Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “egg quality”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed2002

Fecundity and life-history strategies in marine invertebrates.

The reproductive strategies of an organism play a major role in the dynamics of the population and the biogeography and continuity of the species. Numerous processes are involved in reproduction leading to the production of offspring. Although diverse processes are involved in oogenesis (the production of eggs) and spermatogenesis (the production of sperm), the basic patterns of gametogenesis are similar amongst invertebrates, with the proliferation and differentiation of germ cells leading to the final production of mature gametes. The production of gametes, especially eggs, is energetically expensive, and therefore strongly sensitive to selective pressures. An organism can ingest and assimilate a limited amount of energy from the environment. The different ways by which energy is allocated to growth and reproduction in order to maximize fitness forms the basis of the differing life-history strategies that have developed in marine invertebrates. Fecundity is defined as the number of offspring produced by a female in a determined time period. The term fecundity needs to be explicitly defined in each study in order to obtain the maximum information from the data analysed. Because of the variety of egg production patterns found among marine invertebrates, a wide range of methodologies has been developed to quantify fecundity. These include direct egg counts in brooding species, spawning induction in live individuals and histological studies of preserved material. Specific considerations need to be taken into account for colonial organisms, because of their modular organization. The production of eggs requires an optimal allocation of energy into growth and reproduction for the maximization of parental fitness. Fecundity is central in studies of life-history theory and in the development of life-history models because it is directly related to energy allocation and partitioning. There are important relationships and trade-offs between fecundity and other life-history traits, such as egg size, female size and age, age at first reproduction, reproductive effort and residual reproductive value. These trade-offs, together with morpho-functional constraints and genetic variation determine the evolution of life histories through natural selection. Fecundity is a highly plastic character within the limits defined by the bioenergetics and life-history strategy of the organism. Egg production is affected mainly by environmental factors such as food quantity and quality, temperature or presence of toxic elements in the habitat. The differences in fecundity found among closely related species from different biogeographical locations reflect, at least in part, the differing environmental conditions of their habitat.

Adaptation, Physiological↗
PubMed2002

Development of aquatic life criteria for selenium: a regulatory perspective on critical issues and research needs.

The US is currently in the process of revising its freshwater, chronic aquatic life criterion for selenium. The fundamental issues being addressed include which environmental compartment(s) support the most reliable expression of the criterion, which form(s) of selenium should be measured in the medium (media) of choice, and which site-specific water quality (or other factors) should be linked to the expression of the criterion. Literature reviews and a recent workshop were conducted to assess the state of the science on various issues related to water-, tissue- and sediment-based criteria for selenium. Evaluation of many of these issues is ongoing. In terms of water column criteria issues, data limitations will likely restrict the expression of a criterion to operationally defined forms (e.g. total recoverable, dissolved). The specific identity of organoselenium in natural systems is lacking and may not be appropriately represented by free seleno-amino acids (e.g. selenomethionine). The available data do not appear to support quantitative relationships between chronic toxicity and water quality characteristics. In terms of a tissue-based criterion, reproductive tissue (ovary, egg) has been recommended as the tissue of choice, but practical concerns and data availability require consideration of other tissues (e.g. whole-body). Organoselenium (bound to peptides or proteins) is thought to be the form of greatest toxicological importance in fish, however, direct measurements of organoselenium compounds in tissues are very limited. Route of exposure (food vs. water uptake) may prove important for establishing diagnostic tissue residues for selenium based on laboratory data. Data on toxicological aspects of selenium in sediments appear sparse, particularly in relation to different sedimentary forms. Reliable assessments of bioaccumulation will likely be critical for making site-specific modifications to chronic selenium criteria, however, many technical issues for assessing bioaccumulation remain. The need for improved analytical methods for directly speciating organoselenium in various environmental media underpins many of the current data gaps. Improving analytical methodologies to enable affordable and reliable measurement of organoselenium compounds holds significant promise for advancing selenium ecotoxicological research.

Animals↗
PubMed1989

Physiological changes in fowl and turkey spermatozoa during in vitro storage.

1. Although early work on semen storage has been rather empirical in approach, only basic research can provide a framework of biological mechanisms from which improvements in the techniques of cryopreservation and liquid semen storage can progress logically. 2. A major drawback in this work has been the lack of adequate tests for quantitating and differentiating aspects of 'fertility'. 3. Basic research has now provided techniques for assessing: sperm fertilising ability in terms of numbers of fertile eggs; the efficiency of hens' oviducts at accepting and retaining spermatozoa, and sperm 'quality' as motility, metabolism and plasma membrane patency. 4. These techniques may be used for a more critical assessment of the effects of both cryopreservation and liquid semen storage on sperm function, although the integrity of sperm surface proteins may be a more sensitive variable which has yet to be measured. 5. Further improvements in sperm cryopreservation technology are best approached through an understanding of the fundamental cellular and molecular changes which take place during freezing; thus far little is known of such changes in avian spermatozoa. 6. The ideal milieu for maintaining spermatozoa in liquid semen storage should mimic the environment of the oviducal sperm storage tubules; elucidation of the factors involved in progressing steadily.

