Effect of dietary soybean lecithin on reproductive performance of Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards) Broodstock

The effect of increasing levels of dietary phospholipids (PL) on the ovarian development and reproductive performance of Chinese mitten crab Eriocheir sinensis were investigated using four semipurified formulated diets supplemented with 0%, 1.2%, 2.4%, and 3.6% PL. Four groups of 40 females, with an average individual body weight of 95–120 g, were fed the experimental diets for a period of 7 months. Male crabs were introduced into the female rearing system in March, and mating, spawning, and egg hatching occurred in the following month. After 10 weeks of feeding, females fed the diet with 2.4% PL had a significantly higher gonadosomatic index (GSI) than females fed the diet with 0% PL, whereas females fed the diet with 1.2% PL had a significantly higher hepatic moisture content and lower hepatic lipid content than the other groups (P < 0.05). After mating, the spawning rate was higher among females fed diets with 3.6% and 2.4% PL (95% and 92%, respectively) compared with females fed diets with 0% and 1.2% PL (both 81%). The results showed that egg production (total number of eggs/female) and fecundity increased with increasing dietary PL level, with females fed diets with 0% and 1.2% PL supplementation having significantly lower values than females fed the diet with 3.6% PL (P < 0.05). In conclusion, our results suggest that dietary PL supplementation has a positive effect on ovarian development and reproductive performance of E. sinensis broodstock. Further study should aim to investigate the optimal PL level in the broodstock diet of E. sinensis in respect to offspring quality.     

MATURATION,REPRODUCTION, AND GROWTH OF Penaeus vannamei AND P. stylirostris FED NATURAL DIETS

A variety of natural foods have been reported to induce ovarian maturation of penaeid shrimp. In this study, conducted from 19 June to 11 September 1980, four single-food diets (clams, shrimp, squid, and worms) and one composite diet consisting of all four foods were fed to Penaeus vannamei in 3.7-m diameter indoor circular tanks. The shrimp, averaging 28 g, were stocked at a rate of 6.9 m^-2 with a 1:1 male to female ratio. Unilateral eyestalk ablation was performed on half of the females in each tank. Tanks received one turnover of water volume daily and the water temperature and salinity averaged 27.0°C and 28.6 ppt, respectively. Daily photoperiod was maintained at 13 hours of light. Ovarian maturation, spawning, molting rate, and survival were monitored daily and growth and gonad size were measured at termination. The composite diet was the best overall diet, while squid was the best single-food diet, followed by shrimp, worms, and clams. No maturation of unablated females was observed with the exception of one female that developed to stage 3. Although the size of the shrimp was considered marginal for spawning, 5 mated females were observed, but only one (squid treatment) produced viable nauplii. After termination of this study, all shrimp were fed the composite diet for 41 days. During this period, ovarian maturation and spawning occurred in the previously unproductive treatment receiving only clams, and growth rate of shrimp in all previously single-food treatments increased 4 to 7 fold. The composite diet was also fed to two tanks of P. stylirostris (mean initial weight = 45.4 g) for a period of 118 days. During that time, 50 spawns were obtained with up to 3 spawns per female. A total of 4.3 × 10⁵ P. stylirostris nauplii were produced.     

Feeding fermented soybean meal diet supplemented with taurine to yellowtail Seriola quinqueradiata affects growth performance and lipid digestion

