346 MANUAL OF CATTL-E-FEEOraG. 



The cliange effected ia tlio composition of the material is 

 analogous to that which takes place in brewers' grains, viz., 

 a removal of the non-nitrogenous nutrients, here fat, while 

 the greater part of the albuminoids remanis. 



It will be seen at once that the resulting oil cake must 

 have a high nutritive value, since it contains all the protein 

 of the original seed and that portion of the oil which can- 

 not be removed by pressure. Its nutritive ratio is nar- 

 rower than before, and it is better adapted for adding 

 protein to a ration, since larger quantities of it can be used 

 without danger of giving too much oil. At the same time, 

 it is a highly concentrated fodder, and, like all such mate- 

 rials, must be used with caution, and only as a bj'e-fodder 

 to supply the deficiencies of poorer materials. 



Composition. — The composition of oil cake will, of 

 course, vary according to the completeness with whi(*h the 

 oil is extracted. The greater the pressure to whicli it is 

 subjected, the less oil and the more, relatively, of albmui- 

 noids will it contain. A method of extracting the oil 

 which has lately come into use to some extent consists in 

 treating the ground seeds with benzol or bisulphide of 

 carbon, which dissolve the oil The residue from this 

 process is poorer in oil and correspondingly richer in pro- 

 tein than that from the ordinary process of pressiiig, 

 and it seems probable that it would have advantages as 

 fodder over the latter. It is seldom that fat is deficient in 

 the food of our domestic animals ; but it is often desirable 

 to increase its protein, and by means of the extracted oil 

 cake we could accomplish this without unduly increasing 

 the amount of oil. 



The average of all analj^ses of American oil cake yet 

 made are as follows, calculated on the water-free sub- 

 stance : 



