Levels of highly-unsaturated fatty acids, the most important nutritional factors in fry productio... more Levels of highly-unsaturated fatty acids, the most important nutritional factors in fry production of marine fish, were compared between hatchery-produced and wild-caught milkfish Chanos chanos fry. The most striking difference found between the fry was in docosahexaenoic acid (DHA: 22:6n-3) levels: DHA levels in hatchery-produced fry were only 37% and 18% of those in wild-caught fry in the polar lipids and neutral lipids, respectively. However, high DHA levels were detected in ovary and spawned eggs from hatchery-reared broodstock. Investigation on the time course change in DHA levels of hatchery-produced fry revealed that the DHA levels of polar lipids drastically declined from 25% at day 0 posthatching to 5% at day 14 posthatching. Nannochloropsis sp. and rotifers Brachionus sp., which were used as live food from day 2 to day 14, did not contain DHA with relatively high eicosapentaenoic acid (EPA: 20:5n-3) levels. DHA level was restored to 13% in 45-day old fry by feeding of formulated diets with a substantial amount of DHA from day 15. Thus, the lack of DHA in the live food appears to lead to the low DHA level in hatchery-produced fry. On the other hand, the cost of DHA enrichment for one milkfish fry was estimated to be 2.6 Philippines centavos, which is equivalent to about 10% of the market price of milkfish fry. The increase of the production cost might not be accepted in domestic hatcheries under competitive marketing with imported fry. Financial and marketing support by the government will be one of the measures to encourage the stable production of domestic milkfish fry with high quality in the Philippines. It is also necessary to conduct institutional campaigns to inform local fry producers and milkfish farmers of the importance of DHA-enrichment.
Turkish Journal of Fisheries and Aquatic Sciences, Dec 1, 2012
Fatty acids compositions were analyzed in neutral lipids (NL) and polar lipid (PL) of gonads of N... more Fatty acids compositions were analyzed in neutral lipids (NL) and polar lipid (PL) of gonads of Nile tilapia, ayungin and African catfish to elucidate some guesses for the fatty acids requirements for broodstock. The high value detected for both C16:0, C18:1 n-9 in all samples reflects a requirement for energy metabolism during the course of gonad development. The Lower proportion of polyunsaturated fatty acids (PUFA) was found in the NL of all gonads samples compared to PL. The higher percentages of n-3 HUFA in PL with respect to NL, suggests the importance of HUFA in the reproductive processes. In PL and NL, arachidonic acid (ARA) was the most abundant n-6 PUFA (ranged from 2.59 to 11.33% and from 0.16 to 3.19%, respectively). A relatively higher particularly eicosapentaenoic acid (EPA)/ docosahexaenoic acid (DHA) ratio was obtained in both NL and PL. All wild species studied are characterized by high ARA/EPA ratio in PL ranged from 1.72 to 5.47. Therefore, it is necessary to take into consideration not only the individual levels of HUFA but also the correct ratio among them (ARA/EPA/ DHA) through controlling LA and LNA level and ratio in the diets of tropical freshwater broodstocks.
Journal of Aquaculture Research and Development, 2011
Journal of Aquaculture Research & Development J o u rn al of Aq u a c u lt u re Rese ar c h & D e... more Journal of Aquaculture Research & Development J o u rn al of Aq u a c u lt u re Rese ar c h & D evelopm e n t
Japan International Research Center for Agricultural Sciences eBooks, 2007
Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry av... more Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry availability is a major constraint in the development and extension of aquaculture, especially in rural areas of developing regions. Although the mission of hatcheries is to provide a stable fry production and supply for farmers, fry production remains variable due to poor fecundity and low survival. For the last four years (2002-2005), SEAFDEC/AQD and JIRCAS have conducted the collaborative project that was aimed at developing advanced diets for improving egg production/quality (2002-2005) and larvae/fry quality (2004-2005) through dietary manipulation. Larval rearing tests: In 2005, larval rearing tests (4 trials with rotifers) were conducted to investigate the effects of enriched-live food (4treatments: low (CS) and high (DHAPS) HUFA with or without arachidonic acid supplementation) on survival and growth in rabbitfish Sigunus guttatus fry. Fry fed the rotifers enriched with a combination of DHAPS+5% ArA showed the best survival (44.4±4.5% for D17 fry in the 4th trial).Growth was not different among the treatments (CS, CS+5% ArA, DHAPS, DHPS+5% ArA). Broodstock tests: From March, 2005 to January,2006, a feeding test has been conducted to investigate the effects of dietary ArA supplementation (0% for diet 1, 0.3% for diet 2 and 0.6% for diet 3) on egg production and quality of wild-caught and hatchery-bled rabbitfish broodstock. The broodstock spawned 13 times for diet1 (six pairs), 14 times for diet 2 (five pairs) and 17 times for diet 3 (six pairs) during the period of May 2005 to January, 2006. The total numbers ofhatched-larvae were 3,818 x 103 for diet 1, 4,391 x 103 for diet 2 and 4,597 x 103 for diet 3. The % of normal larvae did not differ among the dietary treatments. Considering together with the results of mangrove red snapper (2003) and rabbitfish (2004), the optimum level of ArA incorporation appears to be between 0.5% and 0.7%. Judging from the results of fatty acid analysis, DHA and arachidonic acid should be supplemented to diets at the same time as to make DHA/arachidonic acid ratio appropriate. Thus, the present study clearly shows that dietary arachidonic acid supplementation is very promising for the development of fry production technologies in tropical areas
