Effects of Zn-Organic Supplementation on Growth, Body Composition, Carcass Traits, and Meat Quality of Grazing Lambs Fed with Two Levels of Concentrate

Supplemental zinc in fattening lambs improves their health, performance, and meat quality. However, the Zn effect on grazing animals combined with different levels of concentrate should be known unknown. The objective was to evaluate the Zn-organic effect in the diet of grazing lambs supplemented with two levels of concentrate on growth, dry matter (DM) intake, carcass traits, body composition, meat quality, and fatty acid profile in Longissimus dorsi muscle. Twenty-eight lambs were used in a factorial arrangement of two levels of concentrate (C) feed intake (C-0.75 and C-1.5% of live weight) and two Zn-Met levels (0 and 80 ppm Zn kg−1 DM) on the grazing of Lolium perenne L. Digestibility and dry matter intake, weight gain, and productive performance were measured. At the end of the fattening period (90 d), the lambs were slaughtered and the carcass traits, body composition, instrumental quality, and lipid profile of meat were evaluated. The effect of treatment (T), measurement period (P), and T × P interaction was observed (p < 0.05) for dry matter intake (DMI). For the final live weight (FLW) and daily weight gain (DWG), there was an effect (p < 0.05) of T and P, with Zn-80 ppm + C-1.5% treatment being greater. The live weight at slaughter (LWS) and leg length (LL) showed an effect (p < 0.05) of C × Zn. Zn-80 ppm + C-1.5% treatment was higher in the kidney fat, empty body weight, carcass fat, fat and retained energy but lower in protein content (p < 0.05). The physicochemical characteristics and fatty acid content of meat were not affected (p > 0.05). It can be concluded that the concentrated-organic zinc synergy in grazing lambs improved the performance, weight gain, and body composition, which resulted in heavier carcasses with greater amounts of fat, protein, and energy deposited. Furthermore, the physical and chemical meat traits were not affected, but the n-3 fatty acid content and n-3/n-6 ratio in Longissimus dorsi was affected by the Zn level supplemented.