SCIENTIFIC RESEARCH

Nelson Evening Mail, Volume LXVI, 13 August 1932, Page 11

SCIENTIFIC RESEARCH

IRON IN DELATION TO SHEEP CAWTHRON INSaWIiS'E'S' EXPERIMENTS; COMMENDATION, FROM GREAT BRITAIN A letter in “ixature,” published in London on 25th June by Mr A. T. King, Chief Chemist to the Wool Research Association at Leeds, comments on “a series of important papers,” dealing with bush-sickness by Mr T. Rigg and his colleagues at the Cawthron Institute, and the bearing of the investigation on nutritional problems in connection with wool growth. The leteter contains much of a technical character, and at the request of the Trust Board, the Director of the Cawthron Institute, Professor Easterfield, lias supplied a more popular statement. BUSH SICKNESS The results commented on by Mr King said Professor Easterfield to-day, are the outcome of certain phases of a soil survey of the volcanic districts of the North Island, undertaken by Mr Rigg and Dr. Askew, of the Cawthron Institute, at the request of the Department of Scientific and Industrial Research, which h.as also borne the cost of the investigations. In,the districts mentioned very large areas are subject to a stock disease known as bush-sickness, which affects both sheep and cattle, and renders the land unsuitable for stock raising, though the soil is by no means infertile. The Cawthron experiments support the view put forward by Mr B. C. Aston many years ago that bush-sickness is a deficiency disease due to a lack of iron. This view has met witha good deal ot opposition, and fact which has been quoted against the iron hypothesis is that stock placed on a ploughed paddock free from vegetation in a non-bush-sick area and fed upon fodder railed daily from land known to be bush-sick failed to develop the malady. Mr Rigg and Dr. Askew have shown, however, that the soil swallowed with the fodder is an important source of iron to stock and that the form in which the iron exists in the soil is as important as the actual quantity of the iron. In all bushsick soils examined the amount of “available” iron was very low. On the above mentioned ploughed paddock in the healthy area the sheep would not only ingest a larger quantity of soil than on the ordinary sward in a bush-sick district, but the soil ingested would contain a larger quantity of available iron. It is interesting that the available iron in Moutere Hills soil is sufficient in quantity to prove of some value as an iron lick to sheep on certain bush-sick paddocks on granite wash near Glenhope.

“INTERESTING INTERPRETATION” Commenting on the results Mr King makes the following statement: From these investigations emerges the startling but apparently unassailable conclusion that ingested soil is an absolutely essential supplement to the pasturage, which in itself, in clean condition, is definitely iron-deficient in all these sheep-rearing .areas. The habit of the sheep of ingesting soil has thus provided Mr Rigg with an interesting interpretation of the incidence of the similar “pining” sickness of the Cheviots, which was unknown when the land was overrun with moles, hut made its appearance when the moles were exterminated.” Continuing, tlie Professor said it was Hogg, the Ettrick shepherd, who one hundred yearn ago drew attention to this remarkable fact—he stated that it was his opinion and the opinion general amongst shepherds that the extirpation of the moles was the primary cause of pining or vinquish, the most destructive and ruinous disease amongst sheep at that time in the South of Scotland. How the extermination of the moles could have been the cause of the trouble has hitherto seemed inexplicable, but those who have seen the rapidity with which moles can throw up the soil and subsoil into mole hills in English pastures will readily appreciate the extent -o which these hillocks can act as a source of soil contamination to the pasturage, thus providing an iron ration for the stock.

WOOL AND IRON Iron also appears from the Cawthron experiments to have an important bearing upon wool production. It is a fact well-known fo chemists that wool contains a good deal of sulphur, and that the sulphur is present as a complex compound known as cystine. It has even been stated by a well-known authority that cystine in the fodder is the sole source of the wool sulphur and that the supply of cystine is the limiting factor in wool production. A fact which appeared to spport this claim was that in certain Australian experiments a lick of dried i blood, which is known to contain cystine, ! mused a notable increase in wool production. On this point Mr King quotes Mr Rigg’s own comments. “An interesting ' and unexpected result was the great improvement both in growth and in lustre and elasticity of the new wool grown alter administration of ferric ammonium citrate. It seems possible, _ therefore, that “iron” plays some special role in wool growth. It is possible that the wonderful results in increased wool growth obtained through the provision of a “lick” of blood meal in the Meteor Downs experiment in Queensland may be due partly to the iron content of the blood meal (approximately 0.2 per cent.)? Tt does not seem probable that the great increase in wool growth (averaging 20oz per sheep) was wholly due to the small amount of cystine administered in this way.” SWEEPING CONCLUSION Mr King then states that the sweeping conclusion is evident that the view hitherto widely accepted, which regarded cystine supply as the essential limiting factor in wool production, is now definitely exploded and that the various attempts to influence wool growth directly by the administration of cystine rich fodder were foredoomed to failure. In '■■ding his letter he pOinte out the necessity of carefully examining the data of the nutrition experiments before recommendations are made to pasturalists on nutritional methods of improving the growth and quality of wool. The subject of wool production opens a wide and inviting field of investigation to the well trained scientific worker. The problem may be attacked from many angles and its importance to New Zealand need hardly be stressed. It is not too much to expect- that at the Research Farm now being established by the Cawthron Trust at Stoke, under the will of the late Mr J. W. Marsden, data ' will be collected which will contribute in lio small measure to the solution of the -lifficnltios attending the production of wool of the highest quality.