By : Erin Laborie, Nebraska Extension Educator
The number of growing degree days remaining for the season will influence the amount of light test weight corn harvested this fall. The current standard test weight for corn is 56 pounds per bushel. When corn test weight is below the standard, it is often discounted in price, suggesting the feeding value is lower. However, research has shown that the feeding value of light test weight corn is often similar to normal test weight corn when included in various cattle diets.
A two-year study conducted by the University of Nebraska-Lincoln evaluated feeding light test weight corn during the growing and subsequent finishing phase. Dry rolled corn was included at 37% of the growing diet and 86.2% of the finishing diet (dry matter basis). Cattle fed light test weight corn (46.8 lb/bu) had similar gains and feed efficiency as cattle fed normal corn (56.2 lb/bu) during both the growing and finishing phases. Research at North Dakota State University has shown similar results when light test weight corn was harvested and fed as high-moisture corn to finishing steers. A metabolism study conducted by South Dakota State University showed that the net energy content of light test weight corn (40.8 lb/bu) was not inherently lower than normal corn (53.8 lb/bu) in steers fed finishing diets containing 77.7% whole corn.
Light test weight corn is generally lower in starch but higher in protein and fiber than normal corn. With the variability in corn growing conditions, analyzing the nutrient content of light test weight corn prior to feeding is important from both a cattle performance and financial standpoint.
Cattle feeders that grow their own corn have the opportunity to market light test weight corn through their cattle without sacrificing cattle performance. For cattle feeders purchasing corn, there may be opportunity to capitalize on the discounted price associated with light test weight corn.