Biochemical Composition Of Eggs Research Articles

Mercury compound distribution and stable isotope composition in the different compartments of seabird eggs: The case of three species breeding in East Greenland

Mercury (Hg) is a toxic contaminant of global concern and the impact on Arctic ecosystems, particularly in seabirds, is critical due to large-scale Hg transport towards polar regions and its biomagnification in marine trophic systems. While the adverse effects of Hg on reproductive processes in seabirds are established, the understanding of Hg maternal transfer pathways and their control on Hg reproductive toxicity is limited. The combination of Hg compounds speciation (inorganic mercury and monomethylmercury MMHg) and Hg stable isotope composition in the different egg compartments (yolk, albumen, membrane, and shell) before embryo development was investigated to provide information on (i) Hg maternal transfer mechanisms, (ii) influence of egg biochemical composition on Hg organotropism and (iii) proxies of inputs of Hg contamination. Eggs of three seabird species (the common eider, the black-legged kittiwake and the little auk) collected within the same breeding period (summer 2020) in East Greenland were investigated. For all seabirds, albumen and membrane, the most protein-rich compartments, were the most contaminated (from 1.2 to 2.7 μg g−1 for albumen and from 0.3 to 0.7 μg g−1 for membrane). In these two compartments, more than 82% of the total Hg amount was in the form of MMHg. Additionally, mass-dependent fractionation values (δ202Hg) were higher in albumen and membrane in the three species. This result was mainly due the organotropism of MMHg as influenced by the biochemical properties and chemical binding affinity of these proteinous compartments. Among the different egg compartments, individuals and species, mass-independent fractionation values were comparable (mean ± sd were 0.99 ± 0.11‰, 0.78 ± 0.11‰, 0.03 ± 0.05‰, 0.04 ± 0.10‰ for Δ199Hg, Δ201Hg, Δ200Hg and Δ204Hg, respectively). We conclude that initial MMHg accumulated in the three species originated from Arctic environmental reservoirs exhibiting similar and low photodemethylation extent. This result suggests a unique major source of MMHg in those ecosystems, potentially influenced by sea ice cover.

To invest or not to invest, that is the question: Male presence and genetic relatedness as modulators of female reproductive effort in a shrimp

The present work was aimed at evaluating whether females of a freshwater shrimp, Neocaridina davidi (Bouvier, 1904), allocate differentially to reproduction when reared in the presence of males and in the presence of brothers/non-brothers. Ovarian growth was evaluated in three consecutive maturation cycles. The composition of biochemical reserves was determined in the eggs (i.e., embryos) laid at the end of the first cycle, in 20-day-old juveniles produced at the end of the second cycle, and in the mature ovary of females at the end of the third cycle. When reared in the absence of males, females took longer to mature the ovaries and stored less proteins, triglycerides and cholesterol in the mature ovary. Females reared with brothers took longer to mature the ovaries than females reared with non-brothers, with no differences in the biochemical composition of their mature ovaries. The eggs produced by females mated to brothers showed a lower carotenoid content, higher cholesterol content and a tendency towards lower energy content than those produced by females mated to non-brothers. These results suggest that females are capable of recognizing kin and modulate primary reproductive effort, in terms of ovarian and egg biochemical composition, according to male presence and genetic relatedness.

Biochemical Composition of Eggs, Larvae and Tissues of Macrobrachium tenellum Females Fed Diets with Different Lipid and Protein Levels

One way to approach the nutritional requirements of native shrimp, necessary to consolidate their culture, is to know their biochemical composition. The effect of feeding two levels of lipids (4 and 12% L) and four levels of proteins (30, 35, 40 and 45% P) in M. tenellum females was evaluated with respect to the biochemical composition of their eggs (EG), larvae (LR), gonad (GO) and hepatopancreas (HP). Total protein (TP), total carbohydrate (TC) and total lipid (TL) were estimated. In EG, L and P levels influence TP and TL; TP increases in diets higher than P35. In LR, there are no differences (p > 0.05) in TP and in TL, only diets L4P40 and L12P30 were different (p < 0.05). In GO, there is no trend in TP differences; in TC there was variation in the range of the data and TL was higher in L4P30 and L4P35. In HP, the diets with L4 obtained the highest TP values (p < 0.05); the L12 diets were higher in TL (p < 0.05). In general, diets with an inclusion of L12 showed the highest TP, TC and TL means, within this lipid level the P30 diet stood out; therefore, it is recommended to use a diet with L12P30 in the formulation of balanced feed for the species.

