C. Crowther and H. E. Woodman 435 



protein by sheep is 0-85 gm. nitrogen per 100 gms. digested organic 

 matter. 



In our experiments the proportion of pepsin-soluble faecal nitrogen 

 has ranged in the different periods from 0-40 gm. to 0-63 gm. per 100 gms. 

 of organic matter digested, with an average for the 12 comparisons 

 of 0-52 gm. No definite correlation with the nature of the ration is 

 traceable, the average factors for the two sheep ranging in the different 

 periods from 0-49 to 0-54 — a remarkably narrow range. 



As a matter of interest we have determined not only the pepsin- 

 insoluble protein in the faeces for each period, but also the digestibility 

 of the protein in each feeding-stuff by direct treatment in vitro with 

 HCl-pepsin solution on the lines of the conventional Stutzer-Kiihn 

 method. The results are given in the tables but may be summarised 

 here for convenience of comparison. 



Digestibility of Crude Protein 



In three cases the agreement is reasonably satisfactory, whilst in 

 one of the other two cases (palm kernel cake I) we have reason to think, 

 as will be explained later, that the results deduced from the animal 

 experiment are less reliable than in the case of the other foodstuffs. 

 The only glaring discrepancy (palm kernel meal) is not easily accounted 

 for. The in vitro result given was confirmed repeatedly, and was 

 increased only to 81-2 per cent, by very prolonged (8 days) digestion of 

 the finely-ground meal with HCl-pepsin. 



Before leaving this subject attention may be directed to the relatively 

 large amount of the faeces protein which is dissolved by the HCl-pepsin 

 solution, fully one-half of the total nitrogenous matter being commonly 

 removed thereby. The corrections are consequently large and there 

 can be no doubt that the uncorrected digestion-coefficients for protein 

 commonly used for farm feeding stuffs are in most cases seriously low. 



Joum. of Agric. Sci. vui 29 



