1912.] PUBLIC DOCUMENT — No. 31. 243 



conditions yielding from 50 to 100 per cent, more in a year 

 particularly favorable to its growth. 



Composition of the Corn Plant. — The general conclusion 

 can he drawn that the changes in chemical composition which 

 the plant undergoes in its development are such tliat its maxi- 

 mum feeding value exists at its maturity. 



Digestibility of the Corn Plant. — Digestion experiments 

 conducted with the entire corn plant showed no wide variation 

 in the digestibility of the several varieties, the range being from 

 67 to 77 per cent. With one exception the digestibility appeared 

 to depend upon the percentage of nitrogen-free extract. The 

 higher the percentage of extract or starchy matter present, the 

 higher the digestibility. 



Proportion and Composition of Parts. — The stalks and ears 

 form practically 70 per cent, of the dry matter of the plant, the 

 leaves and husks 30 per cent. 



Relative Pj^oportion of Grain to Cob. — The percentage of 

 grain to cob varies widely, depending to some extent upon the 

 maturity of the plant when cut. The average for the several 

 mature types was 15.5 per cent, cob and 8-1.5 per cent, kernel, 

 while the average for the less mature varieties was 18.1 per 

 cent, cob and 81.9 per cent, kernel. In either case the percent- 

 age of cob was less than that of the Massachusetts legal bushel, 

 which in the case of shelled corn is 56 pounds, and for ear 

 corn 70 pounds, thus allowing 14 pounds, or 20 per cent., for 

 cob. 



Composition of Grain and Cob. — The grain analyzed showed 

 only slight variations in composition. Chemical composition 

 cannot at the present time be considered a factor in the selec- 

 tion of seed corn where the crop is used for the sustenance of 

 live stock. 



There appears to be very little variation in the composition 

 of the corn cob. The net available energy in 100 pounds of cob, 

 after the method of calculation suggested by Ivellner, is 40.2 

 therms as against 85.5 therms in a like amount of corn meal; 

 hence on this basis ground corn cob would have 47 per cent, 

 of the energy value of corn meal.^ 



■ The Kellner method of calculation is the best we have for making comparative estimates of 

 relative values. 



