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by Dr. David Porter Price The advent of winter weather dictates decisions in ration formulation that are not always easy to make. The difficult decisions center around heat of fermentation. During warm or mild weather we do everything we can to reduce fermentation. The reason, of course, is that fermentation is inefficient. Fermentation produces methane and carbon dioxide gases, along with a lot of heat; which are energy losses. Specifically, because of the fermentation losses, 25-40 percent of the energy contained in feeds is lost as heat and gas created by the rumen bacteria. This is the primary benefit of ionophores such as Rumensin Bovatec or Cattylist. They reduce the amount of fermentation, which translates into improved conversions. The use of fat or tallow also reduces fermentation. Ionophores reduce fermentation through bacterial changes in the rumen, while fat coats feed particles and reduces the ability of bacteria to ferment the feed. Theoretically we could pull ionopohres out of the ration and make the animal warmer. The drawback to that is the fact that winter also brings a higher incidence rate of coccidiosis. Youthful cattle feeders may not be aware of the coccidiosis problem, since ionophores have been with us for some 24 years now. That is, ionophores are effective coccidiostats, and those of us who have been in this business more years than we care to admit; remember what it was like before Rumensin and Bovatec came on the scene. If the feedlot uses fat or tallow in the ration, we can pull it out, and likewise make cattle warmer. But there is a drawback to that. Fat tends to moderate problems with bloat and acidosis, which can be due to fluctuating weather and intake, and are therefore more of a threat during the winter. What it boils down to is that we only have one real option with respect to making the cattle feel warmer, and that is increase the roughage. But the problem is economics. On a unit of energy basis, roughages produce more heat (and gas) than concentrates. While this tends to provide heat for the animal, it also demonstrates why concentrates are so much more productive, and therefore less expensive on an energy basis. Therefore, as we add roughage, we also decrease efficiency and increase the cost of gain. In some years and some areas, roughages are relatively inexpensive. In that case winter ration decisions are easy. Add extra roughage. Conversions increase, however warmer cattle should gain slightly better. Beyond that, extra roughage moderates acidosis and usually bloat. When roughages are expensive, decision making is more difficult. In that case think more in terms of winter management rather than winter rations. Add minimal amounts of roughage, and watch the weather closely. Whenever a storm or unusual low is predicted, the cattle are backed up one ration. When the barometer drops unpredictably (usually the day before a storm), consumption will increase rapidly. However, if good basic bunk management is practiced, that type of situation usually doesn't cause any major problems. Bloat and acidosis usually occur only if we are behind the cattle (have let them run out of feed). The worst case scenario being fresh feed put in front of hungry cattle; coincidentally when the barometer drops. An obvious problem is management after a storm. When the cattle have been off feed for a period of time, back them down a ration or fill them with hay before delivering the "top" ration again. Failure to do so will result in more liver abscess, founder, sudden death, as well as ordinary bloat and acidosis. With by-product rations, moisture can be a problem. If the ration is frozen in the bunk, that is synonymous with cattle being out of feed. If the by-products are high in starch such as potatoes, we must treat the cattle just like they were out of feed. That is, back them down to a less concentrated ration to be fed over the frozen ration and/or fill them with hay -- before the high starch ration thaws out.(c) Dr. Porter Price has several books and a subscription newsletter available. For more information, please call Feed*Lot Magazine at (800) 798-9515. |
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