BUSH-SICKNESS

New Zealand Herald, Volume LXXVI, Issue 23338, 5 May 1939, Page 16

BUSH-SICKNESS

MINERAL DEFICIENCY CAWTHRON INSTITUTE TESTS USE OF IRON-FREE EXTRACT BY OUIDIItK An exhaustive test, extending over the two years from November, 1935, to November, 1937, was conducted by H. 0. Askew, of the Cawthron Institute, Nelson, to discover whether other deficiencies than cobalt were responsible for the "bush-sickness" which affects stock at Clenhope, Nelson. Tho experimental sheep, 25 wellgrown hoggets, wore divided into five equal lots, one being retained as control and the remaining four lots being drenched weekly. The first received a 50 c.c. dose of hydrochloric acid, tho second an acid extract of Nelson soil, the third an iron-free extract of Nelson soil and tho fourth lot a drench providing eight m.g. of cobalt which contained 1 per cent of nickel. Result in a Year o At the end of tho first 12 months the controls, as well as lot one, receiving hydrochloric acid, had all developed or died of bush-sickness; those receiving soil extract, iron-free extract and cobalt all remained healthy during the two-year' test, but lots three and four, receiving iron-free soil extract and cobalt respectively, did best and continued growth, and put 011 weight approximately at the same rate. From graphs illustrating their progress, there was 'very little to chooso between these two lots, but the experimenter states in his report that "throughout tho trial the group receiving the iron-free extract was tho best, the cobalt group came next and, the soil-extract group last of tho three." This suggests that there may have been some mineral factor in the iron-free soil extract, additional to cobalt and nickel, which benefited the stock. Analysis of Blood An analysis of the blood of all groups, including controls, did not reveal any deficiency of iron in the blood, although the gums and skins of sheep affected with busii-sickness displayed the pallor usually associated with anaemia. At the end of tho period of trial two sheep from each of the remaining three groups were killed and their livers analysed for cobalt and copper content. There was very little difference in the cobalt content of any of the livers; those from the iron-free soil extract 0 roup had the lowest content, 0.05 p.p.m.; tho soil-extract group. 0.06 p.p.m.; and the cobalt group, 0.08 and 0.09 p.p.m. The copper content of the livers showed considerable variation, but gave no indication that copper plays an important part in bush-sick-ness, and indicated that in the pastures where the tost took Pj acc there was an abundance of copper for health. The experimental indications arc that cobalt is the principal if not the only element in deficient supply, but that there may be some other element, which is not copper, iron or nickel, but which was present in tho iron-free soil extract, which .made it superior to tho cobalt drench. ____