408 WS Distinguished Service Talk: Effects of steam flaking on the carbon-footprint of finishing beef cattle

Grain processing has been used for many decades to improve the digestibility of feed grains fed to finishing beef cattle and to improve animal performance. The most common methods currently used by feedyards in the U.S. are dry rolling (DRC) and steam flaking (SFC). However, the environmental effects of gain processing have not been rigorously studied. This manuscript presents a comparative estimate of the carbon footprint of steam flaking corn in beef cattle finishing diets with and without wet distiller’s grains with solubles (WDGS). Estimates were based on results of published literature and the Intergovernmental Panel on Climate Change. Although SFC required more natural gas and electricity for processing than DRC, feeding SFC decreased the total carbon-footprint by 9 to 13 % per steer. This was primarily due to 30% lower enteric methane production, 13% lower manure nitrous oxide emissions, and 8% lower feed production requirement than when DRC was fed. The carbon-footprints were slightly greater when the diet contained 20% WDGS than when it contained 0% WDGS.

Comparative effects of grain source on digestion characteristics of finishing diets for feedlot cattle: steam-flaked corn, barley, wheat, and oats

Twelve Holstein steers (454 ± 32 kg) with cannulas in rumen and proximal duodenum were used in a generalized randomized block design to compare steam-flaked corn (SFC), barley (SFB), wheat (SFW), and oats (SFO) as grain sources (74% of diet dry matter, flake density = 0.31 kg L−1) on characteristics of digestion. Ruminal organic matter (OM) digestion was similar for SFC-, SFB-, and SFW-based diets, but lower for SFO. Ruminal microbial efficiency was greater for SFW and SFO. Given that the undegradable intake protein (UIP) value of SFC is 57%, the comparative UIP values for SFB, SFW, and SFO were 39.8%, 36.1%, and 47.3%, respectively. Ruminal starch digestion was lower for SFC than the other flaked grains. Total-tract OM digestion and digestible energy were greatest for SFC, intermediate for SFB and SFW, and lowest for SFO. Given the net energy maintenance (NEm) value of SFC is 2.40 Mcal kg−1, the comparative NEm value for SFB, SFW, and SFO were 2.25, 2.36, and 2.17 Mcal kg−1, respectively. Steam flaking results in important modifications of small grains that appreciably affect their comparative feeding value. Current standards underestimates the NE value of SFB, SFW, and SFO, and overestimates the UIP values for SFB and SFO.