Changes In Egg Composition Research Articles

Intergenerational Costs of Oxidative Stress: Reduced Fitness in Daughters of Mothers That Experienced High Levels of Oxidative Damage during Reproduction.

AbstractParental condition transfer effects occur when the parents' physiological state during reproduction affects offspring performance. Oxidative damage may mediate such effects, yet evidence that oxidative damage experienced by parents during reproduction negatively affects offspring fitness is scarce and limited to early life stages. We show in Japanese quail (Coturnix japonica) that maternal levels of oxidative damage, measured during reproduction, negatively predict the number of offspring produced by daughters. This maternal effect on daughters' reproductive success was mediated by an effect on hatching success rather than on the number of eggs laid by daughters. We also observed a negative association between fathers' oxidative damage levels and the number of eggs laid by daughters but a positive association between fathers' oxidative damage levels and the hatching success of those eggs. These opposing paternal effects canceled each other out, resulting in no overall effect on the number of offspring produced by daughters. No significant association between a female's own level of oxidative damage during reproduction and her reproductive success was observed. Our results suggest that oxidative damage experienced by parents is a better predictor of an individual's reproductive performance than oxidative damage experienced by the individual itself. Although the mechanisms underlying these parental condition transfer effects are currently unknown, changes in egg composition or (epi)genetic alterations of gametes may play a role. These findings highlight the importance of an intergenerational perspective when quantifying costs of physiological stress.

Predator-induced maternal effects determine adaptive antipredator behaviors via egg composition

In high-risk environments with frequent predator encounters, efficient antipredator behavior is key to survival. Parental effects are a powerful mechanism to prepare offspring for coping with such environments, yet clear evidence for adaptive parental effects on offspring antipredator behaviors is missing. Rapid escape reflexes, or "C-start reflexes," are a key adaptation in fish and amphibians to escape predator strikes. We hypothesized that mothers living in high-risk environments might induce faster C-start reflexes in offspring by modifying egg composition. Here, we show that offspring of the cichlid fish Neolamprologus pulcher developed faster C-start reflexes and were more risk averse if their parents had been exposed to cues of their most dangerous natural predator during egg production. This effect was mediated by differences in egg composition. Eggs of predator-exposed mothers were heavier with higher net protein content, and the resulting offspring were heavier and had lower igf-1 gene expression than control offspring shortly after hatching. Thus, changes in egg composition can relay multiple putative pathways by which mothers can influence adaptive antipredator behaviors such as faster escape reflexes.

Effect of egg composition and oxidoreductase on adaptation of Tibetan chicken to high altitude

Tibetan chickens have good adaptation to hypoxic conditions, which can be reflected by higher hatchability than lowland breeds when incubated at high altitude. The objective of this trial was to study changes in egg composition and metabolism with regards the adaptation of Tibetan chickens to high altitude. We measured the dry weight of chicken embryos, egg yolk, and egg albumen, and the activity of lactate dehydrogenase (LDH) and succinic dehydrogenase (SDH) in breast muscle, heart, and liver from embryos of Tibetan chicken and Dwarf chicken (lowland breed) incubated at high (2,900 m) and low (100 m) altitude. We found that growth of chicken embryos was restricted at high altitude, especially for Dwarf chicken embryos. In Tibetan chicken, the egg weight was lighter, but the dry weight of egg yolk was heavier than that of Dwarf chicken. The LDH activities of the three tissues from the high altitude groups were respectively higher than those of the lowland groups from d 15 to hatching, except for breast muscle of Tibetan chicken embryos on d 15. In addition, under the high altitude environment, the heart tissue from Tibetan chicken had lower LDH activity than that from Dwarf chicken at d 15 and 18. The lactic acid content of blood from Tibetan chicken embryos was lower than that of Dwarf chicken at d 12 and 15 of incubation at high altitude. There was no difference in SDH activity in the three tissues between the high altitude groups and the lowland groups except in three tissues of hatchlings and at d 15 of incubation in breast muscle, nor between the two breeds at high altitude except in the heart of hatchlings. Consequently, the adaptation of Tibetan chicken to high altitude may be associated with higher quantities of yolk in the egg and a low metabolic oxygen demand in tissue, which illuminate the reasons that the Tibetan chicken have higher hatchability with lower oxygen transport ability.

