156 



THE SCIENTIFIC FEEDING OF ANIMALS 



the reserve supplies, and during heavy milk secretion or rapid growth. 

 The amount of phosphate of lime excreted with the milk is quite marked. 

 A cow giving 12 liters of milk per day excretes 84 gm. of salts which 

 consist of lime 22.6 per cent and phosphoric acid 27.7 per cent. Thus 

 the daily loss of these bone salts amounts to about 37 gm. Since the 

 proportion of salts in milk may be regarded as constant (except in the 

 colostrum), the loss of phosphate of lime is in proportion to the milk 

 yeld. The heavy drain upon the bone-forming salts during pregnancy 

 and increased milk secretion is a general explanation of the relative fre- 

 quency of fragility or brittleness of bones in cows. The requirement for 

 bone salts is influenced by the size and rate of growth of an animal. 



The following table gives the lime and phosphorus requirements of 

 the different species of animals according to sex and age. It should be 

 noted also that animals (except sucklings) can utilize only one-half to 

 one-third of these salts contained in the various feeding stuffs, and that 

 the feed supplied should therefore contain twice or three times the actual 

 requirement of these salts. 



Lime and Phosphoric Acid Requirements of Animals 



According to investigations of Soxhlet, the proportions of the daily 

 amounts consumed and the amounts utilized by a suckling calf of 100 

 pounds live weight are as follows : 



Consumed 



Lime 14.75 gm 14.31 gm.: 



Phosphoric acid 18.90 gm 13.70 gm. 



Utilized 

 97.0% of amount consumed. 

 72.5% of amount consumed. 



