EXPERIMENT STATION RECORD. 



Vol. Vlll. No. 11. 



The question as to effect of food on the composition of milk has again 

 been o])ened, and by no less an authority than Professor Soxhlet, of 

 Munich (see p. 101(3). In the present unsatisfactory state of our knowl- 

 edge of the physiological side of milk production, any scientific contribu- 

 tions on the subject can not fail to be of interest, for until we can learn 

 more definitely the true relation between food and milk, experiments on 

 the value of this or that feeding stuff or ration for milk production can 

 hardly contribute much to the science of feeding for milk and must be 

 confined mostly to the financial side of the question. 



In his latest published work Professor Soxhlet shows that in some of 

 the experiments which have been regarded as conclusive on certain 

 points and which have had much to do with shaping the general opinion 

 of the effect of food on milk, rations were fed which were less digestible 

 than was assumed, i. e., that the j)articular substances tested, like fat, 

 were added to the basal ration in such form that they were not digested 

 by the animal. Hence, no effect could be reasonably expected. His 

 investigations lead him to believe there is no direct transmission of fat 

 from the food to the milk, as some have held; but that normal milk fat 

 IS a product of the activity of the lacteal glands, and that its source is 

 the body fat of the cow. The fat of the food affects the secretion of 

 milk fat by replacing a part of the body fat, and thus causes a trans- 

 mission of the body fat to the milk. He is confident that the fat of 

 the food can effect a one-sided increase in the fat content of the milk; 

 but he states that the fat is the only food constituent capable of doing 

 this. 



Feeding oils, tallow, etc., in such form that they could be assimilated 

 by the animal body resulted in an increased production of f;it, but when 

 the same fats were fed in different form they were without effect be- 

 cause they were not digested. On this ground of failure of digestion 

 Professor Soxhlet explains many of the negative results in "feediug 

 fat into milk,'' which have been regarded as stnmg arguments in the 

 theory that the fat can not be increased by feeding. This suggests the 

 necessity in all feeding work of tliis kind of determining to what extent 

 the rations are actually digested, and especially when substances are 

 fed which may themselves fail to l)e digested or affect the digestibility 

 of the other ingredients of the ration. This point may prove to be 

 of much importance in interpreting the real effect of various materials 

 added to the basal rations, not only in this particular line of work, but 

 also in other feeding experiments. 



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