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Program feeding is effective for growing cattle at low to moderate rates of gain, said Texas Tech research scientist Michael Galyean. "There are also potential environmental advantages that may become more important down the road," Galyean said. Program feeding is a method in which energy equations are used to calculate quantities of feed that are required to supply that animal's maintenance needs and to provide the feed energy needed for a specific rate of gain, Galyean said. It's most often used for growing cattle at low rates of gain, he said. It normally applies to small frame cattle or light weight cattle to be fed a long period of time that may really need a growing period. "It's a very effective program for those kinds of cattle," he said. He added that if those type of cattle are put on feed and allowed to eat freely, they're probably not going to reach the desired carcass weights. If they go through a slow growing period, from 1.8 to 2.0 pounds a day for an extended period of time, a feeder can add carcass weight at the end on those kinds of cattle. "But you do need to make sure that the cattle really need to be grown," he said. "If you've got large frame cattle that don't need a growing period, you're probably not going to have a very efficient program." He also said program feeding has a down side. It offers lower gain and possibly a lower quality carcass grade due to less marbling. Feeders need to be able to accurately predict ad lib intake and accurately predict daily gain, which he said cannot be done presently with the large variation of cattle going into the feedlot. Restrictive feeding, Gilyean explained, is typically applied to either starting cattle on feed or finishing cattle, and is often applied to growing cattle. There are a lot of different forms that restricted feeding can take, Galyean said. Perhaps the most interesting is what is typically referred to in the feeding industry as cleaning up management or slick bunk management. "The feedlot industry uses that quite a bit today," Galyean said. "It's basically a form of time restriction." There are a number of reasons to use a program or restrictive feeding system. One is in a situation where roughage costs are very high, he said. Another is when pasture is limited or very high in cost. "It is a means by which we can, by restricting intake or programming intake of cattle, avoid over consumption and intake variation," Galyean said. Researchers think intake variation like with limited pasture probably effects efficiency. There is some indication of that in literature on the subject, although there does not appear to be a consensus. "We certainly think there is a good biological reason to believe that if animals are on a roller coaster on feed intake, they are probably not going to be as efficient," he said. "This is a way to smooth that out. It certainly simplifies bunk management. You know what you're going to feed the next day." Program feeding also decreases manure loads. "This is one of the things that makes restrictive and program feeding very attractive, and we may have to go that way as environmental regulations become more strict," he said. "This is a feeding system which allows you to know exactly what nutrients you've put out. You know what the intake is going to be on any given day." One of the advantages in a program feeding system is using a high concentrate diet during a growing phase. It's a very easy transition to the finishing diet. There is also evidence suggesting animals that are programmed will have improved feed efficiency. "Obviously, the more you restrict intake the more you're going to decrease the average daily gain," Galyean said. "There's no free lunch. If you don't feed animals as much, they're not going to gain as much, but you do see improvement in efficiency." The improvement in efficiency tends to be a function of how much the feed is restricted, he said. The average response is a 10 percent restriction equals a six percent improvement in feed-to-gain. Galyean said that restricted or programmed feeding does not mean feeders are altering the composition of gain on cattle but are instead decreasing feed wastes and decreasing variations in feeding. Restricted or programmed feeding also probably decreases maintainence requirements, especially in animals that are fed for low rates of gain for an extended period of time. Research indicates cattle eventually reach a typical diminishing returns curve. "As you get more and more intake, you don't have a linear response in daily gain," Galyean said. "You get a diminishing response. That simply means that maximum energy gain is not necessarily going to occur at maximum intake. That tells you that restrictive feeding systems should yield some improvements in efficiency." The trick is to slide back on the scale to a point where there is a good balance between energy intake and energy gain. There are two primary concerns as to why the commercial cattle feeding industry doesn't do this very often, Galyean said. One is the variability within pens. "When you limit or restrict feed intake, you may have some animals that are very much more aggressive than others," Galyean said. "You may have much more potential for under or over feeding. It can increase variability rather than decrease it." That can result in increased risks in metabolic disorders, he said. The second risk is in lower daily gain and lower carcass quality. "If you restrict animals too severely, you're going to really drop daily gain," Galyean said. "If the program gain is below those animals' potential to gain, you're going to lose progress. If those animals are fed about the same length of time or if you take them out to the same carcass weight, you're going to add days. Either way, you've got potential problems." There is also a question of how restricted feeding affects carcass quality, primarily through marbling. Research shows gain is not very different in a growing program with restricted high concentrate diet, versus free fed corn silage. Subsequent finishing gain is not affected by the diet fed during the growing period. Carcass performance is not affected by a restricted growing period followed by a free fed finishing period. |
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