Feeding experiment was conducted to determine whether fermentation and taurine supplementation of soybean meal (SBM) fed to yellowtail improve growth performance and lipid digestion. Six diets were formulated and designated as SBM, SBM supplemented with taurine (SBM + T), SBM fermented by Bacillus spp. (FSBM1), SBM fermented by Lactobacillus spp. (FSBM2), FSBM2 supplemented with taurine (FSBM2 + T), and fish meal (FM). Yellowtail fingerlings with an initial body weight of 42 g were stocked in 200‐L tanks. The fish were fed, each diet was fed twice daily in two separate tanks for 8 weeks. Results showed that lipid digestibility of the SBM diet was significantly lower than that of the FM diet, but SBM diet lipid digestibility was improved by taurine supplementation and fermentation. Lipase activity in anterior intestinal digesta, lipid contents in liver and muscle, and bile acid concentrations in gallbladder and anterior intestinal digesta were significantly lower in fish fed SBM diet than in fish fed FM diet; these parameters were not significantly different between fish fed SBM + T, FSBM2, FSBM2 + T diets and FM diet. Although taurine supplementation or fermentation improved lipid digestibility compared with FM diet, growth parameters were only improved in the fish fed FSBM2 + T diet, indicating that apart from a lack of taurine, SBM contains other factors responsible for inferior growth of yellowtail. These factors can be partially eliminated by Lactobacillus spp. fermentation.     

Influences of dietary fatty acid profile on growth, body composition and blood chemistry in juvenile fat cod (Hexagrammos otakii Jordan et Starks)

This study was conducted to investigate the influence of dietary lipid source and n‐3 highly unsaturated fatty acids (n‐3 HUFA) level on growth, body composition and blood chemistry of juvenile fat cod. Triplicate groups of fish (13.2 ± 0.54 g) were fed the diets containing different n‐3 HUFA levels (0–30 g kg^?1) adjusted by either lauric acid or different proportions of corn oil, linseed oil and squid liver oil at 100 g kg^?1 of total lipid level. Survival was not affected by dietary fatty acids composition. Weight gain, feed efficiency and protein efficiency ratio (PER) of fish fed the diets containing squid liver oil were significantly (P < 0.05) higher than those fed the diets containing lauric acid, corn oil or linseed oil as the sole lipid source. Weight gain, feed efficiency and PER of fish increased with increasing dietary n‐3 HUFA level up to 12–16 g kg^?1, but the values decreased in fish fed the diet containing 30 g kg^?1 n‐3 HUFA. The result of second‐order polynomial regression showed that the maximum weight gain and feed efficiency could be attained at 17 g kg^?1 n‐3 HUFA. Plasma protein, glucose and cholesterol contents were not affected by dietary fatty acids composition. However, plasma triglyceride content in fish fed the diet containing lauric acid as the sole lipid source was significantly (P < 0.05) lower than that of fish fed the other diets. Lipid content of fish fed the diets containing each of lauric acid or corn oil was lower than that of fish fed the diets containing linseed oil or squid liver oil only. Fatty acid composition of polar and neutral lipid fractions in the whole body of fat cod fed the diets containing various levels of n‐3 HUFA were reflected by dietary fatty acids compositions. The contents of n‐3 HUFA in polar and neutral lipids of fish increased with an increase in dietary n‐3 HUFA level. These results indicate that dietary n‐3 HUFA are essential and the diet containing 12–17 g kg^?1 n‐3 HUFA is optimal for growth and efficient feed utilization of juvenile fat cod, however, excessive n‐3 HUFA supplement may impair the growth of fish.     

Effects of fish hydrolysate (CPSP®) on growth and digestive gland lipid composition of Octopus vulgaris (Cuvier, 1797) juveniles

Effects of artificial diets were tested on growth and digestive gland (DG) lipid composition of juvenile Octopus vulgaris. For Experiment I, three diets were used: (i) SQUID (Loligo gahi) as a control diet; (ii) Squid paste and fish hydrolysate CPSP^®, agglutinated with gelatine (GEL20); and (iii) Squid paste, fish hydrolysate CPSP^® and gelatine (GEL40). For Experiment II, three diets were used: (i) SQUID, control diet; (ii) Squid paste, CPSP^® and alginate (ALG10); and (iii) Squid paste, CPSP^® and alginate (ALG20). For both experiments, growth rates for octopuses fed control were higher (P < 0.05), while artificial diets were not different (P > 0.05) between them. All diets promoted similar growth, regardless of the different CPSP^® concentrations and binders. Growth rates obtained were among the highest obtained for O. vulgaris with artificial diets until now. The lower growth obtained with the artificial diets was greatly reflected in the DG fatty acid composition. The most important fatty acid groups, such as n‐3 highly unsaturated fatty acids, decreased in the DG of animals fed artificial diets. Lipid content, particularly neutral lipids, was higher in the DG of octopuses fed squid, indicating higher nutritional condition of these animals compared to those fed the artificial diets.     

