The two primary concerns regarding feeding flood-damaged corn to cattle are soil contamination and microbial contamination.

1. Soil contamination will be much worse for silage than for grain since most of the soil is trapped on lower parts of the plant. Silage made from corn that has been flooded should be analyzed for total ash and minerals. Normal corn silage has about 4 to 4.5% ash (dry matter basis) but flood-damaged silage could have 5 to 7% ash. Soil contamination will reduce the energy value of silage (ash has no energy) and can reduce availability of certain essential minerals, especially copper. If the silage has high ash concentrations make sure the estimated energy value of the silage was calculated from equations that consider ash. If the estimated value does not consider ash, on average high ash corn silage (approximately 6%) will have about 3 to 4% less energy than normal corn silage. Dietary copper should also be increased when high-ash silage makes up a substantial portion of the diet. In most situations, diets that provide about 20 ppm of total copper should be adequate. Soil contamination is not a major concern when flood-damaged corn grain is fed.

2. Microbial contamination caused by flooding can increase the risk of a poor fermentation (silage) and increase the risk of mold and mycotoxin development in both silage and grain. Although no data are available supporting this recommendation, using a proven corn silage inoculant (per manufacturers directions) may reduce the risk of poor fermentation caused by flooding. Good silage making practices (filling rapidly, good packing, covering the silage, letting it sit undisturbed for several weeks after filling) are always important but are even more important when the risk of a poor fermentation is high. The risk of mold and mycotoxin contamination is higher for flood damaged corn grain and silage (remember you can have moldy feed without mycotoxins). For silage, the best remedy is to promote a good fermentation which should inhibit mold growth. Good grain storage procedures will help reduce continued mold growth in grain. Although labs can run assays for some mycotoxins and some labs can provide information on mold counts, collecting a good sample of grain and especially silage is problematic. False negatives are likely because mold and mycotoxins are not spread uniformly within the silage mass. If mycotoxin problems are suspected based on animal performance, talk with your nutritionists about feed additives and other management practices that might help reduce the problem.

Leave a Comment

Name (required)

Email (will not be published) (required)

Website