Transgenerational plasticity as a mechanism of response to marine heatwaves in the purple sea urchin, Strongylocentrotus purpuratus

Kelp forests of the California Current System have experienced prolonged marine heatwave (MHW) events that overlap in time with the phenology of life history events (e.g., gametogenesis and spawning) of many benthic marine invertebrates. To study the effect of thermal stress from MHWs during gametogenesis in the purple sea urchin (Strongylocentrotus purpuratus) and further, whether MHWs might induce transgenerational plasticity (TGP) in thermal tolerance of progeny, adult urchins were acclimated to two conditions in the laboratory – a MHW temperature of 18°C and a non-MHW temperature of 13°C. Following a four-month long acclimation period (October–January), adults were spawned and offspring from each parental condition were reared at MHW (18°C) and non-MHW temperatures (13°C), creating a total of four embryo treatment groups. To assess transgenerational effects for each of the four groups, we measured thermal tolerance of hatched blastula embryos in acute thermal tolerance trials. Embryos from MHW-acclimated females were more thermally tolerant with higher LT50 values as compared to progeny from non-MHW-acclimated females. Additionally, there was an effect of female acclimation state on offspring body size at two stages of embryonic development - early gastrulae and prism, an early stage echinopluteus larvae. To assess maternal provisioning as means to also alter embryo performance, we assessed gamete traits from the differentially acclimated females, by measuring size and biochemical composition of eggs. MHW-acclimated females had eggs with higher protein concentrations, while egg size and lipid content showed no differences. Our results indicate that TGP plays a role in altering the performance of progeny as a function of the thermal history of the female, especially when thermal stress coincides with gametogenesis. In addition, the data on egg provisioning show that maternal experience can influence embryo traits via egg protein content. Although this is a laboratory-based study, the results suggest that TGP may play a role in the resistance and tolerance of S. purpuratus early stages in the natural kelp forest setting.

Factors Modulating the Female Reproductive Performance of the Fiddler Crab Leptuca uruguayensis with Short Reproductive Season.

AbstractThis study aimed to evaluate the factors modulating the female reproductive performance of the fiddler crab Leptuca uruguayensis (Nobili, 1901) during the short reproductive season of a temperate population. We proposed two modulating factors: the age of females (young and old) and the periods of the reproductive season (beginning, middle, and end); we then evaluated the fecundity, reproductive output, egg volume, and biochemical composition of eggs. The fecundity of L. uruguayensis was affected by the size of females, a variable related to their age. Although young females showed lower fecundity, the reproductive output was not affected by the age or by the periods of the reproductive season, suggesting a constant reproductive effort, proportional to female size. The egg volume decreased, and carotenoid content increased at the end of the season for both female ages, probably as a consequence of variations in food availability and changes in the breeding strategies during the season. However, the content of protein and lipids in the egg clutches decreased at the end of the season only in old females spawning for the second time in the season. The main differences in the reproductive parameters were recorded between the beginning and the end of the reproductive season, probably because in these periods females exclusively use one of the breeding strategies. Finally, we determined that both factors, that is, female age and the periods of the short reproductive season, can modulate the reproductive performance of L. uruguayensis in temperate estuaries.

Type of hormonal treatment administered to induce vitellogenesis in European eel influences biochemical composition of eggs and yolk-sac larvae

Egg biochemical composition is among the main factors affecting offspring quality and survival during the yolk-sac stage, when larvae depend exclusively on yolk nutrients. These nutrients are primarily embedded in the developing oocytes during vitellogenesis. In aquaculture, assisted reproduction procedures may be applied enabling gamete production. For the European eel (Anguilla anguilla), reproductive treatment involves administration of pituitary extracts from carp (CPE) or salmon (SPE) to induce and sustain vitellogenesis. In the present study, we compared the influence of CPE and SPE treatments on offspring quality and composition as well as nutrient utilization during the yolk-sac stage. Thus, dry weight, proximal composition (total lipid, total protein), free amino acids, and fatty acids were assessed in eggs and larvae throughout the yolk-sac stage, where body and oil-droplet area were measured to estimate growth rate, oil-droplet utilization, and oil-droplet utilization efficiency. The results showed that CPE females spawned eggs with higher lipid and free amino acid contents. However, SPE females produced more buoyant eggs with higher fertilization rate as well as larger larvae with more energy reserves (estimated as oil-droplet area). Overall, general patterns of nutrient utilization were detected, such as the amount of total lipid and monounsaturated fatty acids decreasing from the egg stage and throughout the yolk-sac larval stage. On the contrary, essential fatty acids and free amino acids were retained. Notably, towards the end of the yolk-sac stage, the proximal composition and biometry of surviving larvae, from both treatments, were similar.

