EXPERIMENTS WITH MEATS AND MEAT SUBSTITUTES AS 



TROUT FOODS ^ 



By H. S. Davis, In Charge A(/rk;ultural Investigations 



and 



R. F. Lord, Jr., Junior Aquatic Biologist 



CONTENTS 



Introduction 123 



Methods 124 



Fresh meat and fish products 126 



Beef liver 126 



Beef heart 128 



Beef melts 129 



Pig liver 129 



Sheep liver 129 



Fresh fish 130 



Cooked meats 131 



Dried animal products 131 



"Clam heads" 131 



Fish meals 134 



Dried animal products — Continued. 



Shrimp meal 136 



Milk products 137 



Cereals and similar products 138 



Wheat middlings 138 



Soybean meal 138 



Mexican pinto beans 139 



Miscellaneous products 139 



Fox food . 139 



Cod-liver oil and yeast 140 



Conclusions 141 



Bibliography 146 



INTRODUCTION 



During the past several years the Bureau of Fisheries has been 

 conckicting a series of feeding experiments with fingerling and 

 yearhng trout. The object of these experiments has been to deter- 

 mine, if possible, the available foods which will give the most satis- 

 factory results when fed to trout in the hatchery or in rearing ponds. 

 These tests have all been conducted from the practical standpoint, 

 and no attempt has been made to carry on fundamental investiga- 

 tions on the nutrition of trout. Accordingly, they have been con- 

 ducted under as nearly typical hatchery conditions as possible, and 

 it is believed that the results attained are a fair criterion of what 

 may be expected from the various rations when fed on a large scale 

 at hatcheries. 



Since environmental conditions have a marked influence on the 

 health and vigor of the fish, we realize that the results obtained with 

 a given diet at different hatcheries may show considerable diversity; 

 and in comparing our results with those from other stations this 

 fact should be kept in mind. Furthermore, there is considerable evi- 

 dence that different species of trout may give quite different results 

 on the same diet, which again greatly complicates the problem for the 

 trout culturist. The majority of our experiments have been con- 

 ducted with the brook trout {Salvelinus fontinaUs), although the 



1 Appendix VII to the Report of the United States Commissioner of Fisheries for 1930. 

 B. F. Doc. 1079. 



123 



