STUDIES IN MINERAL NUTRITION 



By J. B. Lindsey, Research Professor, and J. G. Archibald, Assistant 

 Research Professor, of Chemistry^ 



Part I. MINERAL SUPPLEMENTS FOR DAIRY COWS 



This bulletin is the final report on six and one-half years' investigation on the 

 feeding of mineral matter to dairy cows. Three progress reports^ have already 

 appeared and to these the reader is referred for detailed conclusions up to the time 

 these reports were published. The results previously reported were obtained from 

 a study of the feeding of tricalcium phosphate in the form of steamed bone meal 

 specially prepared for animal feeding. In brief, the conclusion reached was that 

 the benefit received from adding steamed bone meal to the ration of dairy cows 

 under conditions existent in New England is very shght. 



For the past two years (1926-1928) the mineral supplement fed has consisted 

 of a mixture of dicalcium phosphate, sometimes called precipitated bone, and 

 calcium carbonate or limestone, in the respective proportions of four to one. 



It has been shown that lambs and goats assimilate dicalcium phosphate con- 

 siderably better than they do tricalcium phosphate in the form of steamed or 

 calcined bone. It was thought worth while therefore to give the dicalcium 



phosphate a trial. 



Method of Experimentation 



The variation from the experimental procedure described in our previous 

 reports, other than the substitution of the dicalcium phosphate for the tricalcium 

 has been a- further impoverishment of the mineral content of the basal ration. 

 This has been done by substituting for a portion of the hay larger amounts of dried 

 apple pomace which is quite low in mineral matter. The maximum amount of 

 pomace fed daily to any one cow has been seven pounds. The amount of calcium 

 carbonate fed (1 part in 5 of the mixture) was added to maintain the same ratio 

 between calcium and phosphorus that existed when the steamed bone was fed. 



At the commencement of the experiment with dicalcium phosphate (precipitated 

 bone), the herd consisted of 10 milking Holstein cows, 2 milking Jersey cows, 3 

 Holstein heifers and 1 Jersey heifer. At the conclusion, some old cows having 

 been sold and some heifers having freshened, there were 10 milking Holsteins, 

 3 milking Jerseys and no heifers. The animals were well housed and received 

 good care, and except in bad weather were turned daily into adjacent sheltered 

 yards for exercise and sunlight. The cows were barn fed during the entire year; 

 the young stock were turned to pasture from approximately May 20 to October 15. 



The entire herd was fed on a basal ration of first-cut hay, dried apple pomace 

 and a grain mixture during the entire period of observation except during the 

 summer months, when, in addition, non-leguminous green material in the form 

 of oats, millet and corn was fed in amounts not exceeding 25 pounds daily to any 

 one animal. 



1 The work at the station barn was carried out by J. R. Alcock, whose faithful attention to 

 his duties contributed to the success of these experiments. A. W. Magoon assisted Mr. Alcock 

 during the latter part of the experiments. 



2 The Value of Calcium Phosphate as a Supplement to the Ration of Dairy Cows. Jour. Agr. 

 Research. Vol. XXXI, pp. 771-791. October 15th, 1925. 



Mineral Matter for Dairy Cows. Mass. Agr. Expt. Station Bulletin No. 230. April, 1926. 



Mineral Supplements for Dairy Cows. Paper read at the Annual Meeting of the American 

 Society of Animal Production, Chicago, November 26, 1926. Abstracted in Proceedings of that 

 Society for 1926. 



