306 



THE KOTHAMSTED EXPERIMENTS. 



Percentage 

 of nitrogen- 

 ous sub- 

 stance 

 digested. 



Percentage 

 of fatty 

 matter 

 digested. 



Results. 



relating to the series, and at the head of each separate 

 column is given a description of the limited food supplied 

 to each pen. 



The results are calculated for 100 increase in live-weight. 

 Eeferring to the upper division of the table, there are first 

 shown — the amounts of nitrogenous substance (digestible) in 

 the fixed food, the amounts in the increase, and the difference 

 = the amounts available for fat-formation. Next are given — 

 the amounts of fat in the increase, in the total food (digest- 

 ible), and the difference = the newly-formed fat; the amounts 

 derivable from the available nitrogenous substance in the 

 fixed food, and the difference = the amount required to be 

 produced from other sources. Then, in the lower division of 

 the table are given, for each pen, the amounts of fat derivable 

 from the nitrogenous substance of the roots, on the alternative 

 assumptions that 50, 60, 70, 80, 90 per cent, or the whole, of 

 that which they contain will be digestible and available for 

 fat-formation. 



It should be further explained, that 80 per cent of the 

 nitrogenous substance of barley or of malt is reckoned as 

 digestible and available for the purposes of the system. 

 Wolffs estimates were— in 1874, 80 per cent ; in 1888, 77.3 

 per cent; and in 1890, 77 per cent. In malt-dust 80 per 

 cent is assumed to be digestible, against Wolffs estimate of 

 80 per cent in 1874, and 82 per cent in 1888 and 1890. In 

 clover-chaff two-thirds, or 66.7 per cent, of the nitrogenous 

 substance is reckoned as digestible, against a range in Wolffs 

 Tables, according to quality, from 51.4 to 69.9 per cent. In 

 the cases of Swedish turnips and mangels, Wolff assumes 

 the whole of the nitrogenous substance to be digestible and 

 available, drawing no distinction in this respect between the 

 amounts existing as albuminoids, as amides, or in other 

 forms. To this point we shall have to refer in more detail 

 presently. 



Then as to the fat of the foods : the percentage of it reck- 

 oned as digestible is that given in Wolff's tables of 1874. 

 In the case of barley he then reckoned only 68 per cent of 

 the total to be digestible ; but more recently he has supposed 

 the whole of it to be so. For clover-chaff his figures are the 

 same at all three periods, as they are also for mangels. 



Let us now turn to the calculated results as given in the 

 table, and first to those relating to the first series of five pens, 

 in which the fixed food was either barley or malt, and the ad 

 libitum food consisted of mangels only. As already said, the 

 period of experiment comprised only the last ten weeks of 

 fattening. Hence it commenced at a somewhat advanced 

 stage of progress, and the animals were, at the conclusion, 



