Natrition Studies. 77 



Effect of fattening on the carcasses of mature sheep. 



It is shown that, during fattening, these mature sheep made prac- 

 tically no gain in muscle or lean meat, the increase being almost 

 wholly fat. These results show that the fattening of animals is 

 what the term implies — the laying on of fat. 



100. Factors influencing fattening. — The deposition of fat in an 

 animal depends primarily upon the quantity of food consumed in 

 excess of maintenance and growth requirements. Fattening may 

 take place at any age, tho the tendency of young animals to grow 

 greatly reduces the proportion of food usually available for that 

 purpose. Since the process of fattening depends upon the excess 

 of digested nutrients over the w^ants of the body, it is evident that 

 anything that decreases the waste due to external work or to excess 

 of exercise, and which lessens the internal work of digestion and 

 assimilation, may aid in fat formation. Exertion of any kind in- 

 creases the oxidations going on in the body. Vigorous exercise 

 must therefore be avoided in the case of fattening stock and milch 

 cows. Supplying an abundance of feeds that are palatable, concen- 

 trated, and largely digestible tends to rapid fattening, because a 

 large surplus of nutrients then remains after supplying the body 

 needs, which surplus may go to the formation of fat. 



Tlie disposition of an animal to fatten depends upon breed and 

 temperament. While a wild animal, nervous and active, can be fat- 

 tened only with extreme difficulty, domesticated animals are more 

 quiet and usually fatten readily. The restless animal is rarely a 

 good feeder, while the quiet one which is inclined to "eat and lie 

 down" will sliow superior gains. This is not due to difference in 

 digestive or assimilative powers, but rather to the fact that the 

 quiet animal has, from a given amount of food, a greater surplus of 

 nutrients available for fat building. 



The oxidations and decompositions taking place in the body de- 

 pend on the amount of oxygen taken up by the blood. The amount 

 of oxygen that can be absorbed by the l)lood is limited by the quan- 

 tity of blood and by its content of hemoglobin, the characteristic 

 coloring matter of the red blood corpuscles. A small amount of 



