THE COMPOSITION OF ANIMALS 25 



Phosphate of Lime. — The mineral components present in the 

 animal body in the largest quantities are lime and phosphoric acid. 

 They make up the skeleton of the body and form about 80 per 

 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 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 

 danger of not furnishing enough of these two ingredients. The 

 matter should, however, receive attention in feeding pregnant or 

 nursing animals, dairy cows, or young growing animals ; these should 

 always receive feeds high in calcium and phosphorus in their rations. 



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

 Straw and chaff, the cereals and their by-products, roots, and 

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

 legumes and grasses 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 linseed 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 the addition of small amounts of 

 bone meal, calcium phosphate or floats (ground phosphate rock). 



Potassium and Iron. — Other essential mineral elements in the 

 animal body are 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 physio- 

 logically important elements, like fluorin and silicon, since only 

 very small amounts of them are required and an ample supply is 

 as a general rule 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? 



6. 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 animal nutrition. 