Comparative Analysis of Egg Biochemical Composition and Egg Productivity Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792) in Different Stations in Turkey

In the study, two objectives were selected in determining the quality and efficiency of Oncorhynchus mykiss eggs obtained from different stations: (1) to determine the biochemical, amino and fatty acid composition and egg quality, (2) to study the effect of egg productivity on egg quality. The study was conducted in 5 different production areas which is produces the most rainbow trout eggs in Turkey. Broodstocks over 3 years old were randomly selected from the company. After the egg productivity analysis, biochemical analysis were conducted. The most abundant amino acid in all stations was glutamic acid, followed by leucine, lysine, in that order. Total amino acid and essential amino acid (EAA) values were between 30.40±0.93-44.47±0.43 and 15.69±0.25-23.88±0.07 g/100g, respectively. As a result of analysis of fatty acids, docosahexaenoic acid (DHA), oleic acid and linoleic acid values were higher than other fatty acids. In addition, polyunsaturated (PUFA) values were higher than saturated (SFA) and monounsaturated (MUFA) fatty acid values in the eggs obtained from all stations. Consequently, the amino and fatty acid values of rainbow trout eggs were determined to be sufficient for embryonic development of fish and this values showed rainbow trout eggs as potential source of food for human consumption.

Reproductive performance of gilthead seabream (Sparus aurata) broodstock showing different expression of fatty acyl desaturase 2 and fed two dietary fatty acid profiles

Previous studies have shown that it is possible to nutritionally program gilthead seabream offspring through fish oil (FO) replacement by vegetable oils (VO) in the broodstock diet, to improve their ability to grow fast when fed low fish meal (FM) and FO diets during grow-out phase. However, in those studies broodstock performance was reduced by the VO contained diet. Therefore, the present study aimed to determine if it is possible to replace FO by a mixture of FO and rapeseed oil (RO) with a specific fatty acid profile in broodstock diets, without altering gilthead seabream broodstock reproductive performance. Besides, the study also aimed to evaluate the reproductive performance of broodstock with different expression of fatty acid desaturase 2 gene (fads2) a key enzyme in synthesis of long chain polyunsaturated fatty acids. For that purpose, broodfish having either a high (HD) or low (LD) expression of fads2 were fed for three months during the spawning season with two diets containing different fatty acid profiles and their effects on reproductive hormones, fecundity, sperm and egg quality, egg biochemical composition and fads2 expression were studied. The results showed that blood fads2 expression in females, which tended to be higher than in males, was positively related to plasma 17β-estradiol levels. Moreover, broodstock with high blood fads2 expression showed a better reproductive performance, in terms of fecundity and sperm and egg quality, which was correlated with female fads2 expression. Our data also showed that it is feasible to reduce ARA, EPA and DHA down to 0.43, 6.6 and 8.4% total fatty acids, respectively, in broodstock diets designed to induce nutritional programming effects in the offspring without adverse effects on spawning quality. Further studies are being conducted to test the offspring with low FM and FO diets along life span.

