Substitution of Roots for Concentrated Foods. 479 



by 5027.9 pounds of dry matter in mangels, with a gain of 32.38 pounds 

 of fat. At- the same time, 529.8 pounds less dry matter was fed with 

 the mangels. This would seem to show conclusively that one pound 

 of dry matter in mangels is equal to at least 1.05 pounds of dry matter 

 in silage. In eight of the 17 cases, the mangels were fed during a period 

 farther along in the lactation period of the cow than when the silage 

 was fed, so this factor is of equal value to either food. 



As a further evidence of the value of a pound of dry matter in mangels, 

 the production of the different groups of cows has been plotted graph- 

 ically on Plates I and II, and the periods of feeding the different rations 

 have been marked on the plates. The solid black line represents the 

 pounds of milk, and the broken line the pounds of butter fat per week. 

 In all cases, except on Plate I where Group C was fed ration II, the 

 production has remained on a par with the production of the check 

 group. In the case of Group C, Plate I, the fall in production was due 

 not so much to the value of the ration as to the fact that one of the 

 cows, Zelma, was off her feed and did not consume so much dry matter. 



By studying Tables XXI and XXII it can be seen that 20.93 pounds 

 of total dry matter and 7.57 pounds of dry matter in the grain produced 

 one pound of buttjr fat when mangels was fed, as against 22.34 pounds 

 of total dry matter and 8.46 pounds of dry matter in the grain when 

 silage was fed. The amount of dry matter with Check Group A for both 

 years was 22.05 pounds total and 8.33 pounds in the grain for one pound 

 of butter fat. 



Cost of one pound of butter fat. When the cost of production of mangels 

 and of silage was taken into account, however, it was found that while a 

 pound of dry matter in mangels was worth more in the production of 

 butter fat than a pound of dry matter in silage, yet the cost of a pound 

 of dry matter was so much more in mangels than in silage that the cost 

 of a pound of fat when mangels were fed was more than when silage 

 was fed. 



Table XXIV has been prepared from Tables VII, XIV, XV, and XVI. 

 In this table, as in Table XXIII, 17 comparisons are possible. The 

 average cost of production of one pound of fat when silage was fed, 

 was 21.2 cents per pound. When mangels were fed, the cost of a pound 

 of butter fat was 27.9 cents. This shows that mangels cannot be fed 

 economically as a succulent food when silage can be had. 



