Egg Lipid Research Articles

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.

Potential use of seaweeds in the laying hen ration to improve the quality of n-3 fatty acid enriched eggs

An association between dietary fish oil and decreased yolk weight and reduced sensory quality of eggs has been reported when eggs are enriched with n-3 FA from fish oil. Seaweeds are an important source of compounds that seem to increase egg weight when included in the laying hen diet. The objectives of this study were to determine the influence of the dietary seaweeds Macrocystis pyrifera, Sargassum sinicola and Enteromorpha sp. on the physical quality, lipid composition and consumer acceptability of n-3 FA enriched eggs. One-hundred and forty-four 35-week-old Leghorn hens were randomly distributed in four treatments that consisted of the inclusion of 2% of sardine oil (SO) and 10% of each marine alga (MA) in laying hens' diets; a control diet (C) was also prepared. The study lasted 8 weeks and egg physical quality, egg lipids and sensory attributes were evaluated. The results showed that incorporation of 10% M. pyrifera in the diets is an effective way of increasing the n-3 FA content, the albumen height and yolk color, but not the egg weight, when these are enriched with n-3 FA from fish oil. The egg flavor was also not affected.

Biphasic growth in fish II: Empirical assessment

In [Quince, et al., 2008. Biphasic growth in fish I: Theoretical foundations. J. Theor. Biol., doi: 10.1016/j.jtbi.2008.05.029], we developed a set of biphasic somatic growth models, where maturation is accompanied by a deceleration of growth due to allocation of energy to reproduction. Here, we use growth data from both hatchery-raised and wild populations of a large freshwater fish (lake trout, Salvelinus namaycush) to test these models. We show that a generic biphasic model provides a better fit to these data than the von Bertalanffy model. We show that the observed deceleration of somatic growth in females varies directly with gonad weight at spawning, with observed egg volumes roughly 50% of the egg volumes predicted under the unrealistic assumption of perfectly efficient energy transfer from somatic lipids to egg lipids. We develop a Bayesian procedure to jointly fit a biphasic model to observed growth and maturity data. We show that two variants of the generic biphasic model, both of which assume that annual allocation to reproduction is adjusted to maximise lifetime reproductive output, provide complementary fits to wild population data: maturation time and early adult growth are best described by a model with no constraints on annual reproductive investment, while the growth of older fish is best described by a model that is constrained so that the ratio of gonad size to somatic weight ( g) is fixed. This behaviour is consistent with the additional observation that g increases with size and age among younger, smaller breeding females but reaches a plateau among older, larger females. We then fit both of these optimal models to growth and maturation data from nineteen wild populations to generate population-specific estimates of ‘adapted mortality’ rate: the adult mortality consistent with observed growth and maturation schedules, given that both schedules are adapted to maximise lifetime reproductive output. We show that these estimates are strongly correlated with independent estimates of the adult mortality experienced by these populations.

Lipid and protein utilisation during early development of yellowtail kingfish (Seriola lalandi)

The pelagic yellowtail kingfish Seriola lalandi has become a target species for aquaculture in Asia and Australasia. Australasian production is reliant on larviculture from eggs of captive brood stock; however, knowledge regarding the nutritional requirements of larvae of this species is still scarce, particularly in relation to lipids. As a first step in establishing these requirements, eggs and larvae from captive S. lalandi brood stock were examined for differences in total protein, total lipid and lipid classes between individual spawning events, over the spawning season, and during larval development from fertilisation to 15 days post hatch. Results indicate that total protein egg−1 varied significantly between individual spawning events within a season, but neither total lipid nor total protein egg−1 varied significantly across the spawning season. Brood stock egg lipids were made up of approximately 60% phospholipid, 25% wax and/or sterol esters (WE), 15% triacylglycerol (TAG), and small amounts of sterols and free fatty acids. During the early larval period, both WE and TAG were utilised concurrently for energy. The larvae experienced very high mortality around 5–7 days post hatch, which coincided with very low levels of all neutral lipid classes. Although many other factors may also influence larval mortality, these results indicate that lipid provisioning may be an important factor in larval survival during the critical period around first-feeding in this species. Examination of ratios of TAG:ST, often used as a condition index in fish larvae, suggested that some of the larvae were suffering from starvation. However, as egg-derived WE appears to provide a significant source of energy during the early larval period in S. lalandi, it is suggested that WE should be included in any index of larval nutritional state.

