COMPOUNDS OF NUTRITION 37 



It is very evident that, in general, considerably more 

 than half of the weight of the bodies of our domestic ani- 

 mals consists of water, the limits observed in all species 

 and conditions here mentioned being 42.3 and 74.2 

 per cent. 



47. Variations of water-content of animal bodies. 

 The percentage of water varies with the species, age, and 

 condition. Swine carry a notably small proportion. The 

 calf's body, even though fat, is comparatively watery. 

 It is very noticeable that with oxen, sheep, and swine the 

 lean animals contain a much larger proportion of water 

 than the fat. This does not necessarily mean that in the 

 process of fattening the fat is substituted for water, and 

 so expels it from the organism, but that the increase has 

 a much smaller percentage of water than the body in its 

 original lean condition. This is well illustrated by the 

 data from two independent investigations at Rothamsted 

 and at the Maine Experiment Station. The former investi- 

 gation showed that when swine, sheep, and oxen were 

 fattened the increase contained from 20 to 24 per cent 

 of water, this being half the proportion found in the entire 

 bodies of the lean animals. The Maine Station results 

 established the fact that in the increase of two steers 

 from the age of seventeen to twenty-seven months, dur- 

 ing which time a fattening ration was fed, there was 42 

 per cent of water, the bodies of the younger steers hav- 

 ing 58.2 per cent. It is a common remark among unscien- 

 tific people that beef from mature animals "spends" 

 better than that from young, the same observation being 

 made in comparing lean and fat beef. Modern investiga- 

 tion shows clearly that the reason for this lies partly in 

 the difference in water-content. Dry matter, and not 

 water, is the measure of food value. 



