476 Journal of Agricultural Research voi. iii. no. 6 



DISCREPANCIES IN RESULTS 



It is apparent from both Table X and figure 2 that the single results 

 show a considerable range for the same or similar feeds not only with 

 different animals but also, in some instances, between different periods 

 with the same animal. For example, in experiment 209, on steer F 

 with alfalfa hay an increase of the ration from 2,226 to 3,562 gm. of dry 

 matter caused an increase in the (corrected) heat production at the rate 

 of 963 Calories per kilogram, while a further increase to 6,174 gni- re- 

 sulted in a relatively greater increase of the heat production — viz, i ,301 

 Calories per kilogram. 



In the instance just cited one might be inclined to interpret the differ- 

 ence as an effect of the greater feed consumption. The next line in Table 

 X, however, sho%vs an even greater difference in the opposite direction, 

 while it is evident from figure 2 that the data as a whole show about as 

 many differences in one direction as the other and, as pointed out in the 

 previous paragraph, fail to give any distinct evidence of a greater relative 

 increase of heat production on heavy as compared with light feed or on 

 supermaintenance as compared with submaintenance rations, the averages 

 tending, if anything, to be a trifle lower on the heavier rations. 



Unavoidable differences in the muscular activities of the animal, other 

 than those connected with standing and lying, and in other conditions 

 have also to be considered. As already pointed out, the existence of 

 such differences, in spite of the uniformity of the controllable experimental 

 conditions, is indicated by the occasionally considerable divergence of 

 the heat production upon the two days of the calorimeter runs. It is 

 not improbable, therefore, that they may be responsible, at least in part, 

 for the observed discrepancies, so that it is obvious that the average re- 

 sults must be accepted with some reser\'e. On the other hand, however, 

 it must be remembered that these are calculations by difference and that 

 in such a calculation the experimental errors tend to accumulate in the 

 final result. Obviously the greater we make the difference in the factor 

 whose effect is to be determined, the less will be the relative error of the 

 final result.^ We believe, therefore, that the results obtained by a 

 comparison of the extreme rations, as recorded in column 4 of Table X, 

 are decidedly more trustworthy than those computed from the inter- 

 mediate rations, and, notwithstanding the discrepancies just mentioned, 

 are inclined to regard them as expressing the total effect of the feed in 

 increasing the metaboUsm, when variations in the time of standing are 

 eUminated, with a sufficient degree of accuracy to warrant general com- 

 parisons of the average results. These average results, both as to the 

 total heat increment and its factors, are summarized in Table XI. 



1 Out of 13 cases in which the results appear abnormally high or low. there were 6 in which the difference 

 in dry matter consumed was less than i kg., although there were 5 other cases in which, with a similar 

 small difference in the dry matter consumed, apparently normal results were obtained. 



