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At least 721 records · Page 40Linked to original sources
PubMed2006

Cd exposures in fathead minnows: effects on adult spawning success and reproductive physiology.

The primary objective of this study was to determine whether cadmium (Cd) exposures alter reproduction in fathead minnows (Pimephales promelas). Pairs of sexually mature minnows were exposed to waterborne Cd at 0, 12.5, 25, or 50 microg/L for 21 days. During this exposure period, the reproductive success of pairs was assessed. Following the exposure, gonadosomatic index (GSI), male secondary sexual characteristics, male plasma 11-ketotestosterone (11-KT) concentrations, and female plasma estradiol (E2) concentrations were determined. Results of this study show that Cd exposures impair reproduction in fathead minnows. Pairs exposed to 50 microg/L experienced a significant decline in spawning frequency and fecundity relative to unexposed minnows. Cd exposures also caused alterations in male secondary sexual characteristics, as males exposed to 25 microg/L had significantly fewer nuptial tubercles than controls. Furthermore, males exposed to 12.5 microg/L Cd experienced a significant increase in plasma 11-KT concentrations relative to controls. No alterations in GSI or female plasma E2 concentrations were observed.

Animals↗
PubMed2001

Association between feeding perennial ryegrass (Lolium perenne cultivar Grasslands impact) containing high concentrations of ergovaline, and health and productivity in a herd of lactating dairy cows.

Perennial ryegrasses are frequently infected with fungal endophyte (Neotyphodium lolii) to increase the resistance of the plant to insect damage. Unfortunately, a side effect of endophyte infection can be the production of alkaloids, including Lolitrem B and ergovaline, that produce toxic effects in animals. A significant 4.6 litre decrease in milk production in a herd of Holstein-Friesian dairy cows was associated with high concentrations of ergovaline in ryegrass silage. Simultaneously, milk SCC increased significantly over a comparable period and reproductive performance declined. Body condition score and coat condition of cows were adversely affected. Unique aspects of this Case report include; very stable production of the herd over a period of years before and after cessation of feeding silage containing high concentrations of ergovaline; the presence of high concentrations of ergovaline in the silage; and a controlled diet that reduced the risks of variation in feed availability and other sources of toxins. Veterinarians and other farm advisors should be aware of the potential for negative effects on animal health and production of fungal endophyte and the potential for Neotyphodium lolii to produce ergovaline.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

[[The population of Thailand after the reproductive revolution]].

The "population of Thailand is one among the few population groups in [modern times] which has experienced [a] rapid decline in fertility level within two decades. Thailand's population completed the reproductive revolution process so quickly that its age structure has not had time to adjust and still holds the potential for growth for several decades to come.... During the period of reproductive revolution from 1970 to 1990, the population increased by 20 million.... As for the effect of reproductive revolution on the age structure of the population, the pattern is that the proportion of children (under 15 years of age) declines while the number and proportion of population in working-age group (15-59 years of age) and the elderly (60 years and over) tend to increase.... The reproductive revolution also results in a number of positive economic and social implications such as a higher per capita income, [a larger] work force, a gradual reduction in the number of new entrants into the labour market and the decrease in the number of school age population." (SUMMARY IN ENG)

Age Distribution↗
PubMed1993

Evidence for a circannual rhythm of reproduction and prolactin secretion in a seasonally breeding macropodid marsupial, the Bennett's wallaby (Macropus rufogriseus rufogriseus).

Two groups of adult female wallabies were maintained in photoperiod-controlled rooms from June 1987 until August 1988. Group SSH was held on summer solstice photoperiods throughout the experiment; group SN was subjected to weekly stepwise simulated natural changes in photoperiod. Plasma melatonin concentrations reflected photoperiod with high concentrations during the dark phase in both groups. Group SN wallabies commenced oestrous cyclicity on 21 July (+/- 19 days, n = 6) entered reproductive quiescence on 14 February (+/- 10 days, n = 5) and recommenced cycling on 8 June (+/- 3 days, n = 4). Group SSH wallabies began cycling on 27 July (+/- 9 days, n = 7) at a time that was not significantly different from that of group SN. Three out of five of group SSH exhibited a spontaneous period of reproductive quiescence of between 59 and 70 days commencing between 3 December and 25 February. There was a highly significant difference between the transient plasma prolactin response to a dopamine antagonist during cycling and quiescent periods in both groups (P < 0.001) such that the response was increased during periods of quiescence. Our data support the hypothesis that prolactin is involved in the control of seasonal quiescence in the female Bennett's wallaby and demonstrate that spontaneous changes in reproductive state and prolactin can occur when animals are maintained on unchanging long photoperiods.

