FIFTY-SECOND ANNUAL CONVENTION 63 



As I mentioned this morning, two important minerals 

 in the ration of a dairy cow are calcium or lime and phos- 

 phorus. It is very easy to see why the dairy cow needs 

 especially large amounts of these two minerals, as she is 

 constantly losing the minerals from the body in the milk 

 supply. 



In addition young growing animals need fish to build 

 their skeletons. Ninety per cent of the mineral matter of 

 the bony skeleton is made up of calcium and phosphorus. 

 During the past two years very great discoveries have been 

 made with reference to the mineral requirements of live- 

 stock and especially dairy cows. One of the first experi- 

 ments to attract national attention was the experiment 

 started in 1907 and 1908 by Professor Hart and his asso- 

 ciates in our institution. I can't go into the detail of those 

 experiments. Let me just give the main points.- 



When they fed four growing heifers — and later cows 

 as they matured — rations where the roughage consisted 

 only of wheat or oats straw with no legume hay or no silage, 

 no corn whatsoever, there was nutritional disaster, even 

 when they were feeding a fairly well balanced concentrate 

 or green mixture. They were feeding a balanced ration 

 according to old feeding standards, yet disaster followed. 

 The animals became not thrifty, and furthermore when 

 they calved the calves were dead or else were produced 

 in a very weak condition. In many cases the cows aborted. 

 It was found after a considerable period of experimenta- 

 tion, that this disaster was due to a lack of lime or cal- 

 cium, and furthermore to a lack of a vitamine which was 

 deficient in that ration that animals need in order to assimi- 

 late lime and phosphorus. That is vitamine D which I did 

 not discuss this morning. 



Vitamine D or the anti-rickitic vitamine, meaning cur- 

 ing or preventing ricketts — I will discuss ricketts in just 

 a moment. In carrying on these investigations further 

 these men found that the best way of curing this situation, 

 this nutritional disaster, was by supplying legume hay in 

 that ration. If they merely substituted for half of the 

 straw the same amount of legume hay, the ration was made 



