178 Meat Production 



In Armsby's experiment the animal was a three-year-old steer; and 

 it may be inferred from the description of its condition that it contained 

 about 20 per cent, of body fat before and 35 per cent, after fattening. 

 Accordingly the "fattening increase" must have comprised about 

 80 per cent, of fat and '20 per cent, of non-fatty matter. This indicates 

 that the animal had grown a little whilst fattening. 



The observed basal katabolism was 5563 Cal. and 7544 C'al. in the 

 two conditions respectively. In order to ascertain the influence of con- 

 dition, as apart from growth, the latter number must be reduced in 

 proportion to the two-thirds power of the fat-free live weight. Taking 

 for this purpose the mean weights (513 kg. before and 648 kg. after 

 fattening) the corrected figures, i.e. for animals of the same size, are as 

 follows : 



Unfattened FattciH'd 



Condition (body fat, %) 20 35 



Live weight (kg.) 513 (i31 ' 



Basal katabolism (Cal.) 5503 7410 



It will be seen that basal katabolism increases faster than live 

 weight ; but it is fairly obvious that the greater weight to be supported 

 is, to a large extent, the cause of the increase. It is to be expected, 

 therefore, that the curve of basal katabolism will be similar in form to 

 the curve of live weight but will rise more steeply. The latter is ex- 

 pressed by M = 100»i (100 — / ), where m is the fat-free live weight and 

 / the percentage of body fat. If basal katabolism increased in the .same 

 proportion as the live weight the curve would be B = 1006/(100 — /), 

 but as it rises more steeply the formula must be 



100b 

 100 -a/' 



where a is an empirical number, b is the basal katabolism in fat-free con- 

 dition and B is basal katabolism in the same animal when it contains 

 /per cent, of body fat. 



From the data above both a and h can be determined, thus — 



■ 1006 ^.„„ , 1006 „,,,^ 



= 5d63 and r— -- „_ = /410, 



100 - 20a 100 - 35a 



.-. a = 1-247 and 6 = 417.5-.59. 



The live weights and basal katabolism corresponding to different 

 percentages of body fat are given in the table below and the curves 

 shown in the diagram were plotted from the same. The points marked x 

 are those determined in the experiment. 



