What do we call the nutrients that animals consume from grains and by-product feeds?

The correct term for the nutrients that animals consume from grains and by-product feeds is "feed." This term specifically refers to the intended dietary resources given to animals in agricultural settings, which can include grains, forages, and other by-products. Feed is formulated to provide the necessary nutrients that animals require for maintenance, growth, reproduction, and overall health.

Understanding this term helps distinguish it from other options such as "nutrients," which are the specific components like proteins, carbohydrates, vitamins, and minerals found within the feed. Additionally, "food" is a broader term used in human contexts and does not adequately capture the specific purpose of animal feed. "Ration" refers to the specific amount of feed provided to an animal over a set period and can vary based on an animal's dietary needs, but it does not cover all types of feed or by-product feeds. Hence, "feed" is the most accurate term to describe the combination of grains and by-product feeds that constitute a significant portion of an animal's diet in agricultural practices.