20 Bulletin 81 



3. calculation of a feeding ration 



Let it be assumed for the illustration that a farmer has a cow weighing 

 about 900 pounds and giving about 30 pounds of milk a day, to which he 

 wishes to feed a ration balanced according to the Wolff- Leh man n standard; 

 that he has hay (timothy, Kentucky bluegrass, clover, etc., essentially 

 • 'mixed grasses"), fairly mature corn silage, bran and cob meal ; and that 

 he can buy cottonseed meal, Chicago gluten meal, Quaker dairy feed,mixed 

 (wheat) feed, Buffalo gluten feed and hominy chops. How shall he pro- 

 ceed to figure out his ration ? Reference to the standard shows that 

 the 1,000 pound cow should be fed 32 pounds of dry matter, 3.3 pounds 

 protein, 13 pounds carbohydrates and 0.8 pounds ether extract, nutritive 

 ratio, 1:4.5. The ether extract figures are multiplied by 2.25 ' and added 

 to those of the carbohydrates ; and then all the figures are multiplied by 

 nine-tenths. This latter is done because a 900 pound cow weighs nine- 

 tenths what a 1,000 pound cow does, and is held, according to the standard, 

 to need approximately but nine-tenths the nutrition. As a matter of fact 

 she probably needs a little more than this. 

 0.8x2.25=1.8. 13+1.8=14.8. 32.0x .9=28.8. 3.3x.9=2.97. 14.8x .9=13.3. 



The Wolff-Lehmann standard for a 900 pound cow giving 30 pounds 

 milk, therefore, requires that the daily food shall contain 28.8 pounds total 

 dry matter, 2.97 pounds digestible protein, 13.3 pounds digestible carbo- 

 hydrates and ether extract ; and, if this is fed, the nutritive ratio will be 

 1:4.5. 



The next step is to supply these nutrients. The convenience table 

 (pages 50-56) shows that of the feeds on hand bran alone has a nutritive 

 ratio (1:3.8) narrower than the standard. The hay, silage and cob meal 

 have "wide" ratios, (1:10.0, 1:14.8, 1:13.9), all wider than the standard. 

 Hence purchases must be made ; and these must be of goods with narrow 

 ratios. The materials available are found to have ratios as follows from nar- 

 rowest to widest : cottonseed meal, 1:1.0; Chicago gluten meal, 1:1.5; Buffalo 

 gluten feed, 1:2.4; mixed (wheat) feed, 1:3.9; Quaker dairy feed, 1:4.6; and 

 hominy chop 1 :9.2. It is at once perfectly clear that the latter two feeds will 

 not aid in balancing the ration and that the mixed (wheat) feed will not 

 be of much avail. Hence choice should be made of one or more of the first 

 three according to price and other considerations. Let us assume that the 

 cottonseed and Buffalo goods be chosen and proceed to figure our ration. 



It is generally desirable to make as large use of roughages as possible 

 because of their cheapness. The amounts which can be consumed varies 

 with different animals. In dairy feeding, however, more than half and 

 often as much as two-thirds of the total dry matter should be given in the 

 form of roughage. 



i To reduce ether extract to the same food value and — assumedly— feeding value as^the 

 carbohydrates. 



