Straw is the dry stalk of cereal plants, such as wheat, barley, and oats, that remains after the grain and chaff have been harvested. This agricultural byproduct is baled and utilized in various ways, including animal bedding or garden mulch. Straw also holds a specific, functional role in the diets of certain livestock species.
Understanding the Difference Between Straw and Hay
The public often confuses straw and hay, but they are fundamentally different in composition and nutritional value. Hay is forage, typically made from grasses or legumes like alfalfa and clover, and is cut while the plant is still green to maximize nutrient retention. It is a primary feed source, rich in protein, energy, vitamins, and minerals.
Straw is the mature stalk collected after the grain has ripened and been harvested. Since the plant’s energy and nutrients have been directed into the seed, the remaining stalk is low in protein and calories. Straw is composed of high levels of structural carbohydrates, including cellulose and a tough substance called lignin, which is poorly digestible. This makes straw a coarse, low-quality roughage.
The Main Animals That Consume Straw
Straw is incorporated into the diets of large herbivores capable of processing fibrous material. Ruminants, such as cattle, sheep, and goats, are the primary animals that consume straw as part of their feeding program. Their specialized four-compartment stomach, particularly the rumen, contains a dense microbial population that breaks down complex structural fibers, including the cellulose and some lignin in straw.
For mature beef cows that are not lactating, straw can constitute a large percentage of their winter diet when properly supplemented. The palatability and nutritional value of straw can vary depending on the source crop, with oat straw generally considered more palatable than barley or wheat straw. Farmers must carefully supplement straw-heavy diets with protein, energy, and minerals to ensure the microbial life in the rumen remains active.
Equines, including horses, are also sometimes fed straw, though its use requires careful management due to their simpler, non-ruminant digestive system. Straw is sometimes mixed with higher-quality forages to dilute the calorie content for horses that are overweight or prone to certain metabolic conditions. Because the high fiber and low digestibility of straw slows down its passage through the equine gut, there is an increased risk of impaction colic if the animal does not drink enough water. In smaller animals like rabbits, straw is generally used as bedding, while hay is supplied as their primary food source.
Why Straw is Used as a Feed Supplement
Straw’s most significant function in livestock diets is its role as a source of roughage and bulk. This high-fiber content is important for gut fill, which helps to satisfy an animal’s appetite and prevent boredom, especially in confinement feeding situations. In cattle, the physical structure of the straw stimulates rumination, the process of chewing cud, which is necessary for maintaining a healthy rumen environment.
Because straw is low in both energy and protein, it is frequently used as a diluent in a total mixed ration (TMR) to control the overall energy density of the feed. This strategy is employed to prevent over-conditioning in maintenance animals or to meet the specific requirements of livestock during periods of low nutritional demand. By slowing the rate at which feed passes through the digestive tract, the high fiber in straw also allows for more efficient nutrient extraction from the other, more concentrated components of the ration.