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Energy in feeds not constant It does not make any difference what system we use for cattle rations; each feedstuff's energy varies with several factors. This makes the evaluation of the energy content a moving target. The fermentation extent and speed of fermentation are more important than total tract digestibility. Here are some factors: --The processing method, such as cracked or flaked corn. --Moisture in the feedstuff, such as high moisture corn vs. dry corn. --The amount fed, example: If corn is fed in a grower or a finisher ration. --The combination with other ingredients. Roughages cause cud chewing. Two grains may be better than one. Consider: --The maturity of a forage. Mature hay becomes indigestible. --If fed at full feed or limit fed. --Other factors such as heat damage, fermented or non-fermented, the moisture amounts in high moisture grain, and other factors. Speed of digestion vs. digestibility Here is an example: the published energy value of steam flaked corn does not appear to correspond to its outstanding feeding value. This may be true to some extent to the rate of digestion of the flaked corn. Research and practical observations say that two grains in a finish ration may be better than one. This may be caused by one grain being fermented faster than the second may. The combination may be better than one alone. In the case of dry rolled milo, a second fast fermented grain like wheat, barley, or high moisture corn may speed up the fermentation. Beet pulp and soy hulls are two high fiber feeds that have high energy values. This is probably caused by their rapid rate of fermentation in the rumen. To process or not to process grain Corn can be fed whole, coarse cracked, fine rolled or hammer milled and all will get the cattle finished. However, the method and extent of processing is an economic trade-off that effects the energy value of the feed ingredient and its cost per unit of energy. The best example of different effects caused by feed processing is comparing the different processes of sorghum grains (milo). Steam flaked milo grain may be 126% better than coarse rolled milo. Flaked milo at 26 to 28 pounds per bushel has a net energy for gain (NEg) of 68 compared to dry rolled milo as low as 54 NEg per hundred. Dr. Kelly Kreikemeier, a nutritionist at West Point, Nebraska said, "I suspect coarse dry rolled milo has only the energy value of good quality corn silage on an equal dry basis." However, milo grain can be improved considerably by very fine processing. The fine processing effect on milo was determined by John Brethour at the Hays experiment station of Kansas State University (KSU). Reconstituted milo has energy values right up with flaked corn according to the 1984 NRC report. This was proven by Prouty and Hale at the University of Arizona and confirmed by Huck and Kreikeimeir at KSU. Similar differences are found with corn for feed processing. Montgomery now of Garden City, Kansas, and Matsushima perfected the differences in the value of a thin corn flake compared to a coarse flake. This research was done at Colorado State University. Regarding high moisture corn, my partner, John Thornton and I are convinced from our experience, that finely processed high moisture corn has a higher feeding value than coarse rolled high moisture corn. However, Dr. Thornton stresses fine processed high moisture corn may cause more digestives upset. Thornton cautions that to get the efficiency effect of fine processed high moisture corn requires adequate roughage and good bunk management of finishing rations. These are needed to prevent fines build-up and therefore get maximum intake. He stresses a clean bunk feeding system. High moisture corn stored whole in oxygen limited structures and then crushed before feeding is also a high-energy grain. The kernels must be crushed. Wheat, rye, and millet grains are a challenge to improve the energy content by processing. The small berries that escape the processing method will be undigested. Corn silage processing Corn silage is a misused crop. It contains up to 50% grain on a dry basis. The energy can be improved if this forage/grain mixture is processed with a fine cut of one forth inch at ensiling time. In some cases this forage/grain mixture can be ground out of the silo to improve the feeding value. I observed tub ground corn silage thirty-five years ago. This ground silage and supplement made an excellent grow ration. Assigning energy values (and cost per energy unit) Any of the energy schemes will work TDN (total digestible energy) and DE (digestible energy) is similar. Metabolizable energy (ME) is better. The ME system is further refined by the "California" system of net energy for maintenance and gain (NEm and NEg). The NEm and NEg system is used by most feedlot nutritionists for evaluating ingredients and ra-tions. Assigning an appropriate energy value for a feed ingredient is important to determine the best cost for ration formulation. It is also important for prediction or evaluating cattle performance. Considerable judgement is used to determine the values. The target for assigning the energy depends on the factors outlined above. Work with your research contacts, feed people, and nutritionist to determine the energy in your ingredients. Comments or questions on this article can be directed to Dr. James I. Sprague, 1021 N. Second, Garden City, KS 67846. |
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