Effects of Alfalfa Consumption on Estrogen Levels in Ewes

Newsome, F. E.; Kitts, W. D.

doi:10.4141/cjas77-068

Cited by 17 publications

(6 citation statements)

References 18 publications

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“…Kelly et al (1976) noted that very high levels of coumestans inhibited the expression of oestrus in ewes and suggested that this was due to a lack of endogenous oestrogen. Newsome & Kitts (1977) reported that ewes consuming forage containing phyto-oestrogens had plasma levels of oestrogen that were lower and more uniform than those ofcontrol sheep, suggesting an effect on the secretion of gonadotrophins.…”

Section: Introductionmentioning

confidence: 95%

BINDING OF PHYTO-OESTROGEN AND OESTRADIOL-17β BY CYTOPLASMIC RECEPTORS IN THE PITUITARY GLAND AND HYPOTHALAMUS OF THE EWE

Mathieson¹,

Kitts²

1980

Journal of Endocrinology

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The binding of the phyto-oestrogens, genistein and coumestrol by oestrogen receptors in pituitary and hypothalamic cytosol of the ewe was studied in relation to the binding of [3H]-oestradiol-17 beta. It was determined that the interaction of these compounds was competitive. The apparent dissociation constant for oestradiol-17 beta in ewe pituitary cytosol was determined to be 0 x 26 +/- 0 x 12 (S.E.M.) nmol/l. Apparent inhibition constants for coumestrol and genistein were determined to be 60 and 170 nmol/l respectively. These results suggested that phyto-oestrogens can interfere with the normal oestrogen feedback mechanisms with respect to release of gonadotrophine in the ewe.

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Section: Introductionmentioning

confidence: 95%

BINDING OF PHYTO-OESTROGEN AND OESTRADIOL-17β BY CYTOPLASMIC RECEPTORS IN THE PITUITARY GLAND AND HYPOTHALAMUS OF THE EWE

Mathieson¹,

Kitts²

1980

Journal of Endocrinology

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“…Natural dietary exposures to phytoestrogens have been associated with cystic ovaries, irregular estrus, and anestrus in cattle (91), and reduced breeding success in California quail (92). Compromised follicular development (91) and reductions in luteal phase plasma progesterone and E 2 , as well as shortened luteal phases, have been reported in cycling ewes whereas increases in estradiol and cortisol have been reported in pregnant ewes (93,94). Soy isoflavone diets providing doses of 1 mg/kg/day were associated with infertility in captive cheetahs (95).…”

Section: Ovarian Cyclicitymentioning

confidence: 99%

Cross-species and interassay comparisons of phytoestrogen action.

Whitten

Patisaul

2001

Environ Health Perspect

174

105

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This paper compiles animal and human data on the biologic effects and exposure levels of phytoestrogens in order to identify areas of research in which direct species comparisons can be made. In vitro and in vivo assays of phytoestrogen action and potency are reviewed and compared to actions, dose-response relationships, and estimates of exposure in human subjects. Binding studies show that the isoflavonoid phytoestrogens are high-affinity ligands for estrogen receptors (ERs), especially ER beta, but have lower potency in whole-cell assays, perhaps because of interactions with binding proteins. Many other enzymatic actions require concentrations higher than those normally seen in plasma. In vivo data show that phytoestrogens have a wide range of biologic effects at doses and plasma concentrations seen with normal human diets. Significant in vivoresponses have been observed in animal and human tests for bone, breast, ovary, pituitary, vasculature, prostate, and serum lipids. The doses reported to be biologically active in humans (0.4--10 mg/kg body weight/day) are lower than the doses generally reported to be active in rodents (10--100 mg/kg body weight/day), although some studies have reported rodent responses at lower doses. However, available estimates of bioavailability and peak plasma levels in rodents and humans are more similar. Steroidogenesis and the hypothalamic-pituitary-gonadal axis appear to be important loci of phytoestrogen actions, but these inferences must be tentative because good dose-response data are not available for many end points. The similarity of reported proliferative and antiproliferative doses illustrates the need for fuller examination of dose-response relationships and multiple end points in assessing phytoestrogen actions.

