FIFTIETH ANNUAL CONVENTION 81 



tein and a liberal amount of legume hay, there could be no 

 deficiency in calcium (lime) or in phosphorus, for legume 

 hay is rich in calcium, and protein-rich feeds are in general 

 high in phosphorus. Surprising results have, however, been 

 secured in extensive experiments at the Ohio Experiment 

 Station by Forbes, in which high producing cows have been 

 fed such excellent winter rations as alfalfa or clover hay, 

 corn silage, and corn with such high-protein concentrates 

 in addition as wheat bran, cottonseed meal, linseed meal, 

 dried distillers' grains, or gluten feed. 



On these rations the cows in most instances lost calci- 

 um, phosphorus, and also magnesium from their bodies, 

 being able to assimilate and retain so small a portion of the 

 liberal supply in their feed that it was insufficient to meet 

 the requirements in producing the milk. Even when abun- 

 dant amounts of calcium, or both calcium and phosphorus, 

 were added to the ration in such forms as steamed bone, 

 calcium carbonate, or calcium lactate (a soluble form of 

 calcium), the losses of these mineral constituents from the 

 body continued. 



The cause of this condition is still a problem. Possibly 

 the milk producing capacity of our dairy cows has been so 

 increased by selective breeding that it exceeds the ability 

 of high yielding cows to assimilate sufficient mineral nutri- 

 ents from their feed to meet the heavy demand in produc- 

 ing the large flow of milk during the first part of the lacta- 

 tion period. Later on in lactation, or when they are dry, 

 it was found that they are able to build up again the stores 

 of these mineral constituents in their bodies. 



In recent experiments at the Wisconsin Experiment 

 Station, Hart and Steenbock have found that dairy cows 

 and milk goats are able to assimilate calcium more com- 

 pletely from fresh green forage than from dried forage, 

 such as hay. This is undoubtedly due to the fact that such 

 green forage contains larger amounts of the anti-rachitic 

 vitamine, which is necessary for the assimilation of calcium 

 from the food. 



These various trials emphasize the importance of pas- 

 ture and other green forage for dairy cows during the grow- 



