CONGENITAL GOITRE IN LAMBS

New Zealand Journal of Agriculture, Volume 63, Issue 5, 15 November 1941, Page 387

CONGENITAL GOITRE IN LAMBS

An interesting case of congenital goitre in lambs was investigated during September. The loss iUi involved from 90 to 100 lambs. The full particulars of the outbreak and the history of the flock over the season is of direct interest to sheepowners.

It is proposed to forward soil and pasture samples from the farm for analysis and iodine estimation. A salt mixture with potassium iodide is to be used throughout the year so that the sheep may have access to it at all times.

By 1

C. V. DAYUS,

District Superintendent, and

B. A. TAYLOR

and

G. A. THOMPSON,

Veterinarians, Dunedin.

’’T’HE farm consists of 140 acres of THE consists of a portion of low-lying flat land, a portion of which is alluvial and the remainder drained swamp. This has a clay subsoil, containing decaying vegetation, although not peaty, and a portion of it still grows swamp grasses, such as floating sweet grass, knee-jointed foxtail, creeping bent, etc. The area was once subject to flooding, but this i? now largely controlled by the excavation of a contour channel and the erec • tion of a protective stop-bank. Drainage is still not pi "feet, but has very much improved in .be last five years. Most of the area „> - :< =ts of very old-established past’ -■> sown down with ryegrass, rec. ... .d white clover, cocksfoot, and Timothy, and some 45 acres have been resown in the past six years. In addition to this flat area, the farm consists of about 390 acres of hill country, comprising native tussock and grass. The present owner has been on this farm about eight years, and at first went in for dairying, changing over to sheep about four years ago. Because of the nature of the fiat land, it has never had the reputation for “doing” young stock, well, calves and hoggets. At present, it is the custom to winter the two-tooths on the hill country. In the growing season the flat carries considerable feed, and heavy stocking is possible—five sheep per acre, including cattle to keep down the rank growth. Older stock getting past the growing stage do well, and last season fat lambs were got away oft the mothers, which was a new procedure attributed by the owner to the use of lime.

1 ■. : Fertiliser Used

About five years ago the paddocks ( concerned received a dressing of lOcwt. of lime and 2jcwt. of superphosphate per acre. In 1940 the whole area (140 acres) received one ton of lime per acre. Some was applied in the autumn of last, year, but most went on in the spring. ' 1

In 1941 the area of flat carried 550 Romney cross ewes all winter without any other feed (four ewes per acre). The ewes were mixed ages, four-tooth to Aged. Actually, all these ewes, with the exception of a few bought in (which will be referred to later), had been on the same area since they were two-tooths. All the paddocks, were in occupation during the winter, and the ewes received no change-round (the first time this has occurred) until close to lambing, when they were put together on more occasions to leave some paddocks free into which to place the ewes as they lambed.

The two-tooths, numbering 150, wintered on the hill, and at the conclusion of,lambing they will be brought down on to the flat, bringing the stock on this area up to 700 for the summer. The rams were put out on April 12, 1941, and lambing began on September 12 and finished on or about October 3. \

Freedom From Goitre

There were some ewes, 58 in number, which lambed earlier than the main lot. Some of these were aged ewes—2B were left over from a draft which went to the freezing works, and i the remainder were, ewes of mixed ages, the rams gaining access at an earlier date. These 58 ewes lambed in . August, and the . lambs were “marked” before the main lot began to lamb. No cases of goitre occurred in the lambs from these ewes. Another lot, of ought-in ewes” (numbering 60), mostly six-tooth and eight-tooth, were bought at a local sale and put on the flat in July. No cases of goitre occurred in the lambs from these ewes.

No cases of goitre occurred in the lambs from the 150 two-tooth ewes wintered on the hill. Among the remaining 430 ewes on the flat between September 12 and 29 70 to 80 ; lambs had been lost from congenital goitre, and by the time lambing finished, about October 3, 90 to 100 lambs were actually lost—a loss equivalent to 15 per cent, over all, or 20 per cent, in the lambs of the ewes in which the incidence was actually recorded.

Evidence of T hy voids

A few lambs affected . were premature but the majority were up to time. Some affected lambs were born dead, but most appear to have been born alive, but with vitality extremely low, so that many of them died in a short period without ever gaining their feet. There were cases where one lamb of twins was markedly affected and died, while the other was apparently normal and lived. Possibly, if it had been practical to palpate the thyroids of the surviving member some degree of enlargement of the thyroids would have been detected. Several affected lambs showed a tendency to “hairiness,”

although this feature is sometimes a genetical characteristic, especially' of the Romney breed. There were lambs , affected from . four-tooth and 6-tooth ewes, but it is safe to say that the majority of cases were in lambs from ewes full-mouth and over. The thyroids of affected lambs varied in size or palpation from a filbert nut to a large duck egg (that is, one lobe, both lobes did not always show uniform enlargement). Although cases occurred in practically every paddock on the flat, it was -'thought by the owner that one paddock more than any other was implicated. This was one of 24 acres, ploughed and sown down many years ago. It is one of the wettest of - the paddocks on the flat, and four years ago was heavily covered in rushes; This paddock carried 100 ewes since the middle of May, 1941. The rams on the property were palpated, but no enlargement of thyroids could be detected. Some of the ewes were examined (half a dozen), and there were two in which a slight enlargement of the thyroids could be detected.