IODINE CONTENT OF LAMB THYROIDS.

New Zealand Journal of Agriculture, Volume 41, Issue 5, 20 November 1930, Page 302

IODINE CONTENT OF LAMB THYROIDS.

NEW ZEALAND ANALYSES COVERING TWELVE-MONTH PERIOD.

B. W. Simpson,

Rowett Research Institute, Scotland. (On loan to Chemistry

Section, New Zealand Department of Agriculture.)

According to Orr and Leitch (“ Iodine in Nutrition,” 1929), the most important factor affecting the iodine content of the thyroid gland is the iodine content of the food or the intake of the animal. This overshadows differences due to species, age, or sex.

Kendall { Journal of Biological Chemistry, LXXX, No. 2, Dec., 1928) found a 300-per-cent. variation in the iodine content of thyroid glands throughout the year. Seidell and Fenger, working on American sheep, also found a seasonal variation {Journal of Biological Chemistry, XIII). Martin, working on English sheep, found only a variation of o-io to 0-13 per cent, fresh weight {British and Colonial Druggist, LXII). McCarrison has also shown that there is a seasonal prevalence of goitre in humans.

Lowe {Quarterly Journal of Microscopical Science, Feb., 1930) states that in all young animals the thyroid gland goes through alternate periods of activity and rest, and these changes are correlated with the season. A colloid condition of the gland prevails during the autumn and early winter months, this being replaced by a more active condition which continues till the beginning of the summer, when it gives way once more to the colloid condition. In older animals Lowe states that there are no such obvious seasonal changes, the colloid state being most commonly present. In aged animals Lowe found the colloid condition to be the rule, and the glands did not appear ■to respond to sexual or seasonal influences.

According to Lowe, the average weight of the gland in young male sheep is 2-34 grammes and in females 1-98 grammes in autumn and winter, and in spring the average is 2-96 grammes. In summer female lambs had thyroids weighing 2-43 grammes, males 2-37 grammes, yearling males 3-8 grammes, and yearling females 2-6 grammes. Another factor which influences the glands of females at least, besides iodine intake and seasonal variation, is temperature. Generally speaking, the return to the colloid condition coincides with increase of temperature. (Mills, American Journal of ■ Physiology, 46).

Analyses of New Zealand Specimens in 1929-30

The following tables give the iodine content of lambs’ thyroids taken in this country between July, 1929, and June, 1930. These specimens were sent to the Department’s chemical laboratory for analysis throughout the year and have been tabulated according to the date taken, so that thyroids from one area may be compared with those from another at the same time of the year. The maximum amount of iodine is said to be in the gland in the autumn and early winter. The minimum is said to be in the spring.

The lamb from Wairarapa had a thyroid under the normal weight. Small glands seem to be the rule on lime-deficient areas. The Otautau, Ryal Bush, Pomahaka, and Tokonui lambs all have thyroids over the normal weight for their age and for this season. Lambs from those areas and from the Waimea Plains and from' Gore would probably improve in condition and growth if fed additional iodine in the form of a drench or lick. Four grains of potassium iodide a week is the optimum dose.

Compared with the Kaikohe and Bishopdale lambs’ thyroids all the others are low in iodine. The thyroids from Ashburton, Richmond, Owen, and Ahaura all- have below the critical percentage—

0-03 of iodine. Below this percentage the thyroid gland functions imperfectly. The Ahaura glands are extremely deficient in iodine.

The lambs’ thyroids from Ross and Palmerston North are all deficient in iodine. The Canterbury lambs’ thyroids are very low, and this at the time of the year when glands have the maximum amount of iodine.

Methven lambs’ thyroids are all over the normal as regards size, and, although not deficient in iodine, the content is low. The Ahaura lambs’ thyroids are still deficient.

May. — No samples were sent for analysis during this month.

The thyroids of the lambs suffering from “ bent leg ” (“ bowie ” lambs) are very small in size, and the iodine content is low. There

is obviously another mineral deficiency —probably lime — this area. The first thyroid in the June list came from the Dunedin abattoir and is goitrous.

Nine glands were obtained from Tai Tapu in July. The average weight and iodine percentage of these are given. This is a reputed goitrous area. The iodine content of pasture and milk samples from this area is low. These glands received were normal, but verging on the critical iodine percentage (0-03 per cent.).

