242 BETTER DAIRY FARMING 



production slightly but that it may not be economical to do so 

 where feed prices, particularly for protein-rich feeds, are high. 

 Feeding standards are used for computing rations. 



442. Computing a dairy ration. — Suppose it is desired to 

 compute a ration for a 1200-pound cow producing 30 pounds of 

 milk testing 3.5 per cent fat, using those feeds which at current 

 prices will give the cheapest ration and still be satisfactory in other 

 respects. For maintenance the cow will require 1.2 times the 

 requirements for a 1000-pound cow given in Table II. For her 

 production requirements we will use an average of the limits set 

 in the table. For one pound of 3.5 per cent milk this would be 

 0.055 pounds digestible protein and 0.30 pounds total digestible 

 nutrients. For 30 pounds it would be 30 times as much. The cow's 

 requirements would thus be as follows: 



For maintenance 



For 30 lbs. of 3.5% milk 



Totals 2.49 18.510 



The above shows the nutrients the cow must have in a day's 

 ration. Suppose there are red clover hay and silage available on 

 the farm. To obtain the proper variety at least three concentrates 

 must be bought. The next thing to do is to find out from the feed 

 dealer the current prices of various feeds and compute their relative 

 cost in terms of total digestible nutrients. The latter can be 

 obtained for a given feed by multiplying the total digestible nutri- 

 ents in 100 pounds, as given in Table I, by 20 and dividing the 

 result into the price per ton. This result, the cost per pound 

 T.D.N., multiplied by 100 gives cost per 100 pounds T.D.N. 

 This is illustrated below for hominy: 



$38.05 



X100 = $2.25 



84.6X20 

 Suppose the following feeds are available at the prices named: 



