Effect of squid meal in dry pellets on the spawning performance of striped jack Pseudocaranx dentex

SUMMARY: This study was carried out to investigate the effects of dietary squid meal or a combination of squid meal and krill meal as part of the protein source in dry pellets on the spawning of striped jack Pseudocaranx dentex . Five months prior to spawning, 7-year-old fish were divided into three groups of 10 fish each (male : female ratio, 5 : 5). The control group was fed a raw fish mix (RF) and the other two groups were fed either steam-dry pellets with squid meal replacing 50% of their fish meal (fs-DP) or steam-dry pellets containing equal proportions of fish, squid and krill meals (fsk-DP). Feeding was carried out once every other day in 5 × 5 × 5 m floating net cages and the fish were transferred to 65 m³ indoor tanks for spawning. Eggs and yolksac larvae produced were evaluated for their quality and those obtained during the first 2 weeks of spawning were sampled for chemical analysis. The fish had an average bodyweight of 3.5 ± 0.4 kg at spawning. Although egg production of the RF group was significantly higher ( P < 0.05) than that of the dry pellet groups, the fs-DP group produced the best quality eggs with higher fertilization and hatching rates. The fsk-DP group had the lowest egg production and quality. Lipid classes and fatty acid compositions of eggs and yolksac larvae were dependent on the broodstock diets. These results show that the combination of fish meal and squid meal in dry pellets for striped jack improved egg quality but not production whereas the combination of fish meal, squid meal and krill meal was not effective.     

Evaluation of various hCG treatment strategies applied to domesticated pikeperch (Sander lucioperca) broodstock on nest-spawning performance

The aim of the present study was to evaluate the effects of hCG injections on reproductive efficiency by hCG treatment in both male or female brooders of domesticated pikeperch (Sander lucioperca) in the first generation. The study consisted of four treatments based on hormone injection to male or female brooders including T1: both sexes were injected, T2: only females were injected, T3: only males were injected, and T4: without hormone injection. Each treatment which included 14 males and 12 females were introduced to a single rectangular concrete tank with one spawning nest for each mate (a total of 12 nests per tank). Fish were injected by a single dose of 200 IU/kg hCG before transferring to mating tanks. After mating, nests containing fertilized eggs were transferred to circular concrete tanks for incubation and hatching of embryos. According to the results, treatments T3 and T4 did not respond to hormonal stimulation and no fish were spawned. Treatments T1 and T2 showed a positive response to hormone injection. Latency time, fertilization rate, and hatching rate showed no significant difference between T1 and T2 (P?>?0.05), but the number of responded females was significantly higher in T2 (P?<?0.05). The results of the present study demonstrated that it is possible to perform the semi-artificial propagation of domesticated pikeperch via injecting with 200 IU/kg hCG just to females, without the need for hormonal stimulation for males.

     

Effect of dietary protein, lipid and carbohydrate ratio on growth, feed efficiency and body composition of pikeperch Sander lucioperca fingerlings

Pikeperch Sander lucioperca fingerlings were fed nine practical diets containing three levels of protein (P=34%, 43% and 50%), lipid (L=10%, 16% and 22%) and carbohydrate (C=10%, 15% and 20%) for 10 weeks in a recirculating water system at 23°C. Dietary treatments were distributed by orthogonal design with dietary energy content ranging from 15.5 to 23.1 MJ kg^?1 diet. Significant differences (P<0.05) in weight gain (%) and feed efficiency (FE) were observed after feeding trial. Relatively low growth and FE were found in fish fed diets containing 34% dietary protein level compared with that of fish fed diets with 43–50% protein levels, suggesting that 34% dietary protein probably is below the protein requirements of pikeperch fingerlings. Fish fed diets containing P43L10C15, P43L22C20 and P50L16C20 had significantly (P<0.05) higher weight gain and FE than fish fed the diets containing other dietary P/L/C ratios. There was no significant difference in weight gain and FE between fish fed diets of P43L10C15, P43L22C20 and P50L16C20. These results may indicate that pikeperch require at least 43% of dietary protein for adequate growth and FE, and considering the fish growth and feed ingredient cost P43L10C15 diet is more cost‐effective formulation for pikeperch fingerling. However, protein efficiency was not significantly affected by dietary P/L/C ratio.     

