Roughages are an essential but often overlooked part of a cow’s diet. Most of the time, people only focus on things like crude protein, energy, and mineral content. While those are vital for the overall production of cattle, roughages play just as important a role. Consuming a certain amount of roughage is essential to keep the rumen functioning and allow the digestion of things like protein, energy, and minerals.
The rumen, mainly the microbes, needs to be taken care of if the animal is to produce. The purpose of the rumen is to degrade complex structural fibers found in plants. When it does that, it then metabolizes them to make the nutrients that the animal needs. In order to keep them going, the microbes need to be fed just like the animals themselves.
The quality and availability of roughages can have a direct impact on the success of a cattle ranch. Many factors can affect the quality of roughages. Things like rainfall, stage of maturity, and how they are managed can all affect the quality.
What are roughages?
A general definition of roughage is a feed ingredient with a high concentration of slowly degradable fiber. The tradeoff here is that being high in fiber, the forages are low in total digestible nutrients. Roughages include the vegetative part of plants as well as feeding stuff of low total digestible nutrient content on a dry matter basis.
For a ruminant, the term roughage is any feed ingredient that has what is called “long roughage“. Long roughage contains particles that are from 3/8in to 1 1/2in or longer. The length is significant because the longer fibrous material will need to be re-chewed by the animal. They will remain in the rumen for a more substantial period of time than the shorter material.
The crude fiber content will also play a role in defining if it is roughage or not. According to the National Research Council, roughage feedstuffs have a minimum crude fiber content of 18%. The maximum total digestible nutrient of the feedstuff should also be 70%.
What do roughages do?
Roughages provide for what is called the “roughage effect“. This effect means that the long, coarse fiber materials rub against the wall of the rumen. By doing this, the muscles in the wall of the rumen expand and contract. This expansion and contraction stir and mix the food in the rumen.
Mixing the material allows the microorganisms there to break down more of the food. The more contact the microorganisms make with the mix, the more completely it can break them down. Breaking them down more allows more of the nutrients to be absorbed and used by the animal.
Another benefit of roughage in the diet is that the coarse material has to be regurgitated and chewed again to be metabolized by the microorganisms. This action is commonly known as the animal “chewing its cud“. Along with breaking the material down more, the production of more saliva is also of benefit.
A ruminant’s saliva contains buffers that help to keep down the acidity in the rumen. While the stomach is supposed to have some acidity, too much can be detrimental and even deadly to the animal. The fiber-digesting microorganisms in the rumen work best in a neutral to slightly acidic environment. This pH level is typically a problem with animals that are being fed an all-concentrate diet.
How much do they need?
The amount of roughage that a ruminant requires will depend on the species. For example, a cow with a larger rumen capacity and a slower process time will require more than, say, a goat with a smaller rumen. It would be best if you looked at which animals you will be feeding to determine the amount that you will need.
When it comes to measuring the amount of roughage, there are two ways to go about it: Acid Detergent Fiber or Neutral Detergent Fiber. The Acid Detergent Fiber, or ADF, measures the cellulose and lignin content of a feed. Cellulose is a digestible form of fiber, while lignin is an indigestible form. ADF is a good test for measuring the energy value of forages. In contrast, the NDF is superior in valuing a feed’s roughage effect. This superiority is because this test measures the cellulose, hemicellulose, which is a poorly digestible material, and the lignin content of the feed.
When it comes to cattle, the minimal NDF values have been studied very extensively, mainly from the dairy industry. The minimum recommended NDF level here is 25%; below this, the rumen environment can become very volatile and potentially dangerous to the animal’s health. With sheep and goats, the minimum amount has yet to be studied. But it is believed that extensively, they can tolerate somewhere in the 20%-30% area.
There is a difference between a ruminant selecting a diet in the pasture that is 25% NDF over the one that you are feeding them. When animals in a native range select forage each day, they can manipulate their diet as needed. If they eat something one day that makes their rumen more acidic one day than the next, they can search for another forage higher in fiber to balance it out.
How can animals get roughage?
There are three types of roughages that you can feed your animals. They have grazed roughages (such as pasture and range), Preserved roughages ( hay and silage), and crop residues or by-products ( straw and hulls). A producer can feed them in either a fresh, dried, or ensiled state.
If you have to provide roughages in a supplement, it is essential to look a little deeper than what will be on the feed tag. The crude fiber listed on the feed tag does not represent the ADF and NDF values. You will have to do a little more digging to find that stuff out.
The higher the crude fiber, the more roughages that should be in the ration. Animals that are on a feedlot-type ration and are being fed hay along with it should have feed that is at least 16% crude fiber for cattle and 14% for smaller ruminants. Cottonseed hulls, soybean hulls, and rice hulls are some excellent sources to use.
Here in the state of Texas, the percentage of roughages must be listed on the label in the ingredient section. If the roughage level is low and the crude fiber content is high, the fiber is from a source that will probably give little of a roughage effect. I go into more detail on what to look for in a previous post, “How to read a feed tag”.
Some alternatives to roughages
There are sometimes certain conditions that traditional roughages may only be available occasionally. Things like the current drought that is going on in most of the country forages need to be improved in quality or just missing altogether. Add to that the possibility of there not being enough hay for this winter, and producers may have to get creative when it comes to supplementing roughages to their cattle. Here are some options that you can consider.
Cottonseed hulls are considered an excellent source of fiber for cattle diets. They are used mainly in the southern U.S., where cotton production is most common. They are low in protein (3.7%), calcium, phosphorus, and energy, but they are high in fiber (44%). Cottonseed hulls are very palatable and are used as roughages in areas where forages are very scarce. Usually, they are included in grain mixes to increase the bulk density and crude fiber content.
Corn stalks are another alternative that is used. Stalks are what is left over after the grain has been harvested. It can winter non-lactating mature cows very effectively. However, suppose you will be grazing first-cow heifers and fall-calving cows. In that case, you will need to provide additional energy and protein alternatives. Too many downed ears per acre can lead to excessive grain consumption. This increase can lead to digestive disturbances like acidosis and founder.