Japan International Research Center for Agricultural Sciences eBooks, 2007
Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organi... more Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organisms. Seagrass had high linoleic acid and linolenic acid levels with low Ara, EPA and DHA levels, while some species of seaweed had intermediate or high ArA levels (5% to 12%). In starfish, sea cucumber and some species of corals, ArA was the first major fatty acid (20% to 30%), but DHA levels were very low. Bivalves, abalone and shrimps had intermediate ArA levels. Total lipids of abdominal muscle and liver of dugong had respectively ArA levels of 7.8% and 11.0%, which were higher than EPA levels (2.4% and 1.6%), but DHA levels (0.4% and 2.3%) were low. It is clear that ArA is a major fatty acid in coral reef animals. The present results suggest that the existence of an ArA-rich food chain may be widespread in coral reef areas, and that the widespread existence of ArA-rich food chain may lead to intermediate or high ArA contents in tropical species
Six tropical freshwater species were collected from Philippines in order to study the characteris... more Six tropical freshwater species were collected from Philippines in order to study the characteristic of polyunsaturated fatty acids distributions. 16:0 and 18: l n-9 were the predominant saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) in both neutral lipids (NL) and polar lipids (PL). There was an absence or very low values of n3 highly unsaturated fatty acid (HUFA) in NL of all species. However these fatty acids found in PL of all species studied with higher levels. The high proportions of docosahexaenoic acid (DHA) in PL were found with catfish Arius (20.71%), ayungin (17.64%), and snakehead (17.09%) whereas anabas (4.21%) gave lower DHA content. In PL, arachidonic acids (ARA) was found in high proportions, and also is superior to eicosapentaenoic acid (EPA) (ranged from 3.35 to 10.67% and from 0.42 to 4.74%, respectively). Tilapia lipid appears to be intermediate in nutritional quality between all species studied; the proportions of DHA, EPA and ARA in PL were 16.27%, 4.52% and 9.36%, respectively. According to the n-3/n-6 ratio in both fractions, only ayungin is in the range typical of freshwater fish. Our results indicate that the wild tropical freshwater fish studied here are not good sources of n-3 HUFA fatty acids. Therefore, aquatic nutritionists and farmers should combine their efforts in order to manipulate the nutritional quality of these species to enhance their n-3 HUFAs concentrations especially when these species are reared in captivity system. The wash-out strategy may provide an adequate description of the changes in the fillet lipid fatty acid profiles of fatty fish.
World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a ge... more World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a general understanding that the advancement of aquaculture is very important for food security and poverty alleviation, aquaculture in Africa is insignificant compared to the rest of the world. African aquaculture contributed only 1.2% (463 × 10 3 Mt) of world aquaculture production. Moreover, our calculation based on FAO statistics revealed that the average per capita consumption of fish in Africa decreased from 9 kg in 1990 to 7.8 kg in 2001. This decrease in the per capita consumption of fish appears to be a threatening sign for food security in Africa. There are many political, economic and technical issues that are obstructing the development and promotion of aquaculture in Africa. Egypt, the desert but rice producing country, has a long history of aquaculture and is the leading producer, especially of freshwater aquaculture in Africa. Total aquaculture production in Egypt in 2002 was 376 × 10 3 Mt, which supplied 81% of that in Africa. In the present review, based on the case of Egypt, we propose measures and research areas to develop and promote rice-fish culture and desert aquaculture. Rice-fish culture is a model of aquaculture styles for wet and pluvial regions, and desert aquaculture is also a model for arid and semi-arid regions not only in Egypt but also for other African countries. Poor knowledge on fish feeds and feeding technology is one of the major constraints in the expansion of aquaculture. In order to improve and increase the productivity of aquaculture in Africa, we propose measures and research subjects for developing supplementary and complete feeds using regional ingredients.
