Gastrointestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition

Ancestral lineages of dietary exposure to an endocrine disrupting chemical drive distinct forms of transgenerational subfertility in an insect model

Across the globe, many species of insects are facing population decline. This is largely driven by anthropogenic changes to the environment, including the widespread exposure of invertebrates to endocrine disrupting chemicals (EDCs), which impair fertility. To test whether generations of Drosophila melanogaster born from parents exposed to a common dietary EDC, equol, could recover reproductive function, we quantified the reproductive capacity of the two subsequent generations. Using a novel suite of flow cytometry assays to assess sperm functionality in real time, we find that sperm function is compromised across three generations, even after non-exposed in individuals contribute to the breeding population. Though the sex ratio alters in response to EDC exposure, favouring the survival of female offspring, most lineages with ancestral EDC exposure exhibit persistent subfertility in both the male and female. Male offspring with ancestral EDC exposure present with reduced fertility and dysfunctional spermatozoa, whereby spermatozoa are metabolically stressed, lack DNA integrity and present with permanent epigenetic alterations. Across generations, male and female offspring demonstrate distinct patterns of reproductive characteristics, depending upon the specific lineage of EDC exposure. Our results illustrate how dietary EDCs present in agricultural plants could promote transgenerational subfertility and contribute to declining insect populations.

Effects of Mixed Pasture Legume Phytoestrogens on Superovulatory Response and Embryo Quality in Angus Cows

Ovulation and artificial insemination rates have been observed to decrease in sheep and cows when exposed to dietary phytoestrogens at concentrations greater than 25 mg/kg DM. A grazing trial was undertaken to investigate the effects of coumestrol and other key phytoestrogens on the superovulatory response, embryo numbers and quality in beef cows grazing legume pastures. A 7-week controlled grazing trial was conducted with legume and ryegrass pasture treatments, with cows exposed to legumes at two timed treatments, 4 and 7 weeks. Twenty Angus cows were subjected to a conventional estrus synchronization and superovulation protocol. Embryos were recovered via conventional uterine body flushing 7 days post artificial insemination (AI). Numerous phytoestrogens were identified in both pasture and plasma samples, including coumestrol and formononetin. Concentrations of phytoestrogens in the pasture ranged from 0.001 to 47.5 mg/kg DM and 0 to 2.6 ng/mL in plasma. Approximately 50% of cows produced viable embryos 7 days post AI. A significant interaction between the effect of treatment groups on the embryo stage was observed (p < 0.05). The results suggest that concentrations of >25 mg/kg DM of phytoestrogens less than 20 days preceding AI may negatively affect oocyte developmental competence, reduce progesterone production and thus contribute to early embryonic loss.

Evaluation of in vitro bioassays as a screening tool to monitor chemical hazards in cow's milk

Studies on cow's milk have mainly focused on analyzing specific chemical groups and natural components. Therefore, in this study, we evaluated if effect-based in vitro methods could be used as a screening tool to monitor chemical hazards in milk. In total, 32 milk samples were collected from a Swedish dairy company throughout one year. These samples included conventional and organic semi-skimmed as well as raw milk. The milk samples were tested in five in vitro methods covering eight endpoints. These endpoints included cytotoxicity, endocrine disruption (estrogen/androgen induction/inhibition), aryl hydrocarbon receptor activity, oxidative stress and DNA damage. Estrogen and androgen receptor inhibition, in addition to aryl hydrocarbon receptor activity, were the most responsive endpoints, where 10 to 13 out of the 32 milk samples were bioactive. Organic and conventional milk showed no major differences. Overall, no or only low activities were observed in milk samples in the remaining in vitro assays, which is a promising result with regard to applying effect-based methods as a screening tool. Concerning the most responsive assays, more research is needed to understand the normal background variations before they can be used as a screening tool for chemical hazards in milk.

