Egg Volume Research Articles

Гнездовая биология обыкновенной горихвостки Phoenicunis phoenicurus (L., 1758) на юго-востоке Западной Сибири

Гнездовая биология обыкновенной горихвостки Phoenicunis phoenicurus (L., 1758) на юго-востоке Западной Сибири

Calcium anacardate as source of anacardic acid in laying Japanese quail diet.

Anacardic acid is naturally found in various parts of the cashew tree (Anacardium occidentale L.) and marketed as calcium anacardate. This product has antibacterial, antifungal and antioxidant activity, and has been used in humans in the treatment and prevention of cardiovascular and cerebrovascular diseases and tumors. In meat and egg production systems, anacardic acid is used as a substitute for growth-promoting antibiotics. The study objective was to evaluate effects of adding calcium anacardate as source of anacardic acid in laying Japanese quail diet on bird performance and eggs quality. A total of 252 Japanese quail with 22 week-old were studied, using a completely randomized design composed of six treatments with six replicates and seven quails per experimental unit. Treatments applied were: diet without growth promoter; diet with 0,1% growth promoter; and four diets without growth promoter and addition of 0.25; 0.50; 0.75 and 1.0% calcium anacardate (CA), respectively. The data were submitted to analysis of variance and treatment means compared with a SNK test (5%). The data from treatments containing CA were submitted to regression analysis. Treatments did not influence feed intake, egg production, egg weight, egg volume, feed conversion ratio and eggs quality parameters. The addition up to 1% of calcium anacardate in laying Japanese quail diet, does not influence their performance and egg quality.

Interspecific variations in external and internal egg quality among various captive avian species from Punjab, Pakistan.

Present study was planned to determine variations in external and internal quality egg parameters of different avian species including ostrich Struthio camelus, ducks Anas platyrhynchos, chicken Gallus gallus, turkeys Meleagris gallopavo and grey francolin Francolinus pondicerinus. All the birds were kept under similar rearing conditions. A total of 150 eggs were collected for each species to record external features of these eggs. Statistically significant (p<0.05) variations were recorded in egg weight, egg length and egg width between ostrich, ducks, chicken, turkey and quail eggs. Significantly (p<0.05) higher egg weight, egg length and egg width was observed for ostrich eggs while the same was lowest for grey francolin eggs. Similarly, significantly (p<0.05) greater shape index and egg volume values were observed for ostrich eggs while lowest shape index values were recorded for turkey eggs and egg volume was lowest for grey francolin. Significantly, higher (p<0.05) values of egg density were noted for eggs of the quail and the same were lowest for ostrich eggs. Non-significant variations in egg density values were observed between eggs of the ducks, chicken, turkey and grey francolin. It has been concluded that the positive correlations between the internal and external egg quality traits indicated that the traits can be improved through selection.

Изменение массы перепелиных яиц с разной плотностью и индексом формы в прединкубационный период хранения

The range of values of the indicator "density" of freshly laid eggs in representatives of hatching birds with sufficient accuracy determines the quality of the hatching quail egg. The average weight of laid quail eggs weighs 12.57 g with a sample span of 10.4 to 13.6 g. Low variability was observed both in the dynamics of the egg weight and in the density of eggs over the entire storage period. The values of the coefficient of variability, as a rule, did not exceed 9.5%. It has been established that when eggs are stored for 10 days after laying at a temperature of +10-15С, the egg weight decreases by an average of 2.6%, and the density by 2.1% (P&lt;0.05). The density of quail eggs per day of storage decreased by an average of 0.002 g / cm3. The nature of the distribution of the values of the theoretically calculated volume of quail eggs, that is, the relationship between the values of a random variable and the frequency of their occurrence, is analyzed. The formula for calculating the theoretical value of the volume of a quail egg, cm3, has been refined: V=0.485*D*d*d/1000, where D is the longitudinal diameter of the egg, mm; d is the transverse diameter of the egg, mm. The theoretically calculated values of the "egg density" indicator significantly correlated with all the studied parameters. The relationships were moderate in strength and inverse in direction (P &lt;0.05).