Animals↗
PubMed2004

Patterns of behavior across reproductive states of free-ranging female black-handed spider monkeys (Ateles geoffroyi).

Reports on the behavior of spider monkeys (genus Ateles) describe a suite of 5-6 behaviors that are indicative of an estrous female. This study presents hormonal data as an independent measure of reproductive state to determine if these behaviors are associated with any particular reproductive state or stage of the ovarian cycle. Fecal samples collected from 6 free-ranging female black-handed spider monkeys (Ateles geoffroyi) over the course of 11 months were assayed for estrogen (E1C) and progesterone (PdG) metabolites, using an enzyme immunoassay. Behavioral data collected from the same females were analyzed for patterns associated with different reproductive states. A more detailed analysis of behavioral data associated with reproductively cycling periods determined whether each behavior clustered with copulations or a particular phase in the ovarian cycle. Observations of place-sniffing were more frequent for 4 of 5 females when reproductively cycling. Of all copulations observed, 80% occurred when the female participant was reproductively cycling. In addition, the rates of self-clitoral hold and self-clitoral rub behaviors were significantly higher for 2 of 4 and 4 of 5 of females, respectively, when reproductively cycling. No behavior consistently occurred in association with copulations or with any particular phase in the ovarian cycle. Results from this study suggest that the behaviors tested in this paper can provide some information regarding female spider monkey reproductive state (whether or not she is reproductively cycling), but that they are not indicators of estrus in female spider monkeys.

Animals↗
PubMed1987

Absence of nocturnal plasma melatonin surge under long and short artificial photoperiods in the domestic sow.

The circadian plasma melatonin profile of German Landrace sows was determined at 1-h intervals for 31 h after exposure to each of four different artificial photoperiods. Under 12L:12D, melatonin concentrations in four sows during the light phase ranged from 22 +/- 5.9 to 96 +/- 25.1 pg/ml (mean +/- SEM). During the dark phase (total dark) the individual concentrations increased two- to fivefold over the peak individual light phase values in three sows. This nocturnal surge was of 3.8 h duration and peaked at 190, 294, and 546 pg/ml at 0100 h, which was 5.5 h after the onset of dark. The surge was abolished in these animals after exposure to 16L:8D and could not be reinstated by the subsequent exposure to 8L:16D. During the latter two photoperiods the mean concentrations were consistently less than the maximum mean value of 30.8 +/- 10 pg/ml during the dark phase and 55 +/- 21.9 pg/ml during the light phase. All the sows displayed regular estrous cycles during the study, and the day of the estrous cycle on which the samples were obtained under each photoperiod was not significantly correlated with the presence or absence of the nocturnal surge. A separate experiment using different animals confirmed the nocturnal surge under 12L:12D. In two out of four cycling sows the peak concentrations during the dark phase (122 and 110 pg/ml at 0400 and 0500 h) were two- to sixfold higher than those of the light phase. Absence of the nocturnal surge under long and short daylengths may be a factor contributing to the decline in reproductive performance during the summer and winter months.

Animals↗
PubMed2000

Reproduction cycles and strategies of the cold-water sponges Halisarca dujardini (Demospongiae, Halisarcida), Myxilla incrustans and Iophon piceus (Demospongiae, Poecilosclerida) from the White Sea.

