• The Korean Journal of Malacology
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• v.25 no.3
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• pp.189-196
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• 2009

Based on 1,260 samples, the age and growth of purple whelk, Rapana venosa (Valenciennes) (Gastropoda:Muricidae) have been investigated. The samples were collected monthly during one year time (from February, 2004 to January, 2005) from the West Sea of Korea. The age of R. venosa was determined by the ring of the operculum analysis. The relationship between whelk's shell height and ring radius in each ring group was expressed as an equation of linear regression and later a correspondence in each ring formation was determined. Based on the monthly variations in the marginal index (MI) of the operculum, it was assumed that the ring of this species has been formed once a year during the period from July to August. The relationship between shell height and shell width was expressed by the equation SW = 0.7867 SH - 6.3988 ($R^2$=0.8604); and between shell height and total weight by the equation $TW=0.0000626{\times}SH^{3.206}$ ($R^2$=0.8324). The purple whelk's spawning period was estimated through the fatness analysis and has occurred during the period from May to July. Obtained results suggests that the ring formation occurs once a year (in July) and the length of time period since the first ring has been formed on the operculum is approximately 13 months (1.08 year). The purple whelk's growth curves for shell height and total weight fitted to the von Bertalanffy's equation and were expressed as follows: $SH_t=199.653(1-e^{-0.104(t+2.478)}$ $TW_t=1484.105(1-e^{0.104(t+2.478)})^{3.206}$.

• The Korean Journal of Malacology
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• v.32 no.3
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• pp.149-155
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• 2016

To assess the effects of environmental factors on the sustainability of cultured ark shell Scapharca broughtonii production, we investigated the habitat characteristics of shellfish-farming bays (Gangjin Bay, Yeoja Bay, Keoje Bay and Deukryang Bay). We measured the physiochemical parameters (temperature, salinity, dissolved oxygen, nutrients, chemical oxygen demand and Chlorophyll a) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several shellfish-farming bays to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain sizes for Gangjin Bay, Yeoja Bay and Keoje Bay were similar, at the ratio of silt and clay in comparison with Deukryang bay of it. The C/N ratio was more than 5.9, reflecting the range arising from the mix of marine organisms and organic matter. The C/S ratio (more than 4.2) showed that the survey area had anoxic or sub-anoxic bottom conditions. The index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. We suggested that the growth of ark shell Scapharca broughtonii in the shellfish-farming bay was effected by the various environmental conditions.

• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.213-220
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• 2002

This study was conducted to investigate the effects of feeding probiotics on the egg quality and excretal noxious gas in laying hens. One hundred forty four, 36 weeks old ISA brown commercial layer, were employed in a 28 d feeding trial with a 7 d adjustment period. Dietary treatments are 1) control(basal diet), 2) PB0.3(basal diet+0.3% probiotics), 2) PB0.6(basal diet+0.6% probiotics). For overall period, hen-day egg production, egg weight and egg shell breaking strength tended to increase (P>0.05) by dietary probiotic supplementation. Egg shell thickness was improved by supplementation of probiotics(linear effect, P$<$0.01). Diets PB0.3 and PB0.6 improved the yolk color compared to control diet(linear effect, P$<$0.02). As supplementation level of probiotics increased in the diets, egg yolk index tended to increase(linear effect, P$<$0.04). $NH_3$-N concentration in excreta fed PB0.6 diet was significantly (P$<$0.04) lower than either control or PB0.3 diet. In conclusion, supplementing probiotics to a Corn-SBM diet for laying hens increased egg shell thickness, yolk color and decreased egg yolk index, and decreased excretal $NH_3$-N concentration.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.9-17
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• 2003

The gonad index (GI), reproductive cycle with gonad developmental phases, first sexual maturity and the sex ratio of the jedo venus, Protothaca jedensis, on the coastal waters of Boryeong, Korea were investigated by histological study. Samples were collected from the subtidal zone of Boryeong, Korea from January to December, 1999. Monthly changes in the gonad index in femal and male clams gradually increased from February and reached the maximum in May, and then the values rapidly decreased from June and reached the minimum in November as seen in variations of the reproductive cycle. The spawning period of this species was once a year between May and July, there was a spawning peak between June and July when seawater temperature was over 20$^{\circ}C$. The reproductive cycle of this species in female and male clams can be classified into five successive stages: early active stage (December to March), late active stage (February to June), ripe stage (April to July), partially spawned stage (May to July) and spent/inactive stage (July to January). Percentages of first sexual maturity of female and male clams of 30.1-35.0 mm in shell length were 52.6% and 60.0%, respectively, and 100% for the clams over 45.1 mm in shell length. The sex ratio of individuals > 30.1 mm in shell length was 1:1 (X$^2$ = 0.40, p > 0.05).