Potential Fertility and Egg Development (Volume, Water, Lipid, and Fatty Acid Content) through Embryogenesis of Uca Rapax (Decapoda: Brachyura: Ocypodidae)

We examined potential fertility, egg volume, and water, lipid, and fatty acid content through embryogenesis in a population of female U. rapax from Sebastian Inlet, Florida. Carapace width (CW) ranged from 10.80 to 20.09 mm (N = 184), and each female carried 5000 to 30,000 eggs in the last stage of development. Female CW was found to be a good predictor of the number of eggs in the later stage of development (potential fertility = 7.908 CW2.7655, R2 = 0.749). Egg volume increases (from 0.0079 to 0.0134 mm3) was mildly correlated (r = 0.79) with an increase in egg water content (from 60 to 69%). Egg lipid and fatty acid content decreased through embryogenesis, due to its importance as energy source. The most consumed fatty acids were the monounsaturated (97.81 μg . mg dw−1) followed by the saturated (64.34 μg · mg dw−1) and polyunsaturated (38.69 μg · mg dw−1). Fatty acids 16:0, 18:2n-6, 16:1n-7, and 18:2n-6 are consumed preferentially (39.91, 38.45, 29.4 and 23.93 μg · mg dw−1, respectively), while essential polyunsaturated fatty acids, particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), are conserved. Egg fatty acid profile also reflects diet and habitat of adults. A medium-low EPA/DHA ratio suggests U. rapax occupies a medium trophic level. The low ratio (18:1n-7/18:1n-9) and high percentages of 18:1n-9 fatty acid (18%) and essential C18 and C20 polyunsaturated fatty acids (19-23%) suggests adults are omnivores consuming primary producers (like algae and mangrove leaves) and small invertebrates. The high percentage of odd-numbered fatty acids (above 3-3.5%) also suggests scavenger/detritivore behaviour.

The fatty acid and cholesterol composition of enriched egg yolk lipids obtained by modifying hens’ diets with fish oil and flaxseed

The effects of fish oil and flaxseed in the diets of laying hens on the cholesterol and fatty acid composition of egg lipids were studied. Isa-White laying hens and five experimental diets were used. The first diet was used as the control. Fish oil (1.5%), flaxseed (4.32% and 8.64) or both of them (1.5% fish oil and 4.32% flaxseed) were added to the others and hens were fed for 30 and 60 days. The cholesterol and fatty acid composition of the yolks were determined. No significant difference (p<0.05) was found in the cholesterol content of the yolks due to diets except the diet containing 8.64% flaxseed. Total saturated fatty acid content was decreased in all diets compared to the control diet. Total n-3 fatty acid content was significantly greater for all diets. The predominant change in flaxseed containing diets was found in linolenic acid content. Eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid content of all diets was significantly greater.

Changes in Fecundity and Egg Lipid Content of Lake Whitefish ( Coregonus clupeaformis) in the Upper Laurentian Great Lakes between 1986–87 and 2003–05

Lake whitefish ( Coregonus clupeaformis Mitchill), an important commercial species in the Laurentian Great Lakes, have experienced decreased growth and condition in regions of the upper Great Lakes over the past 20 years. Increases in lake whitefish density and decreases in the density of Diporeia spp., an energy rich and historically important part of the lake whitefish diet, have been implicated in the recent declines in lake whitefish growth and condition. The goal of this study was to describe lake whitefish fecundity, egg lipid content, and total ovary lipid content in selected regions of Lakes Huron, Michigan, and Superior in 1986–87 and 2003–05, two time periods with different lake whitefish and Diporeia densities. Under conditions of high lake whitefish density and low Diporeia density, female lake whitefish in the upper Laurentian Great Lakes generally produced fewer eggs. Egg lipid content was higher in 2003–05 than in 1986–87 at all sites, regardless of changes in lake whitefish or Diporeia densities. Total ovary lipid content and lake whitefish abundance were inversely related, while there was no significant relationship between total ovary lipid content and Diporeia density. The amount of energy that lake whitefish invested in egg production was more closely associated with lake whitefish abundance than with Diporeia density. This study provides evidence that recent changes in production dynamics of Great Lakes lake whitefish have not been driven solely by declines in Diporeia but have been significantly influenced by lake whitefish abundance.

