STATICS 133 



Oxen were the subject of the experiment, and the figures 

 have been adjusted to correspond to 1000 Ibs. live weight. It 

 was found that 



(1) When fasting absolutely, the animals lost weight at first 

 at the rate of about 3 Ibs. per day, and the nitrogen in the 

 urine corresponded to about i Ib. of protein in twenty-four 

 hours. Obviously such an experiment cannot be continued 

 for many days, as the animals would soon die. 



(2) When the animals were fed on a ration of fat and carbo- 

 hydrates having thermic value of not less than 35 kt. per day, 

 i.e. enough to supply all the energy required for maintenance, 

 the loss of weight was greatly diminished, and the nitrogen in 

 the urine corresponded to only about 0*3 Ib. of protein in 

 twenty-four hours. 



N.B. There was no nitrogenous matter in the food. 



(3) When small quantities of protein were added to the 

 above ration, there was no increase in the amount of nitrogen 

 in the urine, and the loss of weight was practically arrested. 



(4) When the quantity of digestible protein, added to the 

 non-nitrogenous ration, exceeded about J Ib. per day, the 

 nitrogen in the urine was increased by an amount corre- 

 sponding to the excess of protein ; but there was no increase 

 in the weight of the animal when the static value of the ration 

 as a whole did not exceed the stipulated amount, 35 kt. 

 per day. 



(5) When the animals were fed on mixed ordinary rations, 

 the amount of nitrogen in the urine corresponded to from i Ib. 

 to i J Ibs. per day. 



(6) When the food contained more than Ib. of digestible 

 protein and the thermic value exceeded 35 kt., the animal 

 gained weight. 



The inference drawn from these data is that, for the 

 maintenance of oxen without gain or loss of weight, the food 

 must not only have a thermic value of 35 kt., but also it must 

 contain at least J Ib. of digestible protein per 1000 Ibs. live 

 weight per day. 



The results of many different experiments and observations 

 lend great weight to this conclusion ; but- they also tend to 