Breeding Behaviour of Black-Winged Stilt, Himantopus himantopus (Linnaeus, 1758) in Agricultural Landscape of Punjab, India

During the breeding seasons (2017-2019), the hitherto little known aspects of breeding behavior of Black-winged Stilt, Himantopus himantopus were studied in the ploughed agricultural fields, village ponds and adjacent shallow pools located in rural outskirts in district Ludhiana, Punjab, India. Observations on nest structure, egg laying, incubation, hatching and other behavioural aspects of the parents/chicks were inferred from videorecords, photographs and direct field observations made on 19 clutches containing 59 eggs. In the study area the breeding season extended from April to July. The mean clutch size was 3.29±0.77 (range 1-4, n=19) that differed between the dry ploughed field clutches (3.4±0.70, range: 2-4, n=10) and wet pool/pond sites (2.78±1.09, range: 1-4, n=9). In the dry ploughed fields, the nest scrapes were lined mainly with the wheat rootlets/ straw pieces only. However, the nest material used in/around ponds and pools included predominantly dry twigs, decaying leaves and some thermocol chips. The egg length, breadth, weight, egg shape index and volume (n=54) measured 42.22±2.50 mm, 30.71±1.13 mm, 19.77±2.34 gm, 72.88±3.19 and 20.39±2.36 cm3, respectively. The eggs hatched mostly synchronously after biparental incubation period of 25 or 26 days (n=4). As per traditional method, only 20.34% (12 out of 59 eggs) of the eggs hatched successfully and the hatching success calculated as per the Mayfield Method showed that it was only 2.07% in post-harvest field sites and 36.26% in non-agricultural sites (shallow water pools and edge waters of village ponds). The use of polluted sites as nesting grounds has been opined as a habitat shift and an adaptation in process

Filling gaps in the biology of the endemic and threatened freshwater shrimp Macrobrachium candango (Caridea: Palaemonidae) through basic morphometric and reproductive approaches

Macrobrachium candango Mantelatto, Pileggi, Pantaleão, Magalhães, Villalobos and Álvarez, 2021 is an endemic shrimp species to the Brazilian Central-West region (Brasília, Federal District). The present study aims to analyze the relative growth, morphometry, morphological sexual maturity, and fecundity of this species. Specimens were collected from tributaries of the Paranoá Lake hydrographic basin, Brasília, during sporadic periods between 1983 and 2012. Relative growth was analyzed for different structures (carapace, abdomen, second abdominal pleura, merus, carpus, and propodus). The laterality and heterochely patterns were evaluated based on the dimensions of the propodus length. Fecundity was calculated as the average total number of eggs per female and egg size was measured to obtain the volume. There were differences in relative growth (p < 0.05) of the structures analyzed between juveniles and adults, and distinct allometric patterns were observed between the life stages, which could reflect the habit of these animals at each developmental stage. No pattern of laterality and heterochely was observed between the chelipeds of the animals analyzed (p > 0.05). The lack of laterality may indicate that this species directs energy to the smallest propodus when the largest propodus is injured. Egg volume ranged from 4.41 to 7.71 mm3, and fecundity ranged from 38 to 61 eggs, indicating a life cycle with abbreviated larval development. The characteristics presented herein are unprecedented for M. candango and present relevant information needed to assess the conservation status of this species, which is currently threatened.

Effects of Egg Shape Index on Egg Quality in Partridges

The aim of this study is to investigate the effects of the egg shape index on egg quality traits in Partridge (Alectoris Chukar). For this purpose, the eggs were classified as three different groups in terms of egg shape index which are ≤ 75, &amp;lt; 76 -77 &amp;gt; and ≥ 78 and 114, 56 and 73 eggs were used in the groups, respectively. Albumen ratio, albumen weight, yolk weight, yolk/albumen ratio and Haugh unit were significantly affected by egg shape index in this research. On the other hand, egg weight, egg volume, shell surface area, eggshell thickness, unit surface eggshell weight, shell ratio, albumen index, yolk index, yolk ratio and eggshell weight traits were not affected by egg shape index. It was determined that there was a significant relationship between egg shape index and albumen ratio, albumen weight, yolk weight, yolk/albumen ratio and Haugh unit in this study. According to the findings, eggshape index is an important factor affecting egg quality.

