Growth, Carcass and Meat Characteristics of Grass-Fed Lambs Weaned from Extensive Rangeland and Grazed on Permanent Pastures or Alfalfa

SIMPLE SUMMARY: Meat consumers are nowadays more conscious about the effects of fatty acids on health, preferring meat with low saturated fat content and high levels of omega-3. Grass-fed ruminants have been shown to produce a more desirable fatty acid composition than those that are grain fed. Our study evaluates different lamb finishing systems. Overall, better sensory attribute scores were detected for lambs slaughtered at weaning. Meat from the three lamb production systems studied achieved health claimable levels of omega-3 fatty acids, especially in lambs slaughtered at weaning. There were no differences between the three systems of production for juiciness, however lamb finished on pasture presented a lower flavor score than animals finished on alfalfa or those slaughtered at weaning. The low level of cholesterol found in the three systems studied, along with low levels of total fat and saturated fat, classified these meats as extra lean. Opportunities exist for both, sheep producers and the industry, to take advantage of a more balanced fatty acid composition and health attributes of lamb meat produced in extensive farming systems. Developing finishing strategies on pastoral based systems is crucial to improve production characteristics, such as growth and carcass yield, without compromising the nutritive value of meat. ABSTRACT: Western Patagonia lamb production systems are based on extensive rangeland. The harsh climate limits the adoption of more intensive systems. Therefore, producers must focus on developing differentiated products. The aim of this study was to evaluate growth patterns, carcasses and nutritive value of meat from 45 lambs. Lambs were divided into three groups: 15 lambs were slaughtered at weaning (W), with the remaining 30 weaned lambs being allocated to grazing either alfalfa (AG) or permanent pasture (PPG). AG lambs were significantly heavier and had higher condition scores than PPG lambs. Further, AG lambs showed higher carcass weight and larger tissue depth and commercial cuts. Moreover, W lambs had lower shear force and more tender meat than either AG or PPG lambs. The three systems showed a low shear force and acceptable sensory traits. Low levels of cholesterol, with low levels of saturated fat, classified these cuts of meat as extra lean. W lambs had higher omega-3 fatty acid content than AG or PPG lambs. Overall, results showed that meat from the three lamb production systems showed health claimable levels of omega-3 fatty acids and were low in fat and thereby, can be classified as lean meat.