n=17), B (7.1 - 10 kg, n=15) and C (10.1 - 13 kg, n=14). The frequency of 1st quality carcasses increased with carcass weight, reaching 100% in category C. On average, 72% of the carcasses were scored as 1st quality, without significant differences between feeding systems. The lightness of lamb meat from A carcasses was higher than that from the heaviest ones. Cooking losses showed a pattern opposite to that of pH (mean 5.44; SE 0.058), increasing where pH decreased (categories A and B and concentrate-fed lambs). Shear force values were significantly affected by factors linked to the feeding system; in fact, MC lambs provided more tender meat than MF ones (32.6 vs 46.6 N). As carcass weight increased, moisture concentration decreased steadily (from 77.8% to 75.5%), while lipid content increased progressively (from 1.58% to 3.14%). In agreement with these patterns, the contribution of individual fatty acids (FA) to muscle weight generally increased with carcass weight. A similar trend was observed for the relative concentration of saturated FA and monounsaturated FA, while that of polyunsaturated FA (PUFA) showed an opposite evolution. The feeding system modified the relationship between ω3 and ω6 PUFA series: with respect to MC meat, MF meat presented a higher content of linolenic acid and its long chain ω3 derivatives and a lower content of linoleic acid and its major product, arachidonic acid. As a consequence, MF lambs furnished meat with a ω3/ω6 ratio and an index of thrombogenicity more favourable for human health than those from MC lambs.
