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Grow-out Stage (grow-out + stage)
Selected AbstractsHistopathological studies on viral nervous necrosis of sevenband grouper, Epinephelus septemfasciatus Thunberg, at the grow-out stageJOURNAL OF FISH DISEASES, Issue 7 2004S Tanaka Abstract Viral nervous necrosis caused by sevenband grouper nervous necrosis virus (SGNNV) has occurred in grow-out stages (0,3 years old) of sevenband grouper, Epinephelus septemfasciatus, since the 1980s. In the present study, based on histopathological features of the central nervous system (CNS) in naturally diseased fish, pernasal infection experiments using grow-out fish were performed and pernasal infection was established as a putative invasion route of SGNNV. The definite SGNNV-targeted cells were determined by histopathological studies including indirect fluorescent antibody test and electron microscopy. Nerve cells in the olfactory lobe were most extensively necrotized with vacuolation followed by infiltration of microglia and macrophages. Purkinje cells and Golgi cells were extensively infected in the cerebellum. Megalocells and small nerve cell nuclei were also infected in the preoptic area, thalamus, medulla oblongata and spinal cord. Only a few small nerve cells were infected in the olfactory bulb and optic tectum. The retina of some diseased fish displayed vacuolated bipolar cells of the inner nuclear layer and in the ganglion cell layer. These SGNNV-infected nerve cells displayed viroplasmic inclusions containing virions, vacuoles and myelin-like structures. Based on observed histopathological changes, the lesion of the CNS was characterized by encephalitis but not encephalopathy. [source] Divergent selection for shell length in two stocks of small abalone Haliotis diversicolorAQUACULTURE RESEARCH, Issue 6 2010Wei-Wei You Abstract To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large-selected and small-selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow-out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large-selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow-out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability. [source] Growth and survival of three small abalone Haliotis diversicolor populations and their reciprocal crossesAQUACULTURE RESEARCH, Issue 13 2009Wei-Wei You Abstract The aquaculture industry of small abalone Haliotis diversicolor in southern China is now close to collapse because of high mortality at the grow-out stage. To examine if survival and growth (shell length increase) could be improved by cross breeding among populations, a 3 × 3 complete diallel cross was conducted among three populations from Japan (A), Taiwan (B) and Vietnam (C). Performances in growth rate and survival at early juvenile, later juvenile and grow-out stages were compared among the six reciprocal cross lines and three parental lines. Magnitude of heterosis for survival and growth varied among cross lines in the three growing stages. As to mid-parent heterosis, HAB was significantly (P<0.01) higher than HAC and HBC at all three growing stages for both growth and survival, and all mid-parent heterosis fell between the two corresponding single-parent heterosis. HAB was 6.84% for shell length and 69.09% for survival at Day 420. Our results of high survival heterosis in line AB and line BA show that crossbreeding between different populations can benefit the small abalone breeding programs and the industry. [source] Production of a base population and its responses to F1 selection in the bay scallop, Argopecten irradians irradians Lamarck (1819)AQUACULTURE RESEARCH, Issue 9 2008Haibin Zhang Abstract A base population of the bay scallop, Argopecten irradians irradians Lamarck, was produced by crossing two cultured bay scallop populations. After 1 year of rearing, the top 10% truncation selection of the top 10% (i=1.755) was carried out in the base population of about 1300 adults. A control parental group with a an identical number to the select parental group was randomly selected from the entire population before isolation of the select parental group. The result showed that, at the larval stage, the growth rate of larvae in the selected line was significantly higher than that of the control (P<0.05), and that the genetic gain was 6.78%. Owing to the lower density of control at the spat stage, the mean shell length of the control line was larger than that of the select line at day 100. When the same density was adjusted between two lines in the grow-out stage (from day 100 to 160), the daily growth rate of the selected line was significantly higher than that of the control line (P<0.05). Survival of the select line was significantly larger than that of the control line in the grow-out stage. In conclusion, the results obtained from this experiment indicate that selective breeding from a base population with a high genetic diversity