• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.591-599
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• 2019

The study was conducted to investigate the growth performance of two strains of Korean domestic chickens (KDC, i.e., 1A, and 2A). A total of 600, one-day-old female chicks were allocated in a completely randomized design to give 15 replicates for each strain (10 birds per pen). The chickens were fed (week 0 to 6: ad libitum; week 6 to 12: restricted feeding) commercial diets (week 0 to 5: crude protein 20.3% and metabolizable energy 3,059 kcal/kg; week 5 to 8: crude protein 18.6% and metabolizable energy 3,123 kcal/kg, and week 8 to 12: crude protein 16.7% and metabolizable energy 3,187 kcal/kg) together with fresh water. Body weight (BW) and feed intake were measured bi-weekly to calculate the average daily feed intake (ADFI), average daily gain (ADG), and subsequently the feed conversion ratio (FCR). The results indicate that the 1A crossbreed had a higher (p < 0.05) BW compared to the 2A crossbreed from week 6 to 10. A higher ADG (p < 0.05) was seen in the 1A crossbreed on week 6 and in the 2A crossbreed on week 8. Moreover, no difference (p > 0.05) was observed in the FCR between crossbreed 1A and 2A during the 12 weeks with the exception of week 8. Crossbreed 1A had (p < 0.05) an improved FCR compared to the 2A crossbreed on week 8. In conclusion, the 1A crossbreed had a higher growth performance compared to the 2A crossbreed for 12 weeks after hatching. This data can contribute by helping the KDC market.

• Korean Journal of Ichthyology
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• v.26 no.2
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• pp.89-98
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• 2014

Eggs development and early life history of the endangered Korean dwarf loach, Kichulchoia brevifasciata (Teleostei: Cobitidae) was investigated to provide basic information regarding biological characteristics and restoration. Adult fish specimens were sampled using a spoon net at Geurnsan-myeon, Goheung-gun, Jeollanam-do, Korea from June to July 2011. Since, spawning characteristics were analyzed, and females were induced to spawn by injecting Ovaprim (0.5 mL/kg) and their eggs were artificially fertilized with sperms by the dry method in the laboratory. Total length of mature female were 46~76 mm with GSI $9.6{\pm}3.77%$, and total length of mature male was 42~52 mm with GSI $3.5{\pm}1.04%$. Sex ratio (♂/♀) was 0.10, and there were no secondary sexual characteristics. The number of mature eggs was averaged $60{\pm}28.7$ per female. The lemon yellow eggs were slightly adhesive $1.46{\pm}0.07mm$ in diameter. The embryo hatched approximately 66 h after fertilization at $25^{\circ}C$, and the hatched larvae were averaged $5.5{\pm}0.07mm$ in total length (TL). At 6 days after hatching, the larvae averaged $9.0{\pm}0.29mm$(TL) and their yolk sac was completely absorbed. At 17 days after hatching, they entered the juvenile stage and reached $12.6{\pm}0.24mm$ (TL). At 80 days after hatching, the band patterns and external form of the juveniles were similar to those of adults, and they averaged $33.0{\pm}2.19mm$(TL).

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.84-96
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• 2022