Phytoestrogens: A Review of Their Impacts on Reproductive Physiology and Other Effects upon Grazing Livestock

Legume crops and pastures have a high economic value in Australia. However, legume species commonly used for grazing enterprises have been identified to produce high concentrations of phytoestrogens. These compounds are heterocyclic phenolic, and are similar in structure to the mammalian estrogen, 17β-estradiol. The biological activity of the various phytoestrogen types; isoflavones, lignans and coumestans, are species-specific, although at concentrations of 25 mg/kg of dry matter each of the phytoestrogen types affect reproductive functions in grazing livestock. The impacts upon fertility in grazing livestock such as cattle and sheep, vary greatly over length of exposure time, age and health of animal and the stress stimuli the plant is exposed to. More recently, research into the other effects that phytoestrogens may have upon metabolism, immune capacity and growth and performance of grazing livestock has been conducted. Potential new benefits for using these phytoestrogens, such as daidzein and genistein, have been identified by observing the stimulation of production in lymphocytes and other antibody cells. Numerous isoflavones have also been recognized to promote protein synthesis, increase the lean meat ratio, and increase weight gain in cattle and sheep. In Australia, the high economic value of legumes as pasture crops in sheep and cattle production enterprises requires proactive management strategies to mitigate risk associated with potential loss of fertility associated with inclusion of pasture legumes as forages for grazing livestock.

Research Advances in the Analysis of Estrogenic Endocrine Disrupting Compounds in Milk and Dairy Products

Milk and dairy products are sources of exposure to estrogenic endocrine disrupting compounds (e-EDCs). Estrogenic disruptors can accumulate in organisms through the food chain and may negatively affect ecosystems and organisms even at low concentrations. Therefore, the analysis of e-EDCs in dairy products is of practical significance. Continuous efforts have been made to establish effective methods to detect e-EDCs, using convenient sample pretreatments and simple steps. This review aims to summarize the recently reported pretreatment methods for estrogenic disruptors, such as solid-phase extraction (SPE) and liquid phase microextraction (LPME), determination methods including gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), Raman spectroscopy, and biosensors, to provide a reliable theoretical basis and operational method for e-EDC analysis in the future.

In sacco evaluation of ruminal degradability of isoflavones from full-fat soybean and extracted soybean meal-A pilot study

The aim of the study was to determine the ruminal degradability of dry matter (DM), daidzein, genistein, glycitein and total isoflavones in ground full-fat soybean (GFFS) and solvent-extracted soybean meal (SSBM) using the in sacco method. The experiment was carried out in three replications on ruminally cannulated sheep that were fed twice a day with a diet consisted of hay and supplemental mixture (6:4, DM basis). The nylon bags with 2 g feed samples ground to 2 mm were incubated in the rumen for 0, 2, 4, 8, 16 and 24 h. The effective degradability (ED) of DM, daidzein, genistein, glycitein and total isoflavones was calculated at outflow rate of 0.06 h. The ED of DM in GFFS was 77.8% and was higher than in SSBM being 71.8% (p < 0.001). The ED of daidzein (96.8%) and genistein (93.6%) was higher for SSBM compared with GFFS (93.9% and 92.8%, p < 0.001 and p = 0.003, respectively) while ED of glycitein was lower for SSBM than for GFFS (75.5 and 81.7%, respectively, p < 0.001). All isoflavones in the incubations were extensively degraded in the rumen, and regardless of dietary source, they were almost completely degraded after 16 h of incubation. Further, the disappearance patterns, that is the functions describing the time courses of the analyte disappearance, were assessed. The disappearance patterns of daidzein, genistein, glycitein and total isoflavones were similar and showed greater disappearance of mentioned isoflavones from SSBM compared to GFFS (p < 0.001 for daidzein, genistein and total isoflavones and p = 0.002 for glycitein). The study provides knowledge on the effect of processing on degradability of isoflavones in rumen that can be used to clarify the interrelationship between isoflavones and rumen microbiota.

