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Role of Minerals in poultry nutrition It is recognized, generally, that the most efficient utilization of any ration depends upon the proper balance and quality of the nutrients therein. Minerals are as important, therefore, but no more so, than the other constituents in a properly constructed poultry ration. Although the general functions of minerals in poultry nutrition cannot be divorced from those of other constituents, nevertheless they are very definitely associated with skeletal structure, soft tissues, and maintenance of normal body fluids which influence absorption, secretion, and excretion. Years ago, it was thought that protein, fat, and carbohydrate were the only essential nutrients, but later it was found that the m i n e r a l s a c c o m pa n y i n g c o m m o n feedstuffs were also necessary; in fact, even better growth and egg production could be obtained by supplying additional amounts. Until the beginning of the present century, however, the use of m i n e r a l s u p p l e m e n t s w a s n o t widespread. In asmuch as poultrymen \believed that these materials merely furnished grit and that food calcium came from the organic constituents of the ration, feedstuffs containing an abundance of mineral were usually recommended. Unfortunately, as these were generally high in fiber, At present, there is intense activity in the field of certain "trace" elements which have been found to be of importance in practical mineral supplementation. When it was realized that the addition of a small amount of mineral to poultry rations was beneficial, it was not long before greater amounts were being used, and the poultry industry then passed through a period when the feeding of an excess of cheap minerals was common. The recent trend has been to reduce the amount of mineral supplement, yet supply adequate amounts. The reasons for the poor effects obtained with excess mineral are only now being learned Although grains and their by-products
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contain low concentrations of certain minerals, their contribution to the total intake is considerable since they make up such a large portion of poultry rations. These feedstuffs, along with green feeds, vary in mineral content with the fertility and reaction of the soil, maturity of plant, climate, and insect damage. In order that the poultry nutritionist may proceed intelligently, knowledge of the variability in final composition caused by such conditions is necessary so that means can be taken to assure an adequacy under all circumstances. Calcium, Magnesium, and Phosphorus Calcium and phosphorus are required during early life for sound skeletal development. After maturity, the former is needed for rapid shell formation. Calcium, Magnesium, and Phosphorus Calcium and phosphorus are required during early life for sound skeletal development. After maturity, the former is needed for rapid shell formation. Various calcium compounds, such as the carbonate, sulphate, lactate, gluconate, di- and tricalcium phosphate and silicate, besides such natural materials as oyster shell, limestone, bone meal, rock phosphate, gypsum, and dolomite, serve equally well as sources of calcium when adequate vitamin D is present and toxic elements are absent (Buckner, Martin, and Peter, 1928; Tulley and Franke, 1934; Ackerson, Blish, and Mussehl, 1937). With critical amounts of vitamin D, their availability is proportional to their solubility in dilute acid Since the addition of calcium or phosphorus to a ration deficient in them produced phenomenal results, greater amounts have been tried in an effort to improve rations further. If rations are too high in calcium, however, hatchability may be reduced (Titus, Byerly, Ellis, and Nestler, 1937) or perosis may develop (Schaible, Bandemer, and Davidson, 1938). This adverse effect of an excess of mineral is caused, partially at least, by rendering "trace" elements unavailable.
Dr. Yogesh Paharia B.V.Sc , M.V.Sc ( Nutrition )
Since calcium and phosphorus metabolism are definitely related, their ratio is frequently considered in ration formulation. About one half of the calcium of the ration is retained by poultry, providing the amount is not excessive. They actually utilize calcium and phosphorus in a ratio of about 1.5 to 1, and have the capacity to eliminate excess calcium to an appreciable extent The parathyroids regulate the calcium level in the blood by controlling the withdrawal of calcium from the body and vitamin D acts to sustain the phosphorus level by controlling re-excretion into the intestine. Magnesium occurs in association with calcium in dolomitic limestone and may be harmful if fed in excess to poultry. Recently it has been shown that outbreaks of feather picking and cannibalism in quail can be effectively controlled by increasing the salt content of the ration stepwise by 0.5 percent until the habit is subdued, but not adding more than 2 percent (Titus, 1940). This treatment has not yet been established with chickens, but, aside from this possibility, no benefit accrues from feeding over 0.5 percent of salt in ordinary combinations of feedstuffs. Manganese Rations containing too little manganese or an excess of calcium and phosphorus, produce perosis, lower egg production, and hatchability, and give poor egg-shell structure. The similar effect of highmineral to manganesedeficient rations is caused by the excess mineral adsorbing manganese and rendering it unavailable to the chick Mineral supplements have different
Poultry Planner | Vol. 22 | No.08 | October - 2020
