ESSAYS 



667 



Table III 

 Percentage composition of increase 



Ox 



Sheep (fat) . 

 Sheep (extra fat) 

 Pig 



Ash. 



Protein. 



Per cent. 



-0*64 

 0-84 

 275 

 C46 



Per cent. 



o"67 



3'27 

 8*92 

 8*26 



Water. 



Per cent. 



5'5o 



9-65 



25-08 



27*80 



Fat. 



Per cent. 



94'47 

 86*24 

 63-25 



63*47 



Increase 

 upon 100 

 original 

 weight. 



17*95 



24-94 



149*47 

 99*30 



These results differ substantially from the averages published by Lawes and 

 Gilbert, and they are applicable only to the particular cases. In general, the 

 percentage composition of the increase may be computed directly by the following 

 formula : 



p _ MF-7nf 

 M - m 

 where iT/and m are the net live weights, F and /are the percentages of fat (or any 

 other ingredient) in them respectively (see Table I), and P is the percentage in 

 the increase. 



All the factors in the above expression are variable. The live weight of 

 cattle ranges from about 50 or 60 lb. at birth to over 2,000 lb. when fully grown. 

 M and m may have any values between the extremes, and M may be equal to or 

 even less than m. The data in Table I are not limits. Atwater and Bryant l 

 found less than 1 per cent, of fat in sides of beef described as " very lean." 

 Apparently, in live animals, the fat may vary from about 5 to 50 per cent, though 

 the limits ordinarily attained are perhaps somewhat narrower. At all events, 

 .F and/may have any values between the extremes, whatever these may be, and 

 ^may be equal to or even less than/. 



Variation in the percentages of the other ingredients is almost entirely limited 

 to that due to variation in the percentage of fat. Therefore, in any given animal, 



P'=P{ioo- F)l{ioo-f) 



where p is the percentage of ash, protein, or water in the body when it contains 



/ per cent, of fat, and p' is the percentage when it contains F per cent. The 



theoretical maxima {i.e. when F = o), calculated from the data in Table I, are as 



follows : 



Table IV 



Composition of Non-fatty Matter : 



Ash . 

 Protein 

 Water . 



Half-fat 

 ox. 



Per cent. 



6*4 



22-8 

 70-8 



Fat ox. 



Per cent. 



6-1 

 227 

 71*2 



Old 

 sheep. 



Per cent. 



4*7 

 20-7 



74*6 



Fat 

 sheep. 



Per cent. 



4*8 

 20-8 



74*4 



Extra-fat 

 sheep. 



Per cent. 



6-o 



22'2 



71-8 



Store 

 pig- 



Per cent. 



3*8 

 19-1 



77'i 



Fat pig. 



Per cent. 



2*9 



20-3 

 76-8 



Means. 



Per cent. 



4-96 



21-23 



73*8i 



When F = 50 the percentages are just half those shown in the table, and these 

 are approximately the limits. 



It appears, therefore, that the composition of the increase may vary very 

 widely. The percentage of fat in it may be zero, or even a minus quantity, but 



1 Bull. 28, U.S. Dept. 0) Agric. 1906. 



44 



