Effect of Source on Utilization of Salmon Waste Meals 



As the biological values of animal proteins from different 

 sources vary, evaluations were made of meals derived from two seg- 

 ments of the salmon waste and from two localities — Southeastern 

 Alaska and the Columbia River. This investigation was conducted during 

 19h7 and 19U8 in cooperation with the Seattle Technogical Laboratory 

 of the Branch of Commercial fisheries and financed in part by the 

 Industrial Research and Development Division of the Department of 

 Commerce. 



The preliminary trials conducted in \9h7 indicated that meals 

 prepared from the whole waste did not have as high a growth po- 

 tenial as did those derived from salmon viscera (Table h, Diets k and 

 5) o There were, however, several variables such as the procure- 

 ment of the meals from two sources and variations in the methods of 

 preparation which could have produced these differences. 



In 19)485 salmon off<L and salmon viscera meals, derived from the 

 same source and prepared by an identical method under controlled con- 

 ditions, were tested to evaluate the protein quality of the two sal- 

 mon waste products, Two such sets of evaluations were used employing 

 two methods of preparation (Table 5, Diets 9 and 13, and Diets 10 and 

 12). In both groups the trend was the same, favoring the meal derived 

 from salmon viscera, but only in the group in which the meal was most 

 efficiently utilized were the differences statistically significant. 

 It may be concluded, however, that salmon viscera tunnel-dried at 

 100 degree temperatures produces a greater growth response than does 

 the complete salmon offal prepared by the same process. 



Salmon wastes from different species vary in their proximate 

 analysis. To determine if these differences affected the growth 

 potential of the meals a comparison was made in the 19U8 feeding 

 trials . Two meals prepared in an identical manner but one derived 

 from the viscera of Columbia River chinook salmon and the other from 

 Southeastern Alaska pink salmon were tested at the 10 per cent level 

 in combination with meat and viscera mixture (Table 5, Diets 2 and 9). 

 The diet which contained the chinook salmon viscera meal produced 

 significantly greater gains than did that wh'ch included meal derived 

 from pink salmon viscera. There was one variable, the stage of ma- 

 turity of the fish from which the viscera was obtained, which was not 

 excluded from the experiment. As the season progresses, the pro- 

 portions of eggs, milt, and gastro-intesbinal tract change with the 

 sex products occuring in greater proportions as the fish approach 

 maturity. If both meals were derived from fish at comparable stages 

 of maturity it was by pure chance. Because varying proportions of 

 the sex products in the viscera may alter the biological value of the 

 protein without materially changing the crude protein content, this 

 variable may invalidate the results of the experiment. 



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