Production performance and oxidative stability of milk enriched with n-3 fatty acids in Holstein cows fed flaxseed meal

Six Holstein cows were used in a replicated 3 × 3 Latin Square design to investigate the effect of flaxseed meal on production performance and oxidative stability of milk enriched with n-3 fatty acids. Flaxseed oil was abomasally infused to all cows at 243 g·d−1 which increased milk concentration of α-linolenic acid from 3.08 (pretrial) up to 53.0 mg·g−1 fat. On a dry matter basis, dietary treatments were canola meal (CM; 165 g·kg−1), flaxseed meal (FM; 165 g·kg−1), and CM (165 g·kg−1) + vitamin E (VE; 300 IU·kg−1). Pre-planned contrasts were CM vs. FM and VE vs. FM. No difference was observed on dry matter intake, milk production, and yield of milk protein, and lactose for any of the contrasts evaluated. However, fat yield tended to be lower with FM relative to CM but was not different from VE. Milk enterolactone concentration was 6.8-fold greater with FM than with CM, whereas milk tocopherol was increased by 3.4-fold with VE relative to FM. Increased concentrations of enterolactone or tocopherol were not efficient to significantly modify the time course of appearance of propanal, hexanal, hept-cis-4-enal, and 1-octen-3-one in milk during storage evaluated for 10 d at 4 °C.

Production of Bovine Equol-Enriched Milk: A Review

Simple Summary

Milk and dairy products contain many substances beneficial to human health; moreover, the contents of some of these substances can be enhanced. This is also the case of isoflavones which are compounds of plant origin that can be ingested and metabolized by cattle and, subsequently, secreted into bovine milk. An especially healthful substance called equol is ranked among isoflavone metabolites, commonly produced in the digestive tract of cattle. Equol content in milk can be modified by using feedstuffs with different contents of isoflavones or by milk processing and storage.

Abstract

Milk and dairy products are important sources of nutrients in the human diet because they contain a number of essential substances and other biologically active components. Many of these substances can be modified, and thus offer opportunities to use milk and dairy products as functional food. Isoflavones are particularly important in human nutrition due to their diverse pharmacological and antioxidant properties. The clinical effectiveness of isoflavone-rich products is believed to be dependent on their ability to metabolize daidzein to equol, which may directly exert cancer preventive effects. However, only approximately 30–40% of humans are able to produce equol, while animals, in general, produce equol. Equol is the predominant product of bacterial metabolism of isoflavones and can be found in various amounts in some food of animal origin, especially in milk. Therefore, milk and dairy products can be considered to be sources of equol for humans who are not able to produce this metabolite. When the content of isoflavones in milk is to be modified, two groups of factors should be considered, i.e., dietary factors that include the source of isoflavones and the processing effects on feedstuffs and animal factors that include the intake of isoflavones, ruminal and postruminal changes, and the health and physiological status of animals. The approximate content of isoflavones in milk can be predicted using carry-over rates for different dietary sources or using a formula that describes the relationship between equol concentration in milk and formononetin intake. Processing and storage can affect the content and profile of isoflavones in milk and dairy products.

In vitro metabolism of red clover isoflavones in rumen fluid

The degradation of red clover isoflavones was studied in vitro using a rumen fluid buffer system. Various amounts of red clover extract (5-75 mg) together with hay or concentrate-rich diet were added to 40 ml of rumen fluid obtained from non-lactating and lactating dairy cows, respectively, and incubated for 0, 3, 6, 12 or 24 hr. Following incubation, concentrations of daidzein, genistein, formononetin, biochanin A and equol were determined in the samples. After 3 hr of incubation, isoflavone metabolism and equol production could be observed. The results obtained indicate that hay diet provides better conditions for isoflavone metabolism, as concentrations of daidzein, formononetin and biochanin A were higher in incubations based on the concentrate-rich diet and the production of equol was higher in incubations based on the hay diet. Furthermore, in incubations with higher amounts of added clover extract, a decrease in equol production was observed. Further studies are needed to clarify the role of adaptation of rumen microflora on isoflavone degradation kinetics and to clarify the interrelationship between various dietary factors, rumen microbiota and isoflavones. The knowledge of isoflavone metabolism kinetics in dependence on studied factors will be useful for the optimization of feeding dose.

