Animal nutrition · the basics
Carbohydrates & Fiber
Sugar, starch, and plant fiber take different routes through digestion. The animal determines what those routes can supply.
For poultry, horses, cattle, sheep, and goats. Other species need separate guidance; examples are labeled by species.
In this guide
Carbohydrates are a family
Poultry diets obtain much of their energy from carbohydrates. Sugars and starch differ from the structural carbohydrates in plant cell walls. A fiber number cannot tell you how much starch or sugar is present. [1]
Starch is broken down into smaller sugars for absorption. Animals do not produce the enzymes needed to digest cellulose themselves; microbes provide another route. Digestive anatomy changes how important that fermentation route is. [2]
Microbes turn fiber into an energy source
In cattle, sheep, and goats with developed rumens, microbes ferment carbohydrates and produce volatile fatty acids, also called short-chain fatty acids. The animal absorbs and uses these products for energy. The diet and its physical form affect fermentation. [2]
Horses ferment fiber in the hindgut, mainly the cecum and colon, and use the resulting volatile fatty acids. Fermentation occurs after the small intestine, unlike the rumen pathway. That difference helps explain why cattle feeding advice cannot be copied directly for horses. [3]
Fiber quality changes with the plant
For forage-fed livestock, lignin limits digestion of plant material. As plants mature, the balance of cell-wall material changes. The amount of fiber and how much of it can be fermented both matter; a larger fiber percentage is not a complete description of feeding value. [4]
For horses, forage is central to the diet. Plant species and maturity influence its nutrient supply, and laboratory testing helps assess a hay lot. Review forage quality and the individual horse’s needs before deciding what a concentrate should add. [5]
Different fiber tests answer different questions
On forage reports, neutral detergent fiber (NDF) describes a broad cell-wall fraction; acid detergent fiber (ADF) is a different fraction containing cellulose and lignin. They help interpret forage intake and energy estimates. Neither is interchangeable with the crude-fiber guarantee on a bag. [4]
Ask whether a quoted sugar or starch value was actually measured, what fractions are included, and whether it is as-fed or dry matter. Do not infer a horse’s sugar-and-starch profile from crude fiber alone.
Use the forage report in the feeding conversation
For sheep and goats, forage quality varies with maturity, plant type, weather, and storage. Diet changes need to be gradual so the animals and their microbes can adapt. A supplement should fit the forage and production stage. [6]
Bring a representative forage report, feeding amounts, and the current bag tags to our nutritionist. Pair this guide with Understanding Feed Energy rather than choosing feed by one carbohydrate number.
Sources
Original Tucker Milling guide, informed by these primary sources. The cited institutions do not endorse Tucker Milling. Follow the current product label.
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Accessed October 8, 2026.
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Accessed October 8, 2026.
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Nutrients and Common Feed Sources for Horses ↩
Fiber and fat concepts; exercise-water restriction advice not used. Accessed October 8, 2026.
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Forage Quality Interpretations ↩
Accessed October 8, 2026.
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Accessed October 8, 2026.
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Nutrition and feeding for sheep and goats ↩
Reviewed 2025. Accessed October 8, 2026.