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“…Newsome and Kitts (1977) [123] showed that ewes fed on lucerne had higher levels of phytoestrogen in their plasma and lower levels of endogenous oestrogens than ewes fed grass (Dactylis glomerata), suggesting that gonadotropin stimulation of the ovary was reduced by the presence of phytoestrogen in the plasma. With coumestrol in white clover, Sanger and Bell (1959) [19] found it affected fertilisation but not ovulation.…”

Section: Suppression Of Oestrusmentioning

confidence: 99%

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

Reed¹

2016

Agriculture

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Despite their unrivalled value in livestock systems, certain temperate, pasture, legume species and varieties may contain phytoestrogens which can lower flock/herd fertility. Such compounds, whose chemical structure and biological activity resembles that of estradiol-17α, include the isoflavones that have caused devastating effects (some of them permanent) on the fertility of many Australian sheep flocks. While the persistence of old 'oestrogenic' ecotypes of subterranean clover (Trifolium subterraneum) in pasture remains a risk, genetic improvement has been most effective in lowering isoflavone production in Trifolium species; infertility due to 'clover disease' has been greatly reduced. Coumestans, which can be produced in Medicago species responding to stress, remain a potential risk in cultivars susceptible to, for example, foliar diseases. In the field, coumestrol is often not detected in healthy vegetative Medicago species. Wide variation in its concentration is influenced by environmental factors and stage of growth. Biotic stress is the most studied environmental factor and, in lucerne/alfalfa (Medicago sativa), it is the major determinant of oestrogenicity. Concentrations up to 90 mg coumestrol/kg (all concentrations expressed as DM) have been recorded for lucerne damaged by aphids and up to 600 mg/kg for lucerne stressed by foliar disease(s). Other significant coumestans, e.g., 4'-methoxy-coumestrol, are usually present at the same time. Concentrations exceeding 2000 mg coumestrol/kg have been recorded in diseased, annual species of Medicago. Oestrogenicity of some Medicago species is also influenced by maturity and senescence. Studies in Israel, North America, Europe, New Zealand and Australia have confirmed that coumestans in lucerne, represent an acute or sub-acute loss of reproductive efficiency in herbivores, e.g., sheep, cattle, and possibly horses. When sufficiently exposed peri-conception, coumestrol, sometimes present in lucerne, be it as pasture, hay, silage, pellets, meal, and sprouts, is associated with what can be an insidious, asymptomatic, infertility syndrome. Most livestock research with oestrogenic lucerne has been conducted with sheep. Ewes may be at risk when the coumestrol concentration in their diet exceeds 25 mg/kg. In studies where lambing was compared for lucerne and a phytoestrogen-free treatment, the mean decrease in lambs born/ewe was 13%; ewes on lucerne, exhibited a lower frequency of multiple births.

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Effects of Alfalfa Consumption on Estrogen Levels in Ewes

Abstract: (Guggolz et al. 196l). The levels of can have plasma levels of 5 ng coumesphyto-estrogens found in alfalfa are geo-trol/ml (Lindner 1967

Cited by 17 publications

References 18 publications

BINDING OF PHYTO-OESTROGEN AND OESTRADIOL-17β BY CYTOPLASMIC RECEPTORS IN THE PITUITARY GLAND AND HYPOTHALAMUS OF THE EWE

BINDING OF PHYTO-OESTROGEN AND OESTRADIOL-17β BY CYTOPLASMIC RECEPTORS IN THE PITUITARY GLAND AND HYPOTHALAMUS OF THE EWE

Cross-species and interassay comparisons of phytoestrogen action.

Fertility of Herbivores Consuming Phytoestrogen-containing Medicago and Trifolium Species

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