thdroiioh imderstandiiig of this subject will help us in the 

 consideration of much of the data that will follow. 



In GUI- original studies of feeds and food principles, very 

 little attention was ]3aid to the value of the ash, or the mineral 

 portions of feeds. It was thought that if we fed the right pro- 

 portions of protein, carbohydrates and fats we were meeting 

 all the requirements of the animal. However, more recent 

 investigations and experiences have shown that many times 

 animals do not do well because the food lacks mineral matter. 

 Certain animals have been fed on ash-free food, and it was 

 found that within a few days a decided change took place ; 

 the animal became weak, was unable to eat sufficient food, and 

 if the experiment was continued for a few weeks it died. 



In studvino- the needs of various classes of animals, natur 

 allv the milk of the mother formed the basis for investisi'ation. 



Table 1. — Shotring ihe Importance of Ash, Protein and P-^Or, in the 



Feed for Groicing Stock. 



The foregoing is a very interesting chart on the analysis 

 of milk of various animals. The first column gives the name 

 of the mother. The second, the number of davs after birth 

 required for the young to double its weight. For example, 

 the baby usually doubles its weight in one hundred and eighty 

 days, the colt in sixty days, the calf in forty-seven days, and 

 so on until we reach the rabbit, which doubles its weight in 

 about six days. The third column gives the amount of lime 

 in the milk of the mother. Xotice that the amount of lime 

 ill the milk of these animals is inversely ])ro]iortioned to the 