These glands are quite normal.

September. — No glands were received in this month.

The Wanaka lambs’ thyroids are deficient in iodine, with one exception. Some of the Otago lambs’ thyroids are extremely small in size and have a low iodine content. They resemble the Blenheim glands in this respect.

The Mangamahu gland is extremely deficient, yet the gland is very small. The Taihape and Levin glands are. interesting because they are exactly comparable as regards age and season. December.- — this month twenty-seven glands were obtained from Wairarapa lambs. The average weight was 2-3 grammes, and the iodine percentage 0-03 —on the verge of -deficiency.

Conclusion.

The iodine content of the thyroids of lambs born and bred on definite areas seems to give a fair indication of the amount of iodine available on those areas. Systematic advisory work on iodine feeding to stock could be based on such analytical data. More data and more widespread investigations are, however, required.

Place and Description. Date taken. Weight of Gland. . Iodine Content. Percentage of Iodine. Grammes. Grammes. Karamu, South Auckland ' . . ' 10/1/30 Grammes. 2'3 Grammes. 0-002 1 : 0-105 Wairarapa; weak lamb . . 9/1/30 1’3 0-002 0-127 Carterton . . 7/1/30 3'0 0-002 0-065 Marton . . . . . ... 29/1/30 2-5 o-oxo 0-164 Waimea Plains, Nelson (io miles 23/1/30 2-1 o-oox 0-049 from sea) ; ewe lamb Gore (20 miles from sea) 23/1/30 2'32 0-0008 0-035 Otautau ; four-months lamb 20/1/30 5'8 0-002 0-036 Ryal Bush, Southland ; four-months 22/1/30 3'2 0-002 0-060 lamb Ditto .. . . ... 22/1/30 4'5 0’002 0-036 Pomahaka, Otago ; four-months 27/1/30 3-5 0-003 0-071 lamb Tokonui, Southland ; four-months 27/1/30 3'5 o-oox 0-035 lamb

January, 1930.

Place and Description. ! Date taken. Weight of Date taken. Weight of Gland. Iodine Content. Percentage of Iodine. Grammes. . Grammes. Kaikohe, North Auckland ; seven28/2/30 Grammes. .. 2-9 Grammes. 0-0035 O-I2I months lamb Herekino, North Auckland ; sixSix- 7/2/30 7/2/30 2-8 2-8 0-0021 0-0021 0-075 0-075 months lamb Ashburton : five-months lamb 12/2/30 4’2 . o-oox 0-028 Valetta, South Canterbury ' . . 1/2/30 3’3 0-00 I 0-037 Lincoln ; one year 3/2/30 4-9 0-004 0-080 Murchison ; wether lamb 6/2/30 2'75 0-0017 0-063 Bishopdale, Nelson ; ewe lamb 6/2/30 3-30 0-0038 . 0-115 Stoke ; ewe lamb .. .. , 6/2/30 3-20 0-0012 . 0-039 Murchison (Hunter’s Station) 6/2/30 2-21 0-0007 0-033 Richmond, Nelson 12/2/30 4’15 0-0007 0-017 Motueka, Nelson ; river-flat 12/2/30 2-70 0-0015 0-055 Owen . . ... .. . . 12/2/30 3’15 0-0005 0-017 Owen Junction .. . . 12/2/30 • 3’25 0-0009 , 0-029 Invercargill 18/2/30 i-9 o-ooi 0-073 Ahaura, Westland .. . . ’ 13/2/30 44’9 0-0026 b-oo6 ,, >> 13/2/30 13/2/30 ' 24-7 24’7 O ; OO43 O-OO43 0-018 0-018 13/2/30 20-8 0-0056 >> >) • • 0-027 13/2/30 20-8 0-0056 0-027

February.

Place and Description. Date taken. Weight of Gland. Iodine Content. Percentage of Iodine. Pakaraka, North Auckland ; sevenIO/3/3O Grammes. 2-9 Grammes. 0-0026 0-088 months lamb Pohangina, Wellington; eight to .7/3/30 3’5 0-0008 0-024 nine months Weedon’s, Canterbury ; six months 6/3/30 2-7 0-0009 0-035 Ross, Westland ; six months 12/3/30 24-3 0-004 0-017 12/3/30 13-0 o-ooi o-oir 12/3/30 4-8 o-ooi 0-030 „ ,, „ 12/3/30 12/3/30 6-o 6-o 0-002 0'002 0-025 0-025

March.

