THE DAIRY COW 137 



Cheese. Cheese is also made from milk but this is made- 

 largely of the protein of milk (casein and albumin). This 

 material is coagulated or solidified by heat and an enzyme 

 or acid. As this solidifies it also incorporates some of the fat. 

 Thus, a full cream cheese which is made from whole milk is 

 better than cheese made from skim milk. 



Constancy of Milk. An interesting thing about the com- 

 position of milk is that the milk from a given cow is of con- 

 stant composition. That is, a cow giving 4 per cent, milk 

 will give about 4 per cent, milk all the time. The same is 

 true of a cow giving milk of any other percentage of fat. This 

 is a very important fact to remember when it comes to feeding 

 a cow. 



FEEDING COWS 



Protein. If a cow gives 100 pounds of milk a day and 

 there are a few such cows in the country and this milk is 

 4 per cent, butter fat, she will give nearly 4 pounds of protein 

 each day. Under what conditions, then, will this cow 

 be able to make the 100 pounds of milk per day? Only 

 when she is getting the required amount of protein in her 

 feed; that is, 4 pounds, and enough in addition to this for 

 maintenance. 



It is very plain, therefore, that if a cow is to make 100 

 pounds of milk a day she must have in her daily ration about 

 4>2 pounds of protein. What would happen if this amount of 

 protein were reduced to 2> pounds, or if 2 pounds were taken 

 away? She could then make only 50 pounds of milk per 

 day. She would not drop down suddenly from 100 to 50 

 pounds of milk because she would use some protein from her 

 body. But this would gradually weaken her and injure the 

 milk-making machine. Nothing else takes the place of 

 protein. This simply emphasizes the importance of feeding 

 the proper amount of protein to milk giving cows. 



The principal protein feeds, as shown previously, are clover, 

 alfalfa, pea hay, peas, flax, wheat, bran, oil meal and cotton- 

 seed meal. One of these legumes, either green or in the form 

 of hay should constitute at least one-half of the roughage part 

 of the ration of a dairy cow, and one of the protein concen- 



