Txma Viscera 



The viscera fr<»i yellowfin tvina ( Neothunnus macropterus ) when 

 included in various ccaiposite diets proved very unsatisfactory. In 

 every instance the growth response was poor and an acute anemia 

 developed. Surprisingly enough these anemias developed with diets 

 which were considered to be amply fortified with beef liver (20 percent). 



Tuna Liver 



Tvina liver as the sole diet component produced very low growth rate 

 but contained sufficient of the anti-einemic factor to support blueback 

 salmon for a 24-week period. When substituted for beef liver in the 

 standard meat -viscera-meal mixture, no anemia developed and good growth 

 was maintained during a 12-week, warm water, feeding trial. Tuna liver 

 offers a possible substitute for beef liver in c<aiposite diets at least 

 during periods of warm water. 



Fish meals 



The investigations with fish meals were confined, with two excep- 

 tions, to evaluaticHis of salmon waste products. In these experiments, 

 the effect of source of the meal and method of preparation were explored. 

 Each meal was added at the 10-percent level to a combination of 20 percent 

 each of beef liver, hog liver, and hog spleen, and 30 percent scdmon 

 viscera. 



Diets containing salmon viscera meals were found to produce greater 

 rate of growth than those containing salmon offal meals. Vacuum-dried 

 meals produced better growth response than did tunnel-dried meals, and 

 the tunnel-dried meals were superior to flame-dried products. 



Any of these meals, vdien incorporated in composite diets at the 10- 

 percent level or over, resulted in an increased mortality and poor rate 

 of growth when fed diirine prolonged periods of cold water (45^) • At 

 %fater temperatures of 50*^. or over any of the salmon waste meals made a 

 significant contribution to the growth rate of the fish with no deleterious 

 effects. 



Coomercial mackerel offaJ. meal dried by the air-lift process proved 

 inferior to vacuiun-dried salmon viscera meal but was comparable to 

 commercially prepared, flame-dried, salmon offal meal. 



Flame-dried crab meal derived Ircm the total scrap of the blue crab 

 ( Callinectes sapidus ) proved to be inferior to salmon waste meals when 

 fed during warm water but produced none of the deleterious effects noted 

 in salmon waste meals dviring periods of cold water. 



49 



