IODINE DEFICIENCY AND LIVE-STOCK.

New Zealand Journal of Agriculture, Volume XL, Issue 4, 22 April 1930, Page 226

IODINE DEFICIENCY AND LIVE-STOCK.

A PRELIMINARY INVESTIGATION IN THE WANAKA AREA.

1. Goitre in Lambs.

C. S. M. Hopkirk,

Officer in Charge, Wallaceville Veterinary Laboratory, and

C. V. Dayus, District Superintendent, live-stock Division, Dunedin.

Many parts of New Zealand are known to be short of iodine in the soil and water, but this is particularly the case in the Cold Lakes region of the South Island. Nevertheless it is not common to find more than an odd case of goitre in farm animals in the deficient districts. In October of last year, however, one station-owner in the Wanaka area reported the birth of a large number of lambs with enlarged thyroid glands. . The history of the occurrence may be given as follows.

. A flock of 1,400 crossbred ewes was run on 600 acres of flat at the base of a high range of hills. The flats are rich and grow good feed, mainly English grasses and clovers, though cocksfoot tends ,to become dominant over the rye-grass. Winter fodder, consisting of turnips and clover hay, is also grown on these flats, so that animals do not get food which has been grown in another, district, and therefore any deficiency present in the soil is reflected in the pasture and eventually in the sheep. Some 300 of the 1,400 ewes had been brought down from the hills and placed, with the flock one year previously, as representing the strongest-woolled of the hill sheep. The other 1,100 had been on the flats for two years, and it was lambs from the 1,100 which were affected. About ,200 merinos were also wintered on the flats for the one season only. .

The pastures had been down for a number of years, but some were five and six years old only. The flats were' divided into paddocks of 30 to 50 acres. Previously to 1926 no top-dressing had been done. Since then some of the paddocks on the farm had been top-dressed once or twice, while others had received no treatment. Sulphate of. ammonia had been applied only to a few acres, and not in the paddocks referred to. The health of the sheep was good, and they were in good condition. Ante-partum paralysis was held in check by judicious feeding and exercising, and pulpy kidney occurred in only six lambs during the early season of 1929, but more died at twelve to fourteen weeks from that trouble. The affected sheep had been fed for the last' two years on a lick composed of salt, 112 lb. ; Kerol, 2 pints iron sulphate, 2 lb. ; sulphur, 4 lb. ; rock phosphate, 4 lb. ; calcium carbonate (97 per cent.), 20 lb. An amount of 30 cwt. had been fed over the year.

The ewes commenced lambing in October, and over a hundred were born with enlarged, thyroids, the enlarged lobes being from a hazel-nut to a duck’s egg in size. Some of the larger glands were cystic. Analysis of these thyroids carried out by the Chemical Laboratory of the Agriculture Department showed from 0-0009 P er cent. 'of iodine by weight of gland to 0-0296 per cent, in the case of a gland which was almost normal in size. . Dr. Orr, of the Rowett Institute, gives the normal foetal gland as 0-03 . per cent. The majority analysed were in the vicinity of o-ooi per cent. Besides enlargement of glands the lambs

showed other definite symptoms of iodine deficiency, such as hairlessness, smallness of foetus, a tendency to oedema, and in some cases coarse hair instead of the usual lamb’s wool. If the lambs were born alive and remained alive for three days there was some hope of their living, but many born alive died from weakness without getting on their feet. Further post-mortem examination showed oedema of the meninges of the brain, some congestion of mid-brain, but no definite haemorrhage

was seen. The heart was petechiatech and there were haemorrhages on endocardium. The pericardial sac was filled with fluid ; bladder usually full; kidneys oedamatous, pale, not firm when capsule stripped ; some small areas of congestion showed as mottling through the capsule of the kidneys.

One lamb which was found alive and taken to the house for treatment was given three drops of tincture of iodine in milk three times per day, and in a week was practically normal, the goitre having almost disappeared. In lambs which lived three days, however, the thyroids tended to decrease in size without treatment.

2. Various Aspects of lodine Deficiency and the Wanaka Investigation.

B. W. Simpson, Rowett Research Institute, Scotland. . (On loan to Chemistry Section, New Zealand Department of Agriculture.) - Since iodine is a necessary element in biological processes, its presence in soils, pastures, and animal tissues is of fundamental significance. An investigation into the cause of a high mortality among lambs in the Wanaka area resulted in some interesting data; a description of the occurrence has been given in the preceding section.

