24 CONTROL BULLETIN NO. 157 



FEEDING OILS, FEED SUPPLEMENTS, AND 

 VITAMIN MIXTURES 



Unlike the mixed feed manufacturers, who generally have considerable control 

 over the handling of their products by dealers, the manufacturers of feeding oils 

 and dry vitamin supplements usually relinquish all control over their products 

 once they are delivered to the mixed feed manufacturer. It has been found that 

 in some instances feeding oils were still being used more than two years after de- 

 livery. Obviously, the manufacturer, under such circumstances, cannot be held 

 responsible if the oil is found to be below the guaranteed vitamin potency. 



Recognizing this fact, the Control Service is pulilishing the date of delivery 

 and the date of sampling for all vitamin feeding oils and dry vitamin concentrates. 

 Also, although the Control Service inspector made every effort to make sure that 

 the sample taken was the one described by the label on the container, it is possible 

 that in some cases the original container may have been refilled with another lot 

 of oil. Seeking to determine the vitamin A potency of the oil actually being used 

 at the time of sampling, the Control Service had no alternative but to sample opened 

 containers. At some small plants the opened container was the only one available 

 for sampling. 



The samples of dry concentrates were taken from either previously unopened 

 packages or from those just opened for use in mixing operations. 



The reader should bear in mind that most of the dry vitamin concentrates also 

 carry guarantees of vitamins other than those reported in the table. More emphasis 

 has been placed on the determination of vitamin A because this vitamin and ribo- 

 flavin, to a lesser extent, are more easily destroyed under the usual storage condi- 

 tions than are the other vitamins. In some cases the cost of the guaranteed vitamin 

 A content represents only a fraction of the total cost of the product analyzed. 



