580 EXPERIMENT STATION RECORD. 



The rations consisted of an amount of clover bay estimated to be somewhat less 

 than sufficient for maintenance (5,200 gm.); a considerably smaller amount of clover 

 hay (3,700 gm.); a small amount of clover hay (3,700 gm.) supplemented by a 

 quantity of maize meal (850 gm. ) calculated to be sufficient to make the total ration 

 somewhat less than adequate for maintenance; and the same amount of clover hay 

 supplemented by maize meal enough (4,000 gm.) to provide a ration sufficient for 

 moderate gain. 



The comparison between the first and second periods gives data for determining 

 the net availability of the energy of the clover hay, and the results of the second and 

 third periods for computing the energy of maize meal, while the data of the fourth 

 period al'f< >rds a means < >f ascertaining the percentage utilization of the energy of maize 

 meal in the production < >f gain. Each experimental period covered 21 days, of which 

 the first 11 were regarded as preliminary, and the digestibility of the ration and the 

 income and outgo of matter and energy were measured. 



From the experimental data, which are recorded in full, it appears that the coeffi- 

 cients of digestibility of the dry matter and total protein of the more abundant ration 

 of clover hay were 59.13 and 48.58 per cent, respectively, and for the smaller clover- 

 bay ration 51). 70 and 5.3.19 per cent. In general, the smaller ration was more 

 thoroughly digested, but the authors consider the differences small enough to be 

 within the limits of error. 



When maize meal formed a part of a ration scarcely sufficient for maintenance, the 

 coefficients of digestibility of dry matter and protein were 87.34 and 85.23 per cent, 

 respectively, and in the productive ration 91.50 and 62.30 per cent. The values for 

 proteids in the 2 rations were 80.14 and 66.43 per cent. "The results obtained upon 

 total protein and proteids seem to indicate a decrease in the apparent digestibility of 

 these constituents under the influence of the large supply of carbohydrates in the 

 maize meal." 



In discussing energy values the authors point out that — 



"The relation of the metabolizable energy to tbe amount of matter in the food 

 may be expressed in terms of calories per gram of the total or of the digested organic 

 matter. . . . 



"The metabolizable energy of a feeding stuff may also be expressed as a percent- 

 age of the total or gross energy. Such a percentage is analogous to a digestion coeffi- 

 cient, so that if an average value for it were established for any particular kind of 

 feeding stuff, the amount of metabolizable energy in a given amount of it could be 

 computed from its total energy by multiplication by this coefficient just as the diges- 

 tible dry matter or organic matter can be computed from the total amount present 

 by the use of a digestion coefficient." 



In the case of the clover hay it was found that the metabolizable energy consti- 

 tuted 42.58 per cent of the total energy in the first period, and 44.22 per cent in the 

 second period, or 43.40 per cent on an average. Calculated as a percentage of the 

 energy of digested matter, the values were 75.52 for the first period and 76.18 for the 

 second period, or 75.85 per cent on an average. In the case of the maize meal the 

 metabolizable energy was 64.16 per cent of the total energy on the limited ration 

 and 77.68 per cent on the more abundant ration. When the calculations are based 

 upon the energy of digested matter, the values are 75.06 and 85.53 per. cent, 

 respectively. 



" The above results represent what has been called the 'apparent' metabolizable 

 energy. It is not at all unlikely that the addition of maize meal affected to a greater 

 or less degree the digestibility of the hay to which it was added. 



" In particular, ... it seems possible that it diminished the digestibility of the 

 protein of the total ration. 



"If such was the case, the results . . . [noted] above are too small to represent the 

 actual metabolizable energy of maize meal, just as the corresponding results upon the 



