• Journal of Aquaculture
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• v.6 no.4
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• pp.235-253
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• 1993

The freshwater crab, Eriocheir japonicus inhabits from sub-tropical to temperate zone in Asia. This species belongs to a large size group among freshwater crabs. Common size of this crab is 5-6cm in carapace length and occasionally 7cm in carapace length. This species of crab used to inhabit in estuaries, rivers and inland waters in Korea. However, natural population recently has been rapidly decreased because of pollution and lost their habitats by suburban development. Therefore, development of proper methods of seedling production to increase natural stock became necessity. As parts of achieving this goal, duration from mating to spawning, egg incubation period, and egg development of this species were studied. The influence of temperatures and salinities on the egg incubation and hatching was also investigated. It took 2-8 hours from mating to egg spawning and the spawning lasted 3-9 hours from the first spawning. Egg numbers per female (6cm in carapace length) were 380,000­410,000. Optimum temperature for egg incubation was $17\~23^{\circ}C$ and optimum salinity, $14.0\~31.5\%o$. Incubation period of the eggs at $14^{\circ}C,\;17^{\circ}C,\;20^{\circ}C,\;26^{\circ}C,\;and\;28^{\circ}C$ was 42, 28, 21, 15, and 14 days. respectively. Relation between temperature (X) and incubation days (Y) was LogY = Log 2764.267 - 1.608 LogX. A female can spawn 4-6 times per year by manipulation of environmental conditions. Under the conditions of $18^{\circ}C\;and\;24.5\%o$, it took 6 days up to embryo formation, 18 days up to compound eye formation, 22 days up to abdominal movement, and 25 days up to hatch out as zoea larvae.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.4
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• pp.209-215
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• 2020

A winter forage tetraploid rye (Secale cereale L.) cultivar, 'Daegokgreen', was developed at the Department of Central Area Crop Science, NICS, RDA in 2016. The mutant line 'CG11003-8-B', which was induced from rye cultivar 'Gogu' (diploid) by colchicine treatment, was selected for its excellent agronomic performance and was placed in preliminary yield trials for one year, 2013. The line was designated "Homil59" and was tested for regional yield trials at the four locations in Korea from 2014 to 2016. Finally, the new cultivar was named as the 'Daegokgreen' (grant number 8274). The leaf of cultivar 'Daegokgreen' is wide, long and dark-green color. The cultivar also has a big-size grain with light-brown color. The heading date of cultivar 'Daegokgreen' was April 17 which was 2 days later than that of check cultivar 'Gogu'. The tolerance to cold and wet injury, and resistance to powdery mildew and leaf rust of the new cultivar were similar to those of the check cultivar but the resistance to the lodging of the new cultivar was stronger than that of the check. The average roughage fresh and dry matter yield of the new cultivar after 10 days from heading were 37.0 and 7.7 MT ha-1, respectively, which were similar to those (38.4 and 8.0 MT ha-1) of the check cultivar. The roughage quality of 'Daegokgreen' was higher in crude protein content (8.9%) than that of the check cultivar (7.9%), while was similar to the check in total digestible nutrients (56.9%). This cultivar is recommended for fall sowing forage crops at all of crop cultivation areas in Korea.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.8-31
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• 2023

To understand the distribution and formation mechanism of benthic foraminiferal assemblages, grain size analysis, ¹⁴C radiocarbon dating, and benthic foraminifera analysis were conducted on thirty-two surface sediments collected from the continental shelf of the northern East China Sea, respectively. Surface sediment was composed of sandy mud~muddy sand facies with an average of 52.04% of sand, 13.72% of silt, and 34.20% of clay. These sedimentary facies are palimpsest sediment. Benthic foraminifera was classified into a total of 48 genera and 104 species, including agglutinated foraminifera, calcareous-hyaline, and calcareous-porcelaneous foraminifera. The production rate of agglutinated foraminifera increased toward the Yangtze River area while that of planktonic foraminifera increased toward Jeju Island. Dominant species are Ammonia ketienziensis, Bolivina robusta, Eggella advena, Eilohedra nipponica, Pseudorotalia gamardii, Pseudoparrella naraensis. ¹⁴C radiocarbon datings of Bolivina robusta and Pseudorotalia gamardii with the highest production rate were 2,360±40 yr B.P. and 2,450±40 yr B.P., respectively. In the result of cluster analysis, three assemblages composed of P. gaimardii, B. robusta, and A. ketienziensis-P. naraensis were classified broadly. P. gaimardii assemblage is thought to be formed from about 2.5 yr B.P. at the sea area of the Yangtze River to 50 m in water depth affected by fresh water. B. robusta assemblage is thought to be formed from about 2.4 yr B.P. at the sea area of Jeju Island to 50~100 m affected by offshore water. And then, A. ketienziensisP. naraensis assemblage was formed in the northwest sea area (Central Yellow Sea Mud). These distributions and composition of benthic foraminiferal assemblages formed from about 2.5 yr B.P. in the northern East China Sea are thought to be due to the change of benthic ecology environment that occurred by the sea level increase during the late Holocene.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.97-114
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• 1977