Adverse Effects of Coumestrol and Genistein on Mammary Morphogenesis and Future Milk Production Ability of Mammary Epithelial Cells

Isoflavones are a class of flavonoids present in legumes and are called phytoestrogens because of their estrogen-like activity. Endogenous estrogen is well known to regulate mammary gland morphogenesis during pregnancy. Each isoflavone also has different physiological activities. However, it is difficult to investigate the direct effect of each isoflavone in mammary morphogenesis in vivo because isoflavones are metabolized into different isoflavones by enteric bacteria. In this study, investigated are the direct influences of coumestrol, daidzein, and genistein on mammary structure development and future milk production ability of mammary epithelial cells (MECs) using in vitro culture models. Mouse MECs are cultured in Matrigel with basic fibroblast growth factor and epidermal growth factor to induce ductal branching and alveolar formation, respectively. Coumestrol and genistein inhibit ductal branching and alveolar formation by affecting the proliferation and migration of MECs with the induction of apoptosis. Daidzein hardly influences mammary structure development. Furthermore, pretreatment with coumestrol adversely affects the induction of milk production ability of MECs. These results suggest that each isoflavone differentially influences mammary morphogenesis and future milk production by affecting MEC behaviors. These results also suggest that the culture models are effective to study mammary epithelial morphogenesis in vitro.

Feeding lambs with silage mixtures of grass, sainfoin and red clover improves meat oxidative stability under high oxidative challenge

This study investigated the oxidative stability of meat from lambs fed silages in which timothy grass was totally or partially replaced by sainfoin and/or red clover. Five groups of 8 lambs were fed the following silages: timothy grass (T), mixture (50:50) of timothy with either sainfoin (T-SF) or red clover (T-RC), mixture of timothy, sainfoin and red clover (50:25:25; T-SF-RC), or mixture (50:50) of sainfoin and red clover (SF-RC). Feeding the silages containing red clover (T-RC, T-SF-RC and SF-RC) decreased the deposition of vitamin E in muscle relative to the highly unsaturated fatty acids (P < .001), did not affect the oxidative stability of fresh meat, but reduced oxidative deterioration in cooked meat and in meat homogenates incubated with pro-oxidant catalysts (P < .001). The results of this study demonstrated that feeding lambs with silages containing sainfoin and red clover improve the oxidative stability of meat subjected to strong pro-oxidant conditions and suggest that these effects should be further clarified.

Concentrations of phytoestrogens in conventional, organic and free-range retail milk in England

The effect of dairy management system (conventional, CNV; organic, ORG; free-range, FRG) and month on retail milk phytoestrogen composition was assessed for 12 consecutive months. ORG milk contained more secoisolariciresinol, matairesinol, lariciresinol, sum of plant lignans, daidzein, genistein, formononetin, naringenin, equol, sum of isoflavones and coumestrol, than CNV and FRG milk. This may be explained by the higher supply of pasture, and grazed or ensiled clover, in ORG dairy diets. Seasonal variation in milk phytoestrogen concentrations was higher for ORG than CNV and FRG systems. Phytoestrogen composition did not vary between FRG and CNV milk. Consuming organic milk can increase intake of potentially beneficial lignans and isoflavonoids, and in particular equol; but, any effects on human health from such milk compositional differences cannot be implied.

Isoflavones

Phytoestrogens are naturally occurring nonsteroidal phenolic plant compounds that, due to their molecular structure and size, resemble vertebrate steroids estrogens. This review is focused on plant flavonoids isoflavones, which are ranked among the most estrogenic compounds. The main dietary sources of isoflavones for humans are soybean and soybean products, which contain mainly daidzein and genistein. When they are consumed, they exert estrogenic and/or antiestrogenic effects. Isoflavones are considered chemoprotective and can be used as an alternative therapy for a wide range of hormonal disorders, including several cancer types, namely breast cancer and prostate cancer, cardiovascular diseases, osteoporosis, or menopausal symptoms. On the other hand, isoflavones may also be considered endocrine disruptors with possible negative influences on the state of health in a certain part of the population or on the environment. This review deals with isoflavone classification, structure, and occurrence, with their metabolism, biological, and health effects in humans and animals, and with their utilization and potential risks.

