CONCERNING LOW PROTEIN DIETARIES 143 



to a decrease in the quantity of readily digestible meat and an 

 increase in the vegetable material of these diets. As will be 

 evident from the diets selected above, this explanation will not 

 cover the facts. Diets II., IV., and VI. are practically identical 

 in their absorbability, yet the dog shows considerable variations 

 in the quantity of protein he was able to utilize. It is therefore 

 not quite clear from these experiments that the absorptive func- 

 tion of the intestinal epithelium did not suffer to some extent 

 by the protein content of the dietaries remaining at so low a level 

 for many months. This would be in harmony with the con- 

 clusions arrived at by Munk and Rosenheim from a similar series 

 of experiments, and would militate against the view that a 

 material reduction of the protein in dietaries is to the welfare 

 of the body. 



All these experiments on dogs are open to the criticism that 

 the dog is a carnivorous animal, and that the results are there- 

 fore not directly transferable to man. We shall now refer to 

 some experiments on animals that are more nearly allied in food 

 habits to man. The most important of these are the investi- 

 gations made into the effects of feeding swine on a low and on a 

 high protein dietary respectively. 



The digestive organs of the pig are regarded as being closely 

 comparable to those of man, and the pig, being an omnivorous 

 animal, like man, is not open to the same objection as the dog 

 in estimating the merits or demerits of a low protein dietary. 

 Benedict, quoting from Shutt's valuable and interesting paper,* 

 states that extensive investigations on " soft " pork show con- 

 clusively that when hogs are fed on a low protein diet i.e., 

 Indian corn the pork is of very inferior quality ; while if the 

 protein content of the diet is raised by the addition of skim milk, 

 legumes, or other nitrogenous materials, the quality of the pork 

 is very markedly improved. 



Canadian pork butchers find also that the intestines of hogs 

 fed on low protein rations tear more easily when the carcass 

 is dressed that is, the intestines are not so firm. This would 

 appear analogous to the condition described by Munk and 

 Rosenheim as- occurring in the intestines of the dogs they in- 

 vestigated in their feeding experiments with dietaries deficient 

 in protein. A bad quality of pork is also produced when the 

 diet is excessively high in protein, so that swine are unusually 

 sensitive to marked alterations in the protein content of the diet. 



* Shutt, Bulletin No. 38, Department of Agriculture, Ottawa, Canada. 



