514 NUTRITION OF FARM ANIMALS 



part of the feed energy is diverted to these other purposes, the 

 ration must supply more net energy per pound of milk than 

 would be necessary if all the latter were utilized for milk pro- 

 duction. 



607. Influence of plane of nutrition. It appears to be well 

 established both by common experience and by direct experi- 

 ment that such a diversion of energy from milk production to 

 other forms may in fact take place before the maximum capacity 

 of the milk glands is reached. On moderate rations, the net 

 energy, after satisfying the maintenance requirement, may 

 apparently be utilized entirely for milk production. As the 

 feed is increased, however, the animal does not continue to 

 utilize all the available net energy for milk production up to 

 the limit of its capacity and then suddenly begin to utilize any 

 surplus for fattening. On the heavier rations the concentration 

 of the digested nutrients in the body fluids increases, the organ- 

 ism reaches a higher plane of nutrition, and at a point varying 

 with different individuals this greater concentration of available 

 material causes fattening to begin, which, so to speak, robs the 

 milk glands of feed intended for milk production. 



608. Influence of individuality. The individuality of the 

 animal is a most important factor in this connection. With 

 cows having an inherited tendency toward fattening, as in the 

 so-called beef breeds, this point at which energy begins to be 

 divided between milk production and fattening may be reached 

 on comparatively light rations. Such animals can be brought 

 up to their maximum milk-producing capacity only at the 

 expense of a considerable expenditure of feed for concurrent 

 fattening and are likely to be unprofitable for dairy purposes. 

 On light rations, giving a moderate yield of milk, the mainte- 

 nance requirement constitutes too large a proportion of the feed 

 cost, while with heavier feeding production is directed too 

 largely to fattening. 



With the typical dairy animal, on the other hand, having 

 but a slight tendency to fatten, the feed may be increased well 

 towards the amount required to support the maximum capacity 

 of the milk glands, or in exceptional cases even up to that point, 

 without causing any material diversion to fattening. Such 

 animals, especially if of large milk-producing capacity, are the 

 profitable dairy animals so far as the cost of feed is concerned. 



