INORGANIC NUTRIENTS 155 



will live 12 days when all food is withheld), and dogs will die in from 

 26 to 36 days. 



Under natural conditions animals usually receive sufficient mineral 

 matter^ in their food. When kept in captivity or under domestication, 

 especially when fed under the stable conditions, with factory by-products 

 and receiving straw instead of hay, they are Hable to suffer from lack of 

 these important elements and become diseased (halisteresis). Proper 

 attention should therefore be given to the inorganic constituents of the 

 animal's feed. 



The mineral matter occurs in feeding stuffs in part as inorganic salts, 

 in part as organic compounds. The latter, though occurring in very small 

 quantities are, on account of the facility with which they are absorbed, of 

 great importance. Among the mineral substances which are necessary 

 for the support of life we have potash, sodium, calcium, magnesium, 

 iron, phosphorus and chlorin. They are therefore referred to as bio- 

 genic elements. In addition they have certain special functions to per- 

 form in the economy of the animal organism, as, for instance, the func- 

 tion of phosphate and carbonate of lime in building and maintaining the 

 structure of the bones. If Hme is absent the bones become soft and 

 brittle. Deficiency in the supply of iron is apt to produce anemia, while 

 deficiency in potash causes licking disease, etc. 



The salts of phosphorus are necessary, above all, for the growth and 

 maintenance of the bony structures of the body. Of course these salts 

 have additional functions in the vital processes of the body. The life 

 of every cell is dependent, among other things, on the presence of the 

 nutrient salts. 



The content of lime and phosphoric acid salts is dependent in the first 

 place on the kind of feeding stuff, and the latter, on the other hand, on 

 soil conditions and the moisture content of the soil. In times of drouth 

 there is lack of water as a solvent for the salts; under such conditions 

 plants can take up only a limited quantity of these substances and as a 

 consequence animals are supplied with a deficiency. It is a common 

 observation that softening and brittleness of the bones assumes an en- 

 zootic character in dry seasons. Again in dry seasons (times of stress) 

 feeding stuffs rich in lime, like hay, are frequently displaced by those 

 of an opposite character, Hke straw, which are deficient in lime. The 

 unfavorable effects are further emphasized by increased consumption of 

 the salts in question by the animal organism. This is particularly true 

 with respect to the salts of lime and phosphorus in the latter stages 

 of pregnancy when the bony structures of the fetus draw heavily upon 



2Excess quantities of mineral matter taken up with the food and not used for tissue building 

 are excreted in the feces and urine. When the total ash or mineral matter in the food gives an 

 acid reaction, the phosphoric acid, lime and magnesia are for the greater part excreted with the 

 urine, while under opposite conditions they are excreted with the feces. The ash content of meat, 

 milk, many grains and varieties of oil cake has an acid reaction, while that of green feed and 

 roughage, roots and tubers is alkaline. Since the latter constitute the main nutriment of herbivora, 

 the urine of these animals is alkaline in reaction and consequently poor in phosphoric acid, lime 

 and magnesia; on the other hand, the opposite conditions prevail witb sucklings and carnivora. 