The present study was financially supported by the collaborative project titled “Studies on Susta... more The present study was financially supported by the collaborative project titled “Studies on Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas” between Japan International Research Center for Agricultural Sciences, Japan and the Aquaculture Department, SEAFDEC, Philippines.
Lipoprotein lipase (LPL) is a key enzyme of lipid metabolism. The elucidation of the structure, f... more Lipoprotein lipase (LPL) is a key enzyme of lipid metabolism. The elucidation of the structure, function and regulation of LPL is important for understanding the lipid metabolism in fish. Recently, we have cloned the LPL gene of red sea bream (Pagrus major) and characterized it by cDNA and genomic structure analysis. Subsequently, using the cloned sequence, gene expression has been investigated. We review in this report the features of red sea bream LPL gene. Red sea bream LPL gene spans 6.3kb of the genome and is organized into ten exons and nine introns. The deduced amino acid sequences showed high degree of similarities to the LPLs of other animals. In a 1.1kb 5' flanking region, the homologous sequences for the response elements of Insulin, glucocorticoid and thyroid hormone were detected. These results suggest the hormonal regulation of the LPL gene expression. Red sea bream LPL gene was expressed in various tissues including adipose tissue, heart, liver (hepatopancreas) and muscle. A fourteen-week feeding experiment was conducted to investigate the effects of feeding condition and dietary lipid level. The results suggest that LPL gene expression in visceral adipose tissue and liver is regulated in tissue-specific manner. The expression level in adipose tissue was down-regulated during starvation whereas it was up-regulated in liver. The effects of dietary lipid level on the gene expression were not observed. These results will facilitate further study on the function and regulation of the LPL in fish.
A two-phase experiment was conducted to examine the effects of dietary fat and adiposity on Ž y1.... more A two-phase experiment was conducted to examine the effects of dietary fat and adiposity on Ž y1. feed intake of red sea bream. In Phase 1, juveniles 9.7 g, 20 fish tank , 4 replicates were fed Ž y1 y1. Ž low fat LF; 15.3% fat, 60.6% protein, 22.2 kJ g energy, 0.61 g ml density or high fat HF; y1 y1
Fingerling yellowtail Seriola quinqueradiata (initial mean body weight 4.3 g), an active pelagic ... more Fingerling yellowtail Seriola quinqueradiata (initial mean body weight 4.3 g), an active pelagic fish, were reared under fed (4 weeks) and unfed (1 week) conditions to investigate the effects of swimming exercise on growth performance and whole body composition. The fish were raised in three water velocities: < 0.3 body length/s (bl/s), 1.0 bl/s, and 2.25 bl/s and fed diets containing two fat levels (13.2 and 20.3%). The exercised fish had significantly higher weight gains and feed efficiencies than the unexercised fish in both dietary fat levels. A second-order polynomial suggested that the optimum water velocity for the growth occurred at about 1.6 bl/s. The whole-body crude protein and fat contents were higher in the exercised fish than in the unexercised fish, and consequently apparent body protein and fat retentions were improved in both dietary fat levels by swimming. However, during 1 week starvation, body fat loss/g body weight loss was higher in the exercised fish than in the unexercised fish. The results of the present study clearly show that swimming condition improves growth performance of fingerling yellowtail, and suggest that swimming exercise stimulates both anabolism and catabolism of protein and fat; however, under fed conditions anabolism appears superior to catabolism.
