A two-generation reproduction study to assess the effects of cows' milk on reproductive development in male and female rats

Effect of Ca-octanoate supplementation on concentrations of ghrelin and ghrelin-related hormones in plasma and milk of beef cattle

We aimed to evaluate the effect of dietary calcium (Ca)-octanoate supplementation on concentrations of ghrelin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin in plasma and milk of beef cattle during late gestation and early postpartum. Twelve Japanese Black cattle were offered concentrate without (CON, n = 6) or with Ca-octanoate supplementation at 1.5% of dietary dry matter (OCT, n = 6). Blood samples were collected at -60, -30, and -7 d relative to the expected parturition date and daily from d 0 to 3 after parturition. Milk samples were collected daily postpartum. Compared to the CON group, concentrations of acylated ghrelin increased in plasma as parturition approached in the OCT group (P = 0.02). However, concentrations of GH, IGF-1, and insulin in plasma and milk were not affected by treatment groups throughout the study. Additionally, we showed for the first time that bovine colostrum and transition milk contain acylated ghrelin at a significantly higher concentration than plasma (P = 0.01). Interestingly, concentrations of acylated ghrelin in milk were negatively correlated with those in plasma postpartum (r = -0.50, P < 0.01). Feeding Ca-octanoate increased concentrations of total cholesterol (T-cho) in plasma and milk (P < 0.05), tended to increase those of glucose in plasma at postpartum and milk (P < 0.1). We conclude that feeding Ca-octanoate in late gestation and early postpartum may contribute to increased concentrations of glucose and T-cho in plasma and milk without affecting concentrations of ghrelin, GH, IGF-1, and insulin in plasma and milk.

Harnessing the value of reproductive hormones in cattle production with considerations to animal welfare and human health

The human population is ever increasing while the quality and quantity of natural resources used for livestock production decline. This calls for improved product efficiency and the development of improved and sustainable cattle production methods to produce higher quality products to satisfy the demands of both the modern and transient world. The goal of this review was to summarize the interactions, challenges, and opportunities in cattle production relating to their endocrine system, and how reproductive hormones and others impact economically important traits, animal welfare, and human health. A comprehensive literature search was conducted with a focus on analysis of natural hormones and the use of exogenous hormone administration for reproduction, growth, and development of beef and dairy cattle. Hormones regulate homeostasis and enhance important traits in cattle, including fertility, growth and development, health, and the production of both meat and milk products. Reproductive hormones such as testosterone, estradiol, progesterone, and related synthetics like trenbolone acetate and zeranol can be strategically utilized in both beef and dairy cattle production systems to enhance their most valuable traits, but the impact of these substances must account for the welfare of the animal as well as the health of the consumer. This scientific review provides a comprehensive analysis of the bovine endocrine system's impact on food animals and product quality which is vital for students, researchers, livestock producers, and consumers. Although important advances have been made in animal science and related technological fields, major gaps still exist in the knowledge base regarding the influence of hormones on the production and welfare of food animals as well as in the public perception of hormone use in food-producing animals. Filling these gaps through transformative and translational research will enhance both fundamental and applied animal science to feed a growing population.

In Vivo Study of The Oestrogenic Activity of Milk

Introduction

Milk has been suggested to be a possible source of oestrogenically active compounds. In order to assess the health risk for milk consumers and ensure the safety of this staple part of the human diet, it is important to study the effect of xenooestrogen mixtures present in milk. This investigation used the available in vivo model to learn to what extent such compounds may be endocrine disruptors.

Material and Methods

The recommended immature golden hamster uterotrophic bioassay was chosen. A total of 132 animals were divided into nine groups of experimental animals and positive and negative control groups, each of 12 animals. The experimental females received ad libitum either one of five samples of raw cow’s milk from individual animals or one of four samples of pasteurised or ultra-high temperature treated cow’s milk as retail products. After 7 days, the animals were sacrificed and necropsied. Uterine weight increases were measured as the endpoint of oestrogenic activity in milk.

