MILK PRODUCTION 515 



The relations between feed supply, milk production and fatten- 

 ing outlined in the foregoing paragraphs have been clearly 

 demonstrated in a number of investigations on dairy feeding, 

 such as those of Waters, Caldwell and Weld l and of Waters 

 and Hess 2 at the Pennsylvania station, those by Woll and 

 Carlyle 3 at the Wisconsin station, and especially those by 

 Haecker 4 at the Minnesota station. 



609. Stimulation of katabolism. But while the diminish- 

 ing returns obtained from the feed of the dairy cow as its amount 

 is increased beyond a certain maximum may be explained in 

 part by a diversion of net energy from milk production to fat- 

 tening, it seems to be true also that heavier feeding may cause 

 a larger proportion of the digested organic matter to be oxidized, 

 either as the result of greater muscular activity or by a direct 

 stimulation of the katabolic processes. This is especially evident 

 in breed tests in which heavy rations have been consumed. 

 Striking illustrations of it are afforded by the results of the 

 tests of dairy breeds at the Louisiana Purchase Exposition in 

 1904 as computed by Haecker 5 and by the extensive comparisons 

 of German breeds reported by Hansen. 6 



610. Diminishing returns from feed. It is evident from 

 the foregoing that, with the possible exception of cows of a very 

 pronounced dairy type, the maximum yield of milk can be 

 secured only at the expense of a simultaneous production of 

 more or less body fat and perhaps also of a stimulation of the 

 katabolic processes of the body. Consequently, beyond the 

 point at which this fattening or stimulation begins, the milk 

 production per unit of net energy in the feed must necessarily 

 be a diminishing one, and it is clear that the determination of 

 the net energy requirements for milk production is to a consider- 

 able extent an economic problem. 



Milk will be produced at the least feed (energy) cost per 

 pound when the ration is so adjusted as to produce as great a 

 yield of milk as is possible without causing fattening. 7 If the 



1 Penna. Expt. Sta., Rpt. 1893, p. 24-36. 2 Ibid., Rpt. 1895, p. 24-55. 



3 Wis, Expt. Sta., iyth Rpt. (1900), p. 37-61. 



4 Minn. Expt. Sta., Buls. 79 and 140. 5 Minn. Expt. Sta., Bui. 106, p. 158. 

 8 Landw. Jahrb., 35 (1906), Ergzbd. IV, 147-236; 37 (1908), Ergzbd. Ill, 236- 



410; 2 er Ber. vom Dikopshof (1911), 210, 430. 



7 It may be presumed that the stimulating effect upon the katabolism occurs 

 chiefly in heavy feeding which causes fattening also. 