The fresh water prawn, Macrobrachium rosenbergi(de Man) is a very common species in Indopacific region, which inhaits both fresh and brackish water in low land area, most of rivers and especially aboundant in the lower reaches which are influenced by sea water. It is one of the largest and commercial species of genus Macrobrachium, which is commonly larger than $18\~21cm$ in body length, from the basis of eye-stalked to the distal of telson. As a part of the researches in order to investigate the possibilities on transplantation and propagation of this species, this work dealt with the problems on the effects of chlorinities upon zoeal larvae and post-larvae 1). metamorphosis rate and optimum chlorinity for metamorphosis to post-larve, 2). tolerance and comparative survival rate on various chlorinties, from fresh water to sea water $(19.38\%_{\circ}\;Cl)$, which reared for six days upon each stage of zoeal larvae, 3). accomodation rate on chlonities which reared for twelve days after transmigration into variant chlorinities of the range from $3.68\%_{\circ}$ Cl to $1.53\%_{\circ}$ Cl in the way of rearing of the range from $3.82\%_{\circ}$ Cl to $11.05\%_{\circ}$ upon each stage of zoea, 4). tolerance on both of fresh and sea water upon zoeal larva and post-larva under the condition of $28^{\circ}C{\pm}1$ in temperature and feeding on Artenia salina nauplii, 5). relationship between various chlorinities and grwth of post-larvae under the condition of $28^{\circ}C$ in tmperature and feeding on meat of clam. Thus these investigations were performed in order to grope for a comfortable method on seedmass production. Up to the present, the study on the effects of chlorinity upon earlier zoeal larvae and post-larvae of Macrobrachium species has been scarcely performed by workers with the exception of Lewis(1961) and Ling (1962,, 1967), even so their works were not so detailed. On the other hand, larvae of several species of this genus were reared at the water which mixed sea water so as to carry out complete metamorphosis to post-larva by workers in order to investigate on earlier 1 arval and earlier post-larval development, such as Macrobrachium lamerrei (Rajyalakshmi, 1961), M. rosenbergi and M. nipponense (Uno and Kwoa, 1969; Kwon and Uno, 1969), M. acanthurs (Choudhury, 1970; Dobkin, 1971), M. carcinus(Choudhury, 1970), M. formosense(Shokita, 1970), M. olfersii (Duggei et al., 1975), M. novaehallandiae (Greenwood et al., 1976), M. japonicum (Kwon, 1974) and M. lar (Shokita, personal communication), and there fore it is regarded that chlorinity is, generally, one of absolute factors to rear zoeal larvae of brackish species of Macrobrachium genus. Synthetic results on this work is summarized as the follwings: 1) Zoeal larvae required different chlorinities to grow according to each stage, and generally, it is regarded that optimum range of living and growing is from $7.63\%_{\circ}Cl\to\;7.63\%_{\circ}Cl$, and while differences of metamorphsis rate, from first zoea to post-larva, is rarely found in this range, and however it occurs apparently in both of situation at $7.63\%_{\circ}Cl$ below and $16.63\%_{\circ}Cl$ above and moreover, metamorphosis rate is delayed somewhat in case of lower chlorinity as compared with high chlorinity in these situations. 2) Accomodation in each chlorinity on the range, from fresh water to sea water, is different according to larval stages and while the best of it is, generally, on the range from $14.24\%_{\circ}Cl$ to $8.28\%_{\circ}Cl$ and favorite chlorinity of zoea have a tendency to remove from high chlorinity to lower chlorinity in order to advance larval age throughout all zoeal stages, setting a conversional stage for eighta zoea stage. 3) Optimum chlorinity of living and growth upon postlarvae is on the range of $4.25\%_{\circ}Cl$ below, and in proportion as approach to fresh water, growth rate is increased. 4) Post-large are able to live better in fresh water in comparison with zoeal larvae, which are only able to live within fifteen hours, and by contraries, post-larvae are merely able to live for one day as compared with ?미 larvar, which are able to live for six days more in sea water $19.38\%_{\circ}Cl\;above$. 5) Also, in case of transmigration into higher and lower chlorinities in the way of rearing in the initial chlorinities $ 3.82\%_{\circ}Cl,\;7.14%_{\circ}Cl\;and\;11.05%_{\circ}Cl$, accoodation rate is a follow: accomodation capacity in ease of removing into higher chlorinities from lower chlorinities is increased in proportion as earlier stages, setting a conversional stage for eighth zoea stage, and by contraries, in case of advanced stages from eighth zoea it is incraesed in proportion as approach to post-larva stage in the case of transmigration into lower chlorinity from higher chlorinity. On the other hand, it is interesting that in case of reciprocal transmigration between two different chlorinitiess, each survival rate is different, and in this case, also, its accomodation in each zoea stage has a tendency to vary according to larval stages as described above, setting a conversional stage for eighth zoea stage. 6) It is likely that expension of radish pigments on body surface is directly proportional to chlorinity during the period of zoea rearing, and therefore it seems like all body surfacts of zoea larvae be radish coloured in case of higher chlorinity. 7) By the differences that each zoeal larvae, postlarvae, juvaniles and adult prawn are required different chlorinity for inhabiting in each, it is regarded that this species migrats from up steam to near the estuary of the river which the prawns inhabits commonly in natural field for spawning and growth migration. 8) It had better maintainning chlorinities according to zoeal stage for a comfortable method on seed-mass production that earlier larva stages than eighth zoea are maintained on the range from $8\%_{\circ}Cl\;to\;12\%_{\circ}Cl$ to rear, and later larva stages than eighth zoea, by contraries, are gradually regula ted-to love chlorininity of the range from $7\%_{\circ}Cl\;to\;4\%_{\circ}Cl$ according to advance for post-larva stage.

