the necessary proteins and mineral substances, but lacks filler substance. This lack can 

 be compensated by suitable additions. Carps are at times fed with blood vrtiich has been 

 cooked and put through the meat chopper. In this way food quotients of about 3 are said 

 to have been achieved. From other sources it is suggested to completely absorb the blood 

 in bran. This mixture is said to be durable when pressed into barrels. 



Dehydrated Spleen has very recently appeared on the market at acceptable prices ($^+.11 

 per 100 pounds, fresh spleen $/V.33 in 1932), and it has been tested by Probst on its appli- 

 cability in trout growing. From this it was found that brood which was fed half and half 

 fresh and dried spleen thrived as well as those fed only with fresh spleen. Rearing only 

 with dried spleen failed. But in the mast equally good results were achieved as with sea 

 fish, and with almost equal costs. It is to be noted, however, that Probst is reckoning 

 fresh spleen very high, at $9.7^ per 100 pounds. The food quotient for a food, consist- 

 ing- of 80 percent dried spleen, 12 percent sawdust, i^ percent rye flour, U percent wheat 

 bran amoimted to 7, but by miscalculation of losses only 5.1. 



Blood Flour is made by drying and grinding the blood of slaughtered anijnals. It is 

 to be used like meat flour. Overheated, blackish flours occur frequently but should be 

 rejected for trout growing, on account of indigestibility, 



Blood-Yeast was introduced into trout feeding by Johansen, It consists of a mixture 

 of beer yeast and blood. In manufacturing the dry preparation, ten$)eratures up to 100 "C 

 are used only, so that the protein is not made indigestible as in the case of other dry 

 flours. On account of the low price (1930, $6,27 per 100 pounds) it is used to stretch 

 spleen. Larger additions to the masting food do not pay, 



Cxird is a relatively one-sided food, and also does not contain all of the "building 

 stones" of protein. Besides it is very poor in iron and in vitamins, A one-sided feed- 

 ing with curd leads ve:y quickly to blood impoverishment. Many remote fisheries are 

 dependent upon curd feeding to trout brood. In such cases, it is advisable to improve 

 the food by admixture of blood, spleen, raw eggs, natural food and other substances. If 

 possible the giving of curd should be avoided at least during the first six to eight 

 weeks of the brood feeding. The food quotient is given as about 10 to 15. With carps, 

 a food quotient of 2.8 was achieved by Klee. Curd is today too expensive as carp food. 



Occasionally, other milk products, like centrifuge slime and dried skim milk come 

 into consideration, if only they are cheap enough and do not have too high a fat content 

 (often over 25 percent). 



Poultry Egp.s are occasionally mixed raw with the brood fodder of trout, and serve 

 to in?)rove the quality of the proteins in the fodder. 



Shrimps , Dried shrimps, also erroneously called crabs, shrimp grist and shrimp 

 flour are valuable addition food, rich in mineral and protein, for fresh trout food- 

 stuffs (fish, meat). They are, however, not exactly cheap (1930, $-i,98 per 100 pounds) 

 and have therefore been more and more crowded out of trout feeding by other foodstuffs. 

 Lately in fisheries near the coast, fresh shrimp form a very excellent food (1930, $5.19 

 per 100 pounds) for spawning trout. Unfortunately the shrimps can only be kept one or 

 two days and can be shipped only short distances. Shrimps form one of the few abundant 

 foods closely approaching the natural nutrition of trout and v;hich can be fed canpletely, 

 viscera and all. Fresh shrimps are available principally in the summer and autumn from 

 August to Septentoer. There are fisheries, for which a coast fisherman exclusively catches 

 shrimps at this time. According to Roehler (1928), Riggert announced a food quotient of 

 U for shrimps. According to Heiderich the catch of shrimps, also called crab gammel, 

 took a perceptible upturn after the war due to the introduction of drying. Air drying 

 has only been preserved in small individual enterprises, which in the interest of trout 

 growing, is very regrettable. The crab gaimnel (shrimps), after separating the food 

 crabs, is cooked, (often on board the ship on account of easy spoilage), treated with 

 steam and dried with cold and hot air (180-200"'C), The weight shrinks about 23 percent. 

 Naturally in the strong heating the protein becomes difficult of digestion, vitamins 

 are destroyed. 



U2 



