4 BETTER DAIRY FARMING 



Thus we can understand why the dairy cow needs plenty. During 

 the period of heaviest milk production she does not seem to be 

 able to assimilate enough lime and phosphorus out of her feed. 

 On the other hand some of these minerals which she secretes in her 

 milk she takes out of her bones. This has been observed to occur 

 even where legume roughage and mineral supplements are fed. 

 Toward the end of the lactation period, and particularly while 

 dry, the minerals removed from the bones are restored, provided 

 of course that the feed contains them in a form the cow can use. 

 Sudden falling off of cows in production after a good start in a 

 lactation period may be caused by failure to build up the mineral 

 reserves during the dry period. There is evidence that certain 

 breeding troubles have a similar cause. How then may these min- 

 eral reserves best be built up? 



The first consideration is feeds rich in the minerals in question. 

 A good grain mixture will supply ample phosphorus. Legume hay 

 is rich in lime. Where these feeds are liberally fed, the mineral 

 needs may be taken care of as well as we know how to at present. 

 There are some recent experiments, however, that may have a 

 great practical bearing in this connection. 



13. Lime and phosphorus important.— Adequate mineral 

 nutrition is not simply a case of supplying adequate amounts in 

 the feed. There seems to be a limit to the lime and phosphorus 

 that a dairy cow can assimilate from her feed no matter how much 

 may be supplied. Recently it has been found that there is some- 

 thing, probably a vitamine, in green feed and in leafy roughage 

 cured in a certain way that aids in lime assimilation. In fact, it 

 has been shown that during the heavy lactation, when lime and 

 phosphorus are ordinarily taken out of the bones, this can be pre- 

 vented by the use of the feeds mentioned. This means that the 

 cow on pasture should more readily build up her reserves. The 

 method of curing the leafy roughage so as to preserve this factor 

 responsible for lime assimilation has not been definitely worked 

 out but it may not be long before we will know just how to do it 

 and thus have a feed which will assure adequate mineral assimila- 

 tion at all times. It is evident from work done to date that curing 