Results

The milk samples from individual cows and the retail milk samples did not show oestrogenic activity. However, in three groups, decreased uterine weights were observed.

Conclusion

Considering that milk supplies are beneficial to health, contamination in this food should be avoided. There is a need for further animal experiments and epidemiological studies are warranted to evaluate any causative role of milk in human endocrinological disorders.

Hormones in Food as a Potential Risk for Human Reproductive and Health Disorders

In the last 60 years, milk, meat, and egg worldwide consumption per capita increased 2-, 3-, and 5-fold, respectively. In the same period, several studies have reported a drop of semen quality and an increased incidence of cryptorchidism, hypospadias, and some hormone-related cancers (testicular, prostate, breast, endometrial cancer) in humans. A possible reason for these disruptions is increased exposure to exogenous hormones in food of animal origin. Hormones in food are considered to affect the endocrine system and cell signaling and thus disrupt homeostasis in the consumers. Since food safety assurance is a part of the veterinary service, the risk assessment of hormones in food as potential disruptive compounds is a significant challenge. Numerous cohort and epidemiologic studies and meta-analyses have been performed with respect to find an association between the consumption of food of animal origin and particular health disorders. Additionally, several studies in animal models have been performed to explain the mechanisms of disruptive effects of exogenous hormones. Since contradictory results have been reported, there is no general conclusion about the disruptive effects of exogenous hormones. Further experiments on animals in which long-term treatment with exogenous hormones is performed and further comprehensive endocrinological, toxicological, and human epidemiological studies are needed to confirm or deny the role of exogenous hormones in human health disorders. Moreover, long-term exposure to a combination of several exogenous compounds, such as environmental pollutants and dietary hormones and their additive effects, are also not well known and should be a topic for further studies.

Diet and men's fertility: does diet affect sperm quality?

Male contribution to a couple's fecundity is important, and identifying the dietary factors that can influence male fertility potential is of high importance. Despite this importance, there are currently no clear clinical guidelines for male patients seeking fertility treatment. In this review, we present the most up-to-date evidence about diet and male fertility in humans. We focus on the dietary factors necessary for production of healthy functioning sperm with high fertility potential. Based on this review, men may be encouraged to use antioxidant supplements and to follow dietary patterns favoring the consumption of seafood, poultry, nuts, whole grains, fruits, and vegetables. Evidence is strongest for recommending the use of antioxidant supplements to men in couples undergoing infertility treatment-although the specific antioxidants and doses remain unclear-and increasing consumption of omega-3 fatty acids from fish and nuts.

MECHANISMS IN ENDOCRINOLOGY: Estrogens in consumer milk: is there a risk to human reproductive health?

Possible effects of xenoestrogens on human health, in particular on male reproductive health, have attracted considerable attention in recent years. Cow's milk was suggested in numerous publications as one of possible sources of xenoestrogens that could affect human health. Although milk has undoubtedly many beneficial health effects and could even have a role in reducing incidence of some cancers, concerns were raised about presumably high levels of estrogens in cow's milk. In intensive farming, concentrations of estrogens in milk are higher due to long milking periods that today extend long into the pregnancy, when concentrations of estrogens in the cow's body rise. Numerous studies examined potential effects of milk on reproductive health and endocrine-related cancers in both experimental studies with laboratory animals, and in human epidemiological studies. In the present review article, we compiled a review of recently published literature about the content of estrogens in cow's milk and potential health effects, in particular on reproductive system, in humans. Although results of published studies are not unequivocal, it seems that there is stronger evidence suggesting that amounts of estrogens in cow's milk are too low to cause health effects in humans.

Dietary patterns, foods and nutrients in male fertility parameters and fecundability: a systematic review of observational studies

BACKGROUND

Infertility is a global public health issue, affecting 15% of all couples of reproductive age. Male factors, including decreased semen quality, are responsible for ~25% of these cases. The dietary pattern, the components of the diet and nutrients have been studied as possible determinants of sperm function and/or fertility.

