MILK PRODUCTION 173 



Total Nutrients. It has been shown that each pound of 

 cow's milk contains, on the average, 0*035 Ib- of protein, and 

 fat and sugar together equivalent to 0*14 Ib. of pure starch. 

 It is clear, therefore, that the milk cannot be produced 

 without loss of body weight, unless the cow receives and 

 absorbs into its system at least these amounts of nutrients in 

 addition to what is required for simple maintenance. So far, 

 however, we have no assurance that these quantities are 

 sufficient. When the matter is put to the test, it is found that 

 the quantities mentioned may serve when the yield is very 

 small ; but when it is greater, relatively larger quantities are 

 required. As the amounts of protein and non-nitrogenous 

 nutrients are to be increased correlatively, it is convenient for 

 purposes of calculation to add them together. Thus we obtain 

 ['35 ~\~' I 4= = ] ' T 75 Ib. of total nutrients, of which one- 

 fifth must be protein, as a fundamental figure. 



If the amount of food required were directly proportional 

 to the yield of milk, a cow producing 4 gallons (40 Ibs.) per 

 day would require [0*175 X 40 = ] 7 Ibs. of total digestible 

 nutrients. Experience shows that if the supply of food be 

 limited to this theoretical minimum, the yield of milk rapidly 

 diminishes, and that in order to sustain it at that level, 1 not 

 less than 10 Ibs. of total digestible nutrients are required, in 

 addition to the maintenance ration. On this basis, the amounts 

 of digestible nutrients for any yield of milk may be calculated 

 by means of the following formulae : 



/ 

 \ 



1000 



5000 5000 



N is the total amount (Ibs.) of digestible nutrients; M is 

 the yield (Ibs.) of milk ; P is the quantity (Ibs.) of protein ; 

 and C is the quantity (Ibs.) of non-nitrogenous nutrients 

 reckoned as starch. In practice, it is desirable that a certain 

 amount of the non-nitrogenous matter should be given in the 



1 That is, to prevent a decline more rapid than that due to the advance 

 in the stage of lactation. 



