MINERAL MATTER FOR DAIRY COWS 



By J. B. LINDSEY and J. G. ARCHIBALD 



IXTRODUCTIOX 



It is a well-known fact that all animals require a certain amount of mineral 

 matter in their diet. The fondness of all classes of stock for common salt is 

 so well known that mention of it seems almost superfluous. The sight of a 

 cow chewing a bone or an old shoe, licking the earth, or gnawing at a fence 

 rail is familiar to anyone who has ever lived on a farm. 



Until recent years, however, comparatively little attention has been paid to 

 these outward evidences of mineral hunger, because of the belief that the feeds 

 commonly fed to cows contained sufficient mineral matter (common salt ex- 

 cepted) for their needs. Gradually it has come to be realized that such is not 

 always the case and that shortage of available mineral matter, under certain 

 circumstances, may be a limiting factor in growth and production. The situa- 

 tion has been well summed up by the late Professor Armsby, who said: "Most 

 feeding stuffs, and particularly the mixed rations of farm animals, contain 

 what appear at first sight to be much larger amounts of ash ingredients than 



the body requires This is doubtless true of animals living in a state 



of nature, but it is a questionable assumption under the artificial conditions 

 to which many farm animals are subjected." 



This point of view has become prevalent only within the past decade. Its 

 establishment on a firm basis of fact has been due, in large measure, to the 

 work done in recent years at certain of the experiment stations in this country. 

 For example, it has been shown that in spite of liberal feeding, heavy milking 

 cows excrete daily more mineral matter, particularly calcium and phosphorus, 

 than they consume, or are in what is termed negative mineral balance, and it 

 is only when they reach the advanced stages of lactation (10 pounds of milk 

 daily) that the reverse is true; that is, that they consutne more minerals than 

 they give out. There is, however, no record of prolonged experiments on the 

 effect of feeding mineral supplements to milking cows to help out a mineral 

 deficiency. Realizing the dearth of such information and its importance, this 

 department instituted sucli an experiment in the autumn of 1921, which, modi- 

 fied from time to time to meet changing conditions in the station herd, is 

 still in progress. This paper is a brief report of the work up to October 

 1, 1925. 



Plan of the Experiment 



The main features of the experiment have been: 



1. Feeding the whole herd a ration deficient according to prevailing stand- 

 ards in calcium and phosphorus but adequate in all other respects. 



2. Division of the herd into halves as nearly alike as possible, and the 

 addition to the grain ration of one group, of supplemental calcium and phos- 

 phorus in the form of special steamed hone meal containing but little animal 

 matter. 