Effects of feeding rate and dietary protein levels on the breeding performance of female yellow catfish (Pelteobagrus fulvidraco)

Nutritional components and feeding strategies are multifarious amongst different producers, whereas they are just designed for fish farming but not suitable for improving the reproductive performance of broodfish. Yellow catfish (Pelteobagrus fulvidraco), an omnivorous species, is one of the important aquaculture fish in China. In order to improve the reproductive performance of female yellow catfish (119.86—134.54 g), four feeding strategies (0.5%, 0.75%, 1% and 1.5% BW/d) and three dietary protein levels (34%, 40% and 46%) were examined, respectively, in the two separate trials. The females with moderate feed restriction (1%) showed significant lower mesenteric fat index (MFI) and higher gonadosomatic index (GSI) than the satiation group (1.5%) and excessive feeding restriction groups (0.5% and 0.75%). Females with high MFI were difficult to be artificially propagated and showed a high mortality rate, whilst the fish at 1.0% feeding rate displayed low mortality rate and high ratios of spawned fish, as well as high percentages of fertilization and hatching. Meanwhile, the offspring of 1.0% feeding rate group showed a low malformation rate and high survival rate. Multiple spawning in the same breeding season are applied in yellow catfish to reduce the number of parent fish and increase the fry production, and gonadal recrudescence after spawning might be affected by different nutrient values including dietary protein levels. In the second trail, female yellow catfish were fed with 34%, 40% and 46% crude protein diet at 1% feeding rate for the second spawning, and the best reproductive and breeding performances were observed in the fish group with 46% crude protein diet. These results demonstrate that 1% feeding rate is optimum for the spawning and reproductive performance of female yellow catfish for the first artificial spawning, and 46% dietary protein group had the best reproductive performances in the second spawning.     

Effects of Varying Dietary Protein Levels and Feeding Frequencies on Condition and Reproductive Performance of Channel Catfish to Produce Hybrid Catfish

The interspecific hybridization of channel catfish, Ictalurus punctatus, females with blue catfish, I. furcatus, males has been identified as a method to further improve production; however, lack of spawning success has affected its commercial application. To facilitate our understanding of the interaction of brood stock nutrition and reproductive performance, we evaluated the interaction of feed quality and feeding frequency. Channel catfish females were classified into two genetic groups, namely, high and low spawning. The treatments were offered during the spring season 70–90 d prior to the start of the spawning season. Induced reproduction was performed using luteinizing hormone releasing hormone analog. Condition of the fish as well as reproductive performance using spawning success, egg production, egg size, and fertilization at 48 h were determined. Changing protein level of the diet from 32 to 42% did not influence spawning, fecundity, or fertilization, but affected egg size and biochemical composition of the eggs. Increasing the feeding frequency from three to six times per week negatively affected spawning in one of the two genetics groups, did not affect egg production and egg fertilization, but had a significant effect on egg size. Older fish performed better than younger fish in terms of spawning success and egg production.     

