FISH MEAL IN ANIMAL FEEDING 395 



bonate, 1 part of salt, and skimmed milk ad libitum. To the basal 

 ration was added in the various <^i'oups ultra-violet light, cod-liver 

 oil, and cod-liver meal in amounts varying from 1 to 10 pei- cent. 

 In testing the vitamin A content 10 groups of chicks were fed a basal 

 ration of 92 parts of white corn, 5 parts of yeast, 2 parts of calcium 

 carbonate, 1 ])art of salt, and skim milk ad libitum. To the basal 

 ration in the various groups were added ultra-violet light irradiation, 

 cod-liver oil, and cod-liver meal in amounts varying from 1 to 10 

 per cent, and cod-liver meal and ultra-violet light in combination. 



The chicks in the hrst phase of the experiment were killed for 

 post-mortem examination. The tibia w^as dissected out and soaked 

 in formalin and a longitudinal section from the proximal end treated 

 with 1.5 per cent of silver nitrate and exposed to light. Ash analyses 

 were also made of the bones. In the group receiving the basal ration 

 the ash content of the tibia varied from 33 to 37 per cent, while in 

 all other groups the ash content ranged from 46 to 52 per cent. The 

 silver nitrate test showed good calcification in all groups save the 

 check, where there was a wide uncalcified area of proliferating 

 cartilage. 



It was found that even 10 per cent of the cod-liver meal used in 

 the experiment did not furnish sufficient vitamin A to protect against 

 a deficiency in this respect, although chicks receiving this amount 

 survived longer and did not sliow pathological symptoms in such a 

 marked degree as those receiving less meal. It is concluded that the 

 cod-liver meal used contains sufficient vitamin D to promote good 

 calcification even when fed at a level of 1 per cent, but not enough 

 vitamin A to protect birds from vitamin A deficiency even when fed 

 at a 10 per cent level. 



These results are verified by Hart, Steenbock, Kletzien, Scott, Hal- 

 pin, and Johnson, in their poultry experiments at the AVisconsin 

 Agricultural Experiment Station as shown herewith : " It has been 

 demonstrated that cod-liver meal is an effective source of vitamin D 

 but not of A. A ration containing 1 per cent of this product was 

 sufficient to prevent leg weakness in chicks, but did not prevent the 

 common symptoms of vitamin A deficiencies." 



Unfortunately we possess far too meager a store of knowledge 

 concerning the vitamin potency of fish meal and related marine 

 products, except in the case of cod-liver oil where considerable scien- 

 tific information is available as summarized by Manning (1929b). 

 Needless to say, if a corresponding amount of scientific research had 

 been expended on fish meal or other related marine products, suitable 

 for the dietary of man and beast, as has been completed on cod-liver 

 oil, our knowledge of the science of nutrition would be much ad- 

 vanced. It is only to be hoped that the future will provide such data. 



COMPOSITION OF FISH MEALS 



The composition of a fish meal is obviously of primary importance, 

 as its composition determines its quality and its actual and relative 

 feeding value. Fish meals vary considerably in composition, depend- 

 ing on the kind and freshness of the raw material from which they 

 are manufactured, as well as the methods or processes of manufac- 

 ture. Inasmuch as this subject was dealt with at length in the intro- 

 duction to this manuscript, brief treatment will be given it here. 



