The Causk and Prevention of Lamziekte. 237 



DuriDg- the period of initial high craving, hay cut from the 

 gja^iing areas showed the very small proportion of 0.08 per cent, 

 phosphoric oxide. During the period of rapid growth after the rains, 

 the young grass showed 0.56 per cent, of phosphoric oxide, or seven 

 times as much. During' the period of lowest craving the phosphorus 

 content remained fairly high, and as the craving rose again the 

 percentage of phosphorus in the grass steadily fell. By 15th January 

 it was down to 0.18 per cent, phosphoric oxide. 



The poor response of the craving curve to the second rains is 

 explained by the fact that the ageing vegetation, though green and 

 fairly luxuriant, remained low in phosphorus; the older plants con- 

 iaining propoitionately less than tlie young spring shoots. 



The phosphorus curve and the pica curve are roughly iiiveise to 

 one another, and up to the date of the last analysis the bone-eating 

 increases as the phosphorus in the grass diminishes. It is too soon 

 to sa}' how rigorous the relationship is, but the general trend is 

 borne out by facts obtained from other experiments. 



Generally speaking, a liberal mixed ration rich in phosphorus 

 reduces the craving fairly quickly, though much depends upon the 

 components of the mixture ; and a single ration of Avheat bran con- 

 taining 2 per cent, phosphoric oxide reduces craving in grazing 

 animals in a few weeks, when fed at the rate of about 2 lb. per day. 

 The quantity of bran required appears to be roughly proportional to 

 its phosphorus content. Curiously enough, however, lucerne hay of 

 phosphoric oxide conteiit 0.5 per cent., fed at the rate of 10 lb. per 

 day over a period of six weeks, did not reduce craving in a batch of 

 ten gra55ing animals ; although the absolute phosphorus intake was 

 just as high as in the case of the bran-fed cattle. This observation 

 requires repetition and elucidation, but meanwhile suggests that it 

 is not only the actual proportion of phosphorus which is important, 

 but also the balance of other constituents in the mineral matter of 

 the plant. This is a complicated question and may therefore be 

 left for discussion in a more technical paper. 



It would appear that craving can be removed bj- almost any 

 phosphorus compound, provided it is assimilable and convertible 

 into the form of phosphate. Bone meal, the obvious preventive for 

 bone craving, generally reduces pica almost to zero within a month 

 when fed at the rate of about 4 ounces per head per day, although 

 the quantity required varies throughout the season and is larger with 

 some animals than with others. As soon as the bone meal is with- 

 drawn the craving begins to return, and in the course of a fe^\ weeks 

 comes back to the percentage shown by grazing controls. The winter 

 craving requires rather more bone meal for reduction than does the 

 summer craving — a fact correlated with the phosphorus content of 

 the vegetation. With cows, heifers, and young oxen, a craving 

 removed by bone meal returns rather more rapidly after cessation of 

 dosing than in the case of working oxen. A very heavy ration of 

 bone meal of about 1 lb. per day may sometimes reduce the craving 

 to zero in one or two weeks. If lamziekte is bad, therefore, large 

 quantities (^ lb. to 1 lb.) should be given until the osteophagia 

 subsides. 



Calcium phosphate can take the place of bone meal, and this 

 compound is quantitatively superior to bone meal if fed as precipi- 

 tated calcium phosphate, but inferior if fed as ground minera} 