Los sistemas biofloc: una estrategia eficiente en la producción acuícola

La piscicultura en Colombia es la actividad pecuaria que ha reportado mayor crecimiento en la última década mejorando los indicadores de desarrollo del sector agropecuario nacional. Para hacer más eficiente su producción, se propone la implementación de los Sistemas Biofloc (SB), agregados de comunidades microbianas en forma de flóculos integrados por bacterias, fitoplancton, materia orgánica e inorgánica, generados fácilmente en los estanques; bajo condiciones de recirculación constante de agua, alta oxigenación y suplementación con fuentes ricas en carbono; brindándole condiciones para ejercer control de la calidad del agua, mediante procesos naturales (metabolismo de oxígeno y nitrógeno), realizados por bacterias, fitoplancton y algunas microalgas; que captan e inmovilizan el amoniaco producido en el estaque, (procesos de nitrificación), para producir proteína bacteriana de excelente calidad, fácilmente aprovechable por los peces, que reincorporada a la cadena alimenticia del estanque maximiza la producción de carne de pescado por unidad de área; con utilización mínima del recurso agua (Sistemas de mínimo recambio de agua) por lo que disminuye la posibilidad de la entrada de patógenos y enfermedades al estanque, mejorando la bioseguridad por su actividad como controlador de poblaciones de bacterias patógenas. Asimismo, se ha encontrado un efecto positivo en el desarrollo y la estimulación de algunos mecanismos de defensa del sistema inmunológico innato de peces y camarones, confirmando su papel como compuestos inmunoestimulantes. También presentan otras ventajas nutricionales como mejora en la tasa de ingestión, digestión, absorción, conversión alimenticia, crecimiento, efectos positivos sobre la actividad enzimática digestiva entre otras; incluso optimando el rendimiento reproductivo, los indicadores de fecundidad, desove y composición bioquímica de los huevos en algunas especies acuícolas.

Reproductive broodstock performance and egg quality of wild-caught and first-generation domesticated Seriola rivoliana reared under same culture conditions

Almaco jack, Seriola rivoliana as well as some related species is of great interest in marine fish aquaculture. However, there are few studies about their reproduction in captivity. In this research work, reproductive performance and egg quality in two groups of adult Seriola rivoliana, caught in the wild and domesticated-F1 analyzed and compared, reared under optimal maturation conditions in a commercial private Laboratory. A total of 28 wild adult (>5 kg) were caught at La Paz Bay, Baja California Sur, Mexico, and 30 adult domesticated-F1 broodstock (>5 kg), were obtained from an original stock of 1,000 juveniles (3.5 g body weight) produced at Kona Blue (Hawaii, USA) sea farm. Fishes were transported to the Rancheros del Mar commercial private hatchery, where they were grown to adult size. Both groups were evaluated during eight months (May to December 2012) and compared in terms of reproduction performance (total number of spawning events, monthly spawning frequency, total number of eggs, total number of eggs per mL, and fertilization rate), egg biochemical composition (total proteins, total lipids, total carbohydrates, and triacylglycerides) and egg diameter. Results indicated that wild caught broostock showed a better reproductive performance in terms of fertilization rate, total number of spawning, monthly spawning frequency and total number of eggs produced. However, biochemical composition and egg diameter did not show statistical differences (P < 0.05) between two groups. The reproductive performance of broodstock and quality of eggs analyzed in this study are important traits to improve the aquaculture management of this species.

Embryonic and Larval Development and Effect of Salinity Levels on Egg and Ovary Performance in Rabbit Fish (Siganus guttatus)

In this study we investigated embryonic and larval development of rabbit fish (Siganus guttatus) in captivity. Embryonic development lasted 18-19 hours at 28-30oC, pH: 7.6-8.0, salinity: 30-32‰. Average total length of larvae at day 1 after hatching (DAH) was 1.58 mm, average yolk sac length was 0.35 mm containing one yolk ellipsoid (0.92±0.146 mm in length and 0.54±0.107 mm in width) in dorsal and lateral views. At day 2 (DAH) larval length increased to 2.16 mm, and pigmented eyes, mouth, and caudal-fin rays developed. Day 3 (DAH) larval length was 2.25 mm and the yolk was completely absorbed. Our findings provide fundamental information regarding seed larvae production of rabbit fish. In a further experiment we investigated the effect of salinity on gonad maturation, gonadosomatic index (GSI), egg biochemical composition and fecundities. Broodfish were cultured in three salinities, 25, 30, and 35‰ during reproductive season from February to July 2015. No statistically significant effects on gonadal development, fecundities, and egg quality in rabbit broodfish held in different salinities during the reproductive season were found

Relationships between spawn quality and biochemical composition of eggs and hatchlings of Octopus vulgaris under different parental diets