Fuels for development: evolution of maternal provisioning in asterinid sea stars

For marine invertebrates, larval developmental mode is inseparably linked to the nutritional content of the egg. Within the asterinid family of sea stars there have been multiple, independent, evolutionary transitions to lecithotrophic development from the ancestral, planktotrophic state. To investigate the evolution of maternal investment and development within the Asterinidae, we quantified individual lipid classes and total protein for eggs and larval stages of closely related species representing three developmental modes (planktotrophy, planktonic lecithotrophy and benthic lecithotrophy). Within species, maternal provisioning differed between females indicating that egg quality varied with parentage. Maternal investment was related to egg size but, after correcting for egg volume, we identified two major oogenic modifications associated with the evolution of lecithotrophic development: (1) a reduction in protein deposition that probably reflects the reduced structural requirements of nonfeeding larvae, (2) an increase in deposition of a single class of energetic lipid, triglyceride (TG). The exception was Parvulastra exigua, which has benthic, lecithotrophic development and lays eggs with a lipid to protein ratio close to that of planktotrophs. This oogenic strategy may provide P. exigua larvae with a protein “weight-belt” that assists in maintaining a benthic existence. Asterinids with planktotrophic development used a significant portion of egg TG to build a feeding bipinnaria larva. For Meridiastra mortenseni, female-specific differences in egg TG were still evident at the bipinnaria stage indicating that egg quality has flow-on effects for larval fitness. In lecithotrophic asterinids, TG reserves were not depleted in development to the larval stage whereas protein stores may help fuel early larval development. Available data indicate that there may be two evolutionarily stable egg lipid profiles for free-spawning, temperate echinoderms.

Relative Quantification of Carboxylic Acid Metabolites by Liquid Chromatography−Mass Spectrometry Using Isotopic Variants of Cholamine

Labeling reagents that differ only in their isotopic composition offer a powerful approach to achieve relative quantification between samples by ESI-MS. Heavy and light isotopic forms of cholamine, which contain a positively charged quaternary ammonium group, were synthesized and tested as new labeling reagents for the relative quantification of carboxylic acid-containing metabolites, specifically fatty acids. The positive charge on cholamine ensures that the labeled product is also positively charged under all LC-MS conditions, regardless of mobile-phase pH. This leads to high ionization efficiency and correspondingly high detection sensitivity, demonstrated here for the analysis of fatty acids in positive ion mode ESI-MS after reversed-phase separation under acidic conditions. Good accuracy and precision were obtained by mixing heavy- and light-labeled hydrolyzed egg lipid extracts in different known ratios. The relative quantification results for 10 observed fatty acids had an average absolute error of 4.6% and an average coefficient of variation (CV) of 2.6%. The labeling strategy yielded a median CV of 6% when employed for fatty acid analysis of eggs from chickens fed various dietary supplements.

Variation among females in egg lipid content and developmental success of echinoderms from McMurdo Sound, Antarctica

Egg lipid and protein content of different females of Antarctic echinoderms in McMurdo Sound, Antarctica, were measured to assess variation among females and developmental success. Egg triacylglycerol content of the Antarctic sea urchin Sterechinus neumayeri, when less than 70 ng, correlated with embryos that failed to develop past the 4-day-old blastula stage. In contrast asteroids (Odontaster meridionalis, O. validus, Acodontaster hodgsoni) all produced eggs that developed normally, even with variable egg lipid content. This difference might be related to dietary sources for more herbivorous sea urchins compared to more omnivorous and predatory asteroids. Low egg lipid content, with resulting poor embryonic survivorship, suggests that herbivorous sea urchins may be under unusual levels of nutritional stress in McMurdo Sound during the time frame studied (2004–2005). This nutritional stress might be related to the presence of large icebergs, known to have reduced primary production in the Ross Sea area.

