INSPECTION OF COMMERCIAL FEEDSTUFFS 



21 



For dogs it is generally conceded that 2,000 U.S. P. units of vitamin A per 

 pound furnish an adequate amount. 



Vitamin A is one of the least stable vitamins. The problem of providing 

 amounts of this vitamin that will be nutritionally sufficient in a mixed feed when 

 fed has been a serious one. Recent developments in the coating of vitamin A 

 particles with such materials as microcrystalline wax, pectin, and gelatin indicate 

 that a solution of the problem may be at hand. This does not mean that feeds may 

 now be stored indefinitely without loss of vitamin A and other factors that are im- 

 paired by long periods of storage. 



It is realized that chemical, microbiological, and other laboratory tests on 

 feeds, at present, can tell only a partial story about the nutritive value of a feed. 

 For this reason most large feed manufacturers maintain research farms where 

 their feeds are tested by actual feeding trials. Probably most of these experiments 

 are made with fresh feed. 



It is difficult, if not impossible, for most manufacturers to maintain the rigid 

 control necessary to insure that their products will always be fresh when delivered 

 to the farmer. Therefore, it might be well for all manufacturers periodically to 

 recall sample lots of their feed from dealers for feeding trials on the research farms. 

 The sample lots could represent monthly intervals after manufacture up to the 

 maximum number of months that any particular manufacturer's feeds are found 

 still in the dealer's hands. The feeding tests would show what factors should be 

 either added in greater quantity or better safeguarded in mixtures so that their 

 potency will still be fully effective after the maximum storage periods. 



Vitamin A in Mixed Feeds 