Abstract Three frozen mono-diets (sardine, crab and squid) were supplied to Octopus vulgaris broodstocks, and their effects on the spawn quality and biochemical composition of eggs and hatchlings were studied. Squid and crab diets achieved superior spawn quality, producing in general significantly larger eggs, as compared to sardine diet. Similar differences were also observed in the biometric parameters of hatchlings (ventral and dorsal mantle lengths and dry weight) as well as in the survival of fasted hatchling which were greater in the squid and crab groups with respect to sardine treatment. On the other side, a strong and significant relationship between the mentioned biometrical measures and hatchlings survival was found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. Statistical techniques as multivariate and correlation analyses were used to distinguish dietary groups based on protein content and lipid and fatty acid composition of achieved eggs and hatchlings as well as to relate this composition with spawn quality parameters. The analyses allowed to discriminate the nutrient composition of the early stages which was also found to be significantly correlated to the differences in the spawn quality of the different dietary groups, thereby underlining the importance of the protein content, and lipid classes like phosphatidylethanolamine, phosphatidylcholine, cholesterol and triacylglycerol, as well as docosahexaenoic (22:6n-3) and eicosapentaenoic (20:5n-3) fatty acids in the reproduction of O. vulgaris . Statement of Relevance It has been demonstrated that biochemical composition of the broodstock diet is a major determinant of successful reproduction and offspring survival in teleost fish (Watanabe & Vasallo-Agius, 2003; Bobe and Labbe, 2009). For Octopus vulgaris , our data suggest that the broodstock diet influenced the protein content and lipid composition of eggs and hatchlings, and these nutrients are related to the differences found in the spawn quality. A strong and significant relationship between the measured biometrical parameters and hatchlings survival was also found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. On the other side, the utilization of nutrients during the embryo development can also be seen as an indicator of the nutritional requirements during the early stages of development and be useful for a future advance in the formulation of paralarvae artificial diets. Our results pointed to an embryo catabolism mainly based on proteins, as previously suggested (Lee, 1994; Villanueva and Norman, 2008). Data also suggest that triacylglycerol, sterol ester and phosphatidylcholine were specifically catabolized for energy and/or used to de novo synthesize lipid classes such as PS or PE. Within fatty acids, we found that arachidonic acid was strongly reduced (50–51%) during embryonic development. Further studies on the particular role of AA and the n–3 HUFA (mainly EPA and DHA) for early stages of O. vulgaris are needed, specially taking into account that these FAs are essential for this species (Monroig et al., 2012a,b).

Influence of hormonal induction and broodstock feeding on longfin yellowtailSeriola rivolianamaturation, spawning quality and egg biochemical composition

To optimize broodstock management for Seriola rivoliana, a survey over 5 years was performed to evaluate the effects of successive hormonal inductions with GnRHa or dietary regime on spawning quality. Running males and females with an oocyte diameter > 500 μm were injected with GnRHa. The spawning quality was compared among consecutive years and different moments along the spawning season. Besides, three different feeding regimes were tested. Spawning quality parameters were not significantly affected by time along the spawning season, whereas they were clearly influenced by diet. Particularly, broodfish fed the mackerel regime (M) showed a significantly higher number of eggs than other treatments. Besides, dietary protein content significantly improved broodstock fecundity of S. rivoliana. Moreover, hatching rates were also higher in broodfish fed mackerel and the dietary docosahexaenoic acid (DHA) levels significantly increased this parameter. Despite polar lipids were not significantly affected, neutral lipids fatty acid composition of S. rivoliana eggs showed higher 18:2n-6 in eggs, whereas ARA content was not affected. The results of this study denoted the high fecundity and good spawning quality of S. rivoliana broodfish and suggested the importance of high protein, energy and DHA levels in broodstock diets.

