374 EXPERIMENT STATION RECORD. [Vol. 40 



The complete analytical results, with special reference to the paths of outgo, 

 are given in 16 tables, each cow being treated separately. 



" The most important fact developed by these data is that, irrespective of 

 conditions and in spite of large intake of calcium, this element was eliminated 

 in quantities greater than were contained in the feed. There is but slight 

 evidence that the precipitated bone flour was utilized and no evidence that 

 the calcium lactate or the calcium chlorid was utilized. There is no evidence, 

 therefore, that the limited utilization of calcium by milk-producing cows Is 

 due to the limited solubility of the calcium compounds of the ration. It is 

 worthy of note, also, that the cows were markedly Irresponsive to the intake 

 of magnesium and phosphorus with which calcium is combined in the skele- 

 ton, and that the balances for these elements remained almost invariabh 

 negative in spite of the presence in the rat inns of amounts of the same very 

 much greater than were utilized. The fact thai the heavily-milking cow lo~ 

 calcium at t lie same time that she receives a readily assimilable supply greatly 

 in excess of the amount utilized shows that the calcium stores of the body 

 (the skeletal stores) are more readily accessible for use in milk production 

 than is the calcium of the ration. The cow can store fat and protein in con- 

 siderable quantities in spite of heavy milk production, but her capacity to 

 assimilate mineral matter, especially calcium, appears to be of a distinctly 

 lower and more definitely limited order, . . . 



"In general, the differences in the utilization <>f the mineral nutrients caused 

 by changes in the rat inn were in harmony with the nature of the change; that 



is. an increase in the intake <.f an element was usually followed by an Increased 

 storage or decreased loss of this nutrient, but the response was usually so 

 Sllghl in Comparison with the extent of the change of intake that it became 



apparent that the mineral metabolism of the well-fed, heavily-milking cow Is 

 not Intimately and directly dependent upon the mineral nutrients of the ratlin, 

 but that its character is determined under normal conditions, first, by the 



Inherited impulse to secrete milk. BeCOBd, by the mineral nutrient i - of 



the animal body, and only third by the food supply." 



Both sulphur and nitrogen, which are consumed almost wholly in chemical 



combinations in the protein of the ration, had negative balances in period L 



In the second period there was a marked increase in the Intake of both. nitTO 

 gen balances becoming positive and the sulphur balances, although reduced. 

 remaining negative, In these rations, therefore, an amount of protein sullicient 

 to provide for nitrogen Btorage failed to furnish enough sulphur to maintain 

 equilibrium of this element. 



In part 2 of this bulletin the authors discus-; results of the three years' 

 experimental work. The importance of leguminous fr^\ and the possibility 

 that sterility of high milk producing COWS may he due to disturbances in 

 mineral metabolism are auain emphasized. 



[Pasture grass for dairy cattle on the Belle Fourche Reclamation Project 

 experiment farm], B. Auxe (£7. S. Dcpt. A<jr.. Bur. Plant Indus., Work Belli 

 Fourche Expt. Farm. 1911. pp. 21-2!,. tip. n . The economical feeding of dairy 

 stock on reclamation projects involves the use of grass pasture. These irri- 

 gated pastures are of a permanent nature and while the first cost is somewhat 

 high, the subsequent expense is not great. Notes are given on the carrying 

 capacity of several mixtures. 



Four mixtures were seeded in 1915 and pastured with two cows in 1916 and 

 1917. Three of these were rather elaborate, consisting of from 11 to 14 kinds 

 of grasses. The fourth, composed of 20 lbs. of brome grass, 112 lbs. of slender 

 wheat grass, and 3 lbs. of alfalfa per acre, maintained the cows somewhat 

 longer than the others during the first year and much longer in the second. 