At Makarora, up the valley from the head of the lake, the stock was poorly developed—especially yearling calves, which were small of size sterility was prevalent, and cream - production very low, although the pastures seemed luxuriant and rich. Rams brought into this district grew coarse-haired, and the wool only recovered its fineness when the animals were removed to other pastures. Hairlessness in lambs was also noted. An iodine deficiency was obviously the primary cause of the weak stock in a case near the lake itself. Samples of soils, pastures, milk, and thyroid glands were taken for analysis.

Soils. — The iodine content of soils varies considerably, being in New Zealand anything up to 900 parts in 10 million. Three soilsamples taken from Wanaka gave an iodine content of 6, 15, and 7 parts in 10 million. A soil from Islington, near Christchurch, for comparison, gave 28 parts in 10 million. Two samples from Makarora gave 2 and 15 parts in 10 million. These five soil-samples from Wanaka have extremely low iodine contents.

Pastures. — There is little or no correlation between the iodine content of a soil and the iodine content of the pasture grown on it. Some soils, although rich in iodine, give up none to plants. Generally speaking, these are alkaline soils. Acid soils, on the other hand, give up their iodine very readily to plants.

As there exists a very critical iodine dosage for plants, as well as for animals, above which toxic processes set in and below which full development does not take place, it can be understood why field trials with iodine manuring are often very contradictory. The empirical application of iodine to soils in manures and otherwise is therefore generally useless. If . the nature of "the soil is not taken into consideration the result may well be, as far as the crop is concerned, nil, or a diminution instead of an increase may even result if. the optimum dosage is exceeded. Hilly pastures in New Zealand are generally richer in iodine than valley pastures. This is of interest, because at Wanaka the lambs of hill sheep are healthy ; only those of paddock sheep are affected. The soils at Wanaka which had an iodine content of 6, 15, 7,2, and 15 parts iodine in 10 million grew pastures with 13, 32, 11, 14, and 13 gammas * iodine per 100 grammes of dried material respectively. An Islington pasture, grown on a soil with 28 parts iodine in 10 million and sampled at the same time of the year as the Wanaka pastures, had 95 gammas iodine per 100 grammes dry material. The Wanaka pastures are low in iodine, and this in spite of the fact that the Wanaka stock was getting iodine licks from boxes in the paddocks, so that the natural iodine content was probably much lower.

Milk. — lodine is always found in milk. In New Zealand milksamples the iodine content varies within narrow limits. Milk-samples from the Whangarei area have generally about 6 gammas iodine in 100 c.c., and samples from the Christchurch area about 4 gammas per 100 c.c. One sample from Wanaka contained 2 gammas, and another had only about 1 gamma per 100 c.c.

Thyroid Glands. — The thyroid gland contains a higher percentage of iodine than any other tissue in the animal-body. A deficiency of iodine in the food of an animal reacts on the thyroid gland in such a

way that an. inverse relationship exists between the size of the gland and the iodine content. Glands from the Wanaka area are very large and contain very little iodine. No. 2of Table 1 may be taken as normal for comparison. Dr. Orr found the thyroids of foetal lambs to have about 0-03 per cent, iodine fresh weight. A Wallaceville lamb had a thyroid weighing 0-9 gramme with an iodine content of about 0-06 per cent, fresh weight this animal was about six weeks old. The W anaka lamb thyroid, weights and iodine contents were as follows :

The first five samples are glands of lambs dead at birth or about three days old. The last three glands were obtained from animals which had been fed on iodized lick for four weeks previous. At Makarora a sheep’s thyroid weighing 4-6 grammes gave an iodine percentage of 0-02. A Whangarei sheep’s thyroid weighing 7 grammes had an iodine percentage of 0-2, and an Islington sheep’s thyroid weighing 6 grammes had o-i per cent, iodine. These are given for comparison. At Makarora a foal which died eighteen hours after birth had a thyroid weighing 37-4 grammes with an iodine percentage of 0-003. The iodine content of soils, pastures, milk, and thyroid glands from this Lake country area is therefore low when compared with the iodine content of similar samples from other areas in New Zealand.

A study of the general analysis of milk and pasture samples from Wanaka (tables 2 and 3) in order to ascertain if there is any further mineral deficiency has been rather complicated by the addition of salt licks to the foodstuffs. Cows’ milk from Wanaka, when compared with cows’ milk from Whangarei, samples being taken at the same time of the year and at the same stage of lactation, gave practically the same mineral content. Unfortunately no record of the yields was

kept. The general analysis of November pastures from Wanaka is also of interest. The iodine content is low, in spite of the fact that iodized salt licks were fed from boxes on some of the paddocks. Chlorine - and sodium contents are low and calcium is high.