Effects of replacing dietary fish oil and squid liver oil with vegetable oils on the growth,tissue fatty acid profile and total carotenoids of the giant freshwater prawn, Macrobrachium rosenbergii

A feeding trial was conducted to investigate the complete substitution of either fish oil (FO) or squid liver oil (SLO) with crude palm oil (CPO), canola oil (CO) sunflower oil (SFO) or linseed oil (LO), as the sole added lipid source in diets fed to triplicate groups of giant freshwater prawn, Macrobrachium rosenbergii (initial weight = 0.42 ± 0.01 g) for 6 weeks. Prawns fed the CO or SLO diets showed significantly higher (P < 0.05) specific growth rate than those fed the FO or CPO diets. The feed conversion ratio of the prawns was significantly better when fed the CO diet, compared with the FO, CPO, SFO and LO diets. The muscle eicosapentaenoic acid content of prawns fed the vegetable oil (VO) diets were not significantly different (P > 0.05) from those fed the FO diet, although all VO‐based diets led to a significantly lower docosahexaenoic acid content compared with prawns fed the FO or SLO diet. The whole‐body total carotenoid content was significantly lower for prawns fed the SLO diet compared with prawns on the CO or CPO diets. The successful use of VO instead of marine‐based oils in prawn diets will likely reduce feeding costs associated with M. rosenbergii aquaculture.     

Effects of dietary inclusion of yacon,ginger and blueberry on growth,body composition and challenge test of juvenile rockfish (Sebastes schlegeli) against Edwardsiella tarda

Effects of dietary inclusion of yacon, Polymnia sonchifolia (YC), ginger, Zingiber officinale (GG), and blueberry, Vaccinium ashei (BB), on growth, body composition and challenge test of rockfish against Edwardsiella tarda compared to ethoxyquin were investigated. Three hundred and sixty fish were randomly distributed into 12 flow‐through tanks. Four experimental diets were prepared: the control diet (Con) with 0.1 g/kg ethoxyquin, and YC, GG and BB diets. Each diet was assigned to triplicate tanks of fish and hand‐fed for 8 weeks. Externally normal fish after fourth and eighth weeks of feeding trial were infected with Edwardsiella tarda for challenge test. Weight gain and specific growth rate (SGR) of fish fed the YC diet were greater than those of fish fed all other diets. Feed efficiency, protein efficiency ratio and protein retention of fish fed the YC diet were higher than those of fish fed all other diets. In the both fourth and eighth weeks of infection trials, mortality of fish fed the Con diet was higher than that of fish fed all other diets. In conclusion, dietary inclusion of YC, GG and BB increased weight gain and SGR of fish. YC, GG and BB for 4 and 8 weeks lowered mortality of fish at occurrence of E. tarda.     

Effects of exogenous dietary enzyme on growth, body composition, and fatty acid profiles of cultured great sturgeon Huso huso fingerlings

The effects of enzyme supplementation on growth, body proximate, and fatty acid composition of great sturgeon Huso huso fingerlings were investigated. Multienzyme (Kemin^?) was added to diet in different concentrations (0, 250, 500, 750, and 1,000 mg/kg). Fingerlings were randomly stocked in tanks and fed with the experimental diets three times a day at 5–10% body weight for 46 days. Fingerlings fed diets containing 250 mg/kg exogenous enzyme exhibited higher weight gain and specific growth rate. This level of enzyme in the diet significantly improved feed conversion ratio. Body protein and moisture decreased slightly when fish fed with enzyme-supplemented diets while fat increased. Fingerlings fed with 500 mg/kg enzyme in diet had higher contents of n-3 essential fatty acids and lower n-6/n-3 fatty acid ratio. Optimum growth performance in great sturgeon fingerlings can be obtained by 250 mg/kg multienzyme in the diet.     