Production performance, egg quality characteristics and serum biochemical parameters on Brahma laying hens (Gallus gallus domesticus) fed with supplemented Chromolaena odorata leaf meal

An experiment was conducted to evaluate the effect of graded levels of Chromolaena odorata leaf meal (COLM) on production performance, egg quality characteristics, and serum biochemical parameters on Brahma laying hens. A total of forty-five local laying hens aged 4 to 5 months were weighed and assigned to three treatment groups in a completely randomized design. COLM was used as a supplement and incorporated into the diets at 0, 1, and 2% in diets T0, T1, and T2 respectively. Data were collected on production performance, egg quality characteristics, and serum biochemistry. Results from the study indicate that body weight gain, average weight, and egg volume were low (p&lt;0.05) with treatment T2 compared to control (T0) and the best was obtained with treatment T1. The Haugh unit and percentage hen day production were not negatively affected by the treatment levels of COLM. There were significant (p&lt;0.05) differences in triglyceride, total cholesterol, and urea. Results obtained from this study revealed that the inclusion of 1% of COLM improved the egg quality as well as the health status of the birds without having any detrimental effect on the birds.

Interpopulation Plasticity in a Darkling Beetle Life-History along a Whole Oceanic Island Altitudinal Gradient.

Simple SummaryYoung oceanic islands often harbour poor biodiversity because they need time to be colonised. However, some animal species can be abundant, presenting high densities and being widely distributed through different altitudinal habitats of high oceanic islands. This is the case of the darkling beetle Pimelia laevigata costipennis Wollaston, 1864 on El Hierro, the westernmost island of the Canary archipelago. Therefore, this kind of framework is ideal for studying the variation of one insect species in body size, reproductive strategies, and populations in different environments. This study shows how environmental factors related to rainfall and temperature affect the different populations of this flightless beetle. Furthermore, in the more favourable habitats, located at higher altitudes, these beetles were larger in body size, laid clutches with smaller eggs, the reproduction occurred later, and showed the highest population in abundance. Lastly, this is the first study that assesses the changes of an insect along a whole insular altitudinal gradient, demonstrating apparent modifications to each habitat condition.Insects show remarkable phenotypic plasticity in response to changing environmental conditions. The abiotic factors that determine their phenotypes often vary in time and space, and oceanic islands harbour ideal environments for testing predictions on this matter. The ubiquitous beetle Pimelia laevigata costipennis Wollaston, 1864 (Tenebrionidae) is distributed over the entire altitudinal gradient of the island El Hierro (Canary archipelago), from 0 to 1501 m above sea level. Here, we examine how environmental factors (i.e., rainfall and temperature), associated with the altitudinal gradient, affect the body size, reproductive phenology, clutch size and egg volume, and population dynamics of this ectothermic flightless insect. Pimelia l. costipennis populations inhabiting upland localities, typified by lower temperatures, and greater precipitation and vegetation cover, were larger in body size and laid larger clutches with smaller eggs than those in the lowlands. Moreover, reproduction occurred earlier in the year at lower sites and later at higher sites, whereas activity density was highest in the uplands where it increases with temperature. This study first explores the changes in life history patterns along a whole insular altitudinal gradient, and finds interpopulation plasticity. It confirms that environmental factors associated with species spatial distribution act additively as drivers of phenological and phenotypic expression.