The current study was conducted to evaluate the effect of calcium-enriched fatty acid supplementation on the growth performance, blood metabolites, intestinal morphology, carcass traits, and nutrient digestibility of broilers subjected to chronic heat stress. A total of 210 one-day-old broiler chicks (40.12 ± 0.25 g) were randomly allocated to one of five dietary treatments, to obtain six replicates per treatment. Broilers were subjected to chronic heat stress from day 21 to day 35, post-hatching, at 34℃ for 9 h per day. The body weight (BW) and feed intake of the experimental broilers were recorded weekly, and the average daily gain (ADG) and feed conversion ratio (FCR) were calculated accordingly. Rectal temperature was measured to compare the basal body temperatures between individuals, and blood samples were collected on days 21 and 35 to evaluate basal body temperature, serum total cholesterol, and the triglyceride content of the broilers. On days 21 and 35, one broiler from each cage (n=6) was euthanized to measure carcass trait parameters, nutrient digestibility in digesta, and intestinal morphology. On days 14, 28, and 35, the broilers fed 2.0% calcium-enriched fatty acids had higher BW (p < 0.05) than those fed the other diets. However, no differences (p > 0.05) were found in the average daily feed intake (ADFI) between dietary treatments over the 35 experimental days. On the other hand, on day 21, post-hatching, the broilers fed the 2.0% calcium-enriched fatty acid diet had improved (p < 0.05) dietary feed efficiencies compared to the other treatments. On day 28, the broilers fed the 5.0% of calcium-enriched fatty acid diet also had higher (p < 0.05) dietary feed efficiencies than those fed with the other dietary treatments. No effects (p > 0.05) on carcass weight, nutrient digestibility, intestinal morphology, or blood parameters were found between broilers fed with dietary treatments. This study demonstrated that the inclusion of an additive, containing 2.0% calcium-enriched fatty acid, to broiler diet could ameliorate the negative growth performance of broilers; and no interaction (p > 0.05) was observed between the calcium-enriched fatty acid and nutrient digestibility, digestive anatomy, blood metabolism, and carcass traits of broilers subjected to chronic heat stress conditions for 35 days post-hatching.

• International Journal of Industrial Entomology and Biomaterials
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• v.23 no.1
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• pp.175-178
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• 2011

Yeonnokjam is a newly bred high yield special silkworm strain for spring rearing, bred from Japanese originated green cocoon spinning strain Jam 315 and Chinese originated white cocoon spinning strain Jam 316. This strain showed high hatching ratio of 96% and high healthiness of 96.7% of pupatin ratio. And its spins heavier cocoon with somewhat shorter fiber length but thicker fineness. The merits of these_strains are short larval period and labor saving, and its breeding goals are producing polish green silk and use for education.

• International Journal of Industrial Entomology and Biomaterials
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• v.20 no.2
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• pp.115-116
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• 2010

The Eolrukmal and Hukpyobeom varieties were bred for special purpose such as experience and education. The Eolrukmal variety was selected and succeeded from the $F_1$ of Huka$\times$Galwon in 2004 summer. It has stripes and brown half-moon body marks. The Hukpyobeom variety was selected and succeeded from the $F_1$ of Remone$\times$Hukho in 2004 summer. It has black body color and bright yellow segments. They are healthy yellow cocoon spining varieties showing over 93% of high practical hatching ratio and 93.1% of emergence ratio. The Eolrukmal moth laid 450 egg/batch and the Hukpyobeom moth laid 440 egg/batch.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.351-362
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• 1989

Ecology of Crangon affinis was studied in the Nakdong River Estuary fron June 1988 to May 1989. The growth rate of female was similar to that of male. Size differences, however, were apparent between female and male. Sex ratio varies with season. The major spawning season was from June 1988 to May 1989 except for November 1988. The number of eggs of the largest ovigerous female (35.55mm TL) was over 4,000, while that of the smallest ovigerous female (15.05mm TL) more than 120. The mean number of eggs was 1778. The size of winter eggs is larger than that of the summer eggs. The mean percentage of egg loss from brooding to hatching was $29.06\%$. The rate of egg loss decreases with increasing age. Major component of food organisms includes mysids and polycheates.

• Ocean Science Journal
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• v.43 no.3
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• pp.127-133
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• 2008

Reproductive patterns of an epifaunal amphipod, Pontogeneia rostrata, were studied on Dolsando sandy shore in Korea. The life history pattern was iteroparous, with recruitment mainly occurring from winter to spring. The sex ratio was malebiased, especially during breeding periods. The mean body length of females was significantly larger than that of males. Brood size and egg volume were positively related to the body length of ovigerous females. There was no significant difference in brood size between successive breeding periods, but egg volumes were significantly higher in early winter (December) than in late spring breeding (May and June), increasing the probability of survival to hatching. These traits contribute to more reproductive potential in early winter than in late spring breeding. The mean brood size of epifaunal P. rostrata was larger but the mean egg volume smaller than that of infaunal amphipods in this sampling area. We suggest that reproductive effort for epifaunal species may be proportionally greater than for infaunal species in risky environments.

