AGRICULTURAL EXPERIMENT STATION. 65 



bran and fine middlings. The composition of the two is found not 

 to difftr greatly so far as it is a question of the relative amounts of 

 the several classes of compounds, and the digestibility of the former 

 is found to be much less than that of the latter. These facts 

 regarded in the light of approved theories, warrant the conclusion 

 that the feeding value of the middlings is the greater. But a feed- 

 ing trial in which rations, containing in some periods bran and in 

 others, middlings, are compared, either does not show the expected 

 difference, or declares one altogether larger than other facts seem 

 to warrant. Are we, then, to conclude the theory is wrong? Cer- 

 tainly not from a single trial. Sj many conditions, such as the 

 lengthening of the period of lactation, the temperature of the barn, 

 variations in weight due to a change in intestinal contents, and the 

 unreckoned or unmeasured increase or decrease of the flesh of the 

 animal (if with cows) , enter into a feeding trial as unknown factors, 

 that such differences as ex st between two grain foods may either 

 be covered up or greatly exaggerated. Nothing short of several 

 feeding trials should be allowed to throw a doubt upon the correct- 

 ness of theories that appear to be well substantiated by severe 

 methods of investigation, and even then the points of disagreement 

 ■would, doubtless, be regarded as unsettled questions. 



Fortunately, however, the value to farm practice of the feeding 

 trials here reported is not lessened by apparent discrepancies 

 between the outcome which general principles would seem to dictate 

 and the results actually reached. The experiments which are dis- 

 cussed in this connection are the following : 



(1) The relative feeding value of Southern corn silage and 

 Maine field corn silage. 



(2) The influence of widely differing rations upon the quantity 

 and composition of milk. 



(3) Experiments with swine. 



(a) Relative economy of production with different breeds. 

 (6) The market value of different breeds. 



(c) The comparative value of nutrients from skimmed milk and 

 from vegetable foods. 



(d) The economy of production at different ages. 



