FISHERY INDUSTRIES OF THE UNITED STATES, 1938 213 
red snapper, chum salmon, king salmon, silver salmon, shad, sque- 
-teague, hard clam, blue crab, oyster, and shrimp. Tryptophane was 
determined in the proteins of 28 species as follows: Catfish, cod, croaker 
haddock, halibut, lake herring, sea herring lake trout, Boston mack- 
erel, Spanish mackerel, mullet, pilchard, red snapper, chum salmon, 
king salmon, pink salmon, silver salmon, sockeye salmon, shad, sque- 
teague, albacore tuna, bluefin tuna, bonito, skipjack, hard clam, blue 
crab, oyster, and shrimp. Cystine was determined in the proteins of 
the following 13 species: Cod, croaker, haddock, halibut, Boston mack- 
erel, Spanish mackerel, mullet, red snapper, king salmon, pink salmon, 
silver salmon, shad, and shrimp. 
VITAMIN CONTENT OF FISHERY PRODUCTS 
The only work done on this subject in 1938 was a series of assays 
of the vitamin D content of experimentally prepared fish-liver oils for- 
warded by our Seattle laboratory, in connection with its byproducts 
studies, to our nutrition laboratory at College Park. These determi- 
nations were used as a method of evaluating various methods of han- 
dling and extracting fish livers and are discussed in Investigational 
Report No. 40, entitled “Pacific Salmon Oils,’”’ previously discussed 
in this report. 
SODIUM ALGINATE AS A STABILIZER IN PRODUCTS OF THE DAIRY INDUSTRY 
Sodium alginate is a very useful preparation produced from the 
giant kelp (Macrocystis pyrifera) harvested from waters on the Pacific 
coast. It is used extensively as a stabilizer in such dairy products as 
chocolate milk, ice cream, etc. The results have been very satisfactory 
to the dairy industry from the mechanical standpoint, but regulatory 
authorities have expressed a desire to learn whether sodium alginate 
has any toxic properties. Accordingly, two commercial samples of 
sodium alginate were used in feeding tests with experimental animals 
and were tested in the diet in percentages much higher than would be 
used as a stabilizer in dairy products. The results of these experiments 
showed no indications whatsoever of any toxicity of the sodium algin- 
ate. The detailed conclusions of this study have been assembled in 
a report. 
KELP MEAL IN ANIMAL FEEDING 
This project was inaugurated several years ago by the Dairy Depart- 
ment of the University of Maryland and of the Maryland State Agri- 
cultural Experiment Station at College Park, Md., in cooperation with 
our technologists, to determine whether kelp meal, as a mineral sup- 
plement, had value in improving reproduction in dairy cattle. The 
tests thus far have been conducted with heifers and the prelimimary 
results have been very encouraging. The study is being continued 
with producing or lactating dairy cows on a more extensive scale and 
it is hoped that information of considerable interest and benefit to 
the dairy industry will result from these experiments. Tests of this 
kind with large farm animals, such as dairy cows, require several years 
for the production of conclusive results. However, quite definite im- 
provement in the reproductive record of the animals fed kelp meal 
has resulted thus far. 