Effects of dietary lipid levels on growth,feed utilization,digestive tract enzyme activity and lipid deposition of juvenile Manchurian trout,Brachymystax lenok (Pallas)

Six isoproteic diets were designated to evaluate the effects of dietary lipid levels (from 70 to 270 g/kg) on the growth performance, feed utilization, digestive tract enzyme activity and lipid deposition of juvenile Brachymystax lenok (average initial weight 0.54 ± 0.04 g). Each diet was fed to triplicate tanks (30 fish per tank) in an indoor closed recirculating system for 9 weeks. Final body weight and weight gain were highest in fish fed 190 g/kg diet and lowest in fish fed the 70 g/kg diet. Specific growth rate of fish fed with 190 g/kg diet was significantly higher than those fed with 70 and 270 g/kg diets (p < .05). Protein efficiency ratio of fish fed with 70 g/kg diet was significantly lower than the 110–230 g/kg treatments and was not significantly different from the 270 g/kg treatment. Fish fed with 270 g/kg diet had significantly higher hepatosomatic index and viscerosomatic index than those fed with 70–190 g/kg diets (p < .05). Intraperitoneal fat ratio and the whole‐body lipid content had a trend to increase with increase in dietary lipid level. Muscle crude lipid content increased up to 190 g/kg with increase in dietary lipid level. Lipid retention decreased with increase in dietary lipid level, while no significant differences in protein intake and retention levels were observed in fish among all treatments. Lipase activity of the mixture of pyloric caeca and foregut in fish fed 190 and 230 g/kg diets was significantly higher than those fed 70 and 110 g/kg diets. Midgut and hindgut lipase activities of fish were significantly higher than those fed the 190 and 230 g/kg diets. In conclusion, based on the second‐order polynomial model of WG and FCR, this study suggested that 173.8–195.0 g/kg dietary lipid levels were appropriated for B. lenok.     

Spermatophore production and sperm quality of the river prawn Macrobrachium americanum Spence Bate, 1868 fed with different diets

The effects of different diets on spermatophore production and sperm quality were investigated in the river prawn Macrobrachium americanum. River prawns were cultured and fed with three diets for 244 days: fresh food (50% squid meat, Dosidicus gigas and 50% sardine muscle, Sardinops sagax); commercial pellets (35 Purina®); and a 50:50 mixture of both diets. Spermatophore production was recorded every 24 days on average as the percentage of spermatophores produced per extraction per diet, weight and biochemical composition. Sperm quality was measured as the total number of sperm, the proportion of live/dead sperm and normal/abnormal sperm morphology. There were no significant differences in the mean biochemical composition of M. americanum spermatophores for any of the diets. Biochemical composition was 36.3% protein, 25.8% carbohydrate and 4.6% lipids for all data pooled. The weight of spermatophores and sperm counts was not significantly different among diets, nor were there any differences as a function of the male initial total length (p > .05). Male river prawn reproductive exhaustion was observed as a decline in spermatophore production, weight of the spermatophores and the number of sperm cells per spermatophore, with an increasing proportion of dead and abnormal sperm seen throughout the experiment. The recommended period of maintenance in captivity for male broodstock is less than 115 days. It is recommended to feed broodstock males of M. americanum with commercial pellets because no significant differences were detected with the diets tested; pellets are easier to use, ensuring the same spermatophore production and sperm quality that was obtained with fresh food.     