斑鳜人工繁殖技术初报

2011-2013年,利用野生和经人工驯养的野生斑鳜（ Siniperca scherzeri ）亲鱼进行人工繁殖试验。结果表明：采用地欧酮（ DOM）和促黄体素释放激素类似物（ LHRH -A3）组成的混合药物催产,在17．8-25．4℃水温条件下,斑鳜亲鱼群体的效应时间为24-46．5 h,存在产卵高峰期,产卵持续时间一般长达1-1．5 d。自然产卵高峰期的受精率较高,最高可达80%以上,早期和晚期的较低;而孵化率差异不大,最高可达86．7%。人工授精的受精率可达91．3%,孵化率可达89．3%。未经人工驯养的野生斑鳜亲鱼人工催产的受精率、孵化率都明显低于经人工驯养的。     

Effect of arachidonic acid levels in broodstock diet on larval and egg quality of Japanese flounder Paralichthys olivaceus

This study investigated the effect of dietary arachidonic acid (AA) in broodstock of Japanese flounder on subsequent egg and larval quality. Diets with similar proximate composition and n-3 HUFA level, but with different AA levels (0.1%, 0.6% and 1.2% of diet), were fed to the broodstock from 3 months before and during the spawning season. Spawning was observed from March to May. Total egg production over the spawning season was highest in fish fed the 0.6% AA diet and lowest in fish fed the 1.2% AA diet. All parameters measured as egg quality (percentage of buoyant eggs, hatching rate, larval survival and normality of larvae.) were highest in fish fed the 0.6% AA diet. AA content in eggs proportionally increased with the dietary AA level. EPA content of polar lipids of eggs had a negative correlation with the AA level in diets whereas the DHA content was independent of dietary AA. The results of this study indicate that a supplement of AA at 0.6 g/100 g diet improved the reproductive performance of Japanese flounder, but a higher level of AA (1.2 g/100 g diet) negatively affected both egg and larval quality due to a potential inhibitory effect on EPA bioconversion.     

Effects of dietary keto-carotenoids (canthaxanthin and astaxanthin) on the reproductive performance of female rainbow trout Oncorhynchus mykiss (Walbaum)

The aim of this study was to clarify further the relationship between dietary keto-carotenoids (canthaxanthin and astaxanthin) and reproductive performance in female rainbow trout. Three experiments were undertaken in three successive breeding seasons. In addition to a control diet, fish were fed a canthaxanthin-supplemented diet (200 mg canthaxanthin kg⁻¹ feed, designated as 6mC200) for 6 months prior to spawning (experiment A); the same diet as in A but for either 3 months (3mC200) or 6 months (6mC200) before spawning (experiment B); diets with one of two levels of astaxanthin supplementation, 50 mg (6mA50) or 100 mg (6mA100) kg⁻¹ feed, or a diet with 100 mg canthaxanthin kg⁻¹ feed (6mC100) fed for 6 months (experiment C).
There was no significant influence of carotenoid supplementation on either the frequency of maturing females or the date of maturation. The number of ova per kg of female body weight averaged 2700 and did not vary significantly among fish fed the different diets. Across experiments A, B and C there was no significant difference in egg and larval survival among fish fed carotenoid-supplemented and control diets. In experiment A, 6mC200 females produced smaller eggs than controls but this result was not confirmed in experiments B and C. In general, eyed egg yield appeared partly dependent upon egg size. Alevin weight was also correlated with egg weight. The growth test conducted on fingerlings from experiment B failed to provide any evidence of an effect of feeding carotenoid supplemented diets to the female parent. Pigment analyses conducted on alevins revealed that canthaxanthin fed to the female parent was transferred into the eggs and therefore to the larvae, although canthaxanthin was metabolized within a few weeks after hatching.     

Impact of food type on growth,survival and reproduction of the cyclopoid copepod <Emphasis Type="Italic">Cyclopina kasignete</Emphasis> as a potential live food in aquaculture

