Feeding Lambs from Weaning to Market
by Dr. Gary E. Ricketts
FEEDING LAMBS FROM WEANING TO MARKET
If lambs are weaned in a proper manner, and are eating well, then the adjustment from preweaning to postweaning should go very smoothly. One key to success is to use high-quality feeds and not change rations rapidly. Make any necessary changes in rations gradually by blending greater and greater proportions of the new feed with the old feed over a period of 6 to 8 days. The ration of the early-weaned lamb should be high in digestible energy and fairly high in crude protein. For optimum performance, rations, if self-fed, should contain no more than 25 percent roughage (ground hay) and could contain as little as 10 percent. Although all-concentrate rations can be successfully self-fed, self-feeding should be done only when very careful management and close observation are possible. Poor management may result in a serious problem with overeating disease (enterotoxemia). Also, always provide an adequate supply of clean, fresh water.
The protein needs of rapidly growing young lambs are best met by natural proteins (from corn, hay, soybean meal, and other similar feeds). The protein content of the ration should be approximately 16 percent. Although research indicates lamb gains will be greater on protein levels higher than 16 percent, it is often found that the cost of the additional protein is not paid for by the additional gain.
You can continue feeding creep rations from weaning to marketing, or you can lower the protein content to 13 or 14 percent when the lambs reach approximately 85 to 90 pounds. How much you want to lower the protein content, if at all, will be determined by the frame size and potential growth rate of the lambs, and the weight at which you plan to market them. The protein content of the ration can be lowered by approximately 1 percent for each 3 pounds of the grain mixture that you substitute for each 3 pounds of soybean meal (44 percent crude protein) or for each 2-3/4 pounds of shelled corn you substitute for each 2-3/4 pounds of soybean meal. The protein requirements for lambs close to market weight is less than for younger, more rapidly growing lambs.
What about replacing part of the natural protein with nonprotein nitrogen such as urea? Urea is most effectively used as a replacement for natural protein after lambs have a fully developed rumen. Replacing natural protein with urea before this stage will not allow for optimum performance.
Take care to meet the mineral needs of weaned lambs. Calcium and phosphorus are essential minerals for bone formation but urinary calculi (water belly) can occur when these minerals are not in the proper balance. The ratio of calcium to phosphorus should be approximately 2:1.
Another important mineral is copper. Copper is an essential element for sheep; however, if it is at too high a level in the ration, it may accumulate in the liver and become toxic. In selecting trace mineral mixtures, be extremely careful that the levels of minerals (especially copper) in the finished feed do not exceed recommended levels. If copper toxicity has been a problem, then use a trace mineral preparation that is free of copper. You may also want to check the molybdenum level of your ration, because molybdenum affects copper utilization. In some cases, we find molybdenum levels in the ration to be extremely low. This in turn can cause a copper toxicity problem even when normal copper levels are present. The key is the relationship of these two minerals. Adequate sulphur levels are also important for normal copper utilization.
A good rule is that about 325 to 350 pounds of a high-concentrate ration (no more than 25 percent roughage) is required to produce a 120 pound market lamb, assuming that the lamb is creep-fed and pushed for rapid gains from birth to market.