422 A STUDY OF FARM ANIMALS 



by the pigs, but why, the farmer did not know. Prof. Henry, 

 of Wisconsin, early in experimental swine feeding demon- 

 strated that the bones of hogs that had been fed corn alone 

 were deficient in ash, and broke much more easily than those 

 of hogs fed corn and mineral matter. Since then other 

 experiments have clearly demonstrated that minerals are an 

 actual necessity in the diet of swine as well as of other farm 

 animals. If hogs are fed on clover or alfalfa, with corn, 

 they will obtain in the legumes considerable mineral matter, 

 but where concentrates are largely relied upon for feeding, 



Figure 197. Hogs on alfalfa pasture, Oregon Agricultural Experiment 

 Station. Photograph by the author. 



especially corn, minerals in some form are a necessity. A 

 mixture of equal parts by weight of ground limestone, fine 

 bone meal, and salt will make a satisfactory mineral for 

 swine. Various kinds of mixtures are used by different 

 feeders, many of whom also use flowers of sulphur, copperas 

 and salt, for medicinal purposes, in addition to the other 

 minerals used. For brood sows Prof. W. W. Smith recom- 

 mends* a combination of 12 parts charcoal, 3 parts air- 

 slacked lime, ground bone or ground rock phosphate, and 1 

 part common salt. Wood ashes in the same quantity as 



*Pork Production, 1920. 