This study compared the efficacy of different dietary algae on the growth and reproduction of the cyclopoid copepod Cyclopina kasignete, a potential live food species for fish larvae in aquaculture. The experimental diets for the copepod consisted of three monoalgal diets (Nannochloropsis oculata, Tisochrysis lutea and dry Melosira sp.) and two mixed algae diets (T. lutea?+?N. oculata, T. lutea?+?dry Melosira sp.). The experiment was carried out for 30 days, and the population growth, survival and reproductive performance (generation time, hatching rate, life spawning times, daily offspring production, eggs per sac, lifespan and sex ratio) were used to assess the responses of C. kasignete to different food types. Population growth, survival and reproductive capacities of C. kasignete were significantly affected by the mono and binary species of algal diets. The results showed that copepods exhibited superior growth, survival and productivity when fed on fresh T. lutea, dry Melosira sp. and a mixture of both species compared to other dietary treatments. Copepods produced comparable growth, survival and productivity when fed on diatoms (dry Melosira sp.) as a single or in combination with other algae. This study indicates that cyclopoid copepod C. kasignete grow fast and have the potential to serve as a live food for aquaculture. The algae T. lutea, dry Melosira sp. and their combination are appropriate food to sustain the growth and reproduction of this copepods in mass culture as a potential live food in fish hatchery.     

Effects of reproductive timing and hatch date on fathead minnow recruitment

Abstract –  Timing of reproduction can be an important determinant of recruitment success for fish in strongly seasonal environments, both for individuals hatching at different times over extended spawning seasons and for entire cohorts, if the spawning period is accelerated or delayed among years. To examine potential demographic consequences of delayed spawning, we staggered dates that fathead minnow ( Pimephales promelas ) were introduced into experimental ponds in Alberta, Canada, by 3 weeks and compared growth and survival of offspring from early- and late-stocked fish. By autumn, size and mass were consistently greater in early-hatched minnows, regardless of cohort density. Size differences between treatments persisted through the second summer, which likely contributed to a higher proportion of early-hatched fish reaching sexual maturity as yearlings compared with late-hatched counterparts. Because late spawning can limit growth and subsequent maturation of progeny, temporal variability in reproductive timing should be considered when assessing recruitment potential of new year-classes.     

Replacement of live feed by formulated feed: effect on the growth and spawning performance of Siamese fighting fish (Betta splendens,Regan, 1910)

Partial replacement of live feed (LF) with formulated feed (FF) was performed in Betta splendens to evaluate their growth, survival and reproductive performance. Three hundred B. splendens fry of uniform size (mean weight 0.19 g±0.01) were equally distributed in five treatment groups with each of three replicates in glass aquaria of 35 L capacity. Fish were offered diets of different ratio of LF and FF like T1 (control) – 100% LF; T2 – 75% LF, 25% FF; T3 – 50% LF, 50% FF; T4 – 25% LF, 75% FF and T5 – 100% FF. Highest (P<0.05) body weight gain (% BWG) (67.1±1.03) and specific growth rate (2.34±0.02) were observed in the T2 group. Best feed conversion ratio was also found in T2 (2.40±0.11), which was similar to T1 and T3. The highest survival rate (%) was recorded in T1, T2 and T3 groups (97±1.7), which was similar to T4 and the lowest in T5 (49±2.0). The highest gonadal weight (0.12 g±0.01) and gonadosomatic index (15.17±0.50) was observed in the T3 group during the first sampling after 63 days. No significant changes in spawning performance were observed in the second sampling after 21 days after first sampling. However, T4 group registered the highest fecundity and fertilized eggs at the end of 105 days of experiment. From the present study, it concludes that LF can be successfully replaced to the extent of 25% by FF without any detrimental effect on the growth, survival and spawning performance of B. splendens.     

Effect of dietary essential fatty acids on level of oestradiol‐17β and vitellogenin,reproductive performance and larval quality of striped catfish (Pangasianodon hypophthalmus) in out‐of‐spawning season