Animals↗
PubMed2004

The early sperm gets the good egg: mating order effects in free spawners.

Mating order can have important consequences for the fertilization success of males whose ejaculates compete to fertilize a clutch of eggs. Despite an excellent body of literature on mating-order effects in many animals, they have rarely been considered in marine free-spawning invertebrates, where both sexes release gametes into the water column. In this study, we show that in such organisms, mating order can have profound repercussions for male reproductive success. Using in vitro fertilization for two species of sea urchin, we found that the 'fertilization history' of a clutch of eggs strongly influenced the size distribution of unfertilized eggs, and consequently the likelihood that they will be fertilized. Males that had first access to a batch of eggs enjoyed elevated fertilization success because they had privileged access to the largest and therefore most readily fertilizable eggs within a clutch. By contrast, when a male's sperm were exposed to a batch of unfertilized eggs left over from a previous mating event, fertilization rates were reduced, owing to smaller eggs remaining in egg clutches previously exposed to sperm. Because of this size-dependent fertilization, the fertilization history of eggs also strongly influenced the size distribution of offspring, with first-spawning males producing larger, and therefore fitter, offspring. These findings suggest that when there is variation in egg size, mating order will influence not only the quantity but also the quality of offspring sired by competing males.

Animals↗
PubMed1984

The role of cervical mucus--semen interaction in infertility of unknown aetiology.

An in-vitro penetration assay, which incorporates measurements of sperm motility and forward velocity, was used to investigate sperm-cervical mucus interaction in 20 couples with unexplained infertility. Evidence of impaired cervical mucus penetration was found in this group of patients and in seven couples the results correlated with previous assessment by laparoscopic sperm recovery. The impairment of cervical mucus penetration was found to be due to defective sperm function rather than to the quality of the cervical mucus itself. Of the criteria of semen quality measured in this study, sperm motility and the zona-free hamster egg penetration test showed significant correlations with cervical mucus penetration.

Cervix Mucus↗
PubMed2006

Characteristics attributed to complementary foods by caregivers in four countries of Latin America and the Caribbean.

BACKGROUND: Attributes that caregivers assign to complementary foods have been primarily described in the context of illness, but attributes assigned to foods in everyday circumstances must be understood to effectively promote good complementary feeding. OBJECTIVE: This study aimed to understand how mothers judge complementary foods to be appropriate by cross-cultural examination of food perceptions in four different Latin American and Caribbean countries. METHODS: We used semistructured interviews to assess attributes that mothers ascribed to a list of key foods, both home-made and manufactured, and reasons for feeding or not feeding them. We elicited attributes from 79 caregivers with children 6 to 24 months of age from two urban and perirban sites each in Brazil, Jamaica, Mexico, and Panama. RESULTS: Textual analysis based on six home foods common to the four countries and manufactured foods resulted in six attribute categories, five of which could be positive or negative (Nutrient Content, Effects on Child, Child's Response, Availability and Accessibility, and Other Food Attributes); one (Food Quality and Safety) was only negative. Analysis of attributes of home foods (chicken, eggs, beans, carrots, bananas or plantains, and oranges) revealed many beliefs that were common within and across countries, whereas analysis of the attributes of manufactured foods revealed that these foods were less known. CONCLUSIONS: The consistency of the attribute categories across countries and across home and manufactured foods suggests their relevance to planning programs to improve complementary feeding in Latin America and the Caribbean and possibly other developing countries. These results can be used programmatically to assess the need for and the focus of food education programs, and to indicate which countries will be more receptive to certain foods as a means of improving complementary feeding.

Adult↗
PubMed2002

Sludge accumulation in polishing ponds treating anaerobically digested wastewater.

