Mar. 25. 191 5 Energy Values of Feeding Stuffs for Cattle 463 



In view of this general uniformity, only a comparatively small cor- 

 rection would be necessary in most instances to make the results on an 

 individual animal comparable as regards standing and lying. When, 

 however, it is desired to compare the results obtained with different 

 individuals so as to get a general average, it is clear that the animal 

 which tends to stand most is at a disadvantage and will show a lower 

 net energy value for the same ration not because his feed is any poorer 

 but because the animal is a less efficient converter and that the greater 

 the stimulus to metabolism exerted by standing the greater will this 

 difference become. It is necessary, therefore, to correct the results 

 upon heat production as well as possible to a uniform proportion of 

 standing and lying, so as to render the results applicable to an (assumed) 

 average animal. According to Table VIII the average percentage of 

 time spent standing was 43. In correcting the results, however, we have 

 used 50 per cent as the standard for convenience in calculation — that is, 

 we have taken as the corrected heat production the average of that 

 standing and lying, computed as shown on page 454 for the entire 48 

 hours.' 



OTHER FORMS OF MUSCULAR ACTIVITY 



According to our interpretation of our results, the material increase in 

 the heat production of an animal when standing as compared with that when 

 lying is simply an instance of the well-known influence of muscular exer- 

 tion upon metabolism. Recent investigators, notably Schlossmann and 

 Murschhauser (42, 43) and Benedict and Talbot (14, 15) in experiments 

 upon infants, and Benedict and Homans (12, 13) in similar trials with 

 dogs, have emphasized the disturbing influence of this factor upon com- 

 parisons of different periods. Benedict and his associates, in particular, 

 have devised ingenious methods for determining the degree of muscular 

 activity of a subject and have insisted that only periods of minimum 

 activity can be safely compared. 



We have not yet had the courage to attempt to apply to an animal 

 weighing 1,000 or 1,200 pounds methods like those which have been used 

 so successfully for infants and small dogs, either for the indication of 

 minor movements or for the determination of the pulse rate. It seems 

 likely that the latter, in particular, might be of considerable aid in the 

 interpretation of the results if it should prove possible to devise a form 

 of apparatus which would not be injured by the movements of a heavy 

 animal. 



1 This method of correcting the rcsuUs assumes that the relative intensity of the metabolism of the ani- 

 mal when standing or lying is not afTccted by the proportion of time spent standing. It might be imagined, 

 however, that in a comparatively long period of standing the original stimulus to incidental muscular 

 movements might gradually fade out. so that the average difference in the rate of metabolism in the two 

 positions would be less for long than for short periods. In this case our method of correcting the results 

 would be more or less erroneous. This possibility can be tested to a certain extent by comparing witli 

 each other the two single days of each period. Out of the 64 possible comparisons, that oneof the two days 

 in which the lesser percentage of time was spent standing showed a greater iucrenient of standing over 

 Ildng in 26 cases and a less increment in 37 cases. On the average of the 64 days of maximum standing 

 the percentage of time spent standing was 51.9 and oti the 64 days of minimum standing 43.5. while the 

 corresponding average percentage increases in metabolism during standing were, respectively. 41.98 and 

 41.67. It does not appear, therefore, that within the range of thesocxperiments the ratio of the metabolism 

 when standing to that when lying was materially affected by ttie proportion of time spent standing. 



