Ingested soil and iodine deficiency in lambs

Healy, W. B.; Crouchley, G.; Gillett, R.L.; Rankin, P. C.; Watts, H. M.

doi:10.1080/00288233.1972.10421631

Cited by 31 publications

(13 citation statements)

References 4 publications

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“…In 1971 and 1973, when ewes had been set stocked on the plots for at least 10 months the goitre incidence was above 90% of all lambs born on the sandy soil, while in 1972 it was only 56%, although the numbers in this group were small. This drop in goitre incid- Following a poor autumn growing season the pasture height was less than 3 cm by August 1972, and it was under conditions similar to this that Healy et al (1972) showed that ingestion of soil by grazing ewes reduced the incidence of congenital goitre in lambs.…”

Section: Discussionmentioning

confidence: 99%

“…Field (1964), in England~and Healy (1967) showed that the maximum soil intake occurred during winter when feed availability was lowest, and Healy suggested that a sheep could ingest up to 400 g of soil per day. This amount of ingested soil could obviously be important in supplying the animals requirements for microelements, and it was suspected that soil intake was a major factor in the development of congenital goitre in a field experiment in New Zealand in 1971 (Healy et al 1972). It was discovered that soil intake by ewes at a stocking rate of 22 ewes/ha was much greater than that of ewes stocked at 15 ewes/ha, this being reflected in higher faecal soil levels (69% of D.M.…”

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confidence: 99%

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Congenital goitre in sheep in southern Tasmania

Statham¹,

Bray²

1975

Aust. J. Agric. Res.

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Congenital goitre was first recorded in Tasmanian sheep In 1945. Severe but sporadic outbreaks have since occurred in 1956, 1964 and 1968. The disease seemed to be associated with particular farms and its incidence often differed markedly between ewe flocks on the one farm. A survey indicated that the condition was mainly confined to the Derwent Valley and the northern Midlands. Studies involved a grazing trial near Bothwell, where goitre was endemic, and included supporting animal house tnals and plant growth studies. Soil type was shown to be a major factor in the disease: ewes grazing pasture on a sandy soil produced many more goitrous lambs than ewes grazing pasture on clay soil. Analyses of the two pastures revealed that those on sandy so11 contained less iodine than those on clay soil but neither contained the minimum level necessary to prevent goitre. Observations revealed that outbreaks of the disease followed wet autumns with subsequent lush pasture during pregnancy. This correlation could be explained if pasture grown under moist conditions contained less iodine than pasture grown under moisture stress. However, experiments with the two main pasture species (perennial ryegrass and subterranean clover) showed that plant iodine levels were not affected by the water supply. Two goitrogenic agents, nitrate and thiocyanate, were present in the pastures, but they were not considered to be Important in the aetiology of the disease. Similarly, the drinking water was found to be unimportant, even though the two sources available contained widely different amounts of iodine. Apparently, between-year variation in the incidence of goitre and the effect of soil type can best be explained by a varying iodine intake dependent on soil ingestion which varies with pasture availability. This hypothesis is discussed in the light of the results.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Congenital goitre in sheep in southern Tasmania

Statham¹,

Bray²

1975

Aust. J. Agric. Res.

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“…This would have resulted in the sheep grazing the swede roots, and probably ingesting considerable soil in the process. Soil ingestion is known to be beneficial in terms of supplying I to animals (Healy et al 1972), and may better explain some of the serum T 4 increase measured in late winter. Soil ingestion would certainly have helped to prevent the goitrogenic properties of kale ) being a factor in this study.…”

Section: Discussionmentioning

confidence: 99%

The effects of fertiliser iodine application on herbage iodine concentration and animal blood levels

Smith

Morton

Catto

1999

New Zealand Journal of Agricultural Research

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Two experiments were conducted to evaluate surface applications of potassium iodide and potassium iodate as alternatives to direct treatment of ewes where iodine (I) deficiency may be a problem. In Experiment 1, the hypothesis that grazing of pasture which had been sprayed with a potassium iodide and oil mixture results in increased blood iodine (serum T 4 ) levels in ewes was tested over two years on five farms in Southland and West Otago, New Zealand. The results show that spraying elevated pasture I levels from March to pre lambing. The increased pasture I levels increased serum T 4 levels by only 1.5% in late winter, an increase which was not significant (P > 0.05). There were small increases in lambing percentages (1-5%) due to the spraying in both years, but these were not significant (P>0.05).In Experiment 2, the hypothesis that surface applications of potassium iodide and potassium iodate fertiliser can result in increased herbage I levels was tested on two farms in Southland and West Otago in 1996 and one farm in Central Otago in 1997. The trials ran from mid autumn (March/ April) to late winter (August/September) each year. There was a significant (P < 0.01) increase in pasture I levels after 6 weeks with both forms of iodine fertiliser, and this increase was still significant for the top application rates at the 19-week measurement (P < 0.05 for Southland and West Otago, P < 0.01 for Central Otago). The iodide fertiliser was slightly more effective at increasing herbage I levels than was the iodate. However, despite the efficiency of I uptake being low (4.25% of the applied I taken up by the herbage), herbage I concentrations were lifted to acceptable levels and maintained at such for the duration of the study.

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“…The good summer growth of year 4 mentioned earlier resulted in a 10 kg increase in ewe The high number of lamb deaths in years 4 and 5 were associated with enlarged thyroid glands. Healy et al (1972) considered that the cause of death on the low-stocked areas was associated with lower soil ingestion by the ewes and hence lowered iodine intake compared with the high-stocked ewes,which grazed the pastures closer and ingested more soil. The lower number of enlarged thyroids on the low-stocked limed areas in year 5 (no enlarged thyroids on high-stocked pastures) can probably be explained by soil contamination, the longer-limed pastures in the well grazed patches having more soil on them as a result of fouling in wet weather: hence the iodine intake of ewes on this treatment was correspondingly greater.…”

Section: Discussionmentioning

confidence: 99%