BUSH SICKNESS

Rotorua Morning Post, Volume 2, Issue 547, 2 June 1933, Page 7

BUSH SICKNESS

WITH PARTICUJLAR REFRENCE TO THE LIMONITE TREATME3^T.; No. 2. Mr. C. R. Taylor, of the Agricultujral Department, Rotorlma., comtnibutes a series of valuable articles to the "Morning Post" upon bush' sickness. They will be found well worth following by farmers. Bush sickness appears to be worse in some seasons than others; again this is largely a matter of climatic conditions. As a result of long and careful observation I have noticed it bad in very wet seasons and equally troublesome in seasons of prolonged drought. Excessive rainfall washes the soluble iron down into the subsoil, well out of reach of plant roots, with the result that pia.stures at this time are more deficient in this element, thereby causing bush sickness to appear. more epidemic than usual. In droughty seasons the means of conveyance of plant food to plant roots (moisture) is absent, and 'So a similar deficient condition of the pasture is brought about. Moreover, atmospheric oxygen has, for obvious reasons, a far hetter chance of oxidising the soluble iron, for which it has a great afnnity, into soluble form, and consequently the pasture plant and the animal grazing thereon is further robhed of this essential element which is only present in minute quantities under the hest of conditions. Everything possihle should he done to conserv.e this small amount of soluble iron and consolidation of the ar,ea hy means of rolling and adequate stocking, coupled with the encouragement of a good tight sole of grass will go a long way towards this resirable end, as it will tend to make surplu? rainfall run off the surface into natural watercourses r.ather than percolate through to the subsoil carrying with it soluhe plant food, which is seldam, if ev.er, recovered. Regular phosphatic tQp-dressing is also of eonsiderable henefit in mitigating any harmful effect that might possibly he exerted by manganese compounds on the soluble iron.

Interesting Experiment. Ha.ving briefly touched on the distribution of bush sickness iand the main points leading up to the department's conclusion as to the cause of it, I will now give an outline of a sheep experiment inaugurated in 1931 on the property of Messrs. Hill and Sons, Atiamuri, to demonstrate the possibility of overcoming the trouble in a simple, efficient and practical manner at little cost to the farmer. 1 might ,add that the experiment is still being proceded with. The Whangapoa station was chosen for the following reasons:— (1) Typical of the majority of the farms situated on the Taupo shower; (2) sufiiciency of stafi! to ensur.e the proper carrying out oi the expeiiment, which is most important; (3) a long -and consistent record of lamb mortality due to bush sickness; and (4) its geographical situation allowing farmers from affected districts to view the experiment without undue inconvenience. In May, 1931, 150 four- and sixtooth ewes were chosen as being thoronghly representativ.e of a flock of well over 1000 breeding ewes. These were divided at random into three groups each of fifty ewes. All group'S grazed the same set of five paddocks in rotation, thus eliminating any possihle ladvantage derived from dift'erence in grazing. The only1 difference was in the mineral lidks each received. Gronp 1 was used as the control and received nothing in addition to an ordinary pasture diet; Group 2 received in addition to an ordinary pasture diet a mineral mixture consisting of salt, >and a small amount of the double eitrate of iron and ammonium (commonly known amongst farmers as iron eitrate) ; and Group 3 received in addition to an ordinary pasture diet a mixture consisting of 50 per cent. salt and 50 per cent. hydrated iron oxide, or limonite. Each group was oarefully weighed at the commencement of the experiment and thereafter every month. The average difference in individual weight hetween the control group -and the limonite group, to begin, was only eight pounds in favour of the limonite group, but by Mareh, 1932, after a lapse of ten months, the difference had increased to 561b. No. 2 group, or wh'at we term the eitrate group, would not take kindly to its mineral mixture iat all, only a few out of the 50 partaking of its with any apparent relish, so that for all practical purposes it really constituted a second control group. The reason for this dislike of the mixture was undoubtedly due to the hitter flavour imparted to it by the double eitrate of iron and ammonium. Limonite, it should he noted, has no characteristic flavour, and leaves the salty taste of the mixture quite unchanged. This is a most important advantage it possesses over other iron compounds, especially where the automatic administratiqn of the element to stock is concerned. Limionite Successful.

