EXPERIMENTS ON PIGS. 133 



it not an easy matter to find the necessary facts. The real 

 difficulty is to ascertain how much food the animal requires to 

 sustain the vital functions and keep up the animal heat. It 

 doubtless varies greatly in different breeds and in different 

 animals of the same breed. An animal that was restless 

 would require more than one that was quiet. A "learned" 

 pig would require more than one that had no aim in life but 

 to eat and sleep. But leaving out these considerations, I 

 attempted to solve the question by an examination of the 

 composition of the pig before and after he was fattened, and 

 of the food he had eaten. 



Before commencing their experiments on pigs, Messrs. 

 Lawes & Gilbert selected out a fair average pig and analyzed 

 him. He was found to contain 23.3 per cent, of fat. At the 

 end of ten weeks, when the pigs were fat enough for the 

 butcher, another pig was analyzed, and found to contain 42.2 

 per cent, of fat. The actual material stored up by the pig 

 while fattening contained G3.1 per cent, of fat. 



Indian corn is exceedinglv rich in available carbon. It con- 

 tains say sixty-eight per cent, of starch and seven per cent, of 

 oil. In nutritive value one pound of oil is equivalent to two 

 and a half pounds of starch or sugar. Corn, therefore, con- 

 tains, besides nitrogen, nutriment equal to eighty-five and a 

 half per cent, of starch, or thirty-four and one-fifth per cent, 

 of oil. 



Now, assuming that a pig has eaten just enough food to 

 sustain the vital functions and supply respiration and animal 

 heat, how much pork can we get out of the corn eaten over 

 and above this amount? 



The store pig analyzed by Lawes & Gilbert was, I believe, 

 about nine months old, and weighed ninety-four pounds. He 

 contained twenty-two pounds of fat. How much that pig 

 had eaten I do not know ; but, after he had eaten all the food 

 necessary to sustain the vital functions, sixty-four and a half 

 pounds of corn contain sufficient carbon to furnish all the fat 

 he had stored up during the nine months. 



And there can be little doubt, with ordinary current foods, 

 the test of their value as food for pigs is the amount of avail- 

 able carbon that they contain ; in other words, their value is 

 in proportion to the starch, oil and other digestible carbona- 