World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a ge... more World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a general understanding that the advancement of aquaculture is very important for food security and poverty alleviation, aquaculture in Africa is insignificant compared to the rest of the world. African aquaculture contributed only 1.2% (463 × 10 3 Mt) of world aquaculture production. Moreover, our calculation based on FAO statistics revealed that the average per capita consumption of fish in Africa decreased from 9 kg in 1990 to 7.8 kg in 2001. This decrease in the per capita consumption of fish appears to be a threatening sign for food security in Africa. There are many political, economic and technical issues that are obstructing the development and promotion of aquaculture in Africa. Egypt, the desert but rice producing country, has a long history of aquaculture and is the leading producer, especially of freshwater aquaculture in Africa. Total aquaculture production in Egypt in 2002 was 376 × 10 3 Mt, which supplied 81% of that in Africa. In the present review, based on the case of Egypt, we propose measures and research areas to develop and promote rice-fish culture and desert aquaculture. Rice-fish culture is a model of aquaculture styles for wet and pluvial regions, and desert aquaculture is also a model for arid and semi-arid regions not only in Egypt but also for other African countries. Poor knowledge on fish feeds and feeding technology is one of the major constraints in the expansion of aquaculture. In order to improve and increase the productivity of aquaculture in Africa, we propose measures and research subjects for developing supplementary and complete feeds using regional ingredients.
The characteristics of lipid deposition in juveniles of red sea bream Pagrus major, yellowtail Se... more The characteristics of lipid deposition in juveniles of red sea bream Pagrus major, yellowtail Seriola quinqueradiata, and Japanese flounder Paralichthys olivaceus, were investigated by feeding diets with three lipid levels (approximately 11, 16 and 20%). In red sea bream, the viscera contributed 40-50% to the whole body lipid store and deposited 35-39% of dietary lipid intake (body lipid gain/lipid intake : lipid deposition ratio), while the carcass contributed 40% and deposited 30-37%. In yellowtail, 50% of the whole body lipid store was found and 25% of dietary lipid intake was deposited in the carcass, while less than 10% was found and about 3% was deposited in the viscera. In Japanese flounder, although 80% of the whole body lipid store was located in the carcass, the lipid deposition ratio of the carcass decreased from 33% down to 19% as the increase of lipid intake, and the viscera represented around 10% of whole body lipid store and deposited 3% of lipid intake. Thus, the juveniles showed different traits of body lipid deposition in their responses to changes in dietary lipid level.
Levels of highly-unsaturated fatty acids, the most important nutritional factors in fry productio... more Levels of highly-unsaturated fatty acids, the most important nutritional factors in fry production of marine fish, were compared between hatchery-produced and wild-caught milkfish Chanos chanos fry. The most striking difference found between the fry was in docosahexaenoic acid (DHA: 22:6n-3) levels: DHA levels in hatchery-produced fry were only 37% and 18% of those in wild-caught fry in the polar lipids and neutral lipids, respectively. However, high DHA levels were detected in ovary and spawned eggs from hatchery-reared broodstock. Investigation on the time course change in DHA levels of hatchery-produced fry revealed that the DHA levels of polar lipids drastically declined from 25% at day 0 posthatching to 5% at day 14 posthatching. Nannochloropsis sp. and rotifers Brachionus sp., which were used as live food from day 2 to day 14, did not contain DHA with relatively high eicosapentaenoic acid (EPA: 20:5n-3) levels. DHA level was restored to 13% in 45-day old fry by feeding of formulated diets with a substantial amount of DHA from day 15. Thus, the lack of DHA in the live food appears to lead to the low DHA level in hatchery-produced fry. On the other hand, the cost of DHA enrichment for one milkfish fry was estimated to be 2.6 Philippines centavos, which is equivalent to about 10% of the market price of milkfish fry. The increase of the production cost might not be accepted in domestic hatcheries under competitive marketing with imported fry. Financial and marketing support by the government will be one of the measures to encourage the stable production of domestic milkfish fry with high quality in the Philippines. It is also necessary to conduct institutional campaigns to inform local fry producers and milkfish farmers of the importance of DHA-enrichment.
