EXPERIMENTAL RESULTS 



In the selection of products for test, several factors were con- 

 sidered. First and foremost was the availability of the product. 

 Little or nothing would be gained from the biological assay of products 

 which could not meet the demand of the greatly expanded program for 

 artificial propagation contemplated on the Lower Columbia River. The 

 initial cost of the item was considered to be of secondary importance 

 to its availability although low cost was highly desirable. Cost can- 

 not be regarded as the only criterion for the evalulation of a product,, 

 Not only do prices vary with the demand but low cost items of inferior 

 quality may prove more expensive than items of high r initial cost be- 

 cause of the higher conversion factors and increased mortalities which 

 may result from their use. 



The' discussion of the results of the feeding trials has been 

 organized into five major groups according to the types of diets tested. 

 The groups consist of (1) meat products, (2) fish products, (3) dry 

 meal supplements, (U) potential production diets, and (5) evaluations 

 of the effect of cold storage on prepared diets. Because evaluations 

 of a single type of product were not confined to a single year, the 

 discussion covers the results of the four series of experiments. 



Meat Products 



The meat products used in salmonoid diets are limited to those 

 which are not used extensively for human consumption, either because 

 they are unfit or undesirable. Of this group of meats, flukey beef 

 liver, flukey hog liver, and hog spleen were used in the feeding trials 

 because they were the most generally available in this area and the 

 work of other investigators indicated they offered the greatest pos- 

 sibilities for the vitamin fortification of otherwise deficient diets. 



Flukey Beef Liver 



Flukey beef liver was used as a standard control in all the feeding 

 trials. The 100 per cent beef liver diet invariably produced higher 

 mortality rates than did the standard production diet when fed at water 

 temperatures above 3>0 degrees F. In 19UU and 19U5 these differences 

 were significant and the trend is present in both the 19u7 and 19U8 

 feeding trials. For comparisons, reference may be made to the under- 

 lined control diets in the four tables. Beef liver has not proved 

 entirely adequate when used as the sole diet component in the ration 

 of blueback salmon. It is indicated, however, to be an excellent 

 source of the anti-anemic factor and serves as a fortifying agent in 

 otherwise deficient diets. 



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