established by mass spawning between different populations appears to be a promising method of genetic improvement in bay scallop, A. irradians irradians Lamarck. [source] Growth and performance of Penaeus semisulcatus (de Haan) fed with two commercial shrimp feedsAQUACULTURE RESEARCH, Issue 15 2006Abdul Aziz Al-Ameeri Abstract Two feeding trials were conducted in two stages to compare growth and performance, grow-out (1,9 g b.w.) and fattening (13,19 g b.w.), of Penaeus semisulcatus. Shrimps were fed with two commercial feeds: P. monodon feed and P. japonicus feed. Both experiments were conducted using an indoor flow-through tank culture system. The results reveal that the growth performance of shrimp fed with P. japonicus feeds (0.91 g shrimp,1 week,1) for the grow-out stage was significantly better than shrimp fed with P. monodon feeds (0.63 g shrimp,1 week,1). The growth performance of shrimp fed with P. monodon feed (0.56 g shrimp,1 week,1) for the fattening stage was significantly better than shrimp fed with P. japonicus feed (0.42 g shrimp,1 week,1). The feed conversion ratios of both diets for the two sizes did not differ significantly. Thus, it is recommended that P. japonicus feeds be fed to P. semisulcatus during the grow-out stage. During the fattening stage, the better growth performance of the shrimp fed with P. monodon feed makes it a better feed. However, colour and overall acceptability of shrimp fed with P. japonicus feed were generally higher than those fed with P. monodon feed. [source] Histopathological studies on viral nervous necrosis of sevenband grouper, Epinephelus septemfasciatus Thunberg, at the grow-out stageJOURNAL OF FISH DISEASES, Issue 7 2004S Tanaka Abstract Viral nervous necrosis caused by sevenband grouper nervous necrosis virus (SGNNV) has occurred in grow-out stages (0,3 years old) of sevenband grouper, Epinephelus septemfasciatus, since the 1980s. In the present study, based on histopathological features of the central nervous system (CNS) in naturally diseased fish, pernasal infection experiments using grow-out fish were performed and pernasal infection was established as a putative invasion route of SGNNV. The definite SGNNV-targeted cells were determined by histopathological studies including indirect fluorescent antibody test and electron microscopy. Nerve cells in the olfactory lobe were most extensively necrotized with vacuolation followed by infiltration of microglia and macrophages. Purkinje cells and Golgi cells were extensively infected in the cerebellum. Megalocells and small nerve cell nuclei were also infected in the preoptic area, thalamus, medulla oblongata and spinal cord. Only a few small nerve cells were infected in the olfactory bulb and optic tectum. The retina of some diseased fish displayed vacuolated bipolar cells of the inner nuclear layer and in the ganglion cell layer. These SGNNV-infected nerve cells displayed viroplasmic inclusions containing virions, vacuoles and myelin-like structures. Based on observed histopathological changes, the lesion of the CNS was characterized by encephalitis but not encephalopathy. [source] Divergent selection for shell length in two stocks of small abalone Haliotis diversicolorAQUACULTURE RESEARCH, Issue 6 2010Wei-Wei You Abstract To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large-selected and small-selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow-out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large-selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow-out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability. [source] Growth and survival of three small abalone Haliotis diversicolor populations and their reciprocal crossesAQUACULTURE RESEARCH, Issue 13 2009Wei-Wei You Abstract The aquaculture industry of small abalone Haliotis diversicolor in southern China is now close to collapse because of high mortality at the grow-out stage. To examine if survival and growth (shell length increase) could be improved by cross breeding among populations, a 3 × 3 complete diallel cross was conducted among three populations from Japan (A), Taiwan (B) and Vietnam (C). Performances in growth rate and survival at early juvenile, later juvenile and grow-out stages were compared among the six reciprocal cross lines and three parental lines. Magnitude of heterosis for survival and growth varied among cross lines in the three growing stages. As to mid-parent heterosis, HAB was significantly (P<0.01) higher than HAC and HBC at all three growing stages for both growth and survival, and all mid-parent heterosis fell between the two corresponding single-parent heterosis. HAB was 6.84% for shell length and 69.09% for survival at Day 420. Our results of high survival heterosis in line AB and line BA show that crossbreeding between different populations can benefit the small abalone breeding programs and the industry. [source] | ||||||||||