When ponds are used for wastewater treatment, settleable solids will form a steadily growing bottom sludge layer, which reduces their effective volume. Eventually this sludge must be removed to ensure that the pond maintains the required retention time to keep performing properly. The settleable solids may either be present in the influent or they are formed during the treatment as a result of algal flocculation. An experimental investigation was carried out to evaluate bottom sludge accumulation in a polishing pond used for treatment of UASB effluent. The mass and composition of the bottom sludge formed in a polishing pond was evaluated after the pilot scale pond had been in operation for 1 year and about 60 m3 of digested wastewater had been treated per m3 of pond. The bottom sludge mass represented a solids accumulation of 70 g per m3 of digested wastewater. About half of these solids were the result of settling of influent solids in the first part of the pond, while the other half was attributable to settling of algae, formed in the pond. It is concluded that the bottom sludge growth in a polishing pond is so low, that desludging during the useful life span of the pond will most likely not be necessary. This leads to the important conclusion that excess sludge discharge from UASB reactors (a major factor in operational costs) may be omitted, if a polishing pond is used for post-treatment. The bottom sludge had a high volatile solids concentration (58%) and the macronutrient fractions were also high (3.9% N and 1.1% P of the TSS mass). The bottom sludge was stable and could be dried directly without problems. The hygienic quality of the bottom sludge was very poor: about half the influent helminth eggs during one year of operation were found in the bottom sludge and the faecal coliform concentration was very high.

Animals↗
PubMed2002

Comparison of Biociphos-Plus and TRIS-egg yolk extender for cryopreservation of bull semen.

For optimizing routine freezing of bull semen, we examined three different cryopreservation methods using either TRIS-egg yolk-citrate extender or Biociphos-Plus. Biociphos-Plus (IMV, France) has been marketed as an extender, in which egg yolk is replaced by a sterile soybean extract to reduce the contamination risk derived from animal borne substances. We used 78 bulls of various breeds (Brown Swiss, Holstein, Simmental) between 12 and 23 months of age, and we produced a total of 800-1000 straws (0.25 ml, 20 x 10(6) spermatozoa) from each bull using three different methods. In method A, we used TRIS-egg yolk as extender and packaged at 4 degrees C. In method B, we also used TRIS-egg yolk but packaged at room temperature (RT) between 18 and 22 degrees C. In method C, Biociphos-Plus served as extender and we packaged at RT. We compared methods A, B and C by using post-thaw motility, viability, morphology and osmotic resistance as semen quality parameters. In addition, we recorded 75-day nonreturn rates (NR75) to detect the effect of extenders on fertility. With the exception of primary defects, all laboratory parameters investigated were significantly (P < 0.05) better in methods A (TRIS-egg yolk, 4 degrees C) and B (TRIS-egg yolk, RT), compared to method C (Biociphos-Plus, RT). We recorded no significant difference between methods A and B. We could not verify the differing laboratory results by fertility data (NR75). However, when we analyzed NR75 for a single breed, significant (P < 0.05) differences existed between methods A and B compared to method C in Simmental and Holstein but not in Brown Swiss. We obtained best results in Simmental using method A (69%, n = 3384), while method C (61.4%, n = 763) was superior to methods A (57.6%, n = 698) and B (57.3%, n = 737) in Holstein. After considering various factors like preparation of extender, cost of materials and ambient working temperature, we concluded from our data that bull semen processing using TRIS-egg yolk extender and RT for packaging (method B) produced the best semen quality and field fertility.

Animals↗
PubMed2006

Female freshwater crayfish adjust egg and clutch size in relation to multiple male traits.

Females may invest more in reproduction if they acquire mates of high phenotypic quality, because offspring sired by preferred partners may be fitter than offspring sired by non-preferred ones. In this study, we tested the differential maternal allocation hypothesis in the freshwater crayfish, Austropotamobius italicus, by means of a pairing experiment aimed at evaluating the effects of specific male traits (body size, chelae size and chelae asymmetry) on female primary reproductive effort. Our results showed that females laid larger but fewer eggs for relatively small-sized, large-clawed males, and smaller but more numerous eggs for relatively large-sized, small-clawed males. Chelae asymmetry had no effects on female reproductive investment. While the ultimate consequences of this pattern of female allocation remain unclear, females were nevertheless able to adjust their primary reproductive effort in relation to mate characteristics in a species where inter-male competition and sexual coercion may mask or obscure their sexual preferences. In addition, our results suggest that female allocation may differentially affect male characters, thus promoting a trade-off between the expression of different male traits.

Animals↗
PubMed2006

Deriving site-specific 2,2-bis(chlorophenyl)-1,1-dichloroethylene quality criteria of water and sediment for protection of common tern populations in Bohai Bay, North China.

