The Cause and Prevention of Lamziekte. 239 



possible. Ten cravers sent from Armoedsvlakte were placed on a 

 balanced ration until the craving had disappeared and were then 

 switched over on to this phosphorus-low synthetic ration, derived 

 wholly from products of a non-lamziekte area. The craving was 

 slowly reproduced. This evidence, taken together v\-ith the Armoeds- 

 vlakte tests and the phosphoric acid experiment, affords strong- 

 support for a straiglitforAvard ])hosphorus-deflcien."y theory for the 

 explanation of osteophagia. 



If tbis view is valid and we can call osteophagia a mild deficiency 

 disease, we have a very interesting instance of a physiological abnor- 

 mality which in itself is of no particular consequence, but which is 

 of enormous importance as a link in the etiological chain of a truly 

 devastating disease. It is perhaps difficult to understand how cattle 

 can grow to maturity, reproduce their kind, and complete the cycle 

 of their being as fat well-conditioned beasts, when the veld is deficient 

 in a constituent essential to their metabolism. We would expect the 

 "law of the minimum " to hold, and a minimum of any one necessary 

 dietary factor to control the growth of the animal. But in the spring 

 of this year the weight and condition of the cattle increased most 

 markedly just as the craving became most acute. The fact must 

 simply be that these lieasts get more than their physiological 

 minimum, but less than their o})timum requirements; that the veld 

 is not so deficient as to induce real phosphorus starvation, but merely 

 so deficient as to induce a cry for more. Tiiis raises the very 

 interesting question of minimum phosphorus requirements of cattle, 

 the text-book statements of which would seem to require revision. In 

 osteophagia we have an indicator of considerable value. 



It may be emphasized that individual variation of craving in 

 different cattle is very great, and that although liberal feeding with 

 bone meal, bran, or other phosphorus-rich material, will stop pica in 

 the great majority of cases, a few individuals retain their ctraving 

 very persistently and require very large doses of bone meal over 

 extended periods before the osteophagia disappears. Is there in this 

 a tendency for- ciaving to degenerate into habit? Of an animal so 

 losing its fastidiousness as to minimize the distinc-tion between a 

 slightly rotten bone and a wliolly clean ])one? Or can pica liave more 

 than one origin? 



The habit or predilection aspect of the question is of some 

 interest to the farmer's pocket wlien he proposes to reduce pica by 

 feeding bone meal. If bone meal is supplied ad lib. erstwhile cravers 

 will cheerfully go on eating it long after they are reduced below the 

 point at which they would i)ick up dangerous rotten bones, or even 

 bleached bones, from the veld. Sweet bone meal is something of a 

 " delicatessen " even to the perfectly normal beast, and there is the 

 curions fact, Avhich nmy be called the " second bone jjaradox," that 

 cattle which will no longer chew a sweet bone will readily eat the 

 same bone if it is ground ui> 1o a fine meal. 



In practice, therefore, ]K)ue meal should be given on some definite 

 system, so as to keep down the expense. Not all cattle are cravers, 

 and hence it is not necessary to feed the whole herd. The marked 

 cravers, which are most liable to contract lamziekte, can be picked 

 out by periodic testing against sterilized rotten bones in troughs, 

 much in the manner described already. As craving is manifested 

 the bone-eaters can be separated from the others and fed on bone 



