160 Oat and Tare Silage 



secreted into tlie alimentary tract and escaped re-absorption. Thus the 

 protein digestion coefficients as determined directly represent minimum 

 values, and in view of the possibility of this disturbinjr factor operating 

 unequally in the trials with the difTerent fodders, it was deemed advisable 

 to correct the protein digestibilities by basing them on the amount of 

 pepsin-insoluble nitrogen in the faeces. Accordingly, determinations of 

 the pepsin-insoluble nitrogenous constituents of the faeces were made in 

 all three cases. The error occasioned by the presence of metaboUc pro- 

 ducts in the faeces affects, of course, the accuracy of the digestion co- 

 efficients of all the foodstulT ingredients, but it falls with especial weight 

 upon the protein and ether extract. No satisfactory and reliable method 

 for correcting the ether extract digestibihty has so far been evolved^. 



The sheep were weighed at the beginning and end of each period and 

 account was kept of the nitrogen balance. The wethers employed were 

 the same as were used in the earlier work on oat and tare silage. A study 

 of the results shows an extraordinarily good agreement between the sets 

 of figures obtained for the two sheep. Such agreement is not often met 

 with in work with animals, and it would appear that the two sheep 

 selected for the purpose possessed almost equal digestive capacity. 



The writer's thanks are due to his as.sistant, Mr V. .T. Aylett, for the 

 skilful manner in which lie took charge of the animals and for tJie care 

 with which he carried out the analytical work in connection with the 

 digestibihty trials. 



Table I . Dclaih of ratian-s. 



In planning the rations for the trials, it was, for obvious reasons, 

 intended that the sheep should receive roughly the same weight of dry 

 matter per day throughout. This object, however, was not attained for 

 the following reasons. The first moLsture determinations carried out on 

 preliminary samples of the green oats and tares showed them to have a 

 drv matter content of about 27 per cent. A diet of 4000 gm. of this 

 fodder contained therefore about 1080 gm. of dry matter. By the end of 

 the j)erio(l, however, the thy matter content of the crop rose to over 

 34 per cent, and the mean percentage for the analytical ])erio(l was 



' For fuller information on this jmint, see Crowlher and Woodman, Jniini. of Agric. 

 Sci. 8, 434, 1917. 