The reproductive development of the Demospongiae species Halisarca dujardini (Halisarcida), Myxilla incrustans and Iophon piceus (Poecilosclerida) from Chupa Inlet (Kandalaksha Bay, the White Sea) was studied histologically during 1982-1994 and 1997. These species are all viviparous. Halisarca dujardini inhabits shallow waters (1.5-5 m); M. incrustans and I. piceus are common in a more stable environment at depths between 15 and 25 m. Initiation of sexual reproduction stages is dependent upon water temperature. Reproductive effort is low in Myxilla incrustans and I. piceus (reproductive elements contribute 7.3% and 12% of maternal tissue volume respectively), but much higher in H. dujardini (up to 69% of the parental tissue volume). Reproduction leads to localized destruction of maternal tissue for M. incrustans and I. piceus and complete disorder of central and basal parts of the choanosoma of H. dujardini after each period of reproduction. Myxilla incrustans and I. piceus reproduce throughout the hydrological summer, but reproduction in H. dujardini is restricted to 3 weeks. The average life span of M. incrustans and I. piceus is more than 4 years, and that of H. dujardini is about 7-12 months. The data suggest that M. incrustans and I. piceus are K-strategists, whereas H. dujardini is an r-strategist.

Animals↗
PubMed2004

[Effective size of subpopulations in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka): the effect of relative reproductive success of different-year cohorts].

The effect of variation in reproductive success of cohorts of different year of birth (within generation) on the effective subpopulation (breeding group) size in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka). The annual variation in census size and overlapping of year classes reduced the ratio of the effective subpopulation size to the census size by 7 to 88% in different subpopulations. The total effect of the variance of reproductive success in individual years and the variance of reproductive success of different cohorts reduced the effective size/census size ratio by 68-96%.

Animals↗
PubMed1998

Flaxseed and its lignan precursor, secoisolariciresinol diglycoside, affect pregnancy outcome and reproductive development in rats.

Flaxseed is the richest source of the mammalian lignan precursor secoisolariciresinol diglycoside (SDG). Because lignans have estrogen agonist or antagonist properties, the objective of this study was to determine whether feeding flaxseed to rats during a hormone-sensitive period has reproductive effects. Rat dams were fed a basal diet or the basal diet supplemented with 10% flaxseed, 5% flaxseed or SDG at the level in 5% flaxseed during pregnancy and lactation. At weaning, the offspring were fed the basal diet. Flaxseed had no effect on pregnancy outcome except that the 10% flaxseed diet lowered birth weight (P < 0.05), compared with other treatments, and produced hormonal effects. The female offspring had shortened anogenital distance, greater uterine and ovarian relative weights, earlier age and lighter body weight at puberty, lengthened estrous cycle and persistent estrus (P < 0.05), whereas the males had reduced postnatal weight gain and, at postnatal d 132, greater sex gland and prostate relative weights (P < 0.05), suggesting estrogenic effects. In contrast, compared with the basal diet, 5% flaxseed reduced immature ovarian relative weight by 29% (P < 0.05), delayed puberty by approximately 5 d (P < 0.05) and tended to lengthen diestrus, indicating an antiestrogenic effect. The SDG produced results similar to those of 5% flaxseed, suggesting that lignans were responsible for the observed effects. Lignans were transferred to the offspring via rat dam's milk as indicated by the recovery of radioactivity in the offspring of lactating dams given 3H-SDG. Because flaxseed affects the reproductive development of offspring, caution is suggested when consuming flaxseed during pregnancy and lactation.

Anal Canal↗
PubMed1996

[Features of the reproductive behavior in Russia in the transition period].

"The article is dedicated to the analysis of [the] reproduction behaviour of Russia's population in the transition period (1991-1995) based on the data of the monitoring conducted by the All-Russian Centre for Public Opinion Studies using a representative sample survey covering the country's territory. According to the returns of this monitoring some stabilisation [became] apparent by 1995 referring to reproduction processes in Russia." (SUMMARY IN ENG)

Demography↗
PubMed1998

Sexual maturation and fertility of male and female mice exposed prenatally and postnatally to trivalent and hexavalent chromium compounds.

The reproductive toxicity of trivalent and hexavalent chromium compounds was investigated in male and female mice exposed to 1000 ppm chromium chloride and potassium dichromate via their mother during gestational and lactational periods. Fertility was reduced in male offspring exposed to either trivalent or hexavalent chromium compounds. Body weights and weights of testes, seminal vesicles and preputial glands were reduced in trivalent-exposed male offspring. The exposure of female mice offspring to trivalent and hexavalent chromium compounds delayed sexual maturation. Fertility was reduced in female offspring exposed to either trivalent or hexavalent chromium compounds. The exposure of female mice to hexavalent chromium compound reduced the number of implantations and viable fetuses respectively. Body weight and weights of ovaries and uteri were reduced in trivalent-exposed female offspring. The results indicate that under our experimental conditions, the exposure of male and female mice offspring to either trivalent or hexavalent chromium compounds during gestational and lactational periods impair reproductive functions and fertility in adulthood.