Turkish Journal of Fisheries and Aquatic Sciences, Dec 1, 2012
Fatty acids compositions were analyzed in neutral lipids (NL) and polar lipid (PL) of gonads of N... more Fatty acids compositions were analyzed in neutral lipids (NL) and polar lipid (PL) of gonads of Nile tilapia, ayungin and African catfish to elucidate some guesses for the fatty acids requirements for broodstock. The high value detected for both C16:0, C18:1 n-9 in all samples reflects a requirement for energy metabolism during the course of gonad development. The Lower proportion of polyunsaturated fatty acids (PUFA) was found in the NL of all gonads samples compared to PL. The higher percentages of n-3 HUFA in PL with respect to NL, suggests the importance of HUFA in the reproductive processes. In PL and NL, arachidonic acid (ARA) was the most abundant n-6 PUFA (ranged from 2.59 to 11.33% and from 0.16 to 3.19%, respectively). A relatively higher particularly eicosapentaenoic acid (EPA)/ docosahexaenoic acid (DHA) ratio was obtained in both NL and PL. All wild species studied are characterized by high ARA/EPA ratio in PL ranged from 1.72 to 5.47. Therefore, it is necessary to take into consideration not only the individual levels of HUFA but also the correct ratio among them (ARA/EPA/ DHA) through controlling LA and LNA level and ratio in the diets of tropical freshwater broodstocks.
Journal of Aquaculture Research and Development, 2011
Journal of Aquaculture Research & Development J o u rn al of Aq u a c u lt u re Rese ar c h & D e... more Journal of Aquaculture Research & Development J o u rn al of Aq u a c u lt u re Rese ar c h & D evelopm e n t
Japan International Research Center for Agricultural Sciences eBooks, 2007
Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry av... more Fry of tropical marine fish needed for aquaculture still comes mostly from the wild. Thus, fry availability is a major constraint in the development and extension of aquaculture, especially in rural areas of developing regions. Although the mission of hatcheries is to provide a stable fry production and supply for farmers, fry production remains variable due to poor fecundity and low survival. For the last four years (2002-2005), SEAFDEC/AQD and JIRCAS have conducted the collaborative project that was aimed at developing advanced diets for improving egg production/quality (2002-2005) and larvae/fry quality (2004-2005) through dietary manipulation. Larval rearing tests: In 2005, larval rearing tests (4 trials with rotifers) were conducted to investigate the effects of enriched-live food (4treatments: low (CS) and high (DHAPS) HUFA with or without arachidonic acid supplementation) on survival and growth in rabbitfish Sigunus guttatus fry. Fry fed the rotifers enriched with a combination of DHAPS+5% ArA showed the best survival (44.4±4.5% for D17 fry in the 4th trial).Growth was not different among the treatments (CS, CS+5% ArA, DHAPS, DHPS+5% ArA). Broodstock tests: From March, 2005 to January,2006, a feeding test has been conducted to investigate the effects of dietary ArA supplementation (0% for diet 1, 0.3% for diet 2 and 0.6% for diet 3) on egg production and quality of wild-caught and hatchery-bled rabbitfish broodstock. The broodstock spawned 13 times for diet1 (six pairs), 14 times for diet 2 (five pairs) and 17 times for diet 3 (six pairs) during the period of May 2005 to January, 2006. The total numbers ofhatched-larvae were 3,818 x 103 for diet 1, 4,391 x 103 for diet 2 and 4,597 x 103 for diet 3. The % of normal larvae did not differ among the dietary treatments. Considering together with the results of mangrove red snapper (2003) and rabbitfish (2004), the optimum level of ArA incorporation appears to be between 0.5% and 0.7%. Judging from the results of fatty acid analysis, DHA and arachidonic acid should be supplemented to diets at the same time as to make DHA/arachidonic acid ratio appropriate. Thus, the present study clearly shows that dietary arachidonic acid supplementation is very promising for the development of fry production technologies in tropical areas
Japan International Research Center for Agricultural Sciences eBooks, 2007
Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organi... more Arachidonic acid (ArA) was not a minor component, and ArA distributes widely in coral reef organisms. Seagrass had high linoleic acid and linolenic acid levels with low Ara, EPA and DHA levels, while some species of seaweed had intermediate or high ArA levels (5% to 12%). In starfish, sea cucumber and some species of corals, ArA was the first major fatty acid (20% to 30%), but DHA levels were very low. Bivalves, abalone and shrimps had intermediate ArA levels. Total lipids of abdominal muscle and liver of dugong had respectively ArA levels of 7.8% and 11.0%, which were higher than EPA levels (2.4% and 1.6%), but DHA levels (0.4% and 2.3%) were low. It is clear that ArA is a major fatty acid in coral reef animals. The present results suggest that the existence of an ArA-rich food chain may be widespread in coral reef areas, and that the widespread existence of ArA-rich food chain may lead to intermediate or high ArA contents in tropical species
