By: Donna Amaral-Phillips
University of Kentucky
Monitor corn crop and chop for silage when it reaches the proper moisture level. Although corn silage may have small ears and/or lack of full kernel development, feeding programs can be built around this forage. This crop will be lower in energy and additional energy will need to be added to the diet in the form of corn grain, grain by-products and/or fat supplements.
Test for nitrates after the crop has fermented for 3-4 weeks and before feeding. Ensiling silage (with proper fermentation) can reduce nitrate levels by approximately 50%.
Do not feed corn silage as green chop if drought stressed. Crop may be high in nitrates and cause abortions and death in cattle.
Test for nitrates before feeding corn as green chop or before harvesting crops that accumulate nitrates. Collect 5 to 10 random plants per field, chop the material, place a representative sample in a plastic bag and place on ice and hand-deliver to a testing laboratory. If the sample is shipped overnight to the testing lab, the sample should be frozen and shipped with an ice pack. Your local extension agent may have test strips or a meter to get a preliminary value of the nitrate content.
Nitrates can accumulate in other forages: Besides corn, nitrates can accumulate in johnsongrass, millet, sorghum, sudangrass, sorghum-sudangrass hybrids, and some weeds. These crops should be checked for nitrates before grazing, green chopping, or harvesting for stored feed.
Feeding options: Start by taking an inventory of forages you have on hand and test each to determine its quality. Develop a plan for its most economical use within your dairy operation.
Allocate best quality forages to early lactation cows and highest producing cows through the next feeding year. Lower quality forages can be fed to dry cows, older heifers, and later lactation cows.
Purchase standing corn from neighbors that raised corn for grain that lacks adequate kernel development and ear size.
Forage extender products composed of grain by-products and cottonseed hulls can help extend forage resources. Additional grain by-products can be fed to stretch silage supplies.
For heifers, corn silage can be limit fed or mixed with wheat straw to extend or replace hay supplies.