May, 1929] SIMPLIFIEO TECHNIQUE FOR MEASURING ENERGY 



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process as yet. but it is apparent that errors due to such contamination 

 would be exceedingly small for the following reasons: (1) The determina- 

 tion of digestibility of feed would not be affected at all, because the total 

 weight of feces is known and its analysis is based on a sample of the bulk 

 which has not been contaminated. (2) Urine is collected separately 



Plate 7 — Apparatus for collecting separately the feces and urine from coivs 



merely for the determination of the total nitrogen output. The chance 

 for contamination of urinary nitrogen from feces is exceedingly small, be- 

 cause whatever readily extractable nitrogen the feed may originally have 

 contained has in all probabihty been removed in the digestive tract. (3) 

 The amount of feces which escapes into this drain pan is so small a frac- 

 tion of the total feces that even the total nitrogen of the feed which these 

 feces represent would not be sufficient to cause any significant error in 

 the determination of the urinary nitrogen. 