Relationship between eyed rate and the biochemical composition of eggs and ovarian fluid in Hucho taimen

We investigated the relationship between the eyed rate and the biochemical composition of eggs and ovarian fluid in Hucho taimen.We measured enzyme activity and levels of protein,amino acids,vitamins,and minerals in stage V eggs and ovarian fluid.We used each of these parameters as an independent variable in a re-gression model to predict the eyed rate.There was a significant correlation between the eyed rate and Mg2+-AT-Pase activity,phosphorus levels,and amino acids in the eggs.There was no correlation between the eyed rate and the remaining parameters(protein,acid phosphatase,alkaline phosphatase,aspartate aminotransferase,succinate dehydrogenase,calcium ions,iron ions,vitamin C,and vitamin E).Egg batches with high viability(≥80%) were characterized by the following: Mg2+-ATPase activity above 8.3×10-5 μmolPi/(min·mgprot),levels of phosphorus between 12.97 and 23.03 μmol/g egg,and levels of amino acids between 574.89 and 1 195.40 μmol/g egg.In con-trast,in the ovarian fluid only aspartate aminotransferase activity was correlated with the eyed rate of H.taimen.Egg batches with high viability(≥80%) had aspartate aminotransferase activity 18.14 μmol/min/L ovarian fluid.

Growth maximization in early sardine larvae: a metabolic approach

Sardine larvae are forced to grow as fast as possible to reduce larval mortality. Thus, changes in biochemical composition during the first steps of sardine larval growth are intended to maximize larval growth rate efficiency and survival. Protein and RNA weight-specific growth rates were the highest and their corresponding doubling times the shortest among all the biomolecules, reflecting the importance of fast growth during early stages of larval development. The protein percentage increased and the carbohydrate and lipid percentages decreased during early growth until they reached, respectively, a percentage of 73.7, 3.1 and 18.0%. These percentages would represent the optimal proportion of biochemical components in sardine early larvae and they are the result of the trade-off between, in the short term, the protein proportion necessary to optimize larval movement and growth and, in the long term, the minimum lipid percentage necessary to guarantee energy reserves to fuel metamorphosis. RNA/DNA ratio increases during larval growth up to an asymptotic optimal value of ≈3.5 in postflexion larvae. Nutritional condition of sardine larvae was good and was influenced by the parental effect through the egg biochemical composition and by the growth trajectory determined by the actual environmental conditions.

Lipid dynamics during early development of Hippocampus guttulatus seahorses: Searching for clues on fatty acid requirements

The biochemical composition of eggs and the nutrient dynamics during early ontogeny can provide better understanding on the nutritional requirements of both broodstock and first-feeding fish, thus constituting a valuable tool for improvement of aquaculture procedures. This study constitutes the first record of lipid composition and fatty acid dynamics during early development of seahorses. Lipid content and fatty acid profile were determined for Hippocampus guttulatus eggs and newborn juveniles, and their patterns of consumption were analyzed during embryonic development. H. guttulatus produced small broods (426 ± 128 juveniles) but invested in the production of large eggs (2.44 ± 0.37 mm) that resulted in large fingerlings (15.53 ± 1.28 mm), which may have a high survival capacity. The total lipid content of seahorse eggs (17.6% DW) was within the typical range of marine fish eggs. Eggs were dominated by PUFA (43.9%), mainly n−3 HUFA (17.4% of DHA and 13.2% of EPA), and showed a lower MUFA content (22.5%). Extremely low AA levels (0.6%) and particularly high EPA concentrations resulted in a low DHA:EPA ratio (1.3) and high EPA:AA (22.3) and n−3:n−6 (12.2) ratios. Fatty acid consumption during embryonic development was considerably high (67.8%), reflecting the high requirements of seahorse embryos. Fatty acids were depleted at different rates, with PUFA being preferentially consumed (75.2%), while SFA were selectively retained (59.2%). PUFA constituted the major source of metabolic energy and the fatty acids 16:0, EPA and DHA were the main fatty acids to fulfill the energetic demands of seahorse embryos. Essential fatty acids (AA, EPA and DHA) were not preferentially retained, with EPA being catabolized at a particularly high rate (88.0%). These patterns of embryonic consumption resulted in newborn juveniles with an exceptionally low lipid content (5.0% DW), a predominance of SFA (41.0%) and extremely low EPA levels (5.0%). Fatty acid composition of H. guttulatus eggs and juveniles provided important clues to determine seahorse requirements, so that suitable feeding protocols could be developed. The use of broodstock and juvenile diets that reflect the lipid profile of eggs will allow the accomplishment of nutritional requirements and improvement of seahorse production.