Volume and Lipid, Fatty Acid, and Amino Acid Composition of Golden Shiner Eggs during a Spawning Season

AbstractThe Arkansas baitfish industry leads the nation in production of golden shiners Notemigonus crysoleucas. To determine nutritional requirements for golden shiner broodstock diets, we examined the volume and lipid, fatty acid, and amino acid composition of the eggs produced by a group of captive broodstock over a spawning season. Egg volume was 0.67 ± 0.117 mm3 (mean ± SD); egg volume declined during the spawning season. Total lipid was 15.67 ± 2.99 μg/egg, and triacylglyceride (TAG) concentration was 6.82 ± 1.81 μg/egg. Based on the stability of egg total lipid, the percent neutral lipid, the consistent contribution of TAG to neutral lipid, the consistent TAG concentration, and the stable fatty acid and amino acid profiles, we conclude that the lipid and amino acids in eggs from the experimental group were stable. The eggs should be equally sufficient for embryological development throughout the spawning season, but specific indices of egg and fry quality must be measured to confirm the links among egg size, biochemical composition, and egg and fry quality.

Oogenesis and relevant changes in egg quality of abalone Haliotis discus hannai during a single spawning season

Oogenesis of abalone Haliotis discus hannai was examined histologically during a single spawning season using broodstock of various maturation conditions, which were controlled by effective accumulative temperature (EAT). The quality of eggs spawned was determined in relation to oogenesis. For histological examinations, three to five females were sacrificed at 300, 600, 850, 1050, and 1150 °C days EAT, without induction of artificial spawning. Other females were successfully induced to spawn at 700 °C days EAT and were reared following spawning. Three of these females were then sacrificed every 200 °C days EAT until 1300 °C days EAT. Gonad histology showed that two oocyte cohorts matured in H. discus hannai ovaries during a single spawning season. One mature oocyte cohort could be spawned in multiple times. The second oocyte cohort started developing after the first oocyte cohort had been spawned or reabsorbed, and became fully mature 400 °C days EAT after the first cohort was depleted. For egg quality measurements, three to five females were successfully induced to spawn at 850, 1050, 1150, 1900, and 2350 °C days EAT (Experiment 1). Three females were induced to spawn twice, at 700 and 1500 °C days EAT, resulting in two batches of eggs from the same individuals (Experiment 2). Total lipid and protein content of eggs were measured and were greater in eggs from the second cohort than in eggs from the first cohort. No carbohydrates were detected in eggs and there was no difference in cytoplasm volume between the two cohorts. In hatcheries producing H. discus hannai, it is important to increase post-larval starvation tolerance by increasing the quality of eggs, to yield higher and more consistent survival. The results of this study suggest that H. discus hannai hatcheries should use eggs from the second oocyte cohort, which are of higher quality, rather than eggs from the first oocyte cohort.

Lipid Profile and Fatty Acid Composition of Two Silurid Fish Eggs

The lipid content and the composition pattern of the lipid class including fatty acid composition in the eggs of two different Indian silurid cat fishes Ompok pabda and Wallagu attu have been examined. The lipid content of O. pabda and W. attu (on dry basis) are about 14.7% and 17.8% respectively. The major lipid classes are phospolipid (PL) and triacylglycerol (TAG). The O. pabda egg lipid contains more PL while the W. attu egg lipid contains more TAG. Phosphatidylcholine (PC) constitutes the major phospholipid followed by phosphatidylinositol (PI). PI represents in about 31.7% and 21.3% of total PC in O. pabda and W. attu respectively while phosphatidylethanolamine (PE) (about 28.0%) is significantly higher in the egg of W. attu than O. pabda (9.6%). Cholesterol content in egg of O. pabda is also higher (about 9.6%) than W. attu (4.1%). The lipids are rich in polyunsaturated fatty acids (PUFAs) and they are mainly concentrated in the respective PL fractions. Among PUFAs the arachidonic acid (20:4 n-6 AA) is present at about 9.3% in both egg PL. Eicosapentaenoic acid (20:5 n-3 EPA) is significantly lower in egg lipids of both W. attu (1.8%) and O. pabda (3.2%), whereas docosahexaenoic acid (22:6 n-3 DHA) is predominantly higher (14.6% and 18.1% in W. attu and O. pabda respectively) in their PL fractions.