• Journal of Aquaculture
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• v.5 no.1
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• pp.29-67
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• 1992

Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.

• Journal of Aquaculture
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• v.21 no.4
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• pp.309-316
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• 2008

Effects of the various dietary additives on growth and tolerance of abalone Haliotis discus hannai to the stresses were determined in the 16-week feeding trial. Seventy juvenile (an initial body weight of 4.2 g) abalone per container were randomly distributed into 21, 50 L plastic rectangular containers each. The six kinds of experimental diets were prepared: control (CON) with no additive, by-product of green tea (BPG), extract of figs (EF), extract of green tea (EG), commercially available product of Hearok (PH), and Haematococcus (HC). In addition, dry sea tangle (ST) was prepared to compare the efficiency of the experimental diets. Fishmeal, soybean meal and shrimp head meal were used as the protein source, and dextrin, sea tangle powder and wheat flour, and soybean oil and fish oil were used as the carbohydrate and lipid sources, respectively in the experimental diets. The experimental diets were fed to abalone once a day at a satiation level with a little leftover. The feeding trial lasted for 16 weeks. At the end of the 16-week feeding trial, abalone was exposed to the different types of stresses (air exposure, and sudden changes of rearing temperature and salinity). Survival of abalone fed the sea tangle was highest. However, weight gain of abalone fed the EF, EG and PH diets was significantly (P<0.05) higher than that of abalone fed the BPG diet or dry sea tangle. Shell length of abalone fed the all experimental diets was significantly (P<0.05) higher than that of abalone fed the dry sea tangle. Accumulated mortality of abalone fed the sea tangle was low when exposed to the different types of stresses. Also, relatively low mortality was achieved in abalone fed the HC and EF diets. In considering these results, it can be concluded that the various sources of additives is effective to improve production of abalone, and Haematococcus and extract of figs can be considered as dietary additives to improve resistance of abalone against the different types of stresses.

• Journal of Life Science
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• v.30 no.1
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• pp.45-57
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• 2020

The prenatal period in livestock animals is crucial for meat production because net increase in the number of muscle fibers is finished before birth. However, there is no study on the growth and development mechanism of muscles in Hanwoo during this period. Therefore, to find candidate genes involved in muscle growth and development during this period in Hanwoo, mRNA expression data of longissimus in Hanwoo at 6 and 9 months post-conceptional age (MPA) were analyzed. We independently identified differentially expressed genes (DEGs) using DESeq2 and edgeR which are R software packages, and considered the overlaps of the results as final-DEGs to use in downstream analysis. The DEGs were classified into several modules using WGCNA then the modules' functions were analyzed to identify modules which involved in myogenesis and adipogenesis. Finally, the hub genes which had the highest WGCNA module membership among the top 10% genes of the STRING network maximal clique centrality were identified. 913(6 MPA specific DEGs) and 233(9 MPA specific DEGs) DEGs were figured out, and these were classified into five and two modules, respectively. Two of the identified modules'(one was in 6, and another was in 9 MPA specific modules) functions was found to be related to myogenesis and adipogenesis. One of the hub genes belonging to the 6 MPA specific module was axin1 (AXIN1) which is known as an inhibitor of Wnt signaling pathway, another was succinate-CoA ligase ADP-forming beta subunit (SUCLA2) which is known as a crucial component of citrate cycle.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.8
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• pp.919-928
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• 2017