A Review of Lignan Metabolism, Milk Enterolactone Concentration, and Antioxidant Status of Dairy Cows Fed Flaxseed

Lignans are polyphenolic compounds with a wide spectrum of biological functions including antioxidant, anti-inflammatory, and anticarcinogenic activities, therefore, there is an increasing interest in promoting the inclusion of lignan-rich foods in humans' diets. Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside-a compound found in the outer fibrous-containing layers of flax. The rumen appears to be the major site for the conversion of secoisolariciresinol diglucoside to the enterolignans enterodiol and enterolactone, but only enterolactone has been detected in milk of dairy cows fed flaxseed products (whole seeds, hulls, meal). However, there is limited information regarding the ruminal microbiota species involved in the metabolism of secoisolariciresinol diglucoside. Likewise, little is known about how dietary manipulation such as varying the nonstructural carbohydrate profile of rations affects milk enterolactone in dairy cows. Our review covers the gastrointestinal tract metabolism of lignans in humans and animals and presents an in-depth assessment of research that have investigated the impacts of flaxseed products on milk enterolactone concentration and animal health. It also addresses the pharmacokinetics of enterolactone consumed through milk, which may have implications to ruminants and humans' health.

Determination of in vitro isoflavone degradation in rumen fluid

The aim of this study was to determine the degradation of dietary isoflavones in rumen fluid under 2 feeding regimens. The experiments were performed in vitro using a rumen fluid buffer system. The rumen fluid was taken from cows fed either a hay diet or a concentrate-rich diet (the diet consisted of 34.6% maize silage, 17.6% haylage, 12.8% alfalfa hay, and 35.0% supplemental mixture on a dry matter basis). As a source of isoflavones, 40% soybean extract (Biomedica, Prague, Czech Republic) at levels of 5, 25, 50, and 75 mg per 40 mL of rumen fluid was used. Samples of soybean extract were incubated in triplicate at 39°C for 0, 3.0, 6.0, 12.0, and 24.0 h in incubation solution. The metabolism of daidzein and genistein was faster under concentrate-rich diet conditions. In general, production of equol started after 3 to 6 h of incubation and reached the highest rate after approximately 12 h of incubation regardless of the type of diet or concentration of extract. In most of the experiments, production of equol continued after 24 h of incubation. Generally, equol production was greater under the hay diet conditions. Furthermore, experiments with higher amounts of added soybean extract revealed possible inhibitory effects of high levels of isoflavones on the rumen microflora.

Flaxseed-enriched diets change milk concentration of the antimicrobial danofloxacin in sheep

BACKGROUND

Flaxseed is the most common and rich dietary source of lignans and is an acceptable supply of energy for livestock. Flaxseed lignans are precursors of enterolignans, mainly enterolactone and enterodiol, produced by the rumen and intestinal microbiota of mammals and have many important biological properties as phytoestrogens. Potential food-drug interactions involving flaxseed may be relevant for veterinary therapy, and for the quality and safety of milk and dairy products. Our aim was to investigate a potential food-drug interaction involving flaxseed, to explore whether the inclusion of flaxseed in sheep diet affects concentration of the antimicrobial danofloxacin in milk.

RESULTS

Increased concentrations of enterodiol and enterolactone were observed in sheep plasma and milk after 2 weeks of flaxseed supplementation (P < 0.05). However, enterolactone and enterodiol conjugates were not detected in milk. Milk danofloxacin pharmacokinetics showed that area under the curve (AUC)0-24, maximum concentration (Cmax) and AUC0-24 milk-to-plasma ratios were reduced by 25-30% in sheep fed flaxseed-enriched diets (P < 0.05). Our results demonstrate, therefore, that flaxseed-enriched diets reduce the amount of danofloxacin in sheep milk and enrich the milk content of lignan-derivatives.

CONCLUSION

These findings highlight an effect of flaxseed-enriched diets on the concentration of antimicrobials in ruminant's milk, revealing the potential of these modified diets for the control of residues of antimicrobial drugs in milk.