• The Korean Journal of Malacology
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• v.24 no.2
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• pp.109-119
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• 2008

In order to investigate the possibility of yearly-harvest, we carried out growth experiment(shell height, meat weight and condition index) for of the artificial oyster spat, which suspended in three different times before the season for natural spat around coastal waters of Gyeongnam Province. Shell growth of spats suspended in June showed higher than those in April and May. In meat weight, the growth of spats was significantly elevated from October, of which significant difference was observed depending on growing farms(Gosung$\geq$80 mm) and October on the meat weight level($\geq$5 g).

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.175-185
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• 2012

To clarify reproductive ecology of the melania snail Semisulcospira coreana (v. Martens, 1886) in Bukhan River, gonad development, fatness, gonad index, sex ratio, first sexual maturity of population, monthly change of larvae number and developmental stages in brood pouches were investigated by six identification methods. As maturation progrsses, the sex of the snali can be distinguishable easily by color:: the ovary being blue-green and testis light yellow. The sex ratio of female to male individuals over 13.95 mm shell height was significantly different from 1:1 (${\chi}^2$ = 38.45, p < 0.05). The sex ratio of female to male individuals changed drastically according to the season, Based on the monthly variations of fatness, gonad index and histological analysis, spawning occurred twice a year (spring and autumn) and the mean size of matured eggs was $450{\mu}m$ in diameter. The monthly change of larval number in brood pouch showed also two distinct peaks in March and September during the year. The average number of larvae in brood pouches was 286 - 862 individuals. In this study, the number of larvae in the brood pouches were a minimum in December and a maximum in March (975 larvae). The biological minimum size (the size at 50% of group sexual maturity) of the melania snail was 13.95 mm in shell height in females and males. All females over 15 mm in shell height possesed brood pouches.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.179-183
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• 1980

The efficiency of energy transfer by a population of the farmed pacific oyster, Crassostrea gigas was studied during culture period of 10 months July 1979-April 1980, in Geoje-Hansan Bay near Chungmu City. Energy use by the farmed oyster population was calculated from estimates of half-a-month unit age specific natural mortality rate and data on growth, gonad output, shell organic matter production and respiration. Total mortality during the culture period was estimated approximate $36\%$ from data on survivor individual number per cluster. Growth may be dual consisted of a curved line during the first half culture period (July-November) and a linear line in the later half period (December-April). The first half growth was approximated by the von Bertalanffy growth model; shell height, $SH=6.33\;(1-e^{0.2421(t+0.54)})$, where t is age in half-a-month unit. In the later half growth period shell height was related to t by SH=4.44+0.14t. Dry meat weight (DW) was related to shell height by log $DW=-2.2907+2.589{\cdot}log\;SH,\;(2, and/or log $DW=-5.8153+7.208{\cdot}log\;SH,\;(5. Size specific gonad output (G) as calculated by condition index of before and after the spawning season, was related to shell height by $G=0.0145+(3.95\times10^{-3}{\times}SH^{2.9861})$. Shell organic matter production (SO) was related to shell height by log $SO=-3.1884+2.527{\cdot}1og\;SH$. Size and temperature specific respiration rate (R) as determined in biotron system with controlled temperature, was related to dry meat weight and temperature (T) by log $R=(0.386T-0.5381)+(0.6409-0.0083T){\cdot}log\;DW$. The energy used in metabolism was calculated from size, temperature specific respiration and data on body composition. The calorie contents of oyster meat were estimated by bomb calorimetry based on nitrogen correction. The assimilation efficiency of the oyster estimated directly by a insoluble crude silicate method gave $55.5\%$. From the information presently available by other workers, the assimilation efficiency ranges between $40\%\;and\;70\%$. Twenty seven point four percent of the filtered food material expressed by energy value for oyster population was estimated to have been rejected as pseudofaeces : $17.2\%$ was passed as faeces; $35.04\%$ was respired and lost as heat; $0.38\%$ was bounded up in shell organics; $2.74\%$ was released as gonad output, $2.06\%$ was fell as meat reducing by mortality. The remaining $15.28\%$ was used as meat production. The net efficiency of energy transfer from assimilation to meat production (yield/assimilation) of a farm population of the oyster was estimated to be $28\%$ during culture period July 1979-April 1980. The gross efficiency of energy transfer from ingestion to meat production (yield/food filtered) is probably between $11\%\;and\;20\%$.

