Texas FFA Livestock Judging PracticeTest

Which feed is highest in total digestible nutrients (TDN) among common livestock feeds?

1. Oats

2. Barley

3. Corn

4. Soybean meal

The correct answer is: Corn

Corn is recognized as the feed with the highest total digestible nutrients (TDN) among common livestock feeds. TDN is a measure that reflects the energy content of the feed, and it indicates how much of the feed's nutrients can be digested and absorbed by the animal. Corn is particularly suited for energy-dense diets because it has a high concentration of carbohydrates, primarily in the form of starch. This characteristic makes corn an ideal energy source for livestock, as it provides the necessary calories for growth, maintenance, and production. While oats, barley, and soybean meal are valuable feeds with their own nutritional benefits, they generally contain lower levels of TDN compared to corn. Oats tend to have a higher fiber content, which reduces their energy density. Barley also offers good energy but typically falls short of corn’s TDN. Soybean meal, while an excellent protein source, does not provide the same level of energy as corn, as it is primarily rich in protein rather than carbohydrates. Thus, when assessing total digestible nutrients, corn stands out as the leading choice for energy supplementation in livestock diets.