Researcher Figures Out How Tannins Block Nutrition
Written September 23, 1997
Purdue animal scientist Layi Adeola has figured out why livestock have trouble gaining weight on a diet of tannin-rich sorghum. His work eventually may help livestock, and people, get more nutrition out of lower-cost, tannin-rich grains.
People in Africa and Southeast Asia use sorghum as a dietary staple. Producers in the southern and central United States use it for livestock feed. It's available and fairly cheap, but not as nutritious as tannin-free grains.
"With a high-tannin diet, there can be as much as a 20 percent to 50 percent decrease in weight gain," Adeola says.
When Adeola investigated the problem, he found that tannins attach themselves to certain digestive enzymes bound to the membrane of the small intestine. Unfettered, the enzymes snag passing proteins and carbohydrates, break them down into amino acids and sugars, and make them available to the animal's bloodstream. When bound to tannins, however, the enzymes are unable to catch and break down food molecules. Potential nutrition passes by instead of being absorbed.Adeola would like to foil the tannins. "When we understand the whole picture, we may be able to look for agents that could reverse or decouple the binding between tannins and enzymes."