546 IOWA DEPARTMENT OF AGRICULTURE 



is the only source of bulk. This is not because the cob adds any ap- 

 preciable amount of nutrients but because the bulk added makes it possi- 

 ble for the cow to more completely digest the nutrients present in the 

 corn meal. Corn and cob meal may be made the basis of many of our 

 dairy rations in this part of the country where so much corn is grown. 



The dairy cow is fed for the purpose of supplying her wants in protein, 

 carbohydrates, fat and ash, and as these nutrients perform special 

 functions in the body it is necessary that they be supplied in the proper 

 proportion. A brief explanation of the function of these nutrients may 

 assist in demonstrating their importance. 



Protein, which is one of the most valuable nutrients, is used for the 

 purpose of building and repairing muscle tissue, bones, hide and hair 

 as well as furnishing building material for the foetus and supplying pro- 

 tein to the milk. This is the only nutrient capable of performing this 

 work. 



Carbohydrates and fats supply heat and energy to the body and 

 furnish materials for making body fat as well as that in the milk. Fat, 

 however, is two and a quarter times more valuable as an energy furnisher 

 than carbohydrates. 



Ash supplies the mineral content to the bones and also supplies and 

 maintains the mineral content of the blood stream and tissues and 

 furnishes ash to the milk. 



Generally, in referring to the balance of nutrients, we mean the re- 

 lation between the amount of protein present and the amount of carbohy- 

 drate and fat, inasmuch as the ash pretty well looks out for itself due 

 consideration is given to the other characteristics of the ration. Inas- 

 much as the carbohydrates and fat cannot perform the function of protein, 

 it is necessary to supply enough of this nutrient to take care of the wants 

 of the animal and a lack of this in the ration will limit the production 

 although an abundance of other nutrients might be present. It is also 

 important that too much protein shall not be present in the ration be- 

 cause, while an over-supply may be used to furnish energy, protein is no 

 more valuable for this purpose than carbohydrates and is far more ex- 

 pensive, and besides this, too much protein overtaxes, unnecessarily, 

 some of the essential organs of the body. 



For several reasons it is desirable at all times to supply a ration which 

 comes from several sources. In the first place the cow must always be 

 kept eating and a ration taken from one source may become unpalatable 

 to the cow if fed for a long time. But if several feeds for example are 

 used in making up the grain portion of the ration one of these may be 

 dropped out and another added and the ration made more palatable, and 

 at the same time the cow will not feel the undesirable effect of a sudden 

 change from one grain to another. Furthermore, it has been found that 

 all the proteins are not alike in feeding value and that often two pro- 

 teins are better than the same amount of one protein. Thus, for best 

 results the feeds given a cow should originate with several different 

 kinds of plants, for example, a ration made up of clover hay, corn silage, 

 ground oats, cotton seed meal and corn and cob meal would insure com- 

 plete nutrition if fed in proper amounts. 



