THE ANIMAL BODY— DIGESTION— METABOLISM 19 



Composition of the bodies of farm animals * 



Water Protein Fat Ash 



Per ct. Per ct. Per ct. Per ct. 



Calf, wt. 100 lbs 71.8 19.9 4.0 4.3 



Calf, wt. 300 lbs 66.3 19.0 10.2 4.5 



Growing steer, wt. 700 lbs 60.3 " 18.6 16.6 4.5 



Partly fat steer, wt. 1,000 lbs 53.0 . 17.6 25.0 3.8 



Fat steer, wt. 1,200 lbs 48.6 16.6 31.1 3.7 



Very fat steer, wt. 1,500 lbs 43.5 15.7 37.7 3.2 



Fat lamb 52.3 13.4 31.2 3.2 



Sheep, before fattening 61.0 15.7 19.9 3.4 



Half-fat sheep 55.2 15.4 25.9 3.5 



Fat sheep 46.2 13.0 37.9 3.0 



Very fat sheep 37.1 11.5 48.3 3.1 



Hog, before fattening 58.1 14.5 24.6 2.8 



Fat hog 43.0 11.4 43.9 1.7 



* Not including contents of digestive tract. 



The table shows that 71.8 per ct. of the body of a 100-lb. calf is 

 water and that the proportion of water steadily grows less as the 

 animal matures and fattens, the body of a very fat 1,500-lb. steer 

 containing only 43.5 per ct. water. The percentage of protein remains 

 quite constant during growth but decreases as the animal fattens. 

 On the other hand, the percentage of fat increases gradually during 

 growth, and more rapidly while fattening. Over one-third of the 

 carcass of the fattened 1,500-lb. steer is fat. The percentage of ash, 

 or mineral matter, shows the least change, but decreases as the animal 

 fattens, since the fatty tissue contains but little mineral matter. 

 Similar changes occur in the bodies of sheep and swine as the animals 

 mature and fatten. In general, the bodies of sheep and swine at the 

 same degree of fatness contain less water and protein and considerably 

 more fat than those of cattle. The fat hog, for example, contains 

 43.9 per ct. fat and only 11.4 per ct. protein. Due to their small 

 skeletons, the bodies of swine contain less ash than those of cattle and 

 sheep. 



II. Digestion 



The changes which food undergoes within the digestive tract of 

 animals to separate the useful portion from the waste matter and 

 prepare it for absorption and final use in the body are known as 

 digestion. 



Nutrients and rations. — In discussing stock feeding it is necessary 

 to understand clearly what is meant by each of the following terms: 

 J The term nutrient is applied to any food constituent or group of 

 rood constituents of the same general chemical composition, that aid in 

 the support of animal life. Crude protein, the carbohydrates, and 