Place and Description. Date taken. Weight of Gland. Iodine Content. Percentage of Iodine. Grammes. Grammes. Lincoln ; one -year lamb .. 8/4/30 4-2 0-003 0-069 Methven, Canterbury; seven months 29/4/30 io-8 0-0068 0-063 .a ? . , ? J 29/4/30 6-4 0-0027 0-042 29/4/30 3-3 0-0014 0-043 Ahaura, Westland ; seven months 7/4/30 , 0-023

April.

Place and Description. Date taken. Weight of Gland. Iodine. Content. Percentage of Iodine. Grammes. Grammes. Dunedin 2/6/30 166-85 0-013 0-008 Blenheim ; bowie ” lamb, seven lamb, seven 7/6/30 7/6/30 0’55 0’55 0-0002 0-0002 0-029 0-029 months old * Blenheim ; bowie ” lamb, ten ’ lamb, ten 25/6/30 25/6/30 1-70 1-70 0-0007 0-0007 0-057 0-057 months old

June.

Place and Description. Date taken. Weight of Gland. Iodine t Content. Percentage of Iodine. Tai Tapu, Canterbury .. 1/7/29 Grammes. 3’0 Grammes. . o-oooi 0-032

July, 1929.

Weight of Place and Description. Gland. Iodine Date taken. Weight of Gland. Content. IodinePercentage Content. of Iodine. Percentage Place and Description. of Iodine. Date taken. Wairarapa ; one to two months . . Wairarapa (Carterton) ; one to two months 7/ 8 / 2 9 14/8/29 Grammes. 3’6 3’0 Grammes. 0-005 0-0003 0-0151 o-iio

August.

Place and Description. Date taken. Weight of Gland. Iodine Content. Percentage of Iodine. Wanaka, Otago ; newly born lambs 10/10/29 Grammes. 0-27 Grammes. 0-0002 0-0009 99 99 99 10/10/29 3’2 0-0009 0-030 10/10/29 io-8 o-oooi o-ooi . . 44 10/10/29 io-8 o-oooi o-ooi ' • , 44 , • 10/10/29 60-9 0-0003 0-0005 Maniototo, Otago ; newly born lambs .19/10/29 i-6 0-002 0'112 99 > > ' 99 23/10/29 i-3 0-002. O-I53 99 99 99 26/10/29 0-49 0-0003 0-050 99 9 9 99 29/10/29 1-08 0-001 0-091 Otago ; deformed foetus . 31/10/29 i-3 0-0003 0-019 Otago ; newly born 31/10/29 o-86 0-0009 0-104 ,, 99 31/10/29 o-77 0'001 0-142 31/10/29 I-I2 0-002 0-187 ,, 99 31/10/29 I-I2 0-002 0-187 Otago ; deformed foetus 31/10/29 0-48 0-0004 0-076

October.

Place and Description. i Date taken. | Weight of Gland. Iodine Content. Percentage ■of Iodine. Wallaceville, Wellington . . 15/11/29 Grammes. o-94 Grammes. 0-0006 0-061 Mangamahu, Wellington 29/11/29 o-8o o-oooi 0-012 Taihape, Wellington ; three months 13/11/29 2-04 b-ooi 0-048 old .Levin ; three months old . . 13/11/29. 2-6 ' 0-003 0’112 Maniototo, Otago 4/11/29 i-5 0-0003 0-210 , , 99 .' • • • • . 4/11/29 i-7 0-002 O-I25 . , •• •• •• 4/11/29 1-7 0-002 O-I4O 4/11/29 i-97 o-ooi 0-123 5/n/9 1-2 0-0008 0-066 , , 99 • • * * 5/H/29 1-04 0-0018 0-169 J, 99 5/ii/9 1-02 0-0012 0-123 Otago ; deformed fcetus . 9/11/29 i-5 0-003 0-167 Maniototo, Otago 9/11/29 o-99 9/11/29 o-93 o-ooi 0-119 9/ll/29 i-6i o-ooi 0-090 99 9/i1/29 i-6i o-ooi o-ogo

November.