Over the past several issues we've taken an in-depth look at a number of the by-product feeds that are commonly available to the cattleman. These have included good sources of energy and protein and in some cases a combination of the two. One area that we've only looked at to a limited extent has been that of fiber sources. While soy hulls and citrus pulp are, in fact, fiber sources and quite good ones at that, they have become much more commonly used as an energy source since the fiber they possess is very soluble. The relative ease of digestion of the fiber in these products make them an excellent energy source. In this last segment we'll examine three common fiber sources used in feeds and supplementation. While many cattlemen might state “I've got all the hay and grass I need, why would I want to include these ingredients in my feeding program,” it's important to remember that adequate availability of hay and forage is not a given. Many areas are experiencing shortages of hay and roughage and subsequently need to provide a source of bulk and fiber for the animal. It's also important to recognize that, depending on the feeding situation, it may be necessary to “slow down” the fermentation rate of a given feed in order to prevent conditions such as bloat and acidosis. Finally, in some situations where we have a transition situation and cattle are changing from one nutrient source to another (i.e. grass to confinement feeding) it is necessary to provide a source of fiber in the feed to make the change simpler.
Cottonseed hulls are used mostly in the southern area of the U.S. They are low in protein, calcium, phosphorus and energy and high in fiber. Cottonseed hulls are palatable and are used as a roughage for cattle, especially in areas where good quality forages are scarce. They occasionally are included in grain mixes to increase the bulk density and crude fiber content. They can be helpful in supporting fat test (dairy cattle) in low fiber or low roughage rations. Table 1 outlines basic nutrient values.
Table 1. Typical Analysis for Cottonseed Hulls
Although most common in the Southern U. S., CSH are used very extensively as a roughage source in the across the country. As noted, although they are low in protein and energy they are high in effective fiber and are very palatable to cattle. They may be used as the only source of roughage but are more commonly used in combination with limited amounts of silage and/or hay. Cottonseed hulls are very palatable and cows receiving such rations consume about 15 to 25 percent more dry matter than cows receiving silage-based rations. They are sometimes included in finely textured concentrate mixes to provide bulk and texture as well as supporting the fat percent. Fuzzy cottonseed hulls are preferred over delinted cottonseed hulls since the lint provides a source of very soluble fiber and subsequently a significant portion of the available nutrients. Also, pelleted CSH has also been used in cattle rations and although the pelletizing reduces the effective fiber it does improve the flowability of the feeds in which CSH are included.
Cottonseed hulls also work very well in starting rations for newly weaned calves or fresh cattle just starting in the feedlot. The hulls appear to improve ration texture and subsequently improve palatability. Research has shown that starting rations which include CSH exhibit improved intakes when compared to those without CSH.
Peanut hulls (PH) are used primarily as a roughage extender during periods when cottonseed hulls and other sources of roughage are scarce or expensive. Only coarse or fan-blown peanut hulls contain effective fiber and are considered equal or slightly higher than cottonseed hulls in effective fiber. They are used most often to replace one-third to one-half the cottonseed hulls in a ration. They are very low in energy and if finely ground, are low in effective fiber. Peanut hulls are palatable to cattle and if needed, should be used in lower producing groups because of their low energy content. If PH are added to a ration other sources of energy will be needed to compensate for the low energy level. Table 2 provides some basic nutrient levels for PH.
Table 2. Typical Analysis for Peanut Hulls
A significant benefit to PH is that in peanut producing areas they are typically readily available and inexpensive. Care must be used, however, to not get carried away with apparent cost savings that will ultimately result in a feeding program using PH to an excessive level, compromising energy to the cattle and resulting in reduced performance in terms of either breeding or growth.
Another benefit of PH is that they can be pelletized effectively. This does reduce the effective fiber of this product but allows for feeds in which they are utilized to have a better texture and to flow more freely in bind and augers.
On the negative side, however, it should be noted that addition of PH to a ration can be detrimental to overall performance as noted above. In a study by workers at Ohio State that the inclusion of 10 percent PH in a lamb ration resulted in decreased digestibility of dry matter, organic matter and Neutral detergent fiber when compared to rations without PH or in those using soybean hulls instead. The PH would be expected to have a low digestibility due to their higher lignin (22 to 24 percent) content. Lignin is a fiber component that is very poorly digested.
These factors noted, it is important for the cattleman or the nutritionist to use PH carefully when developing and formulating a feed or supplement. In many cases the performance loss will outweigh the apparent cost benefit. However, in situations where roughage availability is very low this may be a necessary alternative.
Rice hulls (RH) have traditionally been used as an ingredient in ruminant and poultry feeds. Currently, commercial feeds may contain up to five percent to 10 percent of ground rice hulls. Feeding ground RH directly as roughage to cattle, hogs, and horses is a common practice in many countries, although RH have low digestibility and nutritive value. Of all cereal by-products, the RH has the lowest percentage of total digestible nutrients (less than 10 percent). Overall performance and digestibility can be improved by adding a source of nitrogen (protein) and can enhance RH as a feed source. Rice-mill feed is a mixture of RH and other rice milling byproducts and is a more acceptable component of animal feeds. The feed value of rice-mill feed is higher because of the presence of rice bran and polish in the feed. Constraints for RH use as feed are low digestibility, its peculiar size, low bulk density, high ash/silica content, and abrasive characteristics. Table 3 provides some basic nutrient information on RH.
As noted RH have little to no value as a feedstuff and are probably best served as bedding material. They are commonly used in the south in poultry houses as bedding and much of the litter that is latter fed to cattle is composed largely of rice hulls. They are high in silica and fiber. The fiber value is about 39 percent and the TDN 11 percent. During extreme roughage shortages, ground RH may substitute for 10 to 20 percent of the other roughages in the ration. Since they are normally very inexpensive, as noted previously, many commercial feed manufacturers will use some RH as a “filler” to reduce the cost of the ration and to provide some fiber. It is important to remember, however, as noted above, that because of their very low energy levels other energy sources will have to be added to compensate for this shortage.
Table 3. Typical Analysis for Rice Hulls
The use of by-product feeds is here to stay whether it be for provision of protein, energy or fiber. As developing technology emerges to utilize organic materials to produce fuels, food for human consumption, textiles or a host of other consumable products we will find two things to be true:
1) that conventional feeds such as corn will become more valuable in the production of goods not related to the feed industry.
2) that the availability of existing and new by-products will grow significantly.
It is important that we recognize these factors and utilize these resources as they develop.
Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, TX. He can be contacted at Route 4 Box 89 Sulphur Springs, TX 75482, by phone at (903) 885-7992 or by e-mail at firstname.lastname@example.org.