Effects of supplementing a feedlot diet with microalgae (Chlorella vulgaris) on the performance, carcass traits and meat quality of lambs

• Microalgae ( Chlorella vulgaris) increased the omega-3 long-chain PUFA concentration in fresh lamb meat. • Microalgae supplementation did not affect lamb growth performance, wool or meat quality parameters. • Microalgae supplementation did not affect rumen fermentation parameters. This study evaluated the effect of different levels of fresh microalgae ( Chlorella vulgaris ) in a feedlot diet on the performance, carcass traits, and meat quality of lambs. Forty-five, four-month-old wether lambs were randomly assigned to one of three dietary treatments: 1) CONTROL, without algae; 2) MEDIUM, with 0.5 % dry matter (DM) algae; or 3) HIGH, with 1 % DM algae added to a basal diet consisting of barley hay and commercial feedlot pellets in a 41:59 ratio. The lambs were fed for 98 days and then slaughtered. Microalgae supplementation did not affect ( P ≥ 0.09) growth performance, wool quality, rumen fermentation parameters, carcass weight, dressing percentage, or subcutaneous fat thickness of the lambs. However, microalgae supplementation at 0.5 % DM increased ( P ≤ 0.05) the concentration of alpha-linolenic acid (ALA; C18:3n-3), arachidic acid (C20:0), and total omega-3 long-chain (n-3 LC) fatty acids in the longissimus lumborum et thoracis (LTL) muscle of lambs, compared to the CONTROL. Intramuscular fat (%) was similar between the CONTROL and the MEDIUM group (av. 3.65 %), but was lower ( P = 0.044) in the HIGH group (3.1 %). Therefore, our results indicate that adding 0.5 % DM microalgae to lamb diets can increase the levels of alpha-linolenic acid and total n-3 LC PUFA in fresh lamb meat without affecting lamb performance or carcass characteristics.