238 Journal ob^ thk Department op Agriculture. 



phosphate. Not only the quantity of phosphate must be taken into 

 consideration^ but also its availability. 



Sodium phosphate can take the place of calcium phosphate. 



Pure phosphoric acid is rapidly effective when given either in the 

 drinking' water or in the form of a paste made up Avitli mealie meal. 

 The quantity required per day corresponds roughly to the quantity 

 of phosphorus in an effective daily ration of bran, and 16 to 26 gram 

 (phosphoric oxide) per head reduces craving completely in a few 

 weeks' thne, in all but the most persistent cases. 



Whatever substance be fed, it seems that the common factor of 

 phosphorus must always be present. The behaviour with pure phos- 

 phoric acid indicates that the base in combination is unimportant, 

 except in so far as it affects the absorption and utilization of the 

 comjiound itself. The compromise between " cheapness " of com- 

 pound and " efficacy per unit of phosphoric oxide " has not yet been 

 arrived at, but we hope to get some South African firm to put a cheap 

 easily digestible phosphate on the market. Meanwhile we recommend 

 bone meal as the cheapest prophylactic on sale. Compounds of 

 elements necessary for i^lant nutrition, other than phosphorus, do 

 not reduce pica when fed in excess, noi- does plant ash as a whole. 



vSubstances such as sulphur, salt, iron sulphate, mineral acids, 

 organic acids, arsenical compounds, kerol, glauber salts, aromatic 

 drugs, and other non-phosphatic compounds which have been tested, 

 all failed to reduce craving. Strong acids such as hydrochloric, and 

 bases such as lime, show a tendency towards aggravating the craving. 

 This is probably explicable upon the phosphorus hypothesis; increased 

 urinary elimination of food phosphorus in the former case, and 

 decreased absorption from the gut in the latter. 



Incidentally it may be remarked that a high ratio of lime to 

 phosphorus in the mineral matter of a plant may possibly have a 

 similar eft'ect to a low absolute percentage of phosphorus, and we are 

 yet prepared to substitnte an excess-lime hypothesis for a i)hosphorus- 

 deficiency theory. We do not yet wish to bind ourselves to any one 

 single explanation of the observed facts, but wish to avoid adopting 

 too simple an explanation for what may yet turn out to be a 

 complicated business. 



The fact remains, however, that administration of suitable 

 phosphorus-rich materials has so far proved the only way of reducing 

 craving, while lack of phosphorus appe,ars to be the common factor 

 in the production of osteophagia under various conditions. 



This latter point was illustrated by showing that the vegetation 

 of the lamziekte veld at Armoedsvlakte maintained pica, and could 

 produce pica Avhen fed in stalls either as cut hay or as botanically 

 independent grasses. Thus mixed hay, krul grass {Digitaria 

 eriantha), and besem grass {Aristida uniplum.is) all reproduced pica 

 in cattle in which craving had been previously removed on a balanced 

 ration. But low phosphorus content was the recognizable common 

 factor. 



An independent experiment, designed from the opposite angle, 

 was carried out at Onderstepoort, in an area free from lamziekte, in 

 an enclosure devoid of growing vegetation. A ration of wheat chaff 

 (as coarse fodder), selected as low in phosphorus as possible (0.16 per 

 cent, phosphoric oxide), and Fanko, a flaked maize product (breakfast 

 food) containing only 0.09 per cent, phosphoric oxide, was com- 

 pounded so as to provide as low an absolute intake of phosphorus a^ 



