240 JOFRNAL OF THE DEPARTMENT OF AGRICULTURE. 



meal; three or four ounces per head per day, or more (^ to 1 lb.) if 

 lamziekte is rife, and it is necessary to reduce the craving quickly. 

 Testing should be carried out as a matter of weekly or fortnightly 

 routine during the most dangerous part of the year, in order to sort 

 out the animals which develop craving later, and readjust the ration 

 of bone meal for those which are losing pica. 



Since the toxicity of carcass material is usually at its worst 

 during the _ period of the droughts, i.e. in the spring and early 

 summer, this is the time when it is most essential to control craving. 

 In the winter, when overlooked carrion is less toxic, it may be found 

 cheaper to take a small risk th'an to feed expensive bone meal, even 

 if the craving is markedly present. As mentioned earlier, we- shall 

 probably be able to introduce a cheaper substance for reducing 

 craving, but meanwhile the farmer had better stick to bone meal as 

 such, and remember that the more thoroughly he cleans his farm from 

 carcass material the less necessary does the supplementary bone 

 feeding bpcome. 



At this point it should be emphasized that the expense of bone 

 meal feeding should not be debited wholly against protection from 

 lamziekte. A bone meal ration improves the condition of the cattle 

 of the lamziekte areas most markedly, and the farmer will generally 

 find that the increased price he gets for the beasts he puts on the 

 market will more than pay the cost of the bone m'eal. The difference 

 in general thrift, glossy skin, and sleekness of appearance, may well 

 add a pound or two to the cash value of an animal. 



Reverting again to the nature of pica, we may explain that we 

 regard abnormal craving as a nervous disorder which may possibly 

 be produced by some injurious constituent of a diet as well as by lack 

 of a necessary constituent, and perhaps even occur as a secondary 

 condition in other maladies. In passing, it may be again recalled 

 that extreme pica may be manifested not only towards the phosphates 

 (bones) which are lacking, but towards anything at all — the white- 

 wash of a wall or the wire of a fence. 



The wool-eating of sheep, for instance, is a form of abnormal 

 appetite which need bear no relationship to phosphate deficiency — 

 a type of deficiency to which sheep are less susceptible than cattle, 

 and which therefore does not manifest itself as bone-eating. And it 

 may be further added that, with cattle, any circumstance which 

 upsets the beast may temporarily reduce its craving ; a railway 

 journey, a sudden change of diet, an attack of diarrhoea, or the per- 

 manent low health of semi-starvation. This is a circumstance which 

 must not be lost sight of in experimental work. The best conditioned 

 animals are also usually those which show the worst craving, and as 

 cattle fall off in condition they tend to lose craving. It is a common 

 wail of the farmer tliat he loses his best beasts from lamziekte, while 

 the poverty-stricken weeds most frequently escape. 



We Inay now make a few comments on the fifth link of the 

 etiological chain, upon which we are stringing the discussion. 



Composition of Veld Vegetation and Soil. 



We have_ just stated that we believe, tentatively at least, that the 

 main factor in the production of osteophagia concerns the lack of 

 phosphorus in the vegetation. This, however, does not exclude an 

 influence of other variations in the composition of the veld grasses. 