A robust high-throughput fungal biosensor assay for the detection of estrogen activity

Estrogenic active compounds are present in a variety of sources and may alter biological functions in vertebrates. Therefore, it is crucial to develop innovative analytical systems that allow us to screen a broad spectrum of matrices and deliver fast and reliable results. We present the adaptation and validation of a fungal biosensor for the detection of estrogen activity in cow derived samples and tested the clinical applicability for pregnancy diagnosis in 140 mares and 120 cows. As biosensor we used a previously engineered genetically modified strain of the filamentous fungus Aspergillus nidulans, which contains the human estrogen receptor alpha and a reporter construct, in which β-galactosidase gene expression is controlled by an estrogen-responsive-element. The estrogen response of the fungal biosensor was validated with blood, urine, feces, milk and saliva. All matrices were screened for estrogenic activity prior to and after chemical extraction and the results were compared to an enzyme immunoassay (EIA). The biosensor showed consistent results in milk, urine and feces, which were comparable to those of the EIA. In contrast to the EIA, no sample pre-treatment by chemical extraction was needed. For 17β-estradiol, the biosensor showed a limit of detection of 1ng/L. The validation of the biosensor for pregnancy diagnosis revealed a specificity of 100% and a sensitivity of more than 97%. In conclusion, we developed and validated a highly robust fungal biosensor for detection of estrogen activity, which is highly sensitive and economic as it allows analyzing in high-throughput formats without the necessity for organic solvents.

Multiclass analytical method for the determination of natural/synthetic steroid hormones, phytoestrogens, and mycoestrogens in milk and yogurt

Within this study, a new method enabling monitoring of various estrogenic substances potentially occurring in milk and dairy products was proposed. Groups of compounds fairly differing in physico-chemical properties and biological activity were analyzed: four natural estrogens, four synthetic estrogens, five mycoestrogens, and nine phytoestrogens. Since they may pass into milk mainly in glucuronated and sulfated forms, an enzymatic hydrolysis was involved prior to the extraction based on the QuEChERS methodology. For the purification of the organic extract, a dispersive solid-phase extraction (d-SPE) with sorbent C18 was applied. The final analysis was performed by ultra-high-performance liquid chromatography (UHPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS). Method recovery ranged from 70 to 120% with a relative standard deviation (RSD) value lower than 20% and limits of quantification (LOQs) in the range of 0.02-0.60 μg/L (0.2-6.0 μg/kg dry weight) and 0.02-0.90 μg/kg (0.2-6.0 μg/kg dry weight) for milk and yogurt, respectively. The new procedure was applied for the investigation of estrogenic compounds in 11 milk samples and 13 yogurt samples from a Czech retail market. Mainly phytoestrogens were found in the studied samples. The most abundant compounds were equol and enterolactone representing 40-90% of all estrogens. The total content of phytoestrogens (free and bound) was in the range of 149-3870 μg/kg dry weight. This amount is approximately 20 times higher compared to non-bound estrogens.

Changes in equol and major soybean isoflavone contents during processing and storage of yogurts made from control or isoflavone-enriched bovine milk determined using LC-MS (TOF) analysis

The effect of supplementing a basal diet for dairy cows with "Soybean extract 40" (Biomedica, Prague, Czech Republic), containing 40% soybean isoflavones, on the contents of daidzein, glycitein, genistein, and equol in milk as well as fresh and mature yogurts was estimated. To determine the contents of these isoflavonoids, an efficient analytical LC-MS (TOF) technique was used. The "Soybean extract 40" used in our study contained an especially high proportion of daidzein (307gkg-1). In both milk and yogurt samples, the amounts of daidzein and its metabolite equol were significantly higher in samples obtained from cows that received the isoflavone extract-supplemented diet than from those that received the basal diet, as the precursor daidzein contributed to the increased equol concentrations. Fermentation caused significant changes in the daidzein and glycitein concentrations. With maturation, the concentrations of daidzein and equol were unaffected, while the glycitein concentration decreased significantly.

