The Urinary Excretion of Gonadotrophins by Sheep: Extraction Procedure and Day-to-Day Fluctuation in Excretion by Male and Female Castrated Sheep

Symington, R. B.

doi:10.1677/joe.0.0290215

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…Is there an alternative to repeated blood sampling or pituitary collection in such studies? It has been known for many years that biologically active FSH and LH are present in sheep urine (Symington 1964); the urine may act as a repository for gonadotrophins cleared from the circulation over a period of time and may, therefore, reflect the average plasma gonadotrophin concentration. Small samples of urine are used in this way to measure FSH in the human female (cf.…”

Section: Role Of Fsh In Regulation Of Ovulation Ratementioning

confidence: 99%

Reproductive Biology of the Booroola Merino Sheep

Bm¹

1984

Aust. Jnl. Of Bio. Sci.

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This paper reviews the genetic and physiological characteristics of the Booroola Merino, one of the four most prolific sheep breeds in the world, and which was acquired by CSIRO in 1958 from a commercial sheep property, 'Booroola', Cooma, N.S.W. The exceptional prolificacy of this genotypee.g. mean flock ovulation rate in 1982 of 4·2 (range 1-10) and mean litter size of 2· 5 (range 1-7)-is largely attributable to a single gene (F) of uncertain origin which increases ovulation rate. Crosses of the Booroola with other Merinos produce progeny which have a 47-87% increase in ovulation rate, a 45-56% increase in litter size at birth, and a 1-33% reduction in lamb survival relative to control Merinos. This represents a 16-37% increase in the number of lambs weaned per ewe joined in favour of the Booroola crosses.The exact site of action of the F gene is not well established, although it is expressed primarily at the ovary, where more than the normal number of follicles mature and ovulate each oestrous cycle. This may result from some abnormality of the Booroola follicle itself or it may reflect differences in Booroola gonadotrophin secretion. There is some evidence that Booroola ewes have elevated plasma concentrations of follicle stimulating hormone (FSH) early in life and during the oestrous cycle, and that FSH concentrations in the pituitary gland and urine of the adult ewe are also high. These elevated FSH levels in the adult are attributed to an ovarian feedback deficiency, probably because the inhibin content of the Booroola ovary is only one-third that of normal Merino ovaries. The low inhibin content appears to be due to Booroola follicles having significantly fewer granulosa cells than control Merinos. Analogous studies of the prolific D'man sheep of Morocco point to FSH as the main correlate of prolificacy.The testis growth rate, testis size and total daily production of spermatozoa of the Booroola ram are similar to those of normal Merinos, as also are the endocrine characteristics of adult rams. The Booroola gene's expression is evidently sex-limited. Several theories concerning the mode of action of the F gene are being tested.

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Section: Role Of Fsh In Regulation Of Ovulation Ratementioning

confidence: 99%

Reproductive Biology of the Booroola Merino Sheep

Bm¹

1984

Aust. Jnl. Of Bio. Sci.

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“…Until recently the excretion of gonadotrophins had not been measured in nonpregnant farm animals but studies by Robertson and his colleagues and by Symington (1964) have shown that such measurements are possible in castrated sheep maintained in an animal house. MacGillivray & Robertson (1963) have reported an excretion rate equivalent to 0-13-1-31 mg. HMG/24 hr.…”

Section: Discussionmentioning

confidence: 99%

“…The collection apparatus used indoors was that described by Symington (1964). The collection equipment used at pasture was that of Beeston & Hogan (1960); it consisted of a belly funnel with a drainage tube to a stainless-steel cylinder which was mounted on small wheels and pulled behind the sheep.…”

Section: Collection Of Urinementioning

confidence: 99%

“…The method of Johnsen (1958), as modified by Symington (1964), for the extraction of sheep urine was used. Preliminary trials showed that urine from sheep kept indoors contained considerably more gonadotrophic activity per litre of urine than did urine from those at pasture.…”

Section: Extraction Of Gonadotrophinsmentioning

confidence: 99%

“…Bioassays The bioassay techniques used were described in a previous paper (Symington, 1964). In assays of total gonadotrophic activity, human postmenopausal urinary gonadotrophin (HMG 25) was used as the standard at dose levels of 0-6 and 1-2 mg. Doses of alcohol precipitate equivalent to 150 and 300 ml.…”

Section: Extraction Of Gonadotrophinsmentioning

confidence: 99%

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The Urinary Excretion of Gonadotrophins by Sheep: The Effect of Some Nutritional Factors on the Excretion of Gonadotrophins by Castrated Male Sheep

Rb¹

1964

Journal of Endocrinology

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Male castrated Merino sheep were fed indoors on a dry ration or grazed on a good quality pasture. Despite the much greater urine volumes excreted by the grazing animals, the mean daily rates of excretion of total gonadotrophic activity and follicle-stimulating hormone (FSH) were very similar in the two groups. Corresponding levels of excretion of luteinizing hormone (LH) were very variable, owing apparently to deficiencies in the assay technique.When sheep were fed indoors on freshly cut grass, the urine output was almost three-quarters of that of grazing animals but the rate of excretion of total gonadotrophic activity and of FSH was considerably greater than that of grazing animals.The daily output of urine by sheep fed indoors on a dry ration was adjusted to equal that of grazing sheep. Although the amounts of total gonadotrophic activity were smaller than those in the previous experiments, the amounts of FSH excreted were the highest recorded in the entire investigation.The possibility of a temporal fluctuation in the excretion of gonadotrophins is discussed.

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Reproductive endocrinology of prolific sheep: studies of the Booroola Merino

Bindon

Piper

1985

Genetics of Reproduction in Sheep

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The Urinary Excretion of Gonadotrophins by Sheep: Extraction Procedure and Day-to-Day Fluctuation in Excretion by Male and Female Castrated Sheep

Cited by 4 publications

References 15 publications

Reproductive Biology of the Booroola Merino Sheep

Reproductive Biology of the Booroola Merino Sheep

The Urinary Excretion of Gonadotrophins by Sheep: The Effect of Some Nutritional Factors on the Excretion of Gonadotrophins by Castrated Male Sheep

Reproductive endocrinology of prolific sheep: studies of the Booroola Merino

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