■ The dosage of iodine now in use at the Wanaka stations referred to is 2 oz. potassium iodide in 112 lb. of salt, fed from boxes to which the ewes have easy access. Whether this is sufficient to prevent' the recurrence of the high mortality among lambs will be seen next season. The optimum dose for a sheep is 3to 4 grains per week. This small dose ensures the full effectiveness of a mineral ration by increasing the assimilation of calcic oxide, phosphoric acid, and nitrogen in the food.' Ten grains a week is sufficient for a bullock or cow, and 6 grains for a horse or a pig. Poultry show a remarkable reaction to iodine feeding ; grain of potassium iodide fed to a hen per week increases the iodine content of the egg 600 times. The eggs from hens on experiment in Wellington, to which potassium iodide was fed, were 100 per cent, fertile, and 85 per cent, of the chicks were pullets.' If too large a dose of iodine is fed to hens the moult is very complete.

It has been suggested that the thyroid enlargements found at Wanaka may have a causal relationship to the feeding of a lick containing salt, Kerol, lime, (obtained from a friable deposit found in the vicinity), and ground raw rock phosphate. Whether all or any of . these ingredients aggravated the critical condition of the lambs it would be difficult to say. Thyroid enlargement is in many cases associated with limestone country, but no definite correlation between excess of calcium in the soil and incidence of goitre has been found. An experiment is to be carried out on rabbits, which may throw some light on this vexed question. A low iodine basal ration, consisting of hay, grain, and roots from Wanaka, is to be fed to the control group. A second group will get this basal ration. plus lime, a third basal ration plus salt, and a fourth basal ration plus phosphates. If possible, other groups may be added. A comparison of the weights and iodine content of the

thyroid glands should be of interest. In view of the fact that all over Central Otago generally many lambs have small thyroid glands of low iodine content, it may be that at Wanaka some external factor in the shape of excess or deficiency of another mineral made a critical iodine balance definitely negative.

3. Notes on the Wanaka Soils and Pastures Analysed.

R. E. R. Grimmett,

Analyst, Chemistry Section, Department of Agriculture.

In November, 1929, the writer spent several days in the Wanaka area investigating the field conditions, and collecting soil and pasture samples. The following notes refer to the samples analysed by Miss Simpson (as set out in Table 3 in the preceding section).

Samples Z 1331 and 1332 are respectively red-clover green growth and red-clover hay from the same paddock near Lake Wanaka. This is on alluvial flats close to the base of the hills, and is not irrigated. The soil, in common with the rest of the flats, is of schistose origin and silty texture, with in places a stony subsoil. The top-dressing was 2 cwt. superphosphate in the spring of 1929 only. The hay is from the same stack that was used for feeding the ewes during the winter.

Z 1333 is a sample of general pasture from a paddock sown down for nine years. It is on the flats, but receives very litt'e irrigation water. White and red clover with cocksfoot form the bulk of the pasture, which includes also rye-grass, fog, hair-grass, Chewings fescue, crested dogstail, sweet vernal, Poa pratensis, suckling clover, and various weeds. The . growth was green and of medium length, and had not been stocked during the previous fortnight. An iodide lick had been fed on this paddock.

Z 1334 is a sample of general pasture from a paddock, also on the flats, which has been irrigated for the last twenty years. The growth was fairly short and green, having had sheep on it for a fortnight. Rye and white clover were the principal constituents, together with cocksfoot, crested dogstail, red clover, Yorkshire fog, suckling clover, timothy, goose-grass, sweet vernal, and weeds. The top-dressing was 1 cwt. of super and 1 cwt. potash salts, in the spring of 1928 only. An iodide lick was being fed on this paddock.

Z 1335 is a sample of self-established pasture from an unmanured and unirrigated paddock on similar soil to the preceding. The growth was mainly cocksfoot, fog, white and red clover, Poa pratensis, Chewings fescue, danthonia, sweet vernal, goose-grass, and weeds. No lick had been fed here.

At Makarora the rainfall is much higher, and the growth, especially of clovers, is very luxuriant. The soil is mainly alluvial, silty, and derived from schistose rocks. Z 1357 is a sample of general cowpasture, very green and lush, predominantly white and red clover, together with cocksfoot, fog, rye, brown-top, crested dogstail, timothy, and weeds. This is from the farm where improved milk-yield and rearing of calves was reported following the feeding of iodine. Manurial history: 2 cwt. carbonate of lime and 1 cwt. super three years ago, 2 cwt. super last season, and 2 cwt. super and 1 cwt. sulphate of ammonia this season (1929-30).