The immuno-enhancing effects of alginate oligosaccharides from Sargassum coreanum were investigated. The alginate oligosaccharides were produced by an alginate-degrading enzyme from S. oneidensis PKA 1008. The degraded alginate oligosaccharides were visualized by thin-layer chromatography developed using a solvent system of 1-butanol/methanol/water, 4:1:2 (v/v/v). Alginate was degraded into dimmers at 60 h. As a result, the levels of Th1 cytokine [interferon $(IFN)-{\gamma}$ and interleukin (IL)-2] and Th2 cytokine (IL-6 and IL-10) increased with increasing incubation time compared to the control in vitro. Enzymatic extract treatment promoted proliferation of splenocytes at concentrations of 100 and 200 mg/kg at 24 h in vivo. Secretion of $IFN-{\gamma}$ and IL-2 significantly increased in a dose-dependent manner at 24 h as well as induced higher production of IgG2a in serum. Natural killer cell activity was measured and tended to increase. In addition, complete blood cell counts increased in a dose-dependent manner. These results indicate that alginate oligosaccharides produced by crude enzyme from S. oneidensis PKA 1008 may have significant immune activities.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.321-331
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• 2014

Patinopecten yessoensis is known to be farmed only in the northern part of the East Sea today. In an attempt to extend its production area, we have conducted experiments both in the northern and southern parts of the East Sea and studied on their growth in an aim to use the results for increasing overall productivity of the species. Early juvenile scallops producted in February 2014 showed an average shell length of $0.23{\pm}0.002$. The high growth group showed an average shell length and shell height of $4.11{\pm}0.08mm$ and $4.28{\pm}0.09mm$, respectively, in June while they were $23.63{\pm}3.4mm$ and $24.19{\pm}4.5mm$ in October. The low growth group showed an average shell length and shell height of $2.23{\pm}0.7mm$ and $1.99{\pm}0.9mm$, respectively, in June while they were $1.99{\pm}0.9mm$ and $17.59{\pm}4.5mm$ in October. The daily growth rate of the high growth group was 0.037 mm/day and 0.027 mm/day for the low growth group. In August, we measured the shell length of Patinopecten yessoensis from Yangyang-gun, Gangneung-si, Yeongdeok-gun, and Pohang-si. Patinopecten yessoensis from Pohang-si showed the best growth performance with its shell length of $26.90{\pm}3.6mm$. Patinopecten yessoensis from Yeongdeok was the second largest with its shell length of $23.56{\pm}3.4mm$. We presume that optimal water temperature and phytoplankton abundance of the two regions have contributed to the good growth performance of the species.

• Food Science of Animal Resources
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• v.29 no.5
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• pp.627-632
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• 2009

The objective of this study was to investigate the supplementation effect of selenium on beef color stability. A total of 15 Hanwoo steers were divided into 3 groups and 2 groups were administered with 0.9 ppm of one of two organic-selenium products, Organic-Se and Se-SMC (Se-spent mushroom compost) for 4 mon. The third group was the control group, which was not with fed selenium during the same period. The result of this study showed that there was no significant difference in meat color between the control and treatments when Hunter $L^*$, $a^*$, $b^*$, chroma, hue and total color difference (${\Delta}E$) were measured after 30 min of blooming. When the oxymyoglobin (OxyMb) contents were measured after beef samples were ground and stored for 48 h at $20^{\circ}C$ in an incubator, they were 26.04%, 28.52% and 33.78% for the control, Organic-Se and Se-SMC after 14 d of storage and 12.65, 18.98 and 18.72 after 21 d of storage at $4^{\circ}C$, respectively (p<0.05). The control had a significantly higher metmyoglobin (MetMb) content than Organic-Se and Se-SMC (p<0.05). This result indicated that selenium supplementation was effective in preventing the oxidation of myoglobin(Mb) and production of MetMb and thus was able to maintain the purplish fresh red color of the meat.