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

Abstract

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. In Exp. 1, 480 British (pre- dominately Angus) crossbred steers (initial BW = 432 kg; SD = 40 kg) were finished using a 2 × 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 × 3 replicated Latin Square design. The main effects of CARS included quadratic responses (P ≤ 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 ≤ 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 ≥ 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. Including 2.5% CARS in finishing diets improved G:F and increased n-3 fatty acids at the duodenum.