Effects of dietary protein source and protein–lipid source interaction on channel catfish ( Ictalurus punctatus) egg biochemical composition, egg production and quality, and fry hatching percentage and performance

The relative importance of proteins (amino acids) and protein–lipid interactions for reproduction of channel catfish can be assessed qualitatively. We conducted a feeding/spawning trial to determine the effects of protein source and protein–lipid interactions of channel catfish broodstock diets on egg biochemical composition and egg and fry production. A general linear mixed model was used to examine statistical significance ( α = 0.05) among the diets and to compare the main effects using adjusted marginal means (Bonferroni) in order to examine the significance of the lipid source × protein source interaction (contrast statements). All diets contained 36% crude protein and the broodfish were fed on 69 d of the 141-d trial based upon a water temperature dependent schedule. Broodfish fed an all plant protein (PP) diet with 10% fish oil (FO) had lower spawning success (33.3%) than fish fed three diets containing animal protein (58.3%). Fecundity of broodfish fed a control diet containing fish meal (FM), poultry byproduct meal (PBM) and 10% FO (6432 ± 1915 eggs kg female − 1 ), or a diet containing FM–PBM–5% FO and 5% poultry fat (PF);(6420 ± 1930 eggs kg female − 1 ) was greater than fecundity of fish fed the PP–FO diet (1072 ± 371 eggs kg female − 1 ), while fecundity of females fed a diet containing PBM and 10% FO was intermediate (4060 ± 1261 eggs kg female − 1 ). Total egg production was greater for fish fed the FM–PBM–FO–PF diet (38 174.6 ± 11 031.8 eggs·tank − 1 ) than fish fed the PP–FO diet (6571.0 ± 2212.1 eggs·tank − 1 ), while fish fed the FM–PBM–FO (32 114.9 ± 7034.4 eggs·tank − 1 ) or PBM–FO (20 619.3 ± 6084.1 eggs·tank − 1 ) diets had intermediate total egg production. Broodstock fed the FM–PBM–FO–PF diet produced heavier egg masses than broodstock fed the PBM–FO or PP–FO diets. The number of eggs per spawn was greater from fish fed the control and FM–PBM–FO–PF diets than from fish fed the PP–FO diet. No differences in protein-bound amino acid (AA) or free amino acid (FAA) composition were found among eggs when only dietary protein source (FM–PBM, PBM, or PP) was examined. A significant ( P < 0.05) dietary protein by lipid source interaction was found among diets when protein and lipid sources (diet) were used to examine FAA composition among eggs. Eggs produced by fish fed the FM–PBM–FO diet contained greater amounts of total FAA, essential isoleucine and leucine, and non-essential glycine, than eggs from fish fed the other diets. Eggs from broodfish fed the control or FM–PBM–FO–PF diets exhibited greater hatching success and total fry production than eggs from broodstock fed the PP–FO diet. A diet can be formulated to improve reproductive efficiency of channel catfish compared to current production diets. Results from the present experiment indicate that such a diet should contain 10% supplemental lipid as menhaden FO or a 1:1 or greater mixture of FO and PF. Also, the diet should contain 35% crude protein from a variety of plant and animal protein sources. Broodstock performance was enhanced when animal protein sources (two or more preferable) comprised at least 15% of the total diet and menhaden FM comprised at least one third of the animal protein sources.

Effects of dietary lipid source and concentration on channel catfish ( Ictalurus punctatus) egg biochemical composition, egg and fry production, and egg and fry quality

