128 THE SCIENTIFIC FEEDING OF ANIMALS 



protein, 4.0 per cent crude fat and 36.6 per cent mineral matter or ash. 

 It is eaten readily by, and agrees well with, swine and cattle. 



Bone feed meal, phosphate of lime feed or precipitated phosphate of 

 lime, is a by-product of the manufacture of glue from bones. The bones 

 are cleaned and ground and the salts are extracted with hydrochloric 

 acid, precipitated with milk of lime and dried. The powder thus ob- 

 tained is called bone feed meal. It contains about 38 per cent of phos- 

 phoric acid, of which 90 per cent is citrate-soluble. It is white or yel- 

 lowish white in appearance, odorless, and is composed, chemically, of 

 dicalcium and tricalcium phosphate. The dicalcium phosphate is readily 

 soluble in citric acid. It is therefore an index of value, and the amount 

 present should be given in the manufacturer's guaranty. These prepara- 

 tions should be free from toxic substances, especially sodium fluorid, 

 which, in recent years, has occasionally been found present to the extent 

 of from 4 to 5 per cent. It has caused serious poisoning. 



Other substances besides those just mentioned are now and then put 

 upon the market. They consist mainly of tricalcium phosphate, are 

 therefore hard to digest and of low value (degummed bone meal, bone 

 ash, ground mineral phosphate, etc.) 



The experiments of Koehler throw light upon the digestibility or as- 

 similability of some of these salts. Of dicalcium phosphate 55 per cent, 

 precipitated tricalcium phosphate 37 per cent, degummed bone meal 13 

 per cent and bone ash 14 per cent are assimilable. 



Cock chafers or May hugs {Melolontha vulgaris) in seasons when 

 they are plentiful are used as feed for swine. To prevent invasions with 

 Echynorrhynchus gigas, of which the grub of the May bug is the inter- 

 mediate host, it is advisable to boil the "bugs" (beetles) before feeding. 



XL Substitute Feeding Stuffs 



Most of the substitute feeding stuffs have already been referred to 

 and discussed in the preceding chapters. A few additional substances of 

 this character are mentioned below. 



Sea algae. — Sea wrack or seaweed (Fucus serratus, closely related to 

 the widely prevalent F. vesiculosis) and Laminaria flexicaulis (kelp or 

 devil's apron, the fronds of which commonly grow in clusters and are 

 sometimes 30 to 50 feet in length) have been successfully used in feed- 

 ing experiments* with horses (Sauvageau and Moreau). Many Lam- 

 inaria are rich in mannite and are used as food by the Chinese and Jap- 

 anese. Horses do not like them at first but become accustomed to them. 



Dog biscuits before the war were made from poor-grade wheat flour, 

 coarse oat and corn meal, beets, slaughterhouse refuse and American 

 tankage, and contained on the average 9.5 to 10.5 per cent of water, 2.5 

 to 3.9 per cent of salts (phosphoric acid 0.6 to 1.2 per cent), fat 3.3 to 4.1 

 per cent, crude protein 10.5 to 22.7 per cent and nitrogen-free extract 

 60.6 to 66 per cent. These analyses have only a relative value, since the 

 crude protein and crude fat content could easily be supplied with low- 