Six tropical freshwater species were collected from Philippines in order to study the characteris... more Six tropical freshwater species were collected from Philippines in order to study the characteristic of polyunsaturated fatty acids distributions. 16:0 and 18: l n-9 were the predominant saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) in both neutral lipids (NL) and polar lipids (PL). There was an absence or very low values of n3 highly unsaturated fatty acid (HUFA) in NL of all species. However these fatty acids found in PL of all species studied with higher levels. The high proportions of docosahexaenoic acid (DHA) in PL were found with catfish Arius (20.71%), ayungin (17.64%), and snakehead (17.09%) whereas anabas (4.21%) gave lower DHA content. In PL, arachidonic acids (ARA) was found in high proportions, and also is superior to eicosapentaenoic acid (EPA) (ranged from 3.35 to 10.67% and from 0.42 to 4.74%, respectively). Tilapia lipid appears to be intermediate in nutritional quality between all species studied; the proportions of DHA, EPA and ARA in PL were 16.27%, 4.52% and 9.36%, respectively. According to the n-3/n-6 ratio in both fractions, only ayungin is in the range typical of freshwater fish. Our results indicate that the wild tropical freshwater fish studied here are not good sources of n-3 HUFA fatty acids. Therefore, aquatic nutritionists and farmers should combine their efforts in order to manipulate the nutritional quality of these species to enhance their n-3 HUFAs concentrations especially when these species are reared in captivity system. The wash-out strategy may provide an adequate description of the changes in the fillet lipid fatty acid profiles of fatty fish.
World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a ge... more World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a general understanding that the advancement of aquaculture is very important for food security and poverty alleviation, aquaculture in Africa is insignificant compared to the rest of the world. African aquaculture contributed only 1.2% (463 × 10 3 Mt) of world aquaculture production. Moreover, our calculation based on FAO statistics revealed that the average per capita consumption of fish in Africa decreased from 9 kg in 1990 to 7.8 kg in 2001. This decrease in the per capita consumption of fish appears to be a threatening sign for food security in Africa. There are many political, economic and technical issues that are obstructing the development and promotion of aquaculture in Africa. Egypt, the desert but rice producing country, has a long history of aquaculture and is the leading producer, especially of freshwater aquaculture in Africa. Total aquaculture production in Egypt in 2002 was 376 × 10 3 Mt, which supplied 81% of that in Africa. In the present review, based on the case of Egypt, we propose measures and research areas to develop and promote rice-fish culture and desert aquaculture. Rice-fish culture is a model of aquaculture styles for wet and pluvial regions, and desert aquaculture is also a model for arid and semi-arid regions not only in Egypt but also for other African countries. Poor knowledge on fish feeds and feeding technology is one of the major constraints in the expansion of aquaculture. In order to improve and increase the productivity of aquaculture in Africa, we propose measures and research subjects for developing supplementary and complete feeds using regional ingredients.
The present study was financially supported by the collaborative project titled “Studies on Susta... more The present study was financially supported by the collaborative project titled “Studies on Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas” between Japan International Research Center for Agricultural Sciences, Japan and the Aquaculture Department, SEAFDEC, Philippines.
Lipoprotein lipase (LPL) is a key enzyme of lipid metabolism. The elucidation of the structure, f... more Lipoprotein lipase (LPL) is a key enzyme of lipid metabolism. The elucidation of the structure, function and regulation of LPL is important for understanding the lipid metabolism in fish. Recently, we have cloned the LPL gene of red sea bream (Pagrus major) and characterized it by cDNA and genomic structure analysis. Subsequently, using the cloned sequence, gene expression has been investigated. We review in this report the features of red sea bream LPL gene. Red sea bream LPL gene spans 6.3kb of the genome and is organized into ten exons and nine introns. The deduced amino acid sequences showed high degree of similarities to the LPLs of other animals. In a 1.1kb 5' flanking region, the homologous sequences for the response elements of Insulin, glucocorticoid and thyroid hormone were detected. These results suggest the hormonal regulation of the LPL gene expression. Red sea bream LPL gene was expressed in various tissues including adipose tissue, heart, liver (hepatopancreas) and muscle. A fourteen-week feeding experiment was conducted to investigate the effects of feeding condition and dietary lipid level. The results suggest that LPL gene expression in visceral adipose tissue and liver is regulated in tissue-specific manner. The expression level in adipose tissue was down-regulated during starvation whereas it was up-regulated in liver. The effects of dietary lipid level on the gene expression were not observed. These results will facilitate further study on the function and regulation of the LPL in fish.