Animals↗
PubMed1995

Effects of calcium soaps of fatty acids on postpartum reproductive activity in beef cows and growth of calves.

Beef cows were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics and growth of calves. Cows were assigned randomly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets were isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7-d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P < .05; 56.0 vs 50.6 kg, P< .01; 98.8 vs 91.8 kg, P < .01; and 186 vs 173 kg, P < .01, respectively). Body weights at 35 and 50 d postcalving were greater in M than in C cows (334 and 310 kg, P < .01; 329 and 300 kg, P < .01, respectively). A similar tendency was observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P < .01 for M and C, respectively). Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides were greater (P < .01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P < .02). Percentage of pregnant cows during the first half of the breeding season was greater (P < .02) in M (62.5%) than in C cows (35.5%). We concluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calves.

Aging↗
PubMed2006

Endocrine disruptors and reproductive health: the case of bisphenol-A.

Epidemiological studies have reported that during the last 60 years the quantity and quality of human sperm has decreased and the incidence of male genital tract defects, testicular, prostate and breast cancer has increased. During the same time period, developmental, reproductive and endocrine effects have also been documented in wildlife species. The last six decades have witnessed a massive introduction of hormonally active synthetic chemicals into the environment leading some to postulate that the diverse outcomes documented in human and wildlife populations might be the result of extemporaneous exposure to xenoestrogens during development. The estrogen-mimic bisphenol-A (BPA) is used as a model agent for endocrine disruption. BPA is used in the manufacture of polycarbonate plastics and epoxy resins from which food and beverage containers and dental materials are made. Perinatal exposure to environmentally relevant BPA doses results in morphological and functional alterations of the male and female genital tract and mammary glands that may predispose the tissue to earlier onset of disease, reduced fertility and mammary and prostate cancer.

Animals↗
PubMed2005

Biomarker responses and reproductive toxicity of the effluent from a Chinese large sewage treatment plant in Japanese medaka (Oryzias latipes).

The present study was conducted to assess the potential toxicity of the effluent from a large sewage treatment plant (GBD-STP) in Beijing. Japanese medakas (Oryzias latipes) at reproduction active period were exposed to a serial of graded concentrations of the effluent or 100 ng l-1 of 17-alpha-ethinylestradiol (EE2, positive control). Growth, gonadosomatic index (GSI), hepatosomatic index (HSI), reproductive success, induction potency of vitellogenin (VTG) in male fish and that of 7-ethoxyresorufin-o-deethylase activity (EROD) in male fish liver were used as test endpoints. The growth suppression of fish was observed in a dose-dependent manner, resulting in significant differences in both body length and body weight of medaka above 5% effluent. This effluent can inhibit the growth of gonad of medakas and are more sensitive to male than to female. At exposure concentration of 40% and higher, there was an unexpected decrease of HSI values, which may be resulted from sub-lethal toxicity of effluent to fish liver. VTG of plasma in males were induced in all exposure concentration levels, but not in a dose-dependent manner. The concentration of 5% effluent would be the lowest observed adverse effect level (LOAEL) affecting reproductive success when examining fertile individuals, fecundity and fertilization rate. The overt CYP1A response and higher reproductive toxicity may be indicative of low process efficiency of this STP.

Animals↗
PubMed1996

Effect of seasonal host reproduction on host-macroparasite dynamics.

The impact of seasonal host reproduction on the population dynamics of host-macroparasite interactions is considered. We modify the classic Anderson and May model so that parameters associated with host reproduction are periodic functions of time with a period corresponding to a year. This allows us to compare our findings with those already well documented. If, in the absence of any seasonality, a stable steady-state solution exists annual reproduction gives rise to stable annual population cycles. Moreover, the parameter domain for which there is stability is increased by the seasonality. However, if the life span of the free-living stages is reasonably long, and the continuous model has limit cycle solutions, complex behavior can be observed in the seasonally forced case. Results also indicate that if seasonal effects are ignored, regulation of the hosts by the parasite population is overestimated.

Animals↗