Aug. i6, I9I5 Prickly-Pears as a Feed for Dairy Cows 



419 



mination were taken from the fresh material, preserved with chemically 

 pure sulphuric acid, and sent to the Washington laboratories for analysis. 

 Table IX gives coefficients of digestion for each animal in the different 

 trials, together with the character of the ration and the amounts of each 

 feed fed. Complete data for each individual animal will be found in 

 Tables XX to XLII. 



Table IX. — Summary of coefficients of digestion for dairy cows 



METHOD OF CALCULATING DIGESTIBLE NUTRIENTS 



Table X gives the estimated coefficients of digestion for each class 

 of rations fed during the digestion trials, the actual coefficients of digestion 

 as determined by these trials, and the factor showing the difference 

 between the estimated and the actual coefficients. In arriving at the 

 estimated coefficients the average figures for sorghum fodder, com, wheat 

 bran, and cottonseed meal were taken from Henry (8, p. 572-577). while 

 the figures for prickly-pear were taken from our own results as given in 

 Table IX. In determining the digestible nutrients consumed by the dififer- 

 ent groups of cows in this feeding experiment the crude nutrients consumed 

 were multiplied by the average coefficients of digestion as taken from 

 Henry and the resulting products multiplied by the factor of difference 

 for that particular group. This method is given with a full knowledge of 

 the error involved in assuming that the coefficients of digestion for the 

 different constituents are increased or decreased in the same ratio for each 

 ingredient of the ration. As a matter of fact, it is probable that in some 

 rations the digestibihty of one ingredient may be reduced while that of 

 another may be increased. However, calculations using average coeffi- 

 cients and the factors of difference are thought to be more nearly repre- 



