Corn Fields Offer Cows Less Nutrition than a Decade Ago
January 21, 2009 As corn production has changed in the last decade, so has the nutritional benefit of corn grazed in the field.
More efficient combines lose less grain and improved corn hybrids stand up to pests and weather and drop fewer ears. Crop production practices provide just enough fertilizer and water for the crop. Ten to fifteen years ago, about four percent of the corn grain was left in the field due to downed ears and combining losses. Today it's about half that, or about one pound less grain per acre for every bushel harvested.
Historically, producers were advised to start feeding protein supplements when grain was no longer visible in the manure. With less grain in the field, protein is needed earlier, usually about one-half pound of actual protein per cow per day, preferably from natural sources. I'd guess most cows already need it this winter.
The change in energy is a bit harder to judge. As long as husks are available, your cows are okay. Husks are surprisingly high in energy, being 65-70% total digestible nutrients (TDN). But once the husks have been eaten, trampled, or blown away, it gets iffy. Leaves tend to have about 55% TDN, which is about what cows require, but stalks may only have about 45% TDN.
Even with protein supplements, cows eating a fair amount of stalks will lose weight and body condition. Winter is hard enough for your cows. Don't make it any harder by ignoring supplements when needed.
Extension Forage Specialist