Distillers Feeds as Protein Sources for Growing Ruminants2

The concept of feeding combinations of proteins that are slowly degraded in the rumen with urea was investigated with distillers feeds. In a lamb metabolism trial, combinations of urea and distillers dried grains (DDG) or distillers dried grains with solubles (DDGS) replaced urea as sources of supplemental protein without significantly affecting dry matter or nitrogen digestibility of the diets. Means were lower than for soybean meal (SBM)-supplemented diets but not significantly so (P>.05). Steers fed diets supplemented with milo DDG, milo DDG with urea and milo DDGS with urea gained faster (P<.05) than steers supplemented with urea. Two growth trials with corn DDGS demonstrated that corn DDGS-urea combinations could replace SBM as a source of supplemental protein without reducing performance. DDG, both milo and corn, produced a greater complementary effect when fed with urea than did corn or milo DDGS with urea. In two trials with growing steers, DDG-urea and DDGS-urea combinations yielded gains and feed conversions equal to those obtained with SMB; a third trial was inconclusive. The efficiency of supplemental protein utilization was calculated as daily gain above the urea control divided by daily supplemental protein fed. With these protein efficiency values, the comparative value of protein in milo DDG, milo DDGS, corn DDG and corn DDGS to SBM protein were 150, 130, 200 and 180%, respectively, when each protein source was fed in combination with urea. Drying milo distillers solubles in the production of DDGS appeared to be beneficial to the utilization of the soluble fraction of DDGS. Milo-condensed distillers solubles were equivalent to urea in supplementing growing calves.