RECENT WORK ON IRON – STARVATION IN OTHER COUNTRIES.

New Zealand Journal of Agriculture, Volume 43, Issue 4, 20 October 1931, Page 270

RECENT WORK ON IRON - STARVATION IN OTHER COUNTRIES.

B. C. Aston,

Chief Chemist, Department of Agriculture

Two important publications which bear directly on the “ bush sickness ” malnutrition disease in ruminants have come recently to hand, and, confirm the opinion that the trouble is not confined to New Zealand, but occurs on soils of coarse texture in the volcanic-ash country of Kenya Colony and on the non-volcanic sandy soils of Florida, U.S.A. There is little doubt that both diseases are identical with bush sickness.

Dr. J. B. Orr, Director of the Rowett Research Institute, Aberdeen, and Mr. Alexander Holm, Director of Agriculture in Kenya, in the Sixth Annual Report of the Committee on the Mineral Content of Natural Pastures to the Economic Advisory Council’(H.M. Stationery Office, London, 1931, is.) describe the symptoms and surrounding-con-ditions of “ nakuruitis,” a wasting, disease in cattle called after the name of the district Nakuru, in Kenya Colony, where there is a welldefined' area in which cattle do not thrive, a fact first noticed in 1914: The top-soil of this country consists of material which has been erupted from the adjoining extinct Menengai volcano.

The veterinary officers of Nairobi;. British East Africa, in 1918 brought under this Department’s notice the occurrence of this peculiar condition affecting sheep and cattle when grazed on volcanic soils in that Protectorate similar to, if not identical with, they thought, bush sickness as described in the New Zealand reports. They found:that the disease could not be communicated to healthy animals by transfusion of .blood experiments, there was no indication of the cause of death, and no parasites were seen, advanced anaemia being the only symptom discoverable on post mortem examination; Affected animals when transferred to other country known to be healthy recovered, and no cases had been recorded among horses. It. was also reported that the general opinion among farmers was that the disease occurred only on soils of volcanic origin, the affected animals recovering on being moved to nonvolcanic soils, and that cases never occurred on red soil-(redness in soil is always due to iron oxides). The disease seemed to be well known by the Native population in the Masai Reserve. .

Orr and Holm, after referring to the New . Zealand work and the theory that bush sickness was due to a lack of iron in the pasture, give in the above-mentioned publication a precise account of the experiments they undertook with a number of oxen (124) which, except a control group of thirty-one, were allowed access to different salt-licks, all of which contained iron oxide in varying proportions. It may be briefly stated that these experiments lasted from November, 1926, until October, 1927, at which date all the control animals still living- which had-received no iron lick and that group which only received a small amount of iron lick were so weak and emaciated that it would have been difficult to save the lives of any of them; The group of cattle having received an intermediate quantity of iron were intermediate in condition and weight between those which received a smaller .amount and those which received a large amount. Those which received the highest

amount of iron were in the best condition and weight, being an exceptionally fat and healthy lot. These authors therefore conclude that the feeding of salt and iron oxide prevented the onset of this disease, and was found to effect a cure in cases which were not too far advanced.

Reports have since been received that this method of prevention has been applied on several farms and has been found successful, oxen having been kept in good condition for at least a year, whereas, without the use of this simple salt-lick, it was impossible to keep them in good condition for longer than six months without changing them to another district.. This result, say the authors, should be regarded as confirmation of the valuable results obtained in New Zealand as the result of many years’ laborious research on a disease known as “ bush sickness ” which appears to be of the same nature as “ nakuruitis.”

Bulletin 231 of the University of Florida Agriculture Experiment Station, Gainseville, Florida, published in June, 1931, contains an account of “ salt sick,” which the authors, Drs. Becker, Neal, and Shealy, say is an age-old problem with Florida cattle-grazing, on certain types of soils both on the range and in fenced areas. It is the greatest single cause of loss to the cattle industry in the State because of the greatly reduced calf-crop, retarded growth, and reduced beef yields per acre. Many animals die of the condition. Changing cattle back and forth from “ salt sick ” to “ healthy ” ranges lowers efficiency and utilization of the forages. On large areas cattle are no longer raised because ” they just won’t live on this land.”