PATTERN OF LIPID AND ESSENTIAL FATTY ACID CHANGES IN EARLY DEVELOPMENT OF TIGER GROUPER, Epinephelus fuscoguttatus LARVAE

Development of early stage of larvae depends on body energy content. One of energy source in early larval stage is lipid. Lipid in eggs and early larval development stage of tiger grouper (Epinephelus fuscoguttatus) is used for energy and to maintain permeability of membrane cells. Therefore, lipid class for energy decreases and lipid class for maintaining membrane increases. Lipid quality in larvae depends on the content of essential fatty acid. Lipid from larval stage of neurula; 0, 1, 3, 4, 7, 12, 15, 17, and 20 days after hatching were observed on non polar, polar lipid, and essential fatty acid. The result of experiment showed that proportion of non polar lipid from neurula phase to three days larvae (D3) decreased from 81.9% to 36.5% and polar lipid increased from 18.1% to 63.5%. This result showed, that non polar lipid is used for energy and polar lipid for maintaining membrane of cell body. Essential fatty acid, such as EPA and DHA also decreased in non polar and polar lipid. Decreasing essential fatty acids was higher in non polar lipid than these in polar lipid.

Lipid and fatty acid composition of eggs producing larvae with high survival rate in the Japanese eel

Eggs of Japanese eel Anguilla japonica were obtained by artificial induction of maturation. Fertilization and hatching rates, and survival rates of normal larvae were examined. The levels of total lipids and polar lipids (PL) of high quality (HQ; &gt;80% survival rate at 8 days post‐hatch) eggs were significantly lower than low quality (LQ; hatching and survival rates were zero) eggs. The docosahexaenoic acid (DHA) level in PL of HQ eggs, however, was significantly higher than in LQ eggs. In contrast to DHA, arachidonic acid level was negatively correlated with egg quality variables and it was lower in HQ than in LQ eggs. Most of the egg lipid and fatty acid components showed larger variation in LQ than in HQ eggs.

Optimization of Solvent Extraction and Direct Transmethylation Methods for the Analysis of Egg Yolk Lipids

The composition of egg yolk lipids differs greatly from most other food lipids, as it combines high contents of triglycerides and phospholipids, as well as a high proportion of cholesterol. The lipids are organized in lipoproteins and are dispersed in aqueous phase. Classical extraction methods using chloroform and methanol have not been optimized for such a matrix, therefore quantitative extraction yields of egg lipids can be inaccurate. In this study, the original method of Bligh and Dyer is evaluated and adapted for egg lipids. Furthermore, a direct extraction/derivatization method is presented. Solvent extraction resulted in a lipid yield of 31.8 ± 0.89% and total fatty acid yield was 257 ± 2 mg/g yolk whereas the direct method yielded 250 ± 7 mg/g yolk. Gas chromatographic analyses confirmed that lipid recovery was complete for triglycerides and phospholipids as well.

Maternal effects in Wood Ducks: incubation temperature influences incubation period and neonate phenotype

