16 HATCH EXPEEIMENT STATION. [Jan. 



constituents — protein, fat and carbohydrates — on the milk 

 and butter fat, but have rather attempted to observe the in- 

 fluence of the combinations of these groups as they exist in 

 the different foods. It is believed that the former method 

 would yield more definite information on this perplexing 

 subject. 



(b) The Effect of Protein on the Composition of 



Milk. 

 In an early experiment * different amounts of protein 

 were fed, and the effect on the composition of the milk was 

 noted. The experiment showed that the fat content of the 

 milk appeared to be increased. Unfortunately, the ration 

 contained, in addition to the protein, an excess of corn and 

 cotton-seed oil, derived from gluten feed and cotton-seed 

 meal, and "it was not at all clear whether the protein or the 

 oil was responsible for the fat increase. Again, the periods 

 were of too short duration to make clear whether the increase 

 was temporary or permanent. In the next two experimentsf 

 the oil factor was eliminated as far as possible, the protein 

 beino; derived from corn and sluten meals. The leno;th of 

 the periods were increased so as to cover from four to six 

 weeks, and, because of increased facilities for carrying out 

 the experiments, many outside influences bearing^ upon the 

 results Avere eliminated. The results of these two investiga- 

 tions showed no particular influence of the protein upon the 

 several ingredients of the milk, except a very slight increase 

 in the nitrogenous matter of the milk when the largest amount 

 of protein was fed. It therefore seemed probable that the 

 oil in the rations fed in the first experiment above referred 

 to was responsible for the fat increase. 



(c) The Effect of Fat on the Composition of Milk. 

 About this time (1898), Soxhlet, a German investigator, 



made the statement that, contrary to general teachings, the 

 fat of the food — as found in the diflerent oil cakes fed on 

 the continent — did produce a very noticeable increase in the 



* Report of Massachusetts State Experiment Station, 1894. 

 t Ninth and eleventh reports of Hatch Experiment Station. 