Determination of Egg Internal and External Quality Characteristics with Mathematical Formulas in Guinea Hens

This study was carried out to determine some internal and external quality characteristics of 378 eggs collected between March and July from 42-week-old Guinea Hens (Numidae meleagris) raised by the public in Erzincan province, using mathematical formulas. Egg external quality features include shape index 73%, elongation 1.37, egg surface area 55.65 cm2, egg volume 40.39 cm3, shell thickness 0.28 mm, shell weight 3.19 g, number of pores-1 6686.05, number of pores-2 5156.10, number of pores- 3 5043.33 pieces, pore density-1 120.22 pore number/cm2, pore density-2 92.62 pore number/cm2, pore density-3 90.52 pore number/cm2; The yolk weight and white weight of the egg were determined as 6.02 g and 30.89 g, from the egg internal quality characteristics. As a result, in this study, yolk weight, shell weight and shell thickness values of egg internal and external quality characteristics calculated using mathematical formulas based on egg weight without spoiling the egg integrity were found to be lower than the values in some studies determined by measurement, while the white weight value was found to be higher.

Breeding biology of two sympatric Nesospiza finches at Nightingale Island, Tristan da Cunha

Nesospiza finches are a classic example of a simple adaptive radiation, with two ecologically distinct forms confined to the Tristan da Cunha Archipelago, South Atlantic Ocean: an abundant, small-billed dietary generalist, and a scarce, large-billed specialist. These have segregated into two species at Nightingale Island, but there is still local introgression between the two forms at Inaccessible Island. We describe the phenology and breeding behaviour of the two sympatric species at Nightingale Island (2.6 km2): Wilkins’s Finch Nesospiza wilkinsi (Endangered) and Nightingale Island Finch N. questi (Vulnerable). The finch breeding season starts in late October-November but the onset of breeding varies by 4–5 weeks among years. The small-billed Nightingale Island Finch typically (two of three study seasons) starts breeding 1–3 weeks earlier than the large-billed Wilkins’s Finch, unlike at Inaccessible Island where the Wilkins’s Finches start breeding first. Laying of initial clutches was quite well synchronised, peaking 1–2 weeks after the first nests were found. Females constructed the nests, which were mostly (&gt;90%) in dense Spartina arundinacea tussock grass stands and occasionally in ferns or sedge grasses. Clutches comprised one or two eggs, with no difference between Wilkins’s (1.66 ± 0.48) or Nightingale Island finch clutches (1.71 ± 0.46). Incubation periods averaged longer for Wilkins’s Finch (18.3 ± 0.5 d) than Nightingale Island Finch (17.7 ± 0.5 d), but this difference was not statistically significant. Females incubated the eggs, and were fed by the males. The difference in egg volume within two-egg clutches was 2–13% for Wilkins’s Finches (mean 5.9 ± 3.3%) and 1–19% for Nightingale Island Finches (mean 8.4 ± 5.3%). At least 31% of pairs re -laid after their first breeding attempt failed but there was no evidence of double brooding. Repeat nests were 0–20 m (mean 5.6 ± 4.9 m) from the initial nest site and inter-seasonal nest sites for 38 known pairs were 0–33 m apart (mean 12 ± 9 m). No inter-species pairs or hybrid birds were seen, but two instances of inter-species fledgling provisioning were observed.

Trends in an emerging artisanal fishery of the African cyprinid Rastrineobola argentea in Lake Nabugabo, Uganda

AbstractFishing pressure can have strong impacts on fish populations, driving declines in abundance and, occasionally, changing life history traits. However, much of our current understanding of these phenomena derives from studies conducted decades or even centuries after the onset of fishing. Newly established fisheries provide an excellent opportunity to understand this critical early phase. Temporal trends in catch data and life history traits of the cyprinid fish Rastrineobola argentea (Pellegrin), now the target of a burgeoning artisanal fishery in Lake Nabugabo, Uganda, were analysed. Results showed that the R. argentea fishery intensified and became more selective during the first decade since its establishment (2008–2019), while catch‐per‐unit‐effort of R. argentea (fisheries‐independent abundance) at repeatedly sampled sites in the lake decreased over this same time period. Size‐adjusted egg volume and ovary mass increased significantly over the time period, which may reflect a density‐dependent response to a fisheries‐induced population decline.

Variation in male-built nest volume with nesting-support quality, colony, and egg production in whiskered terns.

