Coping with High Corn Prices: Low Starch Diets and Lactation Performance by Dairy Cows

Lactating dairy cow diets with more than 24% starch (DM basis) are common, but recent high corn prices have fueled a desire to feed lower-starch diets. The potential for using digestible neutral detergent fiber or pectin from byproduct feeds or sugars to partially replace starch from corn grain in diets fed to lactating dairy cows was reviewed. Potential modifying effects of corn silage, starch digestibility and ionophore on lactation performance by dairy cows fed low starch diets was also evaluated. Lactation performance was reduced for 18% and 20% starch diets (DM basis) formulated using beet pulp and citrus pulp, respectively, to partially replace corn grain. Lactation performance was not reduced for 16%-17% starch diets (DM basis) formulated using soyhulls to partially replace corn grain. Diets containing 21% starch (DM basis) appear to be acceptable when high-fiber, moderate protein byproduct feeds are used to partially replace corn grain and protein supplement. Feeding corn silage at a higher percentage of the forage, high starch corn silage, sugars and ionophore can reduce the percentage of corn needed in highstarch diets or increase the “corn equivalency” of low-starch diets. The cost of using digestible NDF or pectin from byproduct feeds or sugars to partially replace starch from corn grain needs to be evaluated relative to corn and protein supplement prices. The starch in low-starch diets should be highly digestible.