Soybean-Derived Isoflavone Determination in Rumen Fluid and Milk by LC-MS-(TOF)

Soybean-derived isoflavones belong to the family of biologically active phytoestrogens. The purpose of this study was to develop a sensitive method, which permits quantification of the soybean isoflavonoids and equol in bovine rumen fluid and milk using LC-MS-(TOF). The samples of rumen fluid and milk were obtained from 12 lactating dairy cows ingesting 7,500-9,500 mg of total isoflavones daily. The validation of the developed method showed the limits of quantification to be in the range of 0.9-5.0 ng/mL. The precision was determined as relative standard deviation, which was lower than 25% in all cases. The recoveries of the most isoflavonoids were satisfactory. Lower recoveries of daidzin and glycitin can be solved by adding an internal standard. The presented method will be useful for kinetic studies of isoflavone metabolism in ruminants due to simultaneous quantification of free aglycones and glycosides in the rumen fluid.

Mitigation of Ergot Vasoconstriction by Clover Isoflavones in Goats (Capra hircus)

Ergot alkaloids produced by a fungal endophyte (Epichloë coenophiala; formerly Neotyphodium coenophialum) that infects tall fescue (Lolium arundinaceum) can induce persistent constriction of the vasculature in ruminants, hindering their capability to thermo-regulate core body temperature. There is evidence that isoflavones produced by legumes can relax the vasculature, which suggests that they could relieve ergot alkaloid-induced vasoconstriction and mitigate the vulnerability to severe heat stress in ruminants that graze tall fescue. To test if isoflavones can relieve alkaloid-induced vasoconstriction, two pen experiments were conducted with rumen-fistulated goats (Capra hircus) to determine with ultrasonograpy if isoflavones can (1) promote vascular compliance by countering alkaloid-induced vasoconstriction and (2) relieve already imposed alkaloid-induced vasoconstriction. Goats were fed ad libitum chopped orchardgrass (Dactylis glomerata)–timothy (Phleum pratense) hay prior to conducting the experiments. Measures of carotid and interosseous luminal areas were obtained pre- (baseline) and post-ruminal infusions in both experiments with goats being fed the hay, and for blood flow rate in the carotid artery in Experiment 2. Responses to infusion treatments were evaluated as proportionate differences from baseline measures. Peak systolic velocity, pulsatility index, and heart rate were measured on the last day on treatment (DOT) in Experiment 1, and on all imaging sessions during Experiment 2. For Experiment 1, rumens were infused with ground toxic fescue seed and isoflavones in Phase A and with only the toxic seed in Phase B. The infusion treatments were switched between phases in Experiment 2, which employed a fescue seed extract having an ergot alkaloid composition equivalent to that of the ground seed used in Experiment 1. During Experiment 1, luminal areas of carotid and interosseous arteries in Phase A did not deviate (P > 0.1) from baselines over 1, 2, 3, and 4 DOT, but the areas of both declined linearly from baselines over 1, 2, 3, and 4 DOT in Phase B. By 6, 7, and 8 DOT in Experiment 2, luminal areas of the arteries and flow rate declined from baselines with infusions with the only seed extract in Phase A, but luminal areas and flow rate increased over 4, 5, and 6 DOT with the additional infusion of isoflavones. Peak systolic velocity and heart rate were not affected by treatment in either experiment, but were highest when infused with only ergot alkaloids in both experiments. Treatment with isoflavones was demonstrated to relax the carotid and interosseous arteries and reduce resistance to blood flow. Results indicate that isoflavones can relax persistent vasoconstriction in goats caused by consumption of ergot alkaloids, and mitigate the adverse effect that ergot alkaloids have on dry matter intake.

Analytical methods used to quantify isoflavones in cow's milk: a review

This paper provides an update and comprehensive review of the analytical methods used for quantifying isoflavones and their metabolites in cow’s milk. Isoflavones are secondary plant metabolites that are similar to 17 β-estradiol in chemical structure. They form one of the most common categories of phytoestrogens. Numerous health benefits have been attributed to isoflavones, but many of these compounds are also considered to be endocrine disruptors, with adverse effects on health. These contradictory trends offer an attractive prospect for future research, and therefore, sensitive and reliable analytical methods are required to clarify various issues about isoflavones. For this review, a structured methodology was used to select 26 relevant articles published between 2005 and 2015 from the Scopus and CAB Abstract databases. The review discusses individual steps of the analytical procedures described in these articles, including sample preparation, instrumental analysis and validation. The most commonly used analytical procedure is sample preparation involving liquid-liquid extraction and an enzymatic hydrolysis step followed by liquid chromatography with mass spectrometry analysis. Currently, however, there is no standardized procedure for the sample preparation and analysis of isoflavones in milk.