SummaryMaternal effects often explain a significant amount of variation in offspring phenotype, and can be important in the evolution of life histories. Incubation of eggs is an important maternal effect, and optimal growth and development of avian embryos takes place within a narrow range of incubation temperatures, but the effect of incubation microclimate on neonate phenotype remains relatively unexplored in birds.In this study of Wood Ducks (Aix sponsaLinnaeus) we examined effects of incubation temperature on the length of incubation period and neonate quality. We monitored nest temperatures and incubation periods of naturally incubated Wood Duck nests and found a strong inverse relationship between incubation period and average nest temperature.Next, we collected three unincubated eggs from each of 48 nests, and randomly assigned eggs from each nest to one of three incubation temperatures (34·6, 36·0 and 37·4 °C). Experimental incubation temperatures overlapped average nest temperatures of naturally incubated Wood Duck nests.Hatching success varied with incubation temperature and was lowest for eggs incubated at the lowest temperature. Incubation period of experimental eggs decreased with increasing temperature but was not affected by fresh egg mass.Wood Duck embryos catabolized an estimated 34–38% of egg lipids and 25–33% of egg protein during incubation. Percentage change of lipids increased with decreasing incubation temperature, but not significantly. Embryos incubated at lower temperatures used a greater percentage of protein than embryos incubated at higher temperatures.In analyses using fresh egg mass as the covariate, we found that wet and dry mass of ducklings increased with increasing incubation temperature. Decreases in lipid content of Wood Duck neonates with decreasing incubation temperature were not significant, but eggs incubated at low temperatures produced ducklings that had reduced protein mass and that were structurally larger than ducklings from eggs incubated at high temperatures.Our study illustrates the importance of incubation temperature on the development of Wood Duck embryos. Decisions made by incubating parents that influence egg temperature can modify incubation period and offspring phenotype. Investigations of incubation as a reproductive cost should consider how parental decisions influence both parents and offspring.

POSITIONAL DISTRIBUTION OF FATTY ACIDS IN EGG YOLK LIPIDS

ABSTRACT Numerous methods for the assessment of the positional distribution of fatty acids (FAs) in triacylglycerols (TGs) and phospholipids (PLs) have been described in the literature. Most of them employ enzymatic reactions or chiral separation by high‐performance liquid chromatography. Compared with most other food lipids, egg lipid has a rather unique composition, containing high amounts of TG as well as PL organized in lipoproteins. In this study, we demonstrate that the classical approach employing pancreatic lipase and phospholipase A2 is suitable for application to egg lipids. By using this method, the total distribution of FAs among the single positions of the main lipid classes in egg lipids can be measured in a rather straightforward way. Problems regarding accuracy, especially for the determination of minor and polyunsaturated fatty acids, are discussed. The presented method gave satisfactory results even for polyunsaturates such as docosahexaenoic acid down to amounts of 1% in a specific position.

Lipid uptake by insect oocytes

Approximately 30–40% of the dry weight of an insect egg consists of lipid, mostly triacylglycerol (TAG). Although this lipid is essential for the energy needed by the developing embryo, little is known about the mechanism that leads to the accumulation of TAG in the insect egg. Insect oocytes can readily synthesize TAG from free fatty acids (FFAs) and glycerol, however, de novo synthesis of FAs by the oocyte is marginal. Hence, FAs have to be imported from the fat body or the diet. Insect hemolymph contains two lipoproteins that transport lipids, lipophorin and vitellogenin. Both are taken up via endocytosis by the oocyte, however, this provides only about 10% of the egg's lipid reserves. The rest is unloaded from circulating lipoprotein particles at the oocyte surface in the form of diacylglycerol (DAG), the major lipid transport form in insects, or as FFA. The mechanism of lipoprotein unloading at the oocyte surface is currently unclear. Possible roles of the lipid transfer particle (LTP), FA transporters, and lipoprotein lipase activity are discussed.

THE EFFECT OF EGG QUALITY ON LARVAL PERIOD AND POSTLARVAL SURVIVAL OF AN ABALONE HALIOTIS DISCUS HANNAI

Abstract The effect of egg quality on larval period and postlarval survival was investigated for the abalone Haliotis discus hannai. Broodstock were conditioned for spawning at different effective accumulative temperatures (EAT) and the subsequent larvae were used in experiments. Larval period until spontaneous metamorphosis or death and postlarval survival without food were investigated. Larval period and postlarval survival of offspring from broodstock conditioned at 1,650 and 2,350°C·days EAT were greater than those of larvae from 1050 and 1150°C·days EAT conditioned broodstock. Biochemical composition and egg cytoplasm diameter were measured as egg quality from broodstock conditioned under different EAT treatments. There was a positive correlation between lipid and protein content in eggs. Protein and lipid content showed positive correlations with larval period and postlarval survival without food. The eggs from higher EAT tended to contain higher protein and lipid contents, but there was no signific...