428 SCIENCE PROGRESS 



of these factors is great. The digestible protein in swedes is 

 given by Kellner as "3 per cent. 1 on the sole authority of an 

 experiment upon two sheep, one of which increased in weight 

 seven times as much as the other. 2 



The digestibility of the fibre in turnips varied from o to 

 ioo per cent., 3 and that of protein in oat straw from 12 per cent, 

 to 50 per cent. 4 The result of a " digestibility " or " value " 

 experiment is true only of the particular food, in the case of a 

 certain animal, under certain restricted 5 conditions and cannot 

 be usefully generalised by applying it to the mixed units of 

 ordinary analysis. 



A farmer learns from experience how he must supplement 

 his own roots and fodders. Moreover the good cattleman studies 

 the individual animals and keeps their appetite fresh. " It is 

 the master's eye that fattens the cattle." His rations will fall 

 within certain limits and generally our present science is not 

 warranted in making these limits closer. The primary object 

 of research on feeding values in this country is not to inform 

 practical feeders how to construct their rations but to increase 

 the feeding quality of the foods we grow, which form the 

 main part of these rations. We know what an efficient measure 

 of the required quality did for the sugar-beet industry. If we 

 had an equally true measure of the feeding quality of home- 

 grown foods there is reason for hoping it would in some similar 

 degree benefit the agricultural industry. We could select, 

 breed, manure and cultivate with confidence and the tools which 

 got us increase of feeding quality would help us best to use it. 



CERTAIN OIL FOODS 



(Prof. Hendrick) 



In most of the previous experiments on the substitution 

 of other fats for butter fat, cod liver oil has been used and 

 the opinion is consequently prevalent that this is the only oil 

 which can properly be used. The general purpose of the 

 experiments now described, in which calves were fed with 



1 Scientific Feeding of Animals (Goodwin's Trans. 1909), p. 370. 

 9 Bied. Centr. 20, pp. 12-19, an d Chem. Soc. Abstracts, 1891, p. 595. 



3 Scientific Feeding 0/ Animals, p. 385. 

 1 Ibid. p. 383. 



4 Highland and A gric. Soc. Trans. 1893, p. 344. 