The effects of dietary lipid sources and lecithin on the production of giant freshwater prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> larvae in the Mekong Delta region of Vietnam

The giant freshwater prawn, Macrobrachium rosenbergii, is cultured widely in the Mekong Delta region of Vietnam but it is often difficult or expensive for hatchery operators to purchase commercial diets used as a feeding supplement to Artemia nauplii. Therefore, in the present study, the effects of lipid sources and lecithin on the growth and survival rate of M. rosenbergii larvae were examined in order to develop suitable hand-prepared larval diets for seed production of M. rosenbergii in this area. Six egg custard diets consisting of various ratios of lipid (originating from soybean oil and squid oil) and lecithin were used for rearing Macrobrachium rosenbergii larvae. Treatments in which larvae were fed diets containing squid oil exhibited the highest body length and survival rates (7.14–7.43 mm and 51.1–68.1%, respectively), and differed significantly from other treatments (P<0.05). Use of dietary soybean oil yielded the lowest body length and survival rates (6.29–6.75 mm and 22.0–48.7%), respectively). The supplementation of dietary lecithin did not increase final body weight but did improve larval survival rates. The n-3 HUFA content of prawns fed dietary squid oil was higher than those of animals provided with other diets. These results indicated that the most appropriate diet for rearing M. rosenbergii larvae is the diet containing 3% squid oil and 1.5% lecithin.     

Effect of two extruded diets with different fish and squid meal ratio on growth,digestibility and body composition of Octopus vulgaris (Cuvier, 1797)

The present work studies the growth and body composition of 18 Octopus vulgaris (6 per treatment) fed two extruded diets, namely FMS and 3FMS, based on different fish and squid meal ratios (1:1, and 3:1 respectively). The diets are compared with a control diet based on crab (Carcinus mediterraneus) and bogue (Boops boops). The growing tests were conducted on animals placed in individual 300 L rectangular fibreglass tanks in an open seawater system, containing PVC tubes as shelters, resulting in 100% survival rate. The control group exhibited the highest specific growth rates (SGR = 2.14%BW day^?1), while values of around 0.69%BW day^?1 were achieved by octopuses fed the extruded diets. Even though the three groups of animals showed similar digestive gland indexes, the two extruded diets promoted significant differences in the muscle composition and fatness of the digestive gland. Digestibility of dry matter was not affected by the type of extruded diet, obtaining ADC values of around 88%. The results suggest that squid and fish meal can be both used in dry pelleted extruded diets, with moderate acceptance by the octopus, even though the formulation must be optimized with the aim of improving acceptability and achieve growths in the range of natural diets.     

Effect of different dietary lipid levels on the reproduction of Rhamdia quelen (Quoy and Gaimard, 1824)

Lipids include some of the most important nutrients that affect the survival and growth of fishes in their early life stages. Lipid deficiency prior to spawning may significantly reduce egg production, hatchability and the number of surviving larvae. In this study, we investigated the effects of isocaloric diets containing 80, 140 and 200 g kg⁻¹ of lipids (lipid source, soy oil) for 90 days. The following data were collected at 0, 45 and 90 days: final weight; length; conditioning factor; hepatosomatic, gonadosomatic and visceral fat indices; total plasma protein; testosterone; 17ß‐estradiol; free amino acids; and ovary and muscle fatty acid profiles. Additionally, fecundity, oocyte production, egg morphometric parameters, and larval and postlarval growth were evaluated. Results were not statistically different for husbandry and biochemical parameters, but visceral fat content increased with increase in dietary lipid levels. The fatty acid profiles and composition differed among dietary treatments. The egg diameter and area were significantly low in fish fed the 200 g kg⁻¹ lipid diet, thereby hindering growth, survival and weight compared to those in postlarval fish (P < 0.05). The best reproductive rates were obtained when using diets containing 80–140 g kg⁻¹ total lipids.     