In this paper we first present a method of deriving site-specific water and sediment quality criteria of chemicals for protecting wildlife populations. The method has two steps: (1) identification of the threshold concentration in specific tissue corresponding to a population benchmark response and (2) extrapolating quality criteria on the basis of the bioaccumulation in tissue from the water or sediment (e.g., the bioaccumulation factor (BAF) and biota/ sediment accumulation factor (BSAF)). The method was applied to derive 2,2-bis(chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) quality criteria of water and sediment of Bohai Bay, China, for common tern populations. The benchmark concentration in eggs of the common tern was determined to be 663 ng/g wet weight from the relationship curve between concentration (biotic burden in eggs) and the intrinsic rate of population increase (r) calculated by an age-structured matrix approach. The p,p'-DDE concentrations (mean 58.79 and ranging from 13.14 to 326.60 ng/g wet weight) measured in common tern eggs (n = 35), collected from the Beidagang wetland on the coast of Bohai Bay in China, and those in surface water or sediment from literature values were combined to estimate the probability distribution of BAF and BSAF using the Monte Carlo method. Finally, the marine water and sediment quality criteria of p,p'-DDE in Bohai Bay were estimated to be 4 ng/L and 1.9 ng/g dry weight, respectively.

Animals↗
PubMed1980

Effect of dietary proteins and amino acid deficiencies on urinary excretion of nitrogen and the urea synthesizing system in rats.

A mechanism of regulation in urea biosynthesis under conditions of varying dietary protein quality was investigated in rats adapted to 10% protein diets. A reverse correlation was observed between activities of urea cycle enzymes and urinary excretion of urea under these conditions. The concentrations of several non-essential amino acids in livers of rats fed a 10% gluten diet significantly increased as compared with those of rats fed a 10% whole egg protein diet without change in ornithine concentration. The contents of threonine, serine and ornithine in livers of rats fed a methionine-free diet were higher than those of rats fed a basal diet. The capacity of urea synthesis in vivo of rats fed gluten or a methionine-free amino acid mixture was the same as that of rats fed whole egg protein or basal amino acid mixture. The results suggest that under conditions of varying dietary protein quality, the liver level of free amino acids may regulate mainly the rate of urea synthesis without changes in activities of urea cycle enzymes and that the concentrations of ornithine in addition to free amino acids in liver may play an important role in an increase of urea synthesis in the methionine-deficiency.

Amino Acids↗
PubMed1995

The golden egg.

Explore the source record for details and available documents.

Humans↗
PubMed2005

Role of N-acetylglutamate turnover in urea synthesis of rats given proteins of different quality.

The purpose of this study was to find whether the synthesis and degradation of N-acetylglutamate would affect urea synthesis when the dietary protein quality was manipulated. Experiments were done on three groups of rats given diets containing 10 g gluten, 10 g casein or 10 g whole egg protein/100 g for 10 d. The urinary excretion of urea, the liver concentrations of N-acetylglutamate and free glutamate, the liver activity of N-acetylglutamate synthetase increased with the decline in quality of dietary protein. A reverse correlation was observed between the liver N-acetylglutamate degradation and liver Nacetylglutamate concentration. N-Acetylglutamate concentration in the liver was closely correlated with the concentration of glutamate and the N-acetylglutamate synthetase activity in the liver, and excretion of urea. These results suggest that the greater synthesis and the lower degradation rate of N-acetylglutamate in the liver of rats given the lower quality of protein increase the liver concentration of N-acetylglutamate and stimulate urea synthesis.

Acetyltransferases↗
PubMed2006

Measurement of T-2 and HT-2 toxins in eggs by high-performance liquid chromatography with fluorescence detection.

T-2 toxin is a mycotoxin produced by several species of common fungi capable of infesting human food and animal feeds. Lower-quality feeds given to chickens may be contaminated with T-2 toxin, which may affect their health. The literature suggests that T-2 toxin is transmitted from the hen to the eggs. This article describes the development of a liquid chromatographic assay for T-2 and the related mycotoxin HT-2 in eggs. T-2 and HT-2 toxins were isolated from spiked eggs with a tandem charcoal-alumina-Florisil column and immunoaffinity column cleanup. The isolated toxins were derivatized with the fluorophore 1-anthroyl nitrile, separated by high-performance liquid chromatography, and quantitated by fluorescence. The limit of detection of the method was 1 ng ml(-1) (parts per billion) of T-2 and HT-2 in whole (with shell removed) eggs. The limit of quantitation for both toxins was 5 ng ml(-1). Recoveries from spiked eggs over the range from 5 to 50 ng ml(-1) averaged 89.2% for T-2 and 100.3% for HT-2, with coefficients of variation of 3.5 and 8.2%, respectively. This method is sensitive enough to be used to check for the presence of T-2 or HT-2 toxins in eggs.

Animals↗
PubMed1996

Studies on the development of diluents for the transportation and storage of human semen at ambient temperature.