• Korean Journal of Poultry Science
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• v.40 no.3
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• pp.277-281
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• 2013

The experiment was undertaken to see the effects of Bacillus sp. on the growth performance and disease resistance to Salmonella sp. infections. The use of probiotic microbes in poultry is commonly practiced. In this study, Bacillus subtilis was tested using a total of 120 chicks of age of 1 day after hatching. The growth traits examined were body weight gain and feed conversion rate. And also, the Salmonella resistance of Bacillus subtilis was tested after the chicks were orally administered with Salmonella pullorum by gavage force injections. The result showed that Bacillus subtilis yielded a high feed efficiency, consequently increased growth rate. For the effect of Bacillus subtilis on Salmonella infection, Bacillus subtilis significantly improved the resistance to Salmonella pullorum infection. Various clinical symptoms of Salmonella infection were highly decreased by addition of Bacillus sp.

• Journal of Life Science
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• v.10 no.2
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• pp.164-168
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• 2000

To understand the biological characteristics of Corythucha ciliata occurring in Korea, developmental periods and its susceptibility to several insecticides were examined under growth chamber condition at $25^{\circ}C$. It took 11.1 day from egg to hatch. And duration of each stage up to the 5th nymph after hatching was 4.0, 2.1, 2.0, 2.9, and 4.0 days, respectively. Total duration from egg to adult was 26.1 days, preoviposition period was 12.2 days, and average number of eggs laid by a female was 83.0. Sex ratio of female was 51.6% and lifespan of female adult was 43.2% days. LC50 value of deltamethrin and esfenvalerate were 0.8 and 0.9 ppm, respectively. Insecticidal effects were better in pyrethroids than organophosphates and carbamates.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.3
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• pp.702-710
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• 2017

Recently, in many reptiles (14 genera of turtles in five families), common characteristics of incubation temperatures are known to determine the sexes of hatchlings in many species of turtles, including the map turtles, painted turtles and snapping turtles, emys turtle, etc. According to many researcher's reports, in general, incubation at $25^{\circ}C$ (cooler temperatures) produces all or mostly males, however, incubation at $31^{\circ}C$ (higher temperatures) or higher produces all or mostly females. Exceptionally, even cooler temperature ($20^{\circ}C$) produce females, they produced all or mostly females. Accordingly, it is well-known that incubation temperature is the sex determining agent in these turtles. However, this paper presents study of the sex ratio and nest ecology in natural spawning nest: Observations on hatching sex ratios of eggs collected from natural nests of T. sinensis are similar to a previous report of the same genus Trionyx in the soft-shelled turtles. However, this genus (or species) showed some different phenomena to other kinds of turtles such as various kinds turtles mentioned above. After collection of naturally spawned eggs (17 eggs of T. sisnensis) on the natural nests, a laboratory experiment by the constant incubation temperatures was conducted with natural fluctuating soil temperatures in the natural nest with the soft-shelled turtle, T. sinensis. And also laboratory experiments were conducted using constant incubation temperatures of $25^{\circ}C$ (cooler temp.) and $30^{\circ}C$ (higher temp.) with the turtle, T. sinensis. Exceptionally, it was confirmed that the first and second incubation temperatures can't control sex-determination in the freshwater soft-shelled turtle, T. sinensis. The sex ratio approximated 1:1 (${\chi}^2=0.06$, P>0.05 (the Ist experiment). And the sex ratio approximated 1:1 independently of incubation temperature (${\chi}^2=0.33$, P>0.05 (the 2nd experiment). Consequently, temperature has no effect on sex determination in the genus Trionyx in a soft-shelled turtle.