1 6 MILK PRODUCTION COST ACCOUNTS 



To illustrate the application of this method, certain condi- 

 tions may be assumed: suppose that we have a herd of Guern- 

 sey cows which average i,ooo pounds in weight, that, give on 

 an average 8,500 pounds of milk per year, and that the milk 

 contains 5 per cent of butter-fat.^ The first step is to calcu- 

 late the amount of protein and energy required by the cows. 

 Assume that 20 per cent of the year's feed is secured from 

 pasture. The cows wiU no doubt be on pasture more than 

 20 per cent of the days in the year, but secure some other 

 feed a part or all of the time they are on pasture. We have 

 then to provide feed for 280 days. By referring to Tables I 

 and II we determine the following needs for cows of this sort: 



Protein. Energy. 



Maintenance 5 x 280 = 140 6 x 280 = 1,680 



8,500 pounds 



S per cent milk 062 x 8,500 = 467 36 x 8,500 = 3,060 



Total amounts needed 607 4,740 



The cows must be supplied with 607 pounds of digestible 

 protein and 4,740 therms of net energy. Now let us assume 

 that we are feeding silage and clover hay for roughage. Re- 

 ferring to the formula suggested above, we find that a 1,000- 

 pound cow would consume 6 pounds of hay and 25 pounds of 

 silage, or 1,680 pounds of hay and 7,000 poimds of silage for 

 the 280 days. By referring to Table III we find that 1,680 

 pounds of red clover hay supplies 90.89 pounds of the digest- 

 ible protein and 583.63 therms of net energy. In like manner 

 the protein and energy supplied by the silage can be computed. 



Pounds protein. Therms energy. 



Amount needed 607.00 4,740.00 



Supplied by hay. . .90.89 583.63 



Supplied by silage. 61.60 1,159.20 



Total 15249 1,742.83 



To be supplied by grain 454.51 2,997.17 



Now by turning to Table III we can select a ration that 

 has a ratio of protein to energy equal to that of the part to 



1 "Studies in Milk Production, " Woll, Wise. Exp. Sta., Research Bull. 

 No. 26, p. 74; figures from actual records of cows in contest. 