Unpredictable mild stressors on laying females influence the composition of Japanese quail eggs and offspring's phenotype

Maternal stress effects on offspring development have been studied largely in rodents and primates, and to a lesser extent in farm animals. Potential lack of knowledge concerning prenatal stress on farm animals is regrettable because they are frequently subjected to a variety of husbandry stressors. Above all, effects of maternal stress on poultry offspring have been neglected. Prenatal effects in birds are known to involve maternal steroids present in eggs. In this study, we investigated the effects of daily unpredictable stressors applied to laying Japanese quail on their offspring's morphological and behavioural development. We also investigated the effects of our procedure on female reproductive output and on egg characteristics (weight, composition, yolk sex steroid levels). Our procedure induced only a mild stress: laying and egg fertilization rates of stressed females were not impaired; they remained similar to those of control females. Nonetheless, our stress procedure had an impact on some egg characteristics: stressed females’ eggs were heavier, contained more albumen and tended to have higher yolk testosterone levels than control females’ eggs. Stressed females’ offspring hatched earlier, were heavier at hatching and had a different growth pattern than did control females’ offspring. They also appeared to have a higher emotional reactivity than control chicks when encountering a novel environment and they reacted more strongly following social separation. Our study revealed that mild stressors applied to laying Japanese quail can increase the emotional reactivity of their chicks and suggested that maternal stress effects on offspring are mediated by changes in egg composition and yolk testosterone levels. We stress the particular relevance to the poultry industry of our findings highlighting the importance of taking into account the environment of laying females, as this environment can influence their progeny's behaviour and therefore their subsequent adaptation to husbandry conditions and ultimately their welfare.

Energetics of reproduction: consequences of divergent selection on egg size, food limitation, and female age for egg composition and reproductive effort in a butterfly

Using lines artificially selected on egg size and being subjected to a restricted and an unrestricted feeding treatment, we examined the relationships between egg size, egg number, egg composition, and reproductive investment in the butterfly Bicyclus anynana. Despite a successful manipulation of egg size, correlated responses to selection in larval time, pupal mass, pupal time, longevity, fecundity, or the amount of energy allocated to reproduction were virtually absent. Thus, there was no indication for an evolutionary link between offspring size and reproductive investment. Egg composition, in contrast, was affected by selection, with larger eggs containing relatively more lipid and water, but less protein and energy compared to smaller eggs. Hence, females producing large eggs did not have to sacrifice fecundity due to adjustments in egg composition. Food limitation per se caused only minor changes in egg composition, and there was no general reduction in egg provisioning with female age. The latter was restricted to food-limited females, whereas egg quality remained remarkably similar throughout the females’ life in control groups. We conclude that neglecting changes in biochemical egg composition, depending on genetic background, food availability, and female age, may introduce substantial error when estimating reproductive effort, and may ultimately lead to invalid conclusions. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 403–418.

Chick Development in Free‐Living Great TitsParus majorin Relation to Calcium Availability and Egg Composition

Evidence from a number of avian studies suggests that limitation of exogenous calcium (Ca) may reduce egg quality and retard nestling growth. However, it is poorly understood whether reduction in chick growth in Ca-poor areas is due to insufficient intake of dietary Ca or caused by maternal Ca limitation mediated through subtle changes in composition of eggs. In this study, we provide new evidence that Ca availability during egg formation may indeed affect egg composition and influence chick development of the great tit Parus major at early developmental stages. Ca-supplemented birds breeding in base-poor pine forests produced eggs with elevated yolk Ca concentration compared with controls, while no such effect of supplementation was detected in case of eggshell thickness. Nestling tarsus length in the first half of the nestling period was positively influenced by both yolk dry mass and yolk Ca concentration. The effect of supplementary Ca did not persist throughout the nestling period; initial effects of egg components disappeared as nestlings aged. We conclude that apparently normal eggs may harbor poor nutrient and mineral conditions for chick growth. Such subtle changes in composition of eggs can depress chick growth, especially in harsh years.

Lipid and amino acid metabolism during early development of Atlantic halibut ( Hippoglossus hippoglossus )

Lipid classes, fatty acids, free amino acidsand protein content in captive Atlantic halibut(Hippoglossus hippoglossus) eggs weremeasured to investigate the changes in thebiochemical composition of eggs and larvae inboth the embryonic and early larval stages.Total free amino acids decreased continuously(p < 0.01) over the embryonic and larval stagesinvestigated. Triacylglycerol was significantlygreater at hatch than at all other stages(p < 0.05). When hatching occurred, there wasalso a significant increase in all phospholipidclasses. It is suggested that free amino acidsmay be the source of carbon skeletons for lipidsynthesis at hatching.

CHANGES IN EGG COMPOSITION OF AMERICAN KESTRELS EXPOSED TO DIETARY POLYCHLORINATED BIPHENYLS

Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 µg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.