Z 1358 is a sample of short green general pasture (cow and sheep) from a farm four miles farther up the Makarora Valley than the preceding. The paddock is twelve years old, and was manured with 2 cwt. superphosphate in 1927 and again in 1928. Rye, cocksfoot, and white clover predominate, other pasture constituents being fog, brown-top, Poa pratensis, timothy, Chewings fescue, rushes, cotula species, hydrocotyle species, and other weeds. No lick containing iodine had been fed on this farm.

Z 1359 is a sample of general pasture from an adjacent farm on which also no iodine had been fed. This paddock has been grassed for six years and was top-dressed in the spring of 1928 and in the autumn and spring of 1929, each time with if cwt. superphosphate. The pasture is predominantly white clover, with rye, timothy, crested dogstail, fog, cocksfoot, red clover, brown-top, sedges, and weeds.

Note. —An account of the chemical composition of mica schist silts is given by Mr. B. C. Aston, Chief Chemist, Department of Agriculture, in this Journal for June, 1923, page 329.

* A gamma (7) equals one-millionth part of a gramme.

No. Weight of Gland. Percentage Iodine. Iodine Content. Grammes. Grammes. I 27-0 0-0009 0-0002 2 . . . . 3-2 0-0296 0-0009 3 io-8 0-0012 00001 4 60-9 0-0005 0 0003 5 • • • ■ • • 32’3 6 202-7 0-0007 0-0014 7 .. ■ 2I-I 0-0106 0-0022 8 46-3 0-0525 0-0243

Table 1. —Analyses of Lamb Thyroid, Glands, Wanaka Area.

Whangarei Wanaka Locality. O o p V* hi hi M M M O MM Xhi VO Date. *'o\ to (1 o-io O-II Chlorine (C.I2). 01.0 Chlorine (Cl 2). o o Phosphoric Acid to U> ).O b (P2O5). o Calcium Oxide M CO (CaO). •<t CO o OxidePotassium (CaO). ... oo HIrl MH On Oxide (K 2 0). G\ 9 Potassium (N2).Nitrogen Oxide (I< 2 0). o O Ox Ox 9 Magnesium KQ Nitrogen (N2). 0-02 6 6 to to Oxide (MgO). Magnesium Oxide (MgO). 0-02

Table 2. —Analyses of Cows’ Milk. (Results, except for iodine, are expressed as percentages on the whole milk.)

OJ OJ OJ W KJ >w w N W W 52*1“* ? g0 M West of Lake Lab. No. West of Wan aka Ditto Makarora '. . 1 tr o o 6 P c K 4 • . ; fc £> CD 03 ' ■ P. 0) g S g OCD <3 <3 ‘-I 1 CD Iodine per P/ Material.grammes Dry CO H ooooooo o CO Iodine in Gammas per ico grammes Dry Material. -6 CON) 6 <6 Phosphoric Acid (P2O5'). ON O Phosphoric Acid (P20 5 '). O 6 to to c 6 6 10 VO Calcium Oxide (CaO). 00 O ooooooo o Calcium Oxide (CaO). OOOOOOO o 6o CO +. +1 -O OO cn Co <J\Ui Magnesium Oxide (MgO). Cn CO 4x O o O Magnesium Oxide (MgO). : m 6 £ 6 6 w m ■ m Sodium Oxide (Na2Q). sj V! CO 10 CO Sodium Oxide (Na2Q). Co Co CO CO 6> CO o Potassium Oxide (K2O). O VO • 4Potassium Oxide (K2O). Ct! “ -H- cA 4 O Nitrogen (N 2). v6' do OOOOOOO O . Nitrogen (N2). OOOOOOO O 6 6666666 6 CO -4 Iron (Fe). (0 VO OOOOOOO O Iron (Fe). 6666666 6 6 6 6 o o Manganese (Mn). VO VO -V* MCCQO HM m Manganese (Mn). 6 6 4 Ash. 6 +1 O H » o Ash. Q o cA O O 03 03 6 h OvCn Crude Silica (Si02). VOW 0-0 0-05 Crude Silica (S1O2). o-o5 Trace 0-02 Trace Alumina o . Co O (S). Ooooooo o to CO -d4. o Chlorine

Table 3.-Analyses of November Pastures, Wanaka Area. (Results, except for iodine, are expressed as percentages of the dry matter.)