714 U. S. BUREAU OF FISHERIES 



cial tankage was very poor. Extracted menhaden fish meal was inferior | 

 to commercial unextracted menhaden fish meal. The addition of 

 5 per cent of oleic acid to the diets proved very detrimental to the 

 animals. Fish meals were found to be a much better source of 

 protein than casein. It was also found that when calcium or phos- 

 phorus was added to the diets containing fish meals no better growth 

 response resulted than when none was added. This would seem to 

 indicate that fish meal is in itself an adequate source of calcium and 

 phosphorus in the diet, and that it is not necessary to supplement 

 fish meal with these minerals. 



The bureau has also undertaken, in cooperation with the Bureau 

 of Chemistry and Soils of the United States Department of Agricul- 

 ture in the laboratories of the protein and nutrition division of that 

 bureau, a cooperative research program involving the determination 

 of the comparative vitamin values in fish oils. The total production 

 of fish oils in this country during 1929 was over 12,000,000 gallons. 

 The six most important oils, exclusive of cod-liver oil, are: Pilchard 

 (California sardine), menhaden, Alaska herring, salmon, Maine 

 herring, and tuna; and their annual production ranges from approxi- 

 matelv 6,500,000 gallons for pilchard to 60,000 gallons for tuna. At 

 the present time these oils are used principally in the soap industry, 

 as drying oils in the paint industry, and also to some extent for 

 leather sizing and tempering steel. This investigation was designed 

 to find new uses for these commercial fish oils. Preliminary data 

 indicate that commercial tuna oil is superior to the best obtainable 

 grade of medicinal cod-liver oil in potency of vitamin D, and that com- 

 mercial pilchard oil is equal to the best grade of medicinal cod-liver 

 oil in this respect. As regards vitamin A .potency, the commercial 

 fish oils did not show up as well as medicinal cod-liver oil. Commer- 

 cial salmon oil is approximately half as potent in vitamin A as medic- 

 inal cod-liver oil. The low content of vitamin A in these commercial 

 oils is probably due to the high degree of heat and oxidation to which 

 these oils are subjected in their method of production over a relatively 

 long period of time. 



The importance of these results to the fish-oil industries of the 

 United States can not be too greatly emphasized, for it means that 

 for some of these oils, at least, a new field of usefulness, namely, that 

 of animal nutrition, has been opened. Undoubtedly, improvements 

 in the method of production of these oils would greatly reduce losses 

 of potency. 



In the cooperative program with the Bureau of Chennstry and 

 Soils, studies of the vitamin potency of fish meals and of oysters have 

 been started. . 



Arrangements have been made for practical feeding tests m which 

 various kinds of fish meals and shellfish meals are being fed in the 

 rations of dairy cows. This is a cooperative project involving 60 

 cows located on a dairy farm near Washington. These practical 

 tests are the most comprehensive of their kind ever to be conducted 

 in this country and the results should have far-reaching importance. 

 A number of outside agencies are vitally interested and are cooperating 

 in this undertaking. It is expected that the tests will be completed 

 during the coming year. 



In addition to the above-mentioned cooperative projects, the bureau 

 has under way a number of other cooperative practical feeding tests 



