John Hamiviond 405 



table it will be seen that 100 lbs. of growth in live weight from birth to 

 3 months consists of 74-3 lbs. carcase, 5-8 lbs. pluck and 19-9 lbs. 

 alimentary canal, etc. whereas the same weight put on between 9 and 

 11 months consists of 94-5 lbs. carcase, 3-2 lbs. pluck and only 2-3 lbs. 

 aUmentary canal, etc. 



This difierence in the relative composition of the increase between 

 animals of young and old ages should not be allowed to detract from the 

 relative economy of meat production at early ages in general, but points 

 to the conclusion that where ywfing animals are being killed for meat it 

 is very essential to use an early maturing breed in which the age changes 

 are hastened. 



Data have been collected from various authorities on the Carcase 

 percentage of pigs of different live weights and are given in the table 

 below : 



It will be seen that there is a considerable divergence of opinion as to 

 the dressed carcase percentage at different weights, which may be ac- 

 counted for by differences in breeds and modes of dressing, but all agree 

 that it increases with the rise in live weight. Whether this increase is 

 a function of the age or of the hve weight should be made clear. 

 Henseler(48) has shown that it is due to the latter; he took two pigs 

 from the same Htter — one was fed well and the other starved, both being 

 killed at the same age, but at very different live weights. The well-fed 

 pig gave a carcase percentage of 87 per cent, and the starved one only 

 73 per cent. Under ' Correlation ' (below) it is shown that the carcase 

 percentage within any one breed increases with size independent of age. 



That the carcase percentage will increase with age if the size is kept 

 constant (by controlled feeding) would appear doubtful, since increased 

 carcase percentage is brought about by the growth of muscles, fat and 

 bones which attain their maximum rate of development late in life. 

 When variations due to conformation and differential rates of growth of 

 tissues in the different breeds are considered however it will be seen from 

 Table VII that the carcase percentage may be independent of size : for 

 example. Large Blacks of 5 months old weigh some 20 lbs. heavier than 

 Middle Whites, but while the former have a carcase percentage of 74 per 

 cent, the latter kill at 77 per cent. 



27—2 