Nest building can represent an energetically costly activity for a variety of animal taxa. Besides, the determinants of within‐species variation in the design of nests, notably with respect to natural and sexual selection, are still insufficiently documented. Based on an observational study, we examined the influence of nesting conditions (nesting‐support quality, colony, laying date, and year) on male‐built nest volume and also its potential role as a postmating sexually selected display in the whiskered tern Chlidonias hybrida. This tern species is a monogamous colonial bird with obligate biparental care breeding on aquatic vegetation. Hence, large nesting platforms are expected to be a selective advantage because they would better withstand adverse environmental conditions and provide a secure structure for eggs. Nest size may also serve as a postmating sexual trait, and variation in egg production would be positively associated with nest size. We found that nest volume was adjusted to different environmental cues. A positive relationship was found between nest volume and nesting‐support quality, indicating that the leaf density of white waterlily is essential for nest stability. Variation in nest volume was not correlated to colony size but varied among colonies and years. Male‐built nest volume was also positively associated with mean egg volume per clutch but not with clutch size. The fitness consequences of building a large nest are yet to be studied, and additional investigations are recommended to better understand whether the activity of males early during breeding season (e.g., nest building and courtship feeding performance) really serves as postmating sexually selected signals.

The Role of Intra-Clutch Variation of Magpie Clutches in Foreign Egg Rejection Depends on the Egg Trait Considered

The existence of a coevolutionary process between avian brood parasites and their hosts predicts a lower intra-clutch variation in egg appearance of host eggs among rejecters as this would favor egg discrimination of parasite eggs by hosts once parasitic egg mimicry had evolved. So far empirical tests of this prediction have ignored the fact that different aspects of host egg phenotypes may differ in the relative role of environmental vs. genetic determination, and hence that the role of intra-clutch variation in egg rejection within a population cannot be invariant. Here, we estimated whether the intra-clutch variation in several aspects of host eggshell features is consistently associated to rejection of parasitic foreign eggs across years in a magpie host population parasitized by great spotted cuckoos. We innovatively estimated spottiness by means of the fractal dimension of eggs, which considers the homogeneity of spot pattern complexity in eggshells. Our results show that low intra-clutch variation in the blue-green coloration at the middle area of the eggs associated with a high chance of rejection, but only in one of the 3 years we conducted the study. In addition, females that rejected foreign eggs presented more homogenous spot patterns in their clutches as estimated by their fractal dimension than females that accepted experimental eggs, independently of the year of study. Finally, intra-clutch variation in egg volume of host eggs was not associated to rejection. Analyses at the individual level revealed that the relative role of genetic vs. environmental factors that determine egg phenotype would be feature-specific in magpies, females having a characteristic spottiness, but not color or volume, pattern. Our work stresses the importance of considering a holistic approach including several aspects of variation in host egg phenotype (size, color, and homogeneity of spot pattern), as some aspects might be more susceptible to selection through egg rejection than others, presumably because they are less influenced by variation in the environmental conditions. Moreover, our study highlights the importance of replication in studies on the adaptive value of host traits in egg rejection.

Correlated evolution of larval development, egg size and genome size across two genera of snapping shrimp

Across plants and animals, genome size is often correlated with life-history traits: large genomes are correlated with larger seeds, slower development, larger body size and slower cell division. Among decapod crustaceans, caridean shrimps are among the most variable both in terms of genome size variation and life-history characteristics such as larval development mode and egg size, but the extent to which these traits are associated in a phylogenetic context is largely unknown. In this study, we examine correlations among egg size, larval development and genome size in two different genera of snapping shrimp, Alpheus and Synalpheus, using phylogenetically informed analyses. In both Alpheus and Synalpheus, egg size is strongly linked to larval development mode: species with abbreviated development had significantly larger eggs than species with extended larval development. We produced the first comprehensive dataset of genome size in Alpheus (n=37species) and demonstrated that genome size was strongly and positively correlated with egg size in both Alpheus and Synalpheus. Correlated trait evolution analyses showed that in Alpheus, changes in genome size were clearly dependent on egg size. In Synalpheus, evolutionary path analyses suggest that changes in development mode (from extended to abbreviated) drove increases in egg volume; larger eggs, in turn, resulted in larger genomes. These data suggest that variation in reproductive traits may underpin the high degree of variation in genome size seen in a wide variety of caridean shrimp groups more generally.