OBJECTIVE AND RATIONALE

Previous systematic reviews have been made of the few heterogeneous low-quality randomized clinical trials (RCTs) conducted in small samples of participants and investigating the effect of specific nutrients and nutritional supplements on male infertility. However, as yet there has been no systematic review of observational studies.

SEARCH METHODS

A comprehensive systematic review was made of the published literature, from the earliest available online indexing year to November 2016, in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We have included cross-sectional, case-control and prospective and retrospective studies in which fertile/infertile men were well defined (men with sperm disorders, sperm DNA damage, varicocele or idiopathic infertility). The primary outcomes were semen quality or fecundability. With the data extracted, we evaluated and scored the quality of the studies selected. We excluded RCTs, animal studies, review articles and low-quality studies.

OUTCOMES

A total of 1944 articles were identified, of which 35 were selected for qualitative analysis. Generally, the results indicated that healthy diets rich in some nutrients such as omega-3 fatty acids, some antioxidants (vitamin E, vitamin C, β-carotene, selenium, zinc, cryptoxanthin and lycopene), other vitamins (vitamin D and folate) and low in saturated fatty acids and trans-fatty acids were inversely associated with low semen quality parameters. Fish, shellfish and seafood, poultry, cereals, vegetables and fruits, low-fat dairy and skimmed milk were positively associated with several sperm quality parameters. However, diets rich in processed meat, soy foods, potatoes, full-fat dairy and total dairy products, cheese, coffee, alcohol, sugar-sweetened beverages and sweets have been detrimentally associated with the quality of semen in some studies. As far as fecundability is concerned, a high intake of alcohol, caffeine and red meat and processed meat by males has a negative influence on the chance of pregnancy or fertilization rates in their partners.

WIDER IMPLICATIONS

Male adherence to a healthy diet could improve semen quality and fecundability rates. Since observational studies may prove associations but not causation, the associations summarized in the present review need to be confirmed with large prospective cohort studies and especially with well-designed RCTs.

Dairy intake and fecundability in 2 preconception cohort studies

BACKGROUND

Animal studies have shown that a high intake of galactose, a breakdown product of lactose, increases ovarian toxicity. Few epidemiologic studies, to our knowledge, have examined the association between dairy intake and fertility, and they have had conflicting findings.

OBJECTIVE

We prospectively evaluated dairy intake in relation to fecundability among women who were planning for pregnancy.

DESIGN

Data were derived from preconception cohort studies in Denmark (Snart Foraeldre) and North America [PRESTO (Pregnancy Study Online)] in which women completed a validated food-frequency questionnaire 10 d after enrollment. The dietary intake of dairy foods and their constituents was calculated based on reported frequencies, mean serving sizes, and standard recipes for mixed foods. Outcome data were updated every 8 wk for 12 mo or until reported conception. Analyses were restricted to 2426 women attempting pregnancy for ≤6 cycles at study entry. Fecundability ratios (FRs) and 95% CIs were estimated with the use of proportional probabilities regression models adjusted for potential confounders.

RESULTS

FRs for total dairy intake (≥18 compared with <7 servings/wk) were 1.37 (95% CI: 1.05, 1.78) among 1126 Snart Foraeldre participants and 1.04 (95% CI: 0.78, 1.38) among 1300 PRESTO participants (pooled FR: 1.11; 95% CI: 0.94, 1.31). The elevated FR for total dairy intake among Snart Foraeldre participants was limited to milk consumption and found only among women aged <30 y. There was no clear association between low- or high-fat dairy intake and fecundability in either cohort. Although there was little evidence of an association between dietary intake of calcium, potassium, magnesium, or vitamin D and fecundability, a greater consumption of phosphorus and lactose was associated with slightly higher fecundability in both cohorts.

CONCLUSIONS

Associations between dairy intake and fecundability were generally small and inconsistent across cohorts. Our findings do not support the hypotheses that a greater consumption of high-fat dairy improves fertility or that a greater consumption of lactose or low-fat dairy harms fertility.

Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men

STUDY QUESTION

Is increased consumption of dairy foods associated with lower semen quality?