• Journal of Pharmaceutical Investigation
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• v.31 no.2
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• pp.81-87
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• 2001

The purpose of this study was to investigate the effect of additives on the powder characteristics of peonja dry elixir. Peonja dry elixirs were prepared with various amounts of dextrin using a spray-dryer, and their powder characteristics such as flow, cohesion and compressibility were evaluated as an angle of repose, cohesion index and compressibility index, respectively. Their powder characteristics were not significantly different from one another, indicating that the hydrophilic dextrin, a base of dry elixir hardly affected their powder characteristics. Peonja dry elixirs were prepared with 10% dextrin and various amounts of additives such as mannitol (hydrophilic excipient), sodium lauryl sulfate (surfactant), colloidal silica (hydrophobic excipient) and HPMC (polymer), respectively, and their angle of repose, cohesion index and compressibility index were measured. The powder characteristics of peonja dry elixirs prepared with mannitol were not significantly different from one another, indicating that the mannitol scarcely improved the powder characteristics of peonja dry elixirs. The angle of repose and cohesion index of peonja dry elixirs significantly decreased with increasing amount of sodium lauryl sulfate to 0.3% followed by no significant changes in them. The cohesion index of peonja dry elixir significantly decreased with increasing amount of colloidal silica. The angle of repose and cohesion index of peonja dry elixir significantly decreased with increasing amount of HPMC to 0.3% followed by an abrupt increase in them. However, the compressibility index of peonja dry elixir significantly increased with increasing amount of HPMC to 0.3% followed by an abrupt decrease in them. Our results suggested that a small amount of sodium lauryl sulfate, colloidal silica and HPMC improved markedly the powder characteristics of peonja dry elixirs due to forming stronger and less hygroscopic shell of peonja dry elixirs. Among the peonja dry elixirs studied, the peonja dry elixir prepared with 0.3% sodium lauryl sulfate and 0.3% HPMC had the lowest angle of repose of $27^{\circ}$ and cohesion index of 37.8%, and the highest compressibility index of 38.7%, respectively. Thus, sodium lauryl sulfate and HPMC appear to be promising additives for peonja dry elixir, if used in adequate amounts.

• Journal of Aquaculture
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• v.7 no.2
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• pp.77-87
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• 1994

The study was conducted to develop the suitable abalone's diets for the indoor tank culture. The young abalone Haliotis discus hannai Ino sized ca. 20, 30 and 40 nun in shell length were fed three different diets, dried sea mustard Undaria pinnatifida HARVEY (control), artificial diet and terrestrial plants e. g. Chinese cabbage and Perilla leaf for 2 years. The growth rate of abalones fed an artificial diet was slightly higher than that of abalones from the control. However, the growth rate of abalones from terrestrial plants was significantly lower than that of abalones fed a control or an artificial diet (P< 0.05). The daily feeding rate of young abalones from terrestrial plants was slightly higher than that of abalones from the control. While, that of abalones from an artificial diet was approximately $30\%$ of that of abalones from a control or a terrestrial plants diet. The feed efficiency of abalone from artificail diet was higher than that of abalones from a control or a terrestrial plants diet, and the smaller size of young abalone showed the higher the feed efficiency. The EFA index values ${{\sum}n9/(20:4n6+20:5n3+22:6n3}$ of the dried sea mustard and the artificial diet were 1.26 and 3.64, respectively. These values were favorable, but the value of terrestrial plant, Perilla leaf was 127.00 indicating poor EFA index for normal growth of abalone.

• Journal of Sericultural and Entomological Science
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• v.29 no.2
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• pp.24-30
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• 1987

To investigate suitable breeding system for the improvement of economic characters of the sexlimited dark egg colour strains, the four kinds of breeding methods which are represented as sibmating, repeated backcrossing, multi-backcrossing every other generation, and repeated hybridization were detected from the P to the F6. 1. Pupation ratio was varied between the four kinds of breeding methods and decreased gradually in order of repeated hybridization, mult-backcrossing every other generation and sib-matinv, and repeated backcrossing. 2. Repeated backcrossing, multi-backcrossing every other generation, and repeated hybridization with the exception of sib-mating were consiered as available breeding methods to improve single cocoon weight, cocoon shell weight and cocoon shell ratio of the sex-limited dark egg colour strains. 3. As for the responses of the economic characters form the P to the F6, pupation ratio was fluctuant and unstable, on the other hand single cocoon weight, cocoon shell weight and cocoon shell ratio increased remarkably in the F2, but in the subsequant generatios the increasing rate of each characters were fluctuant irregularly. 4. After the original sex-limited dark egg colour strains were bred under the corresponding breeding methods, from the P to the F6 the economic characters were approached to the level of normal breeding silkworm lines'. 5. It came to the consideration that the autosomal fragment which was translocated on the W chromosome had no physiologically significant effect on the expression of the economic characters because the Expression index (E) of the sex-limited dark egg colour strains was similar to that of normal silkworm lines. 6. From the results, it comes to the conclusion that the useful breeding methods to improve the economic characters of the sex-limited dark egg colour strains will be a line separation including fixation of the characters.