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The lack of iodine, a common element of sea water, is the cause of goiter 

 and other glandular troubles, both in animals and human beings. This iodine 

 deficiency can be remedied through the use of sea foods or the addition of 

 very small amounts of iodine to common salt, a universal condiment; in fact, 

 the presence of a trace of iodine in commercial salt is required by statute in 

 certain states where goiter is epidemic. It is not believed that the addition of 

 iodine to purchased foods or feeds is necessary along our Atlantic seaboard. 



The vitamins have probably attracted more attention in feeding science during 

 recent years than any other single problem of nutrition. While much informa- 

 tion has been obtained, our knowledge of vitamins is still slight and much 

 remains to be done. At the present time the exact chemical composition of 

 vitamins is not known. For some time the value of cod liver oil as a source 

 of the growth producing vitamin A and the antirachitic vitamin D, which pre- 

 vents leg weakness in growing chicks, has received especial emphasis. As a 

 result the Experiment Station is frequently requested to determine the relative 

 value of ditferent oils in vitamin content. A method for determining the vita- 

 min A value of cod liver oil has been approved and given a place in the United 

 States Pharmacopoeia. The index of comparison is the growth produced on 

 young albino rats, previously fed vitamin A free ration, by the feeding over 

 a stated time of the cod liver oil to be tested. The remainder of the ration 

 is vitamin A free. There is no standard method for determining relative 

 vitamin D value. The cost of equii:»ping and maintaining a biological labora- 

 tory for this work is so great that the Experiment Station has not as yet 

 thought it wise to establish such a laboratory. It is suggested that pqultrymen 

 confine their purchase of cod liver oil to reputable manufacturers who test and 

 guarantee their product. 



Feeders should not lose sight of the fact that the basic principles of good 

 feeding practice have not been changed by our more recent knowledge of nutri- 

 tion. Our newer knowledge merely elaborates without detracting from the fact 

 that animals should have the proper proportions of carbohydrates, protein and 

 fat in the rations fed, as laid down by earlier investigators who knew nothing 

 of vitamins, ash deficiency, or the difference in proteins derived from different 

 sources. 



