THE COMPOSITION OF ANIMALS 25 



cent of its entire ash content. In the case of suckling or young 

 growing animals it is important that the feed shall contain a 

 sufficient amount of lime and phosphoric acid. A deficiency of 

 these components in the feed will give rise to serious disorders in 

 the bone structure of the young, as is shown in the case of pigs fed 

 wholly or largely on Indian corn (pp. 300-301). Under ordinary 

 conditions, when mixed rations are fed, there is generally little dan- 

 ger of not furnishing enough of these two ingredients. The matter 

 should, however, receive attention in feeding pregnant or nursing 

 animals, or young growing animals, and heavy feeding of materials 

 low in calcium or phosphorus should be avoided. 



Among the feeds low in lime (calcium) may be mentioned: 

 Straw and chaff, the cereals and their by-products, as gluten meal 

 and shorts, malt sprouts, dried brewers' and distillers' grains, roots, 

 and molasses. Feeds high in lime, on the other hand, are: Hay 

 from grasses and legumes, and many leguminous seeds. Straw, 

 distillery feeds, molasses, mangels, and potatoes are deficient in 

 phosphoric acid, while the small grains, wheat bran, malt sprouts, 

 brewers' grains, and oil meal, are high in phosphoric acid. If the 

 rations fed are rather low in either or both of the ash materials 

 mentioned, the deficiency may be made up by an addition to the 

 feed of small amounts of bone meal, calcium phosphate or floats 

 (ground phosphate rock). 



Potassium and' Iron. Of other essential mineral elements in 

 the animal body, we shall mention only potassium, which is found 

 especially in the cell walls, muscles, and blood; and iron, mainly 

 found in the red coloring matter of the blood (haemoglobin, p. 21). 

 There is no danger that the rations fed farm stock will be deficient 

 in these or other physiologically important elements, like fluorin 

 and silicon, since only very small amounts of them are required 

 and an ample supply is always present in the feeds. 



QUESTIONS 



1. Name the various groups of substances in the animal body and describe 



their main properties. 



2. How much water, fat, and protein are contained in the body of a calf, 



a lean and a fat steer, a fat sheep, and a fat hog? 



3. What is the composition of the increase in live weight during fattening? 



4. Name the different forms in which protein occurs in the animal body. 



5. What is haemoglobin? 



G. What are leucocytes, connective tissues, keratin? 



7. What protein substances are found in the milk? 



8. In what forms is fat found in the animal body? What are the lipoids? 



9. What are the main mineral substances found in the animal body? 



10. Give the office of common salt in the digestion of feeds and in animal 

 nutrition. 