Egg morphometrics and egg shape coefficients for White-faced Ibis (Plegadis chihi)

Egg size is a useful metric for maternal investment, offspring quality, and contaminant studies. Yet these values and the egg shape coefficients required to estimate egg size are not available for many species, including White-faced-Ibis (Plegadis chihi). We provide egg morphometrics derived from 319 White-faced Ibis eggs sampled at Bear River Migratory Bird Refuge, Great Salt Lake, Utah, from 2010 to 2012. Measured egg length (mean ± SD) was 51.20 ± 1.99 mm, egg width was 36.08 ± 1.15 mm, and whole egg mass was 34.1 ± 3.3 g. Estimated whole egg volume was 34.63 ± 3.73 cm3 and estimated egg shape coefficients were 0.507 for Kv (whole egg and egg contents), 0.547 for Kw (whole egg), and 0.524 for Kw (egg contents only). In addition, we documented expected declines in egg mass over time due to incubation (–0.22 g/d) and desiccation during storage (–0.03 g/d), that should be accounted for prior to analyses that use egg mass of freshly laid eggs.

Differences in the effects of sodium selenate and sodium selenite on the mortality, reproduction, lipid peroxidation and glutathione redox status of Folsomia candida Willem 1902 (Collembola)

The average selenium content of the soils worldwide is 0.4 mg kg−1; however, the selenium concentration can be much higher in some areas. Selenium is essential to humans and animals, but it can also be a risk based on the narrow gap between the beneficial and toxic concentrations. There is scarce information in the literature on the effects of various inorganic forms of selenium on soil invertebrates, such as collembolans. Consequently, the goal of our study was to determine if selenium has a negative effect on the collembolan species Folsomia candida and to verify if there is a difference between the effects of the two oxidation forms. The effect of sodium selenite and sodium selenate on Folsomia candida was studied in the laboratory by mortality and reproduction tests also by various sub-lethal and biochemical methods. The methods used in our study included a standard OECD test according to the 232 guideline, and we measured the life history parameters such as relative growth, egg production, and egg volume. For the investigation of lipid peroxidation and glutathione redox status, malondialdehyde (MDA) content, reduced glutathione (GSH) concentration and glutathione peroxidase (GPx) activity were measured. Our results showed that up to a concentration of 0.5 mg kg−1 Se in soil, both selenium forms were beneficial for F. candida. For mortality, the LOAEC (lowest observable adverse effect concentration) was 8 mg kg−1 Se in the soil in the experiments according to the OECD 232 test for both selenium forms. In case of juveniles, sodium selenite was much more toxic than sodium selenate. The LOAEC was 0.5 mg kg−1 for sodium selenite and 8 mg kg−1 in the case of sodium selenate. Sub-lethal parameters showed to be potentially more sensitive than the parameters measured in the OECD 232 test in the case of sodium selenate contamination. For instance, both the number of eggs laid and the relative growth showed significant differences compared to the control group in lower concentrations than the juvenile number or mortality. In the groups treated with sodium selenite, the juvenile number was the most sensitive parameter. Based on our results, it can be stated that sodium selenite may be potentially more toxic to collembolans than sodium selenate. Lipid peroxidation was not initiated by selenium exposure. The glutathione redox system also did not activate either, which suggested that selenium toxicity in collembola is not a consequence of selenium-induced oxidative stress.