A study was conducted to determine the effect of essential fatty acid in striped catfish (Pangasianodon hypophthalmus) broodstock diets on a level of oestradiol‐17β and vitellogenin, reproductive performance and larval quality in out‐of‐spawning season. Five female and five male broodstock were stocked into a net cage (3 × 5 × 1.5 m³) and fed with pelleted diets containing 1.5% fish oil and different amounts of corn oil (CO) in diet formulation, that is 0%, 1%, 2% and 3% respectively. Gonadal development, oestradiol‐17ß and vitellogenin concentrations were examined every 2 weeks. Oestradiol‐17ß and vitellogenin concentrations showed an increase during the maturation process. The significantly highest percentage of female mature, fecundity, hatching rate, larval production and larval survival rate were obtained from fish fed with 2% corn oil in the diet. This result revealed that the administration of 2% corn oil in the diet as a source of n‐6 (linoleic acid) and 1.5% fish oil as a source of n‐3 (linolenic acid) can improve the reproductive performance of striped catfish broodstock in out‐of‐spawning season.     

饲料营养对亲鱼生殖性能的影响研究进展

营养对鱼类生殖具有重要的调节作用。亲鱼阶段的营养不仅影响亲鱼的性成熟、配子产生、繁殖力、受精率、受精卵的孵化率和胚胎发育,而且还影响仔稚鱼的质量和存活率;适当的营养可促进鱼类的繁殖性能,而营养缺乏或者过量将降低其繁殖性能。本文总结了饲料中的蛋白质、脂肪、糖、维生素和钙磷等矿物元素的含量和来源等因素对亲鱼生殖活动各个环节的影响,对饲料中一些关键营养素的供应提出了建议,并结合陆生动物的研究结果,对能量、脂肪及必需脂肪酸等调节鱼类繁殖性能的作用机制进行概括和推断。     

The effect of cyclooxygenase (COX) inhibitors on Japanese medaka (Oryzias latipes) reproduction parameters fed with high level of arachidonic acid (20:4 n-6)

Broodstock of mature Japanese medaka (Oryzias latipes Temminck and Schlegel, 1846) (mean weight 0.45 ± 0.03 g; age 6 months) were maintained in glass aquaria (8 males and 8 females in each aquarium). The fish were fed commercial feed (group C) or this feed was supplemented with arachidonic acid ARA (2 % of total fatty acids in feed; group A) and one of the COX inhibitors: resveratrol (group AR) or NS-398 (group ANS) with amount 20 mg kg^?1 BW day^?1 of one of the COX inhibitors. The effect of 2 weeks of feeding experimental diets on reproductive parameters (fecundity, embryo and larval survival, hatching rate, and larvae body weight) was analyzed. Larvae (obtained from experimental dietary treatments) were reared for 2 weeks. The percent of spawning female and fecundity was similar in dietary treatments. COX inhibitors in broodstock diet caused a decrease in embryo survival rate. Eggs of medaka from group ANS and AR revealed the lowest hatchability rate. In contrast, group A revealed a higher hatchability rate at the same time. Larval body weight after hatching was significantly the highest in this group. At the end of the experiment, larvae body weight ranged from 1.62 ± 0.43 mg in group AN to 2.89 ± 0.74 mg in group A. These results show that the COX inhibitors decreased gamete and larval quality regardless of high levels of ARA in broodstock diet.     

Effect of substituting live feed with formulated feed on the reproductive performance and fry survival of Siamese fighting fish, Betta splendens (Regan, 1910)

