DIGESTIBILITY OF FISH. 9 



Summary of digestion experiments, with butter fish in a simple mixed diet. 



Experiment No. 



Subject. 



Protein. 



Fat. 



Carbohy- 

 drates. 



Ash. 



452 



D. G. G 



R.L.S 



O.E.S 



Per cent . 

 93.2 

 92.2 

 89.6 



Per cent. 

 94.0 

 92.3 

 83.3 



Per cent. 

 98.2 

 97.4 

 97.7 



Per cent. 

 89.4 



454 



77.1 



455 



75.8 











91.7 



89.9 



97.8 



80.8 









In the digestion experiments made with butterfish, the subjects ate 

 an average of 471 grams of fish daily, which supplied 93 grams of 

 protein and 23 grams of fat. The protein, fat, and carbohydrates 

 of the total diet were found to be 91.7 per cent, 89.9 per cent, and 



97.8 per cent digested, respectively. The values 91.7 per cent and 



89.9 per cent for the digestibility of the protein and fat of the total 

 diet become 91.9 per cent and 86.4 per cent, respectively, if allow- 

 ance is made for the undigested protein and fat resulting from the 

 basal ration. The estimated value, 86.4 per cent, for the digesti- 

 bility of the fat of butterfish is somewhat lower than that of the 

 other fish fats here reported. This lower value is no doubt in part 

 due to the "heaping up of errors" involved in estimating the diges- 

 tibility of a fat of a single food when it represents so small a por- 

 tion of the total fat eaten. The subjects reported that they re- 

 mained in normal physical condition during the experimental 

 periods, except that subjects D. G. G. and O. E. S. reported that 

 the diet produced a constipating effect, which was due, no doubt, 

 to its very complete utilization. 



GRAYFISH. 



The grayfish (Sgualus acanthias, Linnaeus), which is very abundant 

 and easy to catch, though known to be wholesome, of good flavor, 

 and usable for many appetizing dishes, has not been utilized to any 

 extent in this country for food purposes, but has been considered 

 largely as a source of oil and fish scrap, a fishery industry by-product 

 of value for fertilizer material. Recently the Bureau of Fisheries 

 has devoted considerable attention to the possible use of this fish in 

 human nutrition and is of the opinion that it constitutes a cheap and 

 very wholesome food. 



In the literature consulted, no reports were found of the digesti- 

 bility of grayfish. In order to judge of the value of the grayfish in 

 the dietary, it seemed desirable to obtain information on this point, 

 and, accordingly, tests were made in which canned grayfish was 

 served in the form of a fish loaf in conjunction with the simple basal 

 ration employed in the other tests reported in this paper. The canned 

 fish used for this study was supplied by the Bureau of Fisheries and was 

 taken to be representative of a large pack put up by a commercial 

 concern under the direction of the Bureau of Fisheries. 



