Effect of feeding system on fatty acid profile of lambs of three Veneto Region Alpine breeds

The aim of this trial was to investigate the effect of diet, breed, gender and the tissue on the fatty acid (FA) profiles of lambs of three native Italian sheep breeds. Thirty-six lambs, belonging to flocks subjected to an in situ conservation program (Legnaro-Villiago), were used. Six males and 6 female lambs for each breed: Alpagota, Brogna and Foza, were divided in three groups characterized by different feeding systems: pasture, penned in an open barn and fed with hay and concentrate and penned in the open barn and fed with hay and concentrate added with rpCLA supplement. At the age of 225 days the lambs were slaughtered, samples of muscles, fatty depots and liver were collected and analyzed for FA profile. FA were extracted and analyzed through GC. Data were analyzed by PROC MIXED of SAS considering the effect of the feeding system, breed, gender, age and tissue. The random effect of animal was used to test feeding system, breed, gender and age, whereas the effects of tissue and corresponding interactions were tested on the residual. Among the factors of variation of FA profiles feeding system was the most important one because, respect to the dry diets, pasture did not caused a variation of proportion among SFA, MUFA and PUFA, but changed the proportion within SFA (C18:0;C18:1vaccenic), and PUFA (C18:2c9 t11 CLA; >C18:3 α Linolenic; <C20:4n6 arachidonic), and decreased the omega6/omega3 ratio (3.28 vs. 6.17; P<0.0002). The supplementation of rpCLA on barn diet increased both CLA isomers (C18:2c9, t11, P=0.010, and C18:2 t10, c12, P=0.018). The tissue was the most important within-animal cause of variation and affected all the individual FA and their categories. Liver presented a FA profile very different from that of muscles and fatty depots and, among these last tissues, kidney fat was very peculiar.