318 THE ROTHAMSTED EXPERIMENTS. 



Food con- The first column shows, that the amount of total dry sub- 

 5oooaT r stance of fo °d actually consumed by the herd, per 1000 lb. 

 live-weight, live-weight, per day, was scarcely 20 lb., whilst "Wolff's x 

 estimated requirement, as stated at the foot of the table, is 

 24 lb. But his ration would doubtless consist in larger pro- 

 portion of hay and straw-chaff, containing a larger proportion 

 of indigestible and effete woody-fibre. The figures show, in- 

 deed, that the Rothamsted ration supplied, though nearly 

 the same, even a somewhat less amount of total digestible 

 constituents than Wolff's. 

 Consump- Of digestible nitrogenous substance, the food supplied 

 Nitrogenous ^-64 lb. per day, whilst the amount estimated to be required 

 matter for for sustenance merely is 0.57 lb. ; leaving, therefore, 2.07 lb. 

 aUdZuk- availa Me for milk-production. The 23.3 lb. of milk yielded 

 -production, per 1000 lb. live-weight per day would, however, contain 

 only 0.85 lb. ; and there would thus remain an apparent 

 excess of 1.22 lb. of digestible nitrogenous substance in the 

 food supplied. But, against the amount of 2.64 lb. actually 

 Wolfs Consumed, Wolff's estimate of the amount required for sus- 

 tenance and for milk-production is 2.5 lb., or but little less 

 than the amount actually consumed at Rothamsted. On the 

 assumption that the expenditure of nitrogenous substance 

 in the production of milk is only in the formation of the 

 nitrogenous substances of the milk, there would appear to 

 have been a considerable excess given in the food. 

 is milk-fat But Wolffs estimate assumes no excess of supply, and 

 d fromti- that tne wn °l e is utilised ; the fact being that he supposes 

 buminoids the butter-fat of the milk to have been derived largely, if not 

 7rates b °or~ w h°Uy> from the albuminoids of the food. 

 both?' It has been shown that although it is possible that some 



of the fat of a fattening animal may be produced from the 

 albuminoids of the food, certainly the greater part of it, if 

 not the whole, is derived from the carbohydrates. But the 

 physiological conditions of the production of milk are so 

 different from those for the production of fattening increase, 

 that it is not admissible to judge of the sources of the fat of 

 the one from what may be established in regard to the other. 

 It has been assumed, however, by those who maintain that 

 the fat of the fattening animal was formed from albuminoids, 

 that the fat of milk must be formed in the same way. Dis- 

 allowing the legitimacy of such a deduction, there do, never- 

 theless, seem to be reasons for supposing that the fat of 

 milk may, at any rate in large proportion, be derived from 

 albuminoids. 



Thus, as compared with fattening increase, which may in 



1 Landw. Fihtterungslehre, 5te Aufl., 1888, p. 249. 



