FIFTY-SECOND ANNUAL CONVENTION 65 



ducing capacity to a much greater extent than we have 

 developed her mineral-assimilating capacity. We haven't 

 known anything about minerals until the last few years, 

 in their relation to dairy production. In other words there 

 is no question in my mind but what a good share of the 

 good producing dairy cows during the winter time and in 

 the full flow of production are steadily losing calcium and 

 perhaps also phosphorus from their bodies; and probably 

 even by the use of any miner-al supplicant we can add to 

 the ration, we cannot cure or prevent it, judging from these 

 results, unless we use impracticable rations. 



We might ask, why doesn't the cow finally fade away, 

 because the cow in the attempt to keep the composition of 

 her milk constant, her force of maternity makes her take 

 the calcium and phosphorus from her bones to produce a 

 normal milk for her offspring and for our offspring. 



So far as we know the situation, based upon the fur- 

 ther experiments of Dr. Forbes, when a cow gets along 

 further in lactation, when she is producing less milk and 

 especially when she is drying, then she is able to build 

 again the calcium and the phosphorus stores of her body, 

 because then there is not the heavy drain for calcium and 

 phosphorus that there is in the production of a large 

 amount of milk, thirty and forty pounds and beyond. Fur- 

 thermore, it is essential that all possible advantage be given 

 the cow by producing an adequate ration so that she will 

 lose as small an amount of mineral as may be during the 

 heavy part of her lacteal period. 



The experiments of Dr. Forbes and others have shown 

 very clearly that if the cow is fed timothy hay you will 

 have a much more serious condition than if fed with an 

 abundance of legume hay, therefore do the best you can 

 for the cow by supplying an abundance of legume hay. 



Now just a little about vitamine D and its relation to 

 mineral assimilation. First, after vitamines A, B, and C 

 had been discovered, people were in a quandary with ref- 

 erence to certain points. For many years the disease called 

 ricketts had been known, in fact for twenty-five years and 

 over, but until 1918 there had been practically no advance 

 in the knowledge with reference to ricketts. Ricketts is a 



