Evaluation of condensed algal residue solubles as an ingredient in cattle finishing diets and the effects on digestibility and fatty acid flow

Objective: Our objective was to evaluate the effects of inclusion of condensed algae residue solubles (CARS) in corn-based cattle finishing diets on performance, carcass characteristics, and duodenal concentrations of fatty acids.Materials and Methods: In Exp. 1, 480 British (pre-dominately Angus) crossbred steers (initial BW = 432 kg; SD = 40 kg) were finished using a 2 x 3 factorial treat-ment arrangement. Treatments were CARS (0, 2.5, 5% of diet DM) displacing dry-rolled corn: high-moisture corn (DRC: HMC) or steam-flaked corn (SFC). In Exp. 2, feed-ing 0, 2.5, or 5% CARS in SFC diets was evaluated for digestibility and fatty acid flow using 6 ruminally can-nulated steers in a 3 x 3 replicated Latin Square design. Results and Discussion: The main effects of CARS included quadratic responses (P & LE; 0.01) for carcass-ad-justed final BW, ADG, G:F, hot carcass weight, 12th-rib fat, and YG. The main effects of diet indicated SFC di-ets had greater (P & LE; 0.02) G:F, hot carcass weight, and 12th-rib fat compared with DRC: HMC diets. In Exp. 2, inclusion of CARS in the diet did not affect total-tract DM, OM, or NDF digestibility (P & GE; 0.52). Total fatty acid flow at the duodenum was unaffected (P = 0.18) by treat-ment. However, there was a linear increase (P < 0.01) in C16:0, C18:0, C18:1 trans, C18:1 vaccenic acid, and C22:6 omega-3 docosahexaenoic fatty acid flow as CARS inclu-sion increased. Implications and Applications: Including 2.5% CARS in finishing diets improved G:F and increased n-3 fatty acids at the duodenum.