Effects of increased tank bottom areas on cuttlefish (Sepia officinalis,L.) reproduction performance

The objective of this research was to determine the effects of using tanks with different bottom areas/volumes on the growth and reproduction of the European cuttlefish, Sepia officinalis. One hundred and eighty‐four juvenile cuttlefish (46.1 ± 20.9 g) were used to test replicates of 9000 L (6.67 m²), 750 L (1.54 m²) and 250 L (0.79 m² – control). Growth and reproduction data were registered. In addition, egg proximate composition differences were assessed by collecting egg samples from each tank. Regarding growth, no statistical differences between tank types were found (P > 0.05), but total absolute mortality was lower in 9000 L tanks. As for reproduction, differences were found (P < 0.05) between individual tanks for mean egg (MEW), male (MW ♂ ) and hatchling (MHW) weights; and egg batch number. One of the 9000 L tanks displayed the highest overall and individual fecundity (16 593 and 1383 eggs respectively) and egg viability (~72%) ever obtained in our facilities. Differences (P < 0.05) regarding egg proximate composition of different tanks were noted. Significant (P < 0.05) correlations were established between the duration of reproduction stage and batch, MEW and MW♀, egg viability and MHW, and MHW and egg ash content. The present results might be related to sex ratios, differences in weight between ♀ and ♂, and/or derived from breeders condition.     

Nutritional quality of different starches in feed fed to juvenile yellow perch,Perca flavescens

This study determined whether accumulated liver and visceral lipid in yellow perch can be alleviated by feeding an appropriate starch source. We compared the growth performance, nutritional composition and health of yellow perch fed a control diet (no added starch) and three diets with corn, potato or wheat starch (200 g/kg diet) to replace an equal proportion of fishmeal in the control diet. Dietary starch led to increased bulk density, hardness and gelatinization levels of feed pellets compared with the control diet. At the end of an 8‐week feeding, all fish fed the test diets had similar growth rates (p > .05). However, the wheat starch diet resulted in significantly enlarged livers and increased accumulation of lipid in the liver, viscera and whole body (p < .05). This diet also caused significantly higher levels of fasting glucose, aspartate aminotransferase and alkaline phosphatase activities in serum than the control diet. Liver cell diameters were larger, and Kupffer cell numbers were lower in the fish fed the wheat starch than those fed the control diet. Potato or corn starch had less impact on fish health and is considered to be an appropriate carbohydrate sources for yellow perch under the current testing conditions.     

Effects of dietary astaxanthin on growth,antioxidant capacity and gene expression in Pacific white shrimp Litopenaeus vannamei

Pacific white shrimp Litopenaeus vannamei (1050 individuals with initial weight of 1.01 ± 0.001 g) were fed either control diet or one of six dietary astaxanthin (AX) concentration (25, 50, 75, 100, 125 and 150 mg kg⁻¹) diets for 56 days in 35 tanks (30 shrimp per tank). After 56 days of culture, shrimp‐fed AX125 and AX150 diets had higher (P < 0.05) weight gain, specific growth rate, total antioxidant status and lower (P < 0.05) superoxide dismutase (SOD), catalase (CAT) than shrimp fed control diet. After low dissolved oxygen stress for 1 h, survival rate of shrimp fed AX75, AX100, AX125 and AX150 diets was higher (P < 0.05) than that of shrimp fed control diet. Hypoxia inducible factor‐1α (HIF‐1α), cytosolic manganese superoxide dismutase (cMnSOD) and CAT mRNA expression levels of shrimp fed seven diets were significantly down‐regulated under hypoxia than under normoxia, but their expression levels were higher under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet. About 70‐kDa heat‐shock protein (Hsp70) mRNA expression level of shrimp fed seven diets was significantly up‐regulated under hypoxia than under normoxia, but its expression level was lower under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet.     

Effect of diets on carotenoid content,body coloration,biochemical composition and spermatophore quality in the “red cherry” shrimp Neocaridina davidi (Caridea,Atyidae)

In aquarium industry trade markets, Neocaridina davidi, the “red cherry” shrimp, is one of the most attractive ornamental shrimps due to the striking reddish coloration of females. Five commercial diets formulated for ornamental species were evaluated over a 90‐day period in N. davidi males and females, based on survival, biochemical composition, body weight, carotenoid content and body coloration. Furthermore, histological and histochemical analyses of the male reproductive system were performed to evaluate the spermatophore quality. In all treatments, survival was >80%, and protein content was similar in both female and male shrimps. Lipid content was higher in females and males fed on a diet having the highest lipid level. Carotenoid content was higher and body coloration was brighter in females and males fed on a diet containing the highest carotenoid level. Histological and histochemical analyses of the spermatophore structure and composition showed no differences among diets, suggesting that the five commercial diets are adequate for satisfactory growth and spermatophore quality of N. davidi. The diverse sources and quantities of carotenoids in the highest carotenoid level diet render it more suitable for colour enhancement of this species.     