This study aimed to elucidate the effect of partial or complete replacement of live feed (LF) (Tubifex) with formulated feed (FF) on the reproductive performance of Betta splendens. Three hundred B. splendens fry (average weight 0.19 ± 0.01 g) were equally distributed into five different groups, each with three replicates. They were fed for 105 days with following different diets: control (C)—100% LF; T1—75% LF, 25% FF; T2—50% LF, 50% FF; T3—25% LF, 75% FF, and T4—100% FF. Results showed that the average number of hatched larvae (654 ± 101) and fry survival after 2 weeks of rearing (428 ± 70), after completion of three spawning, were recorded highest in the control group, which was, however, not significantly different from the T1, T2, and T3 groups. At the end of the feeding trial, the highest hatching percentage (90.3%) was registered in the T2 group, which was not significantly different from the control and T1 groups. The T2 group also recorded highest fry survival (65.54%) after completion of three spawning, which was not significantly (P < 0.05) different from the T1 and T3 groups. Control diet contained higher saturated fatty acid (63.23%) than formulated diet (29.80%). In the whole-body tissue, highest level of EPA (0.42%) and DHA (3.13%) were found in the T4 group followed by T3 group. The DHA/EPA ration was recorded highest in the T2 group (10.96%), which did not differ significantly from the T1 and T3 groups. Significant positive correlation was observed between saturated fatty acid levels in fish whole-body tissue and number of hatched larvae (Y = 30.81 × −825.3, R ² = 0.968) and fry survival after 2 weeks of rearing (Y = 21.38 × −580.9, R ² = 0.967). Considering all these factors, it can be concluded that the live feed Tubifex can be replaced up to 50% without any adverse effect on the reproductive performance and fry survival of B. splendens.     

Fructose 1,6 bisphosphatase activity in liver and gonads of sea bass (Dicentrarchus labrax). Influence of diet composition and stage of the reproductive cycle

The fructose 1,6 biphosphatase (FBPase) activity was measured in the liver and gonads of broodstock sea bass that were fed three experimental diets over the reproductive cycle. Enzyme activity was measured at the pre-spawning (November), spawning (February) and post-spawning (May) periods. Additionally, some biometric indices were calculated at these three times. The different diets, one with standard composition (51% protein, 13% lipid, 10% digestible carbohydrates), one with a high-carbohydrate content (32% protein, 13% lipid, 32% digestible carbohydrates) and one deficient in ω3 essential fatty acids (51% protein, 13% lipid, 10% digestible carbohydrates), had similar affects on growth and gonad development, as deduced from the similar weight, condition factor, hepatosomatic index, gonadosomatic index and liposomatic index over the reproductive cycle. FBPase activity was detected at all times in the liver of both sexes, and in the ovaries but not in the testes. In general, females showed greater liver activity than males, especially at spawning time. During post-spawning, FBPase activity fell in tissues of both sexes. Enzyme activity was also affected, mostly in the liver, by the different types of feed; hepatic activity in fish fed the high-carbohydrate diet fell during the spawning and post-spawning periods, though at a different level for each sex. The diet deficient in ω3 EFA presented the lowest FBPase activity, compared with the other diets, in females during the spawning period; there was very little change in males or females over the reproductive cycle. The results showed that the highest gluconeogenic activity in sea bass broodstock occurred at the spawning time and the females had larger glucose requirements than males over the reproductive cycle, as demonstrated by the absence of FBPase activity in testes. This work also confirmed the adaptative capacity of this enzyme to different nutritional and physiological conditions.     

Effects of feeding diets containing various dietary protein and lipid ratios on the growth performance and pigmentation of post-juvenile coho salmon Oncorhynchus kisutch reared in sea water

Six extruded dry diets formulated to contain one of two levels of digestible protein (37% or 44%) and one of three levels of digestible lipid (16%, 23% or 30%) on a dry weight basis and a seventh diet (commercial control) were used to feed triplicate groups of post‐juvenile coho salmon Oncorhynchus kisutch in sea water. Fish were fed to satiation twice daily for 168 days. Growth performances were monitored every 28 days. On day 168, samples were taken from each replicate group per dietary treatment for determinations of whole‐body and muscle proximate compositions. Fatty acid compositions and astaxanthin concentration in both the experimental diets and fish flesh were assessed by gas chromatography (GC) and high‐performance liquid chromatography (HPLC) respectively. Coho salmon fed diets containing the higher lipid levels (23–30%) exhibited improved feed efficiency, protein efficiency ratio, percentage protein deposition and percentage gross energy utilization. Higher protein content diets supported better growth than those that had lower protein content, but the former led to lowered protein efficiency ratio, percentage protein deposition and gross energy utilization. Fish fed the diets with high lipid levels (23% or 30%) also had higher astaxanthin content in raw flesh.     