Interaction of Isoflavones and Endophyte-Infected Tall Fescue Seed Extract on Vasoactivity of Bovine Mesenteric Vasculature

It was hypothesized that isoflavones may attenuate ergot alkaloid-induced vasoconstriction and possibly alleviate diminished contractility of vasculature after exposure to ergot alkaloids. The objective of this study was to determine if prior incubation of bovine mesenteric vasculature with the isoflavones formononetin (F), biochanin A (B), or an ergovaline-containing tall fescue seed extract (EXT) and their combinations affect ergotamine (ERT)-induced contractility. Multiple segments of mesenteric artery and vein supporting the ileal flange of the small intestine were collected from Angus heifers at slaughter (n = 5, bodyweight = 639 ± 39 kg). Duplicates of each vessel type were incubated in tissue culture flasks at 37°C with a 50-mL volume of Krebs–Henseleit buffer containing: only buffer (control); or 1 × 10⁻⁶ M EXT; F; or B; and combinations of 1 × 10⁻⁶ M EXT + F; 1 × 10⁻⁶ M EXT + B; 1 × 10⁻⁶ M F + B; or 1 × 10⁻⁶ M EXT + F + B. After incubation for 2 h, sections were mounted in a multimyograph chamber. The ERT dose responses were normalized to 0.12 M KCl. Pretreatment with F, B, and F + B without EXT resulted in similar contractile responses to ERT in mesenteric artery and all incubations containing EXT resulted in a complete loss of vasoactivity to ERT. In mesenteric artery pretreated with EXT, treatments that contained B had higher contractile responses (P < 0.05) at ERT concentrations of 1 × 10⁻⁷ and 5 × 10⁻⁷ M. Also, treatments containing B tended (P < 0.1) to have greater responses than treatments without B at ERT concentrations of 1 × 10⁻⁶, 5 × 10⁻⁶, and 5 × 10⁻⁵ M. In mesenteric vein pretreated with EXT, treatments containing F had greater contractile responses to ERT at 1 × 10⁻⁵, 5 × 10⁻⁵, and 1 × 10⁻⁴ M (P < 0.05). These data indicated that F and B at 1 × 10⁻⁶ M and their combination did not impact the overall contractile response to ERT in mesenteric vasculature. However, F and B may offset some of the vasoconstriction caused by prior exposure to ergot alkaloids.

Phytoestrogens and their metabolites in bulk-tank milk: effects of farm management and season

Phytoestrogens have structures similar to endogenous steroids and may induce or inhibit the response of hormone receptors. The objectives of the present study were to compare the effects of long-term vs. short-term grassland management in organic and conventional dairy production systems, compare organic and conventional production systems and assess seasonal variation on phytoestrogen concentrations in bulk-tank milk. The concentrations of phytoestrogens were analyzed in bulk-tank milk sampled three times in two subsequent years from 28 dairy farms: Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. The proportion of red clover (Trifolium pretense L.) in the herbage was positively correlated with milk concentrations of the mammalian isoflavone equol. Therefore, organically produced bulk-tank milk contained more equol than conventionally produced milk, and milk from ORG-SG farms had more equol than milk from ORG-LG farms. Milk produced during the indoor-feeding periods had more equol than milk produced during the outdoor feeding period, because pastures contained less red clover than fields intended for silage production. Organically produced milk had also higher concentrations of the mammalian lignan enterolactone, but in contrast to equol, concentrations increased in the outdoor-feeding periods compared to the indoor-feeding periods. There were no indications of fertility problems on ORG-SG farms who had the highest red clover proportions in the herbage. This study shows that production system, grassland management, and season affect milk concentrations of phytoestrogens. However, compared to soy products, milk concentrations of phytoestrogens are low and future studies are required to investigate if the intake of phytoestrogens from dairy products has physiological effects in humans.