SUMMARY ANSWER

We found that intake of full-fat dairy was inversely related to sperm motility and morphology. These associations were driven primarily by intake of cheese and were independent of overall dietary patterns.

WHAT IS KNOWN ALREADY

It has been suggested that environmental estrogens could be responsible for the putative secular decline in sperm counts. Dairy foods contain large amounts of estrogens. While some studies have suggested dairy as a possible contributing factor for decreased semen quality, this finding has not been consistent across studies.

STUDY DESIGN, SIZE, DURATION

The Rochester Young Men's Study (n = 189) was a cross-sectional study conducted between 2009 and 2010 at the University of Rochester.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Men aged 18-22 years were included in this analysis. Diet was assessed via food frequency questionnaire. Linear regression was used to analyze the relation between dairy intake and conventional semen quality parameters (total sperm count, sperm concentration, progressive motility, morphology and ejaculate volume) adjusting for age, abstinence time, race, smoking status, body mass index, recruitment period, moderate-to-intense exercise, TV watching and total calorie intake.

MAIN RESULTS AND THE ROLE OF CHANCE

Total dairy food intake was inversely related to sperm morphology (P-trend = 0.004). This association was mostly driven by intake of full-fat dairy foods. The adjusted difference (95% confidence interval) in normal sperm morphology percent was -3.2% (-4.5 to -1.8) between men in the upper half and those in the lower half of full-fat dairy intake (P < 0.0001), while the equivalent contrast for low-fat dairy intake was less pronounced [-1.3% (-2.7 to -0.07; P= 0.06)]. Full-fat dairy intake was also associated with significantly lower percent progressively motile sperm (P= 0.05).

LIMITATIONS, REASONS FOR CAUTION

As it was a cross-sectional study, causal inference is limited.

WIDER IMPLICATIONS OF THE FINDINGS

Further research is needed to prove a causal link between a high consumption of full-fat dairy foods and detrimental effects on semen quality. If verified our findings would mean that intake of full-fat dairy foods should be considered in attempts to explain secular trends in semen quality and that men trying to have children should restrict their intake.

STUDY FUNDING/COMPETING INTEREST(S)

European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Lack of biologically active estrogens in commercial cow milk

Recently, many studies have investigated potential estrogenic compounds in the human diet. Several of these investigations have studied cow milk, a mainstay of the diets of both young and old. In vitro studies have determined that estrogens can be found in milk, and that the concentration of estrogen may be correlated to the fat content in the milk. Regardless, the majority of these studies have concluded that the levels of estrogens in milk are too low to have a physiological effect. However, a recent study found that commercial 1% cow milk was uterotrophic in rats, suggesting that it contained biologically significant levels of estrogen. Using the rat model, we tested milk samples from commercial sources and with varying fat content for estrogenic activity. Ovariectomized female rats were given milk ad libitum for a period of 2 wk. After 12 d of treatment, rats were tested sequentially in an open field and an elevated plus maze to determine any effect of milk on anxiety levels. Upon completion of the behavior testing, uterine weights were examined. Regardless of milk type, no difference was observed in daily volume of milk consumed. Contrary to previous publications, no differences existed in either the behavior or the uterine weights between animals that consumed any milk type and the negative controls. These results demonstrated that none of the commercial milk types that we tested contained biologically significant estrogenic activity.

Effects of cow's milk on reproduction in ICR male mice

OBJECTIVE

To study the effects of Cow's milk on the reproduction in male mice.

METHODS

Twenty-four male mice were divided randomly into two groups: milk group (M) and control group (C). Each mouse was given 10 mL milk per day from 4 to 16 weeks in the group M. At the age of 17 weeks, all the mice were sacrificed.

RESULTS

Serum testosterone was decreased in the group M (P=0.037). No significant difference was found in weight of testes, seminal vesicle or adrenal gland of mice between the groups C and M. However, the weight of seminal vesicle decreased when expressed in g/100 g body weight in the group M. Epididymal sperm concentration, motility, morphology, and sperm head number were not affected by milk.