Although investigation work had been going on in Florida at this Station for over forty years, the experts do not seem to have got on the track of the cause until recently. The authors say investigation of “ salt sick ” at the Florida Station has proved this condition to be a naturally occurring nutritional anaemia in cattle the feed of which has been restricted largely to grass forages grown on certain white and grey sandy soils, and residual muck and peaty soils not subject to overflow from more fertile watersheds. It was found that forage plants grown on these soils contain less of iron, or of iron and copper, than those from more fertile areas. When affected cattle were given iron and traces of copper to supplement these forages the condition was overcome in all but most advanced cases.

A number of illuminating photographs in the bulletin show cattle with the characteristic appearance of that known here as “ bush sickness.” A cow treated daily with 3 oz. of a 6-per-cent. solution.of ’ferric ammonium citrate as a drench recovered fully, and the blood from containing only one-third the normal amount of red pigment returned under the treatment to ; that of normal composition. For range cattle the bulletin recommends a lick containing salt, iron oxide, and a little copper sulphate. In advanced cases, the authors advise the New Zealand treatment of ferric ammonium citrate to which an amount of copper sulphate* has been added. They promise further details about this interesting condition in cattle in the next technical bulletin on the subject issued by the Station.

An interesting, statement of the bulletin under .notice that swine are affected with salt sick ” in. common with the ruminating animals cattle, sheep, and goats proved to be correct will help to strengthen the opinion that bush sickness is a . pure deficiency disease. There has always hitherto been a suspicion that bush sickness was confined to ruminants and due in some way to the difference in the digestive system of this class of animal compared with that of other classes, but if swine are susceptible it will do much to support the iron theory and rationalize the treatment. Swine are known to be particularly susceptible to conditions favouring anaemia, but eat copiously of iron-containing substances when allowed, such as earth, cinders, rock, &c., and so may better cope with any deficiency in the pasture. These researches emphasize the fact that other countries are taking advantage of original, work done in New Zealand and are adapting the treatment of ruminants in deficiency areas to accord with the new knowledge, also with the expenditure of a very small outlay few pence annually per head of stock —are farming large tracts of land which have in the case of Florida, presented, as the Americans phrase it, an age-old problem. It must also be remembered that in the Cheviot Hills, between England and Scotland, sheep-farming presented the same problem as it does in our bush-sick areas, and that the disease there known as “ pining ” excited the interest of the poet Hogg ( . The Ettrick Shepherd ”) so long ago as 1807, when he accurately described the symptoms which are exactly those of bush sickness, in sheep. There is reason to believe that iron starvation in ruminants is not confined to soils derived from acid volcanic rock, but may be found in any sandy soils or soils abnormally coarse in texture where animals cannot benefit by a change to finer soil on the same farm. The New Zealand investigation did not last so long as that in Florida (forty years), since it was only started in 1900 and the first evidence that deficient iron was the cause was published some twelve years later (this Journal, August, 1912, p. 124). The New Zealand farmer has, however, paid in more ways than one for the knowledge gained in the treatment of bush sickness during the past twenty years, and he should be the first to profit by the discoveries made in New Zealand, Either the carbonate of iron or the hydroxide of iron in ground condition suitable for making into a stock lick is now on sale at the Rotorua office of this Department, and the farmer only requires to' purchase elsewhere the salt to mix with the iron, the total cost of this treatment only being a few pence per animal yearly. Either the hydroxide or the carbonate has proved to be particularly suitable for' making a lick for sheep, for which the citrate is not so suitable. The advantage of the hydroxide and the finely-ground carbonate of iron when used mixed with salt as a stock-lick is that sheep are found' to take these forms of iron, while they generally refuse to take the citrate of iron and ammonium under the same conditions.

* Copper is not required in New Zealand " bush-sick ” districts, where it exists in plants in the soil and herbage in adequate amounts.

Note. Where large quantities of the hydroxide are required the charge for |-ton lots and over will be ss. 6d. per hundredweight, and for lesser quantities 6s. per hundredweight, plus, in each case, the freight from Ruatangata, which must be paid in advance when consigned to flag stations.