Out-of-season spawning of cultured pikeperch [Sander lucioperca (L.)]

The aim of this study was to determine the effectiveness of out‐of‐season spawning of cultivated pikeperch (fish that were reared from the larval stage in re‐circulating systems and fed commercial feed exclusively) stimulated hormonally with human chorionic gonadotropin (hCG). The impact of fish age (2+ and 3+) and hormone dosage [200 or 400 IU hCG kg⁻¹ body weight (BW)] on spawning was analysed and expressed as the share of stripped females, commercial fecundity (% BW) and survival of embryos until the eyed‐egg stage (EES index). The possibility of utilizing changes in female pikeperch body weight (CBW index) that are observed following hormone injections as an additional indicator for determining maturity was also investigated. The age and hormone dosage were not noted to have a significant impact on the number of stripped females (≥80% on all groups), the latency period (90–100 h), commercial fecundity (11.3–13.3% BW) or the values of the EES index (61–73%; P>0.05). The mean value of EES from the 3+ age group females was higher than that in the 2+ females, and the interaction between the tested factors (fish age and hormone dosage) wasstatistically significant (P<0.05). In the fish from the control group (injected with a 0.9% NaCl solution), no progress was noted in the maturation of oocytes and no eggs were obtained from any female. It was noted that these females lost BW over the course of the subsequent 24 h of the measurements (P<0.05). In the groups of females that were stimulated hormonally, the opposite phenomenon was observed; in these groups, the CBW index increased significantly between 48 and 96 h following hormone injection. The value of the CBW index was not noted to have been statistically significantly determined by either hormone dose or fish age (P>0.05). The regression equations that described the dependence between CBW and the oocyte maturity stage were highly significant statistically, and the determination coefficient R² assumed a value of 0.76. The most significant increase in BW was related to the oocytes achieving maturity stage III. The BW of pikeperch females with oocytes in this stage was 103% higher than the initial BW. This might be a valuable and useful tool for determining maturity in females of this fish species.     

花[鱼骨]人工繁殖技术的研究

本文主要研究了花[鱼骨]的繁殖生物学和人工繁殖技术。经过实验摸清了花的性成熟年龄和成熟最小型,性腺的发育状况,花的繁殖力、产卵时间和水温、雌雄鉴别等;比较了不同催产药物对花的催产效果,2008年催产率达100%,受精率95.3%,孵化率95%,获鱼苗14.12万尾。     

绿色微囊藻等不同食物对大型生长和脂类成分的影响

The growth and reproduction of Daphnia magna fed with Microcystis viridis and Chlorella spp respectively and 20% fish oil + 80% yeast and yeast were studied. The intrinsic rate of natural increase of Daphnia magna (rm) was 0.243 fed with Microcystis viridis, 0.301 with Chlorella spp., 0.244 with 20% fish oil + 80% yeast and 0.193 with yeast. The result showed that：Daphnia magna fed with Microcystis viridis had lower growth rates than that fed with Chlorella spp. an d 20% fish oil + 80% yeast which both had full fatty acids. And the Daphnia magna fed with yeast was the lowest. So the fatty acids composition of diet may affect the growth of Daphnia magna. This paper further examined total lipids and main HUFA (EPA and DHA) compositions of the continuous three generations of Daphnia magna (in order to get rid of t he effects of former diet) fed with different of above diets (except the yeast). The result showed that:the three generations of the D. magna fed with Microcystis viridis had the lowest total lipids and the percentages of the HUFA (EPA, and no DHA) have a significant decrease and get the lowest EPA in the final experiment because of the very low HUFA especially EPA and DHA in Microcystis viridis. So the results indicate that Microcystis viridis with low HUFA made the lower growth rate, spawn ing rate and hatching rate of Daphnia magna.