Preovulatory LH characteristics and time of ovulation in the prolific Booroola Merino ewe

Bindon, B. M.; Piper, LR; Thimonier, J.

doi:10.1530/jrf.0.0710519

Cited by 18 publications

(8 citation statements)

References 8 publications

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“…area and height) revealed no differences between the genotypes. These findings are consistent with those reported by Bindon et al (1984) who showed that the timing of the preovulatory LH surge and LH peak concentrations were similar in Booroola and control Merino ewes, not-withstanding their different ovulation rates. Although implantation of progesterone did not provoke an LH 'surge' there was at least a partial recovery of the acute suppressive effects of progesterone some 20 h later; this was much more obvious after the implantation of 1 progesterone envelope than with 3 envelopes.…”

Section: Discussionsupporting

confidence: 92%

Effects of oestradiol-17 , progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene

McNatty

Hudson²,

Collins³

et al. 1989

Reproduction

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Summary. The although there were significant effects of the steroids and bFF with respect to dose (P < 0\m=.\05). At 6 days after steroid implantation, no gene-specific effects were noted for the plasma concentrations of FSH although significant effects of dose of oestradiol (P < 0\m=.\01) but not progesterone were noted. Also at 6 days after steroid implantation, no gene-specific differences in the pulsatile patterns (i.e. peak frequency or amplitude) of plasma LH concentrations were noted although there were significant effects of steroid dose (P < 0\m=.\05) on frequency and/or amplitude.It is concluded that the higher ovulation-rate in FF than ++ Booroola ewes is unlikely to be due to gene-specific differences in the sensitivity of the hypothalamic\p=n-\ pituitary axis to ovarian hormones.

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Section: Discussionsupporting

confidence: 92%

Effects of oestradiol-17 , progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene

McNatty

Hudson²,

Collins³

et al. 1989

Reproduction

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“…No differences have been noted in the time from the onset of estrus to the preovulatory LH surge nor in the duration of the preovulatory LH surge itself [31]. These findings suggest that the early increase in progesterone during the luteal phase may be due at least in part to the earlier development of the CL.…”

Section: Discussionmentioning

confidence: 64%

Concentrations of Progesterone, Follistatin, and Follicle-Stimulating Hormone in Peripheral Plasma Across the Estrous Cycle and Pregnancy in Merino Ewes That Are Homozygous or Noncarriers of the Booroola Gene1

Xia¹,

O’Shea²,

Murison³

et al. 2003

Biology of Reproduction

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The circulating concentrations of progesterone, FSH, and follistatin across the estrous cycle and gestation were compared in Australian merino sheep that were homozygous for the Booroola gene, FecB, or were noncarriers. The Booroola phenotype is due to a point mutation in the bone morphogenetic protein receptor 1B. Progesterone concentrations began to rise earlier and were higher in the Booroola ewes than in the noncarriers on most days of the luteal phase but not during the follicular phase of the cycle. Follistatin concentrations remained unchanged across the estrous cycle in both groups of ewes, with no differences between genotypes. FSH concentrations were higher in Booroola ewes than in noncarrier ewes on most days of the estrous cycle, with a significantly higher and broader peak of FSH around the time of estrus. Progesterone concentrations were significantly higher in early and midgestation in Booroola ewes but were lower toward the end of gestation than those in noncarriers. FSH declined in both groups across gestation, with lower concentrations of FSH in Booroola ewes during midgestation. Follistatin remained unchanged across gestation in Booroola ewes and noncarrier ewes with a twin pregnancy but declined across gestation in noncarrier ewes with a singleton pregnancy. These results suggest that follistatin concentration is not regulated by the FecB gene during the estrous cycle and pregnancy but is influenced by the number of fetuses. However, the FecB gene appears to positively affect both progesterone and FSH during the estrous cycle and across pregnancy, which suggests that bone morphogenetic proteins play an important role in the regulation of both hormones.

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“…This is shown by the fact that ovulation occurs on average, 7·5 h earlier after onset of oestrus in Booroola ewes than in C Merinos, despite a similar timing of the LH discharge (Bindon et al 1984a). This may mean that Booroola pre-ovulatory follicles are more sensitive to endogenous LH, perhaps as a result of having more LH receptors in the mural granulosa layer.…”

Section: Role Of Lh and Lh Pulse Frequencymentioning

confidence: 96%

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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Preovulatory LH characteristics and time of ovulation in the prolific Booroola Merino ewe

Cited by 18 publications

References 8 publications

Effects of oestradiol-17 , progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene

Effects of oestradiol-17 , progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene

Concentrations of Progesterone, Follistatin, and Follicle-Stimulating Hormone in Peripheral Plasma Across the Estrous Cycle and Pregnancy in Merino Ewes That Are Homozygous or Noncarriers of the Booroola Gene1

Reproductive Biology of the Booroola Merino Sheep

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