Effect of feeding tuna oil supplement protected against hydrogenation in the rumen on growth and n-3 fatty acid content of lamb fat and muscle

To re-evaluate the incorporation of n-3 fatty acids into depot fats and muscle a group of lambs were fed indoors a concentrate ration supplemented (3% DM) with much lower levels than used previously of rumen-protected tuna oil for 42 days. A second group of lambs were fed diets supplemented with tallow (3% DM) to make the diets iso-caloric. There was no difference in final liveweight, average daily gain, hot carcass yield, or dry matter intake (DMI) between lambs fed with tallow and tuna oil-supplemented diets. Both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in muscle tissue samples from tuna oil-fed lambs were thrice those in tallow-fed lambs (1.81% v. 0.61% for EPA; 1.51 v. 0.44% total fatty acids for DHA). There were also significant incorporations of EPA and DHA into omental and perirenal fat. The level of linolenic acid in both muscle and adipose tissue of tuna oil fed lambs was double that of tallow-fed lambs. Feeding protected tuna oil significantly enhanced the n-3 fatty acid content of lamb meat.