Storage of human semen samples at ambient temperature for 24 h resulted in a significant loss of sperm motility from a mean 45.1 +/- 1.8% to 13.8 +/- 1.1% (n = 148). This motility loss was associated with a significant increase in the osmolality of the seminal plasma and the induction of peroxidative damage to the spermatozoa. Both of these detrimental changes could be prevented by diluting the original semen sample 1:1 with a citrate-egg yolk, buffer (CYB). In the presence of this extender all aspects of semen quality were efficiently preserved for 24 h, including sperm movement, penetration of a cervical mucus substitute, the acrosome reaction and sperm-oocyte fusion. CYB extension also permitted the use of chemiluminescent tests of leukocyte contamination to be performed on semen samples stored for 24 h at ambient temperatures. As a preservation medium, CYB was found to be superior to alternative formulations lacking citrate and storage at ambient temperatures was preferable to 4 degrees C. Significant improvements in motility retention were also observed when CYB was supplemented with pentoxifylline, although this treatment significantly stimulated peroxidative damage in the spermatozoa. However, if the pentoxifylline was combined with antioxidants then this collateral peroxidative damage could be reduced and the performance of CYB significantly enhanced. These results have implications for the design of diluents permitting the long-term storage and transportation of human semen samples at ambient temperatures.

Animals↗
PubMed2003

Subtle manipulation of egg sex ratio in birds.

Mothers are predicted to overproduce male or female eggs when the relative fitness gains from one sex are higher and outweigh the costs of manipulation. However, in birds such biases are often difficult to distinguish from differential embryo or chick mortality. Using a molecular technique to identify the sex of early embryos, we aim to determine the effect of maternal nutrition on zebra finch (Taeniopygia guttata) egg sex ratios after 2 days of incubation, which is as close to conception as is currently possible. We found no overall bias in the sex ratio of eggs laid and sex did not differ with relative laying order under any diet regime. However, mothers on a low-quality diet did produce a female bias in small clutches and a slight male bias in large clutches. On a high-quality diet, mothers produced a male bias in small clutches and a female bias in large clutches. Those on a standard diet produced a roughly even sex ratio, irrespective of clutch size. These observed biases in egg sex are partly in line with predictions that, in this species, daughters suffer disproportionately from poor rearing conditions. Thus, when relatively malnourished, mothers should only rear daughters in small broods and vice versa. Sex-ratio patterns in this species therefore appear to be subtle.

Adaptation, Physiological↗
PubMed1983

Comparison of post-thaw sperm motility after freezing in liquid nitrogen with protective media of either glycerol or glycerol-egg-yolk-citrate.

Thirty semen samples with a mean prefreezing motility of 70.4% were frozen for 1 month in liquid nitrogen by means of a modified Barkay's method and with either glycerol or glycerol-egg-yolk-citrate (GEYC) as protective media. The post-thaw motility was found to be 37.9% and 30.7% and cryosurvival rate (CSR) was 54.6% and 44.4%, respectively--the difference being significant (P less than 0.05). When samples achieving at least 40% of post-thaw-motility (PTM) in either medium were selected, the mean prefreezing motility increased to a 71.6%, and the PTM and the average CSR were 44.1% and 62.2% and 35.5% and 50%, respectively, when either glycerol or GEYC was used. It appears that glycerol alone is superior to a mixture of GEYC for cryo-preservation of sperm if the technique mentioned above is used and PTM is a criterion for sperm quality.

Citrates↗
PubMed1977

Effects of DDT on eggshell quality and calcium adenosine triphosphatase.

Adult mallard ducks were fed a diet containing 50 ppm DDT for 6 months. Eggs laid during this period were collected and eggshell weight, thickness, and calcium were determined. Chronic ingestion of DDT resulted in production of eggshells that were significantly thinner and lighter than those of controls. Total calcium of thinned eggshells was also reduced; however, calcium per gram of eggshell was not altered, indicating that other eggshell constituents were not incorporated as well. Calcium adenosine triphosphatase activity in the microsomal fraction of eggshell gland epithelium was assayed in control and DDT-fed ducks. Enzyme activity in DDT-fed ducks was reduced to 65% of control values. Since Ca-ATPase has been shown to be associated with calcium transport, enzyme inhibition may be responsible for decreased eggshell weight and thickness. Electron microscopic evaluation of microsomal fractions showed elements of the plasma membrane, including cilia and microvilli, as well as rough and smooth endoplasmic reticulum. Inhibition of calcium transport at the plasma membrane of mucosal epithelium is proposed as a possible mechanism of DDT-induced eggshell thinning.

Adenosine Triphosphatases↗