CONCLUSION

Cow's milk has adverse effects on the reproductive system in ICR male mice. Further studies are needed to clarify the specific effects of milk on reproductive health.

Consumption of commercial whole and non-fat milk increases the incidence of 7,12-dimethylbenz(a)anthracene-induced mammary tumors in rats

BACKGROUND

Breast cancer has become the most common cancer among women worldwide. Although the consumptions of milk and dairy products were considered to be a risk factor for breast cancer in some epidemiological studies, the results were inconsistent.

METHODS

In the present study, female Sprague-Dawley rats received a single oral dose of 5mg 7,12-dimethylbenz(a)anthracene (DMBA). One week later, the animals were divided into four groups: whole milk (WM), artificial whole milk (A-WM), non-fat milk (NFM) or artificial non-fat milk (A-NFM) mixed with commercial powder chow. Rats were palpated weekly to monitor tumor development. At week 20 after DMBA administration, rats were decapitated and the volume and weight of mammary tumor were recorded.

RESULTS

Tumor incidence, the cumulative number of tumors and the sums of tumor volume were higher in the WM and NFM groups than in the A-WM and A-NFM groups both at palpation and at autopsy.

CONCLUSION

Combining our previous studies, we found the consumption of milk promoted the development of DMBA-induced mammary tumors in rats independent of the fat level.

17Beta-estradiol and estrone concentrations in plasma and milk during bovine pregnancy

Estrone (E1) and 17beta-estradiol (E2) are present in milk, but the mechanism(s) that regulate their appearance in milk are not known. The objectives of this study were to determine the impact of stage of pregnancy on the concentrations of E1 and E2 in plasma and milk and to determine the correlations between plasma and milk E1 and E2 and with milk components throughout pregnancy. Blood and milk samples were collected from 13 cows every 28 d throughout pregnancy. The E1 and E2 were quantified in plasma and milk using RIA after organic solvent extractions and Sephadex LH-20 column chromatography. Plasma E1 concentrations averaged 0.8, 16.9, and 41.8 pg/mL in trimesters 1, 2, and 3, respectively. The respective E1 concentrations in milk averaged 0.6, 7.9, and 27.1 pg/mL. The E2 concentrations in plasma averaged 0.5, 0.9, and 2.0 pg/mL; milk E2 averaged 0.3, 0.9, and 5.0 pg/mL. Plasma and milk E2 concentrations were greater in trimester 3 compared with trimesters 1 and 2. The E1 concentrations in milk were significantly correlated with plasma E1 concentrations (r = 0.77), percentage of milk fat (r = 0.50), and milk yield (r = -0.43). The E2 concentrations in milk were significantly correlated with plasma E2 concentrations (r = 0.93), percentage of milk protein (r = 0.63), and milk yield (r = -0.57). The milk-to-plasma ratio of E2 increased from 0.4 during trimester 1 to 2.2 in trimester 3, which suggested that the mechanism(s) regulating the appearance of E2 in milk may change over the course of pregnancy.

Naturally occurring estrogens in processed milk and in raw milk (from gestated cows)

The occurrence of the steroid hormones estrone (E1), 17alpha-estradiol (alphaE2), 17beta-estradiol (betaE2), and estriol (E3) in processed bovine milk with different fat contents and in raw milk from (non)gestated cows was investigated. Following liquid extraction, optional enzymatical deconjugation, C18 solid-phase extraction, and derivatization, estrogens were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Free and deconjugated E1 (6.2-1266 ng/L) was the major estrogen followed by alphaE2 (7.2-322 ng/L) and betaE2 (5.6-51 ng/L), whereas E3 was detected regularly at the detection limit of 10 ng/L. The lowest and highest concentrations were determined in raw milk from nonpregnant and from cows in the third trimester of gestation, respectively. The estrogen concentration in processed milk coincides with that of raw milk between first and second trimesters, reflecting the contribution of lactating pregnant cows to the final consumable product. The daily intake of total investigated estrogens through milk is 372 ng, which is dramatically more than currently recognized.