Sulfuric acid is added to distiller’s grain to manage starch fermentation during ethanol production and the acid makes the rumens of beef cattle more acidic. An acidic rumen environment inhibits the bacteria needed for optimum fiber digestion, and reduces the amount of energy the animal can get from dietary fiber.
Overall dry matter intake decreased as the calcium oxide percentages increased when feeding distiller’s grains with solubles (DDGS). The efficiency of gain (pounds of gain per pound of feed) increased as the calcium oxide percentage increased and peaked at slightly more than 1% of the total dry matter. Steers fed close to 1% calcium oxide required fewer days on feed.
Hot carcass weight, fat thickness, ribeye area, yield grade, marbling score, and quality grade did not differ among treatments in the performance trial.
Digestibility was studied to assess calcium oxide’s effect on ruminal pH, Volatile Fatty Acids (VFA), and nutrient digestibility. In all tests, calcium oxide moderated the changes in ruminal pH typically seen when feeding DDGS.
“You want to moderate variations in ruminal pH, and keep pH at a healthy level for digestive bacteria,” says Jon Schoonmaker, Purdue University assistant professor of animal science. “Calcium oxide provides a tool to do that when feeding DDGS.”
Calcium oxide did not affect dry matter, organic matter, or crude protein digestibility. However, the digestibility of neutral detergent fiber and acid detergent fiber increased with increasing calcium oxide in the diet.
Calcium oxide’s stabilizing effect on ruminal pH could potentially be utilized in other types of distiller’s grains, like wet distiller’s grain with solubles (WDGS) and modified-wet distiller’s grain (MDGS). “Be sure to add one percent calcium oxide on a dry matter basis. That accounts for differences in moisture,” says Ron Lemenager, Purdue University professor of animal science.
The high sulfur content of DDGS makes exceeding sulfur limits in the feeders’ diet something to watch for if feeding higher percentages of the ethanol byproduct. If this is a concern, eliminating sulfur from the mineral supplement is a start. A nutrient analysis, so the ration can be adjusted to keep sulfur below 0.4% in the diet, is a good idea. In addition, adapting cattle to greater dietary sulfur concentrations by gradually adding DDGS may aid in the animals’ ability to safely dispose of sulfur.
“Distiller’s grain is a by-product of our corn producers,” says Lemenager. “If adding calcium oxide makes it a more valuable asset, then that benefits agriculture and not only the beef industry.”
The U.S. Food and Drug Administration deemed calcium oxide to be safe as a feed ingredient in 1975, and if included in diets at low concentrations, does not harm the cattle. However, calcium oxide does require some safety precautions when it’s handled in its pure form, as it can irritate or cause burns on the skin and can irritate nasal passages if inhaled. Typically, anyone handling calcium oxide needs to wear gloves and masks.
Dean Peterson writes from Michigan.