INTRODUCTION 



During the past few years, the fishing industry has been 

 confronted with the increasingly difficult problem of annually 

 disposing of thousands of tons of fish scales, as fillets have re- 

 placed unprocessed fresh fish in sales volume. Harbors nearby to 

 plants normally allow for an inexpensive area of scale disposal, but 

 unless tidal flows are strong, pollution may result. 



Attempts to use the scales as fertilizer on local farms 

 have been unsuccessful, and the incineration of scales would be 

 costly. Chemical engineers and pharmaceutical houses have been asked 

 for suggestions for utilizing the scales, but this approach, too, 

 has been unsuccessful. In order to determine whether the scales may 

 have value as a source of protein in farm-animal diets, the nutritive 

 value and some factors affecting the nutritive value of the nitrogen 

 compounds in whole scales are being studied. 



Part of this work — rat-feeding studies to compare the 

 nutritive values for growth, the biological values for maintenance, 

 and the digestibilities of pollock fish scale and of casein-lactalbumin 

 protein — is reported herein. The nitrogen content of pollock scales 

 is equivalent to about 60 percent crude protein (N x 6.25). 



Very little research has been conducted with fish scales in 

 the past, and none has been conducted that would promise a solution to 

 the proposed problem. For many years, however, investigators have 

 been studying the nutritive value of similar biological materials, 

 Meunier et al. (1927), Routh and Lewis (1938), and Routh (I9k2a, 19h2b) 

 have investigated the nutritive possibilities of wool, and Wagner and 

 ELvehjem (I9ix2, 19U3) and Newell and Elvehjem (I9u7) have investigated 

 the nutritive quality of some waste keratins. The nutritive values of 

 meal from untreated and treated chicken feathers have been studied by 

 Routh (I9i;2b), Binkley and Vasak (1950), Wilder et al. (1955), Feedstuff s 

 (1956), as well as others. 



In general, these studies have indicated that scleroproteins 

 are nutritionally inadequate but can be used as a partial source of 

 protein with proper supplementation. As far as is known, no studies 

 have been conducted to determine the feed value of fish scales, the 

 scleroprotein now being considered. 



MATERIAL AND ANALYSIS 



The fish scales used in this study were kindly furnished by 

 the staff of the Fishery Technological Laboratory, U. S. Bureau of 

 Commercial Fisheries, East Boston, Massachusetts. Pollock ( Pollachius 

 virens) were scaled by hand. The scales were washed with water, 

 drained, spread in pans, and dried in an oven at 100° C. They were 

 shipped to this laDoratory, where they were ground as finely as possible 



