PAfiT II. CHEMICAL COMPOSITION OF HATCHERY FEEDS 



By Neva L. Karrick* and William Cl«gg* 



Introduction 



This section of the report presents data on the composition of 

 mixed diets and tndiridual diet components used in feeding blueback 

 salmon fingerllngs at the Leavenworth Laboratory of the Branch of Fish- 

 ery Biology, Fish and Wildlife S(9i:nrice. The materials were analyzed 

 for proximate con^osition and for several B vitamins (riboflavin, 

 niacin, biotin, and vitamin Bto). Materials fed during 1947 and 1948 

 were analyzed for thiamine content. 



Four generaJ. groups of materials were analyzed. These included: 

 {l) slaughterhouse waste, (2) salmon cannery waste, (3) processed fish 

 waste, and (4) mixed dieT;s. At present, a high percentage of slaughter- 

 house waste is used in hatchery feeds. The CcUinery waste is used to a 

 lesser extent and was tested as a partial or a complete substitute for 

 the slaughterhouse waste. The processed materials were tested to de- 

 termine their value as possible supplements in the hatchery fish diets. 



Experimental 



The samples for analysis were prepared as follows: Samples from 

 the cannery waste, the slaughterhouse wastes, and the mixed diets were 

 disintegrated in a blender. Samples of waste materials were stored at 

 -18°C. and samples of diet mixtures at -29°C. Samples of meal were 

 ground as fine as possible in an attrition-type mill (figure Il-i), and 

 stored at -18°C. Maximum fineness of the grind of the meal is essential, 

 not only to obtain a uniform sample but also to allow complete extrac- 

 tion of the vitamin. 



Vitamin B-jjg in the fish meal samples was extracted by adding water 

 to the sample and autoclaving the mixture at 15 pounds pressure for 

 1 hour. Vitamin B-jjj in tissues and mixed diets was extracted by adding 

 water to the sample and heating to 100°C. The mixture was stirred 

 continuously during the heating period. Riboflavin and niacin were 

 extracted from all samples by overnight incubation of 1 gram samples with 

 30 milligrams each of papain and takadiastase at 37°C. and at pH 4»5. 

 Biotin was extracted by autoclaving the samples with 6 N hydrochloric 

 acid at 1$ pounds pressure for 2 hours. 



Microbiological assays were used to determine the riboflavin, niacin, 

 biotin, and vitamin B-^ content of the samples. The basic procedure used 

 for the riboflavin, niacin and biotin assays was described by Roberts and 

 Snell (1946). Stock cultures of Lactobacillus casei and Lactobacillus 

 arabinosus were maintained on agar stabs as recommended by the Association 

 of Agricultural Chemists (1949 )• 



* Chemist, Fish and Wildlife Service, Fishery Technological Laboratory, 

 Seattle, Washington. 



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