280 



THE ROTHAMSTED EXPERIMENTS. 



Construc- 

 tion of the 

 tables, 

 showing 

 average 

 composi- 

 tion of 

 animals. 



Composi- 

 tion of ani- 

 mals at 

 different 

 stages of 

 feeding. 



a higher percentage of both fat and total dry substance, than 

 the entire body of the animal. 



It is obvious, however, that the results of the analyses of 

 the ten animals do not supply data directly applicable for the 

 estimation of the composition of animals in the very various 

 conditions in which they are dealt with in practice, or of their 

 increase over any given period under varying conditions of 

 feeding. Accordingly, we have constructed tables founded on 

 the analytical results above referred to, showing the probable 

 average percentage composition of the different descriptions 

 of animal, each at eight gradationary points from the store to 

 the very fat condition ; and the factors thus obtained have 

 been applied for the calculation of the composition of the in- 

 crease in a number of cases of ordinary practice, or of direct 

 experiment in which the weights of the animals at the com- 

 mencement and at the conclusion of a fixed period, the general 

 character of the food they consumed, and their final condition, 

 were more or less fully known. It is admitted that these 

 eight conditions do not cover all the variations of composition 

 occurring in actual practice ; but at the same time there can 

 be no doubt that by the aid of such factors the feeder would 

 be enabled to calculate, with sufficient approximation to the 

 truth for all practical purposes, the composition of the store 

 animals he buys or sells, and of the fat ones he sells. At 

 any rate, we believe that the results are the best that existing 

 knowledge enables us to provide. 



It is impossible to go into any detail here, either as to the 

 composition of the animals at the different stages, or as to 

 the estimated composition of their increase, but the results 

 may be briefly summarised as follows : — 



In the case of oxen, the figures representing the composi- 

 tion of the animals at different stages of progress show — that 

 the percentage of mineral matter ranged from 5.15 in the 

 store to only 3.43 in the very fat condition ; that of the nitro- 

 genous substance from 18.0 in the store to only 13.1 in the 

 very fat state ; and that of the fat increased from 11.7 in the 

 store to 37.4 in the very fat condition. Again, the percentage 

 of total dry substance increases from only 34.8 in the store 

 to 54.0 in the very fat condition. Lastly, the percentage of 

 water decreases from the store to the very fat condition. 



The parallel results for sheep show that the percentage of 

 mineral matter ranges from 3.25 in the store to only 2.90 in 

 the very fat animal ; the nitrogenous compounds from 15.5 

 per cent in the store to only 10.9 per cent in the very fat 

 condition ; and against these reductions the fat increases from 

 14.5 per cent in the store to 45.8 per cent in the very fat con- 

 dition ; and the total dry substance from 33.2 per cent to 



