(II'. I-' '.HT 



Volume XII April, 1922 Part II 



THE CHEMICAL COMPOSITION 

 OF ANIMAL BODIES 



By J. ALAN MURRAY, B.Sc. 



University College, Reading. 



(With 1 Text-figure.) 



In a previoiLs communication (i) the author pointed out that the chemical 

 composition of the bodie.s of farm animals is determined when the per- 

 centage of fat is known; for the composition of the uou-fatty matter is 

 practically the same in all, it is not affected by the " condition" (fatness) 

 and it varies only to a slight extent with the age of the animals. The 

 averages, in round numbers, deduced from Lawes and Gilbert's analyses (2) 

 were as follows: 



These conclusions were necessarily more or less tentative in character 

 because the data referred to only ten animals in all. viz., two pigs, three 

 cattle and five sheep. More extensive data, recently to hand, aft'ord a 

 striking confirmation of the general thesis and enable us to determine 

 the influence of age and the individual variation with greater precision. 



Haecker(3) records separate analyses of the whole bodies of 49 indi- 

 viduals (cattle) ranging from about 100 lb. to 1500 lb. live weight and 

 from 3-.5 percent, to 35 per cent, of body fat. Swanson(4) records separate 

 analyses of the whole bodies of 36 individuals (pigs) ranging from about 

 201b.to4001b.live weight and from 5 per cent, to 60 per cent, of body fat. 



In Haecker's experiments the animals were arranged in groups ac- 

 cording to size with intervals of about 100 lb. average live weight between 

 them. The mean values for each group are shown in Table I below*. 



The empty body weight is, of course, the live weight minus the 

 refuse, i.e. the contents of stomach, intestines and urinary bladder. The 

 fat-free empty weight is the weight of non-fatty matter in the actual 

 body. It is found from the empty body weight by 



m = M(100 - F)/100 

 or, directly from the live weight, by 



m = M'(100- F ~ /J)/100, 



Jouin. of Agric. Sci. xii . 8 



