Divergent values in feed efficiency promote changes on meat quality of fattening lambs

Fattening lambs in Mediterranean countries are produced under intensive production systems where high concentrate intake levels are reached. It is also well known that fattening lambs may present wide differences in feed efficiency, so the ability to transform the feed consumed into meat is variable and may impact the profitability of the farm and the quality of the final product obtained. Accordingly, it is essential to understand the differences in meat quality caused by divergent feed efficiency values before making recommendations to the farmers. Therefore, the aim of the present study has been to study the effects of two groups of Assaf fattening lambs with differences in feed efficiency on physicochemical parameters, fatty acid content and volatile compounds of meat. Lambs were fed a complete pelleted diet (CPD) ad libitum and slaughtered when they were 85-days old. The results obtained reveal that the less efficient lambs presented no differences in caracass and non-carcass parameters, but increased tenderness of the meat, probably caused by reduced cooking losses and higher amounts of several fatty acids (e.g., 17:0, 19:00, 20:0, c12−18:1, t10−18:1 + t11−18:1, 19:1, c11−20:1, t18:2). Other physicochemical traits such as chemical composition, pH or colour changes of meat under refrigerated storage were not significantly affected by feed efficiency in the present study, but volatiles compounds responsible of the flavor of cooked meat (e.g., 2-pentylfuran) presented a trend towards significantly lower values (P = 0.056) in low efficient lambs. All these results suggest the need for a deeper knowledge (including differential gene expression analyses and sensory characteristics) regarding the overall effects of feed efficiency on meat quality before implementing breeding programs for high efficient Assaf fattening lambs.