Relationship between weight, volume and specific gravity of goose eggs before incubation

In this study, the relationships between the weight, volume and specific gravity of eggs are revealed by calculating egg's volume and specific gravity depending on the weight of the egg, breadth and length, which are only three variables, with mathematical equations. Eggs to three goose genotypes, Grey China, Linda and Native geese from Aksaray region taken from six breeders were used. Eggs (n=481) were weighed and Length, Breadth measurements made with a precision of 0.01 mm. Average weights in genotypes from large to small in Linda, Native and Chinese geese were detected as; 165.9, 137.2 and 131.1 g, respectively, and the average egg volume was found as; 152.0, 126.0 and 120.3 cm3, respectively. Specific gravity from large to small in Linda, China and Native has occurred as; 1.092, 1.091 and 1.089 g/cm3. Egg volume was calculated with mathematical equations and results were close to real, and accordingly the calculated Specific gravity was also detected to be realistic. These results were obtained easily by only three variables, egg weight, and Length and Breadth values. This method can pave the way to obtain a lot of information about the egg with Specific gravity.

The grades and freshness assessment of eggs based on density detection using machine vision and weighing sensor

The water displacement and flotation are two of the most accurate and rapid methods for grading and assessing freshness of agricultural products based on density determination. However, these techniques are still not suitable for use in agricultural inspections of products such as eggs that absorb water which can be considered intrusive or destructive and can affect the result of measurements. Here we present a novel proposal for a method of non-destructive, non-invasive, low cost, simple and real—time monitoring of the grading and freshness assessment of eggs based on density detection using machine vision and a weighing sensor. This is the first proposal that divides egg freshness into intervals through density measurements. The machine vision system was developed for the measurement of external physical characteristics (length and breadth) of eggs for evaluating their volume. The weighing system was developed for the measurement of the weight of the egg. Egg weight and volume were used to calculate density for grading and egg freshness assessment. The proposed system could measure the weight, volume and density with an accuracy of 99.88%, 98.26% and 99.02%, respectively. The results showed that the weight and freshness of eggs stored at room temperature decreased with storage time. The relationship between density and percentage of freshness was linear for the all sizes of eggs, the coefficient of determination (R2) of 0.9982, 0.9999, 0.9996, 0.9996 and 0.9994 for classified egg size classified 0, 1, 2, 3 and 4, respectively. This study shows that egg freshness can be determined through density without using water to test for water displacement or egg flotation which has future potential as a measuring system important for the poultry industry.

Breeding responses to environmental variation are age- and trait-dependent in female Nazca boobies.

Age and environment are important determinants of reproductive parameters in long-lived organisms. These factors may interact to determine breeding responses to environmental change, yet few studies have examined the environmental dependence of aging patterns across the entire life span. We do so, using a 20-yr longitudinal data set of reproductive phenotypes in long-lived female Nazca boobies (Sula granti), a monogamous seabird breeding in the eastern tropical Pacific. Young and old females may suffer from inexperience and senescence, respectively, and/or practice reproductive restraint. Breeding performance (for breeding participation, breeding date, clutch size, egg volume, and offspring production) was expected to be lower in these age classes, particularly under environmental challenge, in comparison with middle-aged breeders. Sea surface temperature anomalies (SSTA) represented interannual variation in the El Niño-Southern Oscillation (ENSO) and were one proxy for environmental quality (a population count of clutch initiations was a second). Although only females lay eggs, both sexes care for eggs and nestlings, and the male partner's age, alone or in interaction with female age, was evaluated as a predictor of breeding performance. Middle-aged females performed better than young and old birds for all reproductive traits. Pairing with a young male delayed breeding (particularly for old females) and reduced clutch size, and pairing with an old male reduced offspring production. Challenging environments increased age effects on breeding probability and breeding date across young to middle ages and for offspring production across middle to old ages. However, important exceptions to the predicted patterns for clutch size and fledging success across young to middle ages suggested that trade-offs between fitness components may complicate patterns of trait expression across the life span. Relationships between breeding participation, environment, and individual quality and/or experience in young females may also contribute to unexpected patterns for clutch size and fledging success, traits expressed only in breeders. Finally, independent of age, breeding responses of female Nazca boobies to the ENSO did not follow expectations derived from oceanic forcing of primary productivity. During El Niño-like conditions, egg-laying traits (clutch size, breeding date) improved, but offspring production declined, whereas La Niña-like conditions were "poor" environments throughout the breeding cycle.