564 



SUCCESSFUL FARMING 



general. The cereal grains, the oil meals and most mill feeds are low in 

 crude fiber. 



The Fats, sometimes called "ether extract/' include all the fats and 

 oils found in the feed. Practically all plants contain some fats, although 

 usually in only small amounts. In animals, fats occur much more abun- 

 dantly, occurring in nearly every organ and tissue. Fat animals often 

 contain 40 or 50 per cent of fat. The fat of the ration is used in the animal 

 as a source of energy and as a source of body fat. It is about two and one- 

 quarter times as valuable as protein and carbohydrates for these purposes. 

 Tankage and the oil meals contain the largest amounts of fat of the ordinary 

 feeding-stuffs. 



roof of mouth 

 tongue 



salivary esophagus 



ducts omasum, or 



manyplies 



reticulum. or honeycomb 



abomasitm, or 

 rennet (true stomach) 



The Digestive Tract of a Cow. 1 



Digestion of the Nutrients. — Before the nutrients can be of any use 

 to the animal they must be digested and taken up by the blood. Digestion 

 is the process of separating the useful constituents of the feed from those 

 that are useless, and changing the useful constituents to such form that 

 they may be taken up by the blood. These processes take place in the 

 mouth, stomach and intestines. Inasmuch as only the digestible nutrients 

 of a feed are of value to an animal, the amount of digestible components 

 of the feed are of special interest to the stockman. Table I shows the per- 

 centages of the digestible nutrients in the ordinary feeding-stuffs. (See 

 Appendix to this book.) 



The Nutritive Ratio. — Proteins are used primarily for growth and 

 repair, while carbohydrates and fats are used for energy and fat production. 

 The nutritive ratio expresses the value of a feed or ration as a flesh pro- 



1 Courtesy of Iowa State College. 