Effect of protein level in purified diet and of density,ammonia and O2 level on growth of juvenile European eels (Anguilla anguilla L.)

The influence of protein level in a purified diet and of density on the growth of Anguilla anguilla in indoor and outdoor containers was examined. The average weight increase of eels that were fed on a diet of pellets containing 35%, 45%, or 55% protein was significantly higher than the mean weight increase of eels fed on pellets containing 25% protein. The production per m³ was higher in the groups fed 45% or 55% protein level in the diet than in the groups fed 25% or 35% protein. Dissolved oxygen in the water of the growing tanks was 7–9 ppm in all groups. Ammonia production was lower in the group fed on pellets containing 25% protein and higher in the groups receiving higher protein diets.Eel growth at low density (4 kg/m³) was almost the same as at high density (30 kg/m³) for both slowly growing and moderately growing eels. Production was higher in the groups stocked at high density and lower in those stocked at low densities. The production of slowly growing eels was lower than that of moderately growing eels.     

Effects of varying dietary protein levels on growth, reproductive performance, body and egg composition of rohu, Labeo rohita (Hamilton)

A 360‐day feeding trial was conducted to observe the influence of varying levels of dietary protein on growth, reproductive performance, body and egg composition of rohu, Labeo rohita. Twenty fish (40.4 ± 0.24 cm; 852 ± 4.9 g), stocked in outdoor concrete tanks (200 m²), in duplicate, were fed diets with varying levels (200, 250, 300, 350 and 400 g kg^?1) of crude protein exchanged with carbohydrate to apparent satiation, twice daily, at 09:00 and 17:00 h. Higher (P < 0.05) weight increment was discernible in fish fed dietary protein ≥300 g kg^?1. Gonadosomatic index was comparable (P > 0.05) among fish of different dietary groups except those fed 200 g kg^?1 protein diet which produced least values. Egg diameter remained unaffected (P > 0.05) by variations in levels of dietary protein. Relative fecundity was maximum (P < 0.05) in fish fed 250 and 300 g kg^?1 protein diets. With the exception of fish fed 200 g kg^?1 protein diet, fertilizability (%) remained unaffected (P > 0.05) by variations in dietary protein level. Hatchability (%) followed the trend of variations almost similar to that of fertilizability. Proximate composition of muscle and eggs varied significantly (P < 0.05) with dietary protein levels. For broodstock L. rohita, a dietary protein level of 250 g kg^?1 was found optimum with regard to its reproductive performance, egg quality and composition.     

Effect of dietary marine lipids on female white bass ova compositions and progeny survival

We evaluated white bass ovum fatty acid composition as well as embryonic and larval survival after varying n-3 and n-6 long-chain polyunsaturated fatty acid (LC-PUFA) concentrations in maternal diets. Diets containing graded levels (0, 33, 66, or 100%) of squid to menhaden oils were fed daily to apparent satiation to female white bass for 8 weeks prior to spawning. Embryonic survival was negatively related to maternal squid oil intake (P = 0.015, R ² = 0.970). Squid oil-fed broodstock produced ova with decreased 20:5n-3 and increased C₁₈ polyunsaturated fatty acid concentrations, largely reflecting the fatty acid profile of squid oil. Within ovum phospholipid, accumulation of 18:2n-6 may have altered biological function resulting in the lower embryonic survival among ova produced from the squid oil-fed broodstock. Our data suggest the importance of feeding white bass broodstock diets high in total n-3 LC-PUFA (at least 4.0% dry matter), and 20:5n-3-rich lipid sources such as menhaden oil can be effectively utilized by female white bass to produce quality ova.