WITHIN-CLUTCH TRADE-OFFS BETWEEN THE NUMBER AND QUALITY OF EGGS: EXPERIMENTAL MANIPULATIONS IN GULLS

We experimentally increased the number of eggs laid by Lesser Black-backed Gulls and examined the relationship between egg number and egg quality. Egg quality was measured in terms of egg composition and the probability that an egg would give rise to a fledged chick. In measuring the latter, we removed the potentially confounding effects (1) between parental quality and egg quality and (2) between increased egg production and parental condition, using a cross-fostering protocol in which eggs were reared by control parents. Lesser Black-backed Gulls were capable of producing, on average, almost three times the normal clutch of three eggs. Although egg mass did not fall below that of the last laid egg in normal clutches, as the clutch extended beyond three, experimental eggs contained relatively less lipid and relatively more water. Overall, the percentage of eggs that gave rise to fledged chicks (when reared singly by a foster parent) declined significantly with position in the experimental laying sequence; about two-thirds of the eggs laid at the beginning of the laying sequence gave rise to fledged chicks, whereas only about one-third of the last laid eggs did so. This was not due to any seasonal change in the capacity of foster parents to rear the chicks, and neither hatching nor fledging success of the eggs was related to their fresh mass. Thus, as more eggs are laid, important changes in egg composition occur that have, in themselves, substantial effects on offspring survival. This study provides clear evidence of a trade-off between egg number and egg quality.

Within-Clutch Trade-Offs between the Number and Quality of Eggs: Experimental Manipulations in Gulls

We experimentally increased the number of eggs laid by Lesser Black-backed Gulls and examined the relationship between egg number and egg quality. Egg quality was measured in terms of egg composition and the probability that an egg would give rise to a fledged chick. In measuring the latter, we removed the potentially confounding effects (1) between parental quality and egg quality and (2) between increased egg production and parental condition, using a cross-fostering protocol in which eggs were reared by control parents. Lesser Black-backed Gulls were capable of producing, on average, almost three times the normal clutch of three eggs. Although egg mass did not fall below that of the last laid egg in normal clutches, as the clutch extended beyond three, experimental eggs contained relatively less lipid and relatively more water. Overall, the percentage of eggs that gave rise to fledged chicks (when reared singly by a foster parent) declined significantly with position in the experimental laying sequence; about two-thirds of the eggs laid at the beginning of the laying sequence gave rise to fledged chicks, whereas only about one-third of the last laid eggs did so. This was not due to any seasonal change in the capacity of foster parents to rear the chicks, and neither hatching nor fledging success of the eggs was related to their fresh mass. Thus, as more eggs are laid, important changes in egg composition occur that have, in themselves, substantial effects on offspring survival. This study provides clear evidence of a trade-off between egg number and egg quality.

Intra-Clutch Changes in Egg Composition and Shell Quality in Laying Hens.

Intra-clutch changes in egg composition and shell quality were examined using two laying hen strains (High line: 40 hens, Low line: 39 hens) which were developed by a divergent selection for yolk-albumen ratio. Oviposition time was recorded every 30 minutes from 5: 30 to 18: 30 for a duration of 90 days at about 270 days of age. The eggs of individual hens were collected every day from three consecutive clutches. Only the hens that formed the clutches determined apparently by their oviposition time were used for the analyses. Statistical analyses were performed separately for the four clutch size groups.The lag in oviposition time was the longest for the last egg of the clutch (terminal egg). There was no difference in the oviposition interval between lines. The changes in egg weight of consecutive eggs within a clutch showed that the first egg of the clutch was the heaviest and then the weight gradually decreased. The decrease in weight the low line was estimated to be 3.0-4.0g, or 6% of the 1st egg, while the decrease in weight in the high line was 1.5-2.0g (4% of the first egg). The yolk weight of the 2nd egg was heavier than that of other eggs in the same clutch, and decreased by 1.0-1.5g in both lines. Albumen weight showed a remarkable decrease from the first egg to the 3rd or the 4th eggs of the clutch, then the decrease tended to be smaller. The decrease in the low line, which had a larger amount of albumen, was estimated to be larger. Thick albumen weight tended to decrease as the serial number within a clutch increased. However, thin albumen weight increased slightly in eggs laid at later positions of the clutch. Egg-shell weight, thickness and strength showed a clear increase in the terminal egg of the clutch.