The control group gave birth to 3b per cent. of lambs, the eitrate group 76 per cent., and the limonite group 100 per cent. By the end of February, 1932, all the lamhs in the control and eitrate group were dead. At this period 45 limonite lamhs were alive and doing well, their average live weight being 781b, which may he re-. garded as highly satisfactory. On [ Atigust 20, 1932, these lamhs5 were again weighed, this time going just over 1001b. The five deaths recorded were all due to lamhs hecoming bogged in swamps and in no way was their death associated with hush sieknjcss. This year • we • are breeding from the •> ewe lamhs of -this :grOup, now hoggets, the wethers having been sold as fats only a. few months back — th'e first time such a' 'thing has been achdeved on this station.' in-, 12'y'ears of farming experienee. - ; - i- V * v It is now neeessary to go back a / few months to see how the ewes fared. On February 24, 1932, in the control group, 11 ewes were. hlive out of, 50; in- the eitrate group, 17 ewes were alive out: -of 50;; and in the limonite group1 45 ewe^ were •alive>'0ut- ofiifi.0. The following month, to save- further

unnecessary loss to the owners, it was 5 decided that the remaining ewes in | the control and eitrate groups, by ! now in a very weak and emaciated ' condition, should be given Group 3's ; limonite mixture in the hopes that a cure would be effected in th'ose cases ! not too far advaneed. With the ex~ ception of ahout half a dozen all the others fully recovered and developed into quite! useful sheep again. They were then admitted to the flock ewes, their period of experimental useful- | ness having passed, it having been proved that limonite was not only a ; preventivfe, but a cux!e of) bush sickness. The limonite group was oarried on for another twelve months to see if a second crop of healthy lamhs could be obtained, but it was unfortunate that limonite from a deposit in Nelson was then being used in place of that obtained from Whangarei1 Used in the previous year and this proved disappointing, in that several lambs slipped back in condition quite appreciahly by Christmas time. It was immediately decided to revert once again to the use of Whangarei limonite, and I am pleased to be ahle to s-ay that the majority recovered and are now quite norma!. But for1 this

misadventure, which ds liahle to happen in experimental work of this nature, I am confident that our second lambing would have proved every hit as successful as the first. As it is, we still have a. large percentage of very fine lamhs that would command favourable notice in any district. Last season the limonite lamhs clipped ian average individual fleece of 11.51b, whilst the limonite ewes averaged 8.6 1b. These figures are well ahove the average for the Rotorua district and compare more than favourably with the clip from the hest sheep lands in this Dominion. Limonite is a hydrated form of iron oxide and it is thought the degree of hydration influences the assimilability of its iron content in the animal's stomach in much the same way as it is known that certain factors interfere with the availability of soil iron to the plant. If this is so, great care will have to he exercised in the selection of iron ore deposits for lickmaking purposes, as iron, usually in comhination with other suhstano'es, occurs in nature in a variety of forms such as limonite, haematite, magnetite and spathic iron ore or iron carhonate, and only a few of these exist in ia state ahle to he utilised hy the animal to its advantage. Happily, there are hundersd of thousands- of tons of proven material in the Whangarei 'district alone, so that a shor-t-age is not likely to occur for many years. From the foregoing, which is necesaarily brdef, and the experienee in Kenya Colony, it is ohvions that ample evidence has heen provided of the efficacy of limonite as a means of keepdng sh'eep, lamhs, and cattle heasts in a healthy and profitaible condition on bush-sick country and iat a cost well within the reach of every farmer. For sheep, the cost per head per year worked out at 5id, -and for cattle ahout ls. This small expenditure on a minerial supplement often represents the difference between a dead lamb and one fit for the freezing works; between ia s'ick cow producing only a pint or two of rnilk per day and one in perfect health producing as many gallons. In other words, a divi-dend-paying investment. In conclusion, I have no "hestitatdon in saying that the circumstances th'at has held in check the progress of what is commQnly spoken of as the pfim'ice country for sa long is no longer to be feared if farmers will; only make as regular a practice of giving limonite to thedr stock as they give.'ttop-pressing to their pastures.