We conducted a study to determine the effects of lipid source (poultry fat, PF or menhaden fish oil, FO) and concentration (4 or 10% lipid supplementation) in channel catfish broodstock diets on subsequent egg biochemical composition, egg production, and egg and fry quality. Three female and one male USDA-103 strain three-year-old broodfish were stocked into 16 3860-L outdoor tanks in January and randomly assigned one of the four diets (four replicates per diet). Fish were fed based on a water-temperature-dependant schedule. Spawning cans were added to tanks when water temperature reached 21 °C, and the cans were examined three times weekly for egg masses. Masses were enumerated, weighed, measured, analyzed for proximate and fatty acid composition, and incubated. Date to hatch, hatching success, fry growth and survival, and fingerling growth and survival were monitored. Supplementation of catfish broodstock diets with 10% fish oil increased spawning success, fecundity, total egg volume (matrix removed), individual egg weight, eggs·spawn − 1 (volumetric), total egg lipid concentration, hatching success, and fry survival compared to a control diet with 4% fish oil. The 10PF diet performed similarly to the 10FO diet in all measured parameters except egg fatty acid composition, although results for the 10PF diet did not always differ from those of the 4FO or 4PF diets. The 10FO diet produced significant decreases in egg saturates and MUFA, and increases in n−3 HUFAs and the ratio of n−3: n−6 fatty acids compared to all other diets. However, in fish fed the 10FO or 10PF diets the differences in egg fatty acid composition did not result in different rates of hatching success, fry survival, or fingerling production. Improved spawning performance of catfish fed 10%-lipid diets may be due partly to increased dietary energy relative to the 4%-lipid diets. Although the dietary n−3: n−6 fatty acid ratios of the 10PF (0.3) and 10FO (5.6) diets were quite different, similar concentrations of HUFAs such as DHA and AA were present in the eggs of fish fed either diet. This indicates that catfish can synthesize HUFAs from 18-carbon precursors and deposit the HUFAs in the egg, and that a variety of lipid sources may be suitable for use in catfish broodstock diets. Current methods of channel catfish egg and fry production using growout diets with 28–32% protein and 6–7% lipid are suboptimal based on the results of this study.

Production and biochemical composition of eggs from neritic calanoid copepods reared in large outdoor tanks (Limfjord, Denmark)

Populations of Acartia tonsa (Dana) and Centropages hamatus (Lilljeborg) were monitored in outdoor enclosures imitating the natural estuarine environment in northern Denmark from August 2003 to February 2004. A. tonsa was predominant in summer while C. hamatus dominated from October and onwards. Mean egg production was normally higher in C. hamatus as compared to A. tonsa and continued until late December before a decrease was observed. Hatching success remained high even in February at temperatures below zero degree indicating that no diapause eggs were produced. Further, the egg quality evaluated from the fatty acids (AA, EPA and DHA) and amino acid contents did not change markedly during the study period. From this observation it is strongly suggested that nauplii originated from copepod eggs produced throughout the monitored sampling period constitute an adequate live feed for fish larvae probably even year round.

Egg Composition in Relation to Female Age and Relaying: Constraints on Egg Production in Thick-Billed Murres (Uria Lomvia)

Abstract There is growing awareness that costs associated with egg production play a significant role in shaping avian life histories. The life-history strategy of the Thick-billed Murre (Uria lomvia), a colonial, cliff-breeding seabird of Arctic waters, is characterized by a high annual adult survival rate, deferred breeding, and laying of a single-egg clutch. The single-egg clutch is a widespread phenomenon among seabirds and is generally thought to reflect demands of chick provisioning, rather than egg production. We compared composition of eggs laid by Thick-billed Murres most likely to be physiologically constrained in their capacity to produce eggs (young females with no prior experience, and females forming replacement eggs) to that of first eggs laid by early laying females (typically older, more experienced members of the population). Young, inexperienced females laid 4–18 days past the populationwide median laying date, and their eggs averaged 13% lighter in mass than those laid by early layers. Compared to early laid eggs, shell mass on young females’ eggs was similar to that predicted from egg mass, but their eggs had a lower yolk-to-albumen ratio. There was little difference between the two groups in relative protein content of albumen, relative protein or lipid content of yolk, or amino acid makeup of protein in yolk or albumen. Replacement eggs averaged 6% lighter in mass than first eggs laid by the same females earlier that season. As with young females’ eggs, replacement eggs had shells similar in mass to that predicted from egg mass, but lower yolk-to-albumen ratios, when compared to early laid eggs. Both protein and lipid concentrations in yolk were similar in first and replacement eggs, but replacements were deficient in albumen protein. Amino acid makeup of protein in yolk and albumen was similar in the two groups. Those results suggest that any limitations on egg production acting on young, inexperienced females are manifested in delayed laying and reductions in overall egg mass and proportional yolk content, but not in variation in biochemical composition of their eggs. Limitations on females forming replacement eggs are manifested not only in reduced egg mass and yolk content (as with young females), but also in changes in the biochemical composition of eggs; in particular, evidence suggests that relaying females may face a deficit of endogenous protein. The existence of such limitations suggests that demands of egg production can be significant even in a species that lays a single-egg clutch.