A two-phase experiment was conducted to examine the effects of dietary fat and adiposity on Ž y1.... more A two-phase experiment was conducted to examine the effects of dietary fat and adiposity on Ž y1. feed intake of red sea bream. In Phase 1, juveniles 9.7 g, 20 fish tank , 4 replicates were fed Ž y1 y1. Ž low fat LF; 15.3% fat, 60.6% protein, 22.2 kJ g energy, 0.61 g ml density or high fat HF; y1 y1
Fingerling yellowtail Seriola quinqueradiata (initial mean body weight 4.3 g), an active pelagic ... more Fingerling yellowtail Seriola quinqueradiata (initial mean body weight 4.3 g), an active pelagic fish, were reared under fed (4 weeks) and unfed (1 week) conditions to investigate the effects of swimming exercise on growth performance and whole body composition. The fish were raised in three water velocities: < 0.3 body length/s (bl/s), 1.0 bl/s, and 2.25 bl/s and fed diets containing two fat levels (13.2 and 20.3%). The exercised fish had significantly higher weight gains and feed efficiencies than the unexercised fish in both dietary fat levels. A second-order polynomial suggested that the optimum water velocity for the growth occurred at about 1.6 bl/s. The whole-body crude protein and fat contents were higher in the exercised fish than in the unexercised fish, and consequently apparent body protein and fat retentions were improved in both dietary fat levels by swimming. However, during 1 week starvation, body fat loss/g body weight loss was higher in the exercised fish than in the unexercised fish. The results of the present study clearly show that swimming condition improves growth performance of fingerling yellowtail, and suggest that swimming exercise stimulates both anabolism and catabolism of protein and fat; however, under fed conditions anabolism appears superior to catabolism.
World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a ge... more World aquaculture production in 2002 reached 39.8 million metric tons (Mt). However, despite a general understanding that the advancement of aquaculture is very important for food security and poverty alleviation, aquaculture in Africa is insignificant compared to the rest of the world. African aquaculture contributed only 1.2% (463 × 10 3 Mt) of world aquaculture production. Moreover, our calculation based on FAO statistics revealed that the average per capita consumption of fish in Africa decreased from 9 kg in 1990 to 7.8 kg in 2001. This decrease in the per capita consumption of fish appears to be a threatening sign for food security in Africa. There are many political, economic and technical issues that are obstructing the development and promotion of aquaculture in Africa. Egypt, the desert but rice producing country, has a long history of aquaculture and is the leading producer, especially of freshwater aquaculture in Africa. Total aquaculture production in Egypt in 2002 was 376 × 10 3 Mt, which supplied 81% of that in Africa. In the present review, based on the case of Egypt, we propose measures and research areas to develop and promote rice-fish culture and desert aquaculture. Rice-fish culture is a model of aquaculture styles for wet and pluvial regions, and desert aquaculture is also a model for arid and semi-arid regions not only in Egypt but also for other African countries. Poor knowledge on fish feeds and feeding technology is one of the major constraints in the expansion of aquaculture. In order to improve and increase the productivity of aquaculture in Africa, we propose measures and research subjects for developing supplementary and complete feeds using regional ingredients.
The characteristics of lipid deposition in juveniles of red sea bream Pagrus major, yellowtail Se... more The characteristics of lipid deposition in juveniles of red sea bream Pagrus major, yellowtail Seriola quinqueradiata, and Japanese flounder Paralichthys olivaceus, were investigated by feeding diets with three lipid levels (approximately 11, 16 and 20%). In red sea bream, the viscera contributed 40-50% to the whole body lipid store and deposited 35-39% of dietary lipid intake (body lipid gain/lipid intake : lipid deposition ratio), while the carcass contributed 40% and deposited 30-37%. In yellowtail, 50% of the whole body lipid store was found and 25% of dietary lipid intake was deposited in the carcass, while less than 10% was found and about 3% was deposited in the viscera. In Japanese flounder, although 80% of the whole body lipid store was located in the carcass, the lipid deposition ratio of the carcass decreased from 33% down to 19% as the increase of lipid intake, and the viscera represented around 10% of whole body lipid store and deposited 3% of lipid intake. Thus, the juveniles showed different traits of body lipid deposition in their responses to changes in dietary lipid level.
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Papers by Hiroshi Ogata