Changes in Egg Composition of Lines Selected for Divergence in Yolk Cholesterol Concentration

The changes in the proportions of the egg, percentage yolk dry matter, and percentage yolk fat as a response to selection pressure for divergence in yolk cholesterol concentration of the Cornell randombred Leghorn (LC) and the Athens-Canadian randombred (AC) population were determined. Differences were observed between the two populations and in the high and low cholesterol lines within populations.The egg weight of the LC population was significantly greater and the yolk weight less than that of the (AC) population, resulting in a significantly lower percent yolk in the LC population. Yolk dry matter of the LC population was slightly, but significantly, lower than that of the AC population.Both egg and yolk weights of the high cholesterol lines in both populations were significantly greater than that of the low lines. The differences were not proportional; percent yolk of the high cholesterol line was significantly lower than that of the low line. The percent dry matter of the high cholesterol line in the AC, but not in the Leghorn population, was significantly higher than that of the low line. These differences did not appear to be a response to the selection pressure for divergence of yolk cholesterol concentration. When total cholesterol mass was calculated on the basis of total amount in the yolk or gram of dry matter, the divergence between the high and low lines was similar to that when expressed as milligrams cholesterol per gram whole yolk. Correlations between yolk cholesterol concentration and other egg traits were low.

Effects of a (n−3) polyunsaturated fatty acid‐deficient diet on profiles of serum vitellogenin and lipoprotein in vitellogenic trout (Salmo gairdneri)

During the 6 months of vitellogenesis, 3-year-old female trout (Salmo gairdneri) were fed either an enriched (E) or an (n-3) polyunsaturated fatty acid (PUFA)-deficient (D) diet; serum vitellogenin (VG) and lipoproteins (d<1.21 g/ml) were analyzed at the third month of vitellogenesis (September) and at ovulation (December). The serum content of high density lipoproteins (HDL), the major protein class, maintained a mean value of 1500 mg/dl at both stages and with both diets. On the contrary, very low density lipoproteins (VLDL) were 90% higher during vitellogenesis than at spawning time, whereas excess vitellogenin circulated at this period (6580 mg/dl serum with diet E). The diet deficient in (n-3) lowered serum vitellogenin content by 16% in September and by 26% in December. The degree of (n-3) PUFA incorporation moderately decreased in low density lipoproteins (LDL) and in HDL with the (n-3)-deficient diet. The effect was more pronounced for 20∶5. On the other hand, essential 22∶6 was incorporated into vitellogenin at the same rate in September as in December with diet E (23% and 25%, respectively), whereas after a 3-month deficiency, the percentage fell to 12%; this percentage rose again to 19% at spawning time. These findings show that, although stored (n-3) PUFA were not exhausted after a 6-month dietary deficiency, the incorporation of essential fatty acids (EFA) into vitellogenin during the early stages of oogenesis was low, suggesting changes in egg composition that may influence hatching.

The effect of a uterine irritant on the composition of the egg in the fowl.

Huston & Nalbandov (1953) and van Tienhoven (1953) were the first to draw attention to the possibility that egg formation in the fowl is influenced by factors arising in the oviduct itself, and although their claim for the existence of a neural link between the oviduct and the anterior pituitary gland has not yet been confirmed (Sykes, 1962), it has been shown that shell formation can be profoundly disturbed by the presence of a foreign body in the uterine region of the oviduct (Sykes, 1953; Lake & Gilbert, 1964). The gross changes in egg composition which occur after the insertion of a single loop of cotton thread in the uterus of the hen are reported here. The shell (with membranes) and the yolk were weighed, and the albumen content obtained by difference. Shell calcium was determined by oxalate precipitation after wet ashing (King & Wooton, 1956). In the presence of

The Effect of Season and Age of Bird : 2. On the Chemical Composition of Egg White

THE EXTENT that season, environmental temperature, management practices, nutrition, genetics, age of layer, etc. effect egg quality have been extensively studied. However, satisfactory explanations for these quality variations in relation to differences in composition which effect physical and performance characteristics associated with quality have not been elucidated. Smith et al. (1954) found that the composition of eggs produced by a hen was an individual characteristic and that changes in egg composition could be associated with laying rate, environmental temperatures and age of the layer. They reported that higher temperatures increased the dry matter, phosphorus, sodium, and potassium levels of egg white.Cotterill and Winter (1955) proposed that the dissociation of a complex between lysozyme and ovomucin might be responsible for one stage in egg white thinning. They showed that increases in the ionic strength and pH of the medium caused a dissociation of the complex. This protein interaction appeared to …

Effect of artificial changes in egg composition on hatchability and chick growth.

Summary and ConclusionsArtificial decrease in albumen quality and quantity caused by local X-irradiation of the oviduct reduces the hatchability of eggs. The distribution of embryo mortality is different from that encountered in normal eggs: very early mortality is markedly increased. Chicks from such eggs have a lower hatch weight; however, no effect on subsequent chick growth was observed.