• Korean Journal of Poultry Science
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• v.46 no.4
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• pp.279-286
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• 2019

Currently, feather-sexing, which is based on differences in feather development at hatching, is a widely used chick sexing method in the poultry industry. For effective chicken feather-sexing, paternal early-feathering (EF) chickens and maternal late-feathering (LF) chickens must be bred. Therefore, it is critical to identify the effect of EF and LF patterns on production traits in chickens. Thus, the purpose of this study is to analyze and compare the production performances between 522 EF and 232 LF chickens in order to establish the Korean native chicken feather-sexing lines. The results showed that the survival rate of the LF group was significantly higher than that of the EF group from hatching to 52 weeks of age (P<0.05). Body weight, however, was not significantly different between the two groups at all ages. LF and EF groups did not significantly differ in age at first egg laying. However, the hen-day and hen-housed egg production of the LF group were significantly higher than those of EF group (P<0.01). No significant differences were found between the EF and LF groups in all egg quality indicators such as egg weight, eggshell color, albumin height and Haugh unit. Because the breeding target of Korean native commercial chicken is meat-type chicken, feather-sexing strains of Korean native chicken should be established using weighing-based paternal EF lines and laying-based maternal LF lines. Therefore, these results are critical for establishing desirable and effective feather-sexing strains.

• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.295-306
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• 2009

This experiment was conducted to investigate the effects of dietary calcium (Ca) and vitamin $D_3$ metabolite on eggshell quality and hatching egg production in aged egg-type breeder hens. A total of five hundred and forty 60-week-old Hy-Line Brown breeder hens were randomly allocated to nine treatments in a $3\times3$ factorial design to determine the effects of dietary Ca levels (3.3, 3.9, and 4.5%), combined with three levels of 25-hydroxycholecalciferol [25-$(OH)D_3$ 0, 75, and $150{\mu}g/kg$], on eggshell quality and egg production for 10 weeks. There were significant Ca and 25-$(OH)D_3$ effects (P<0.01) on egg production rate. There was a linear (P<0.01) increase in eggshell strength and thickness with increasing dietary Ca and 25-$(OH)D_3$ levels. Dietary 25-$(OH)D_3$ had a significant effect (P<0.05) on hatchability of egg although fertility was not influenced by dietarylevels of Ca and 25-$(OH)D_3$. Dietary Ca levels affected Ca content in tibia (P<0.05). These results indicated that relatively high levels of dietary Ca in combination with 25-$(OH)D_3$ had a beneficial effect on improving eggshell quality and reproductive performance in aged egg-type breeder hens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.113-120
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• 1971

In 1971, about 150,000 fingerlings of grass and silver carps were produced and distributed from the Fishculture Laboratory of Pusan fisheries College. The adults Were those transplanted from Japan in 1963. Findings during the process of this production are summarized as following : 1. Brood fish must be handled with a great care during the catching, hormone injection and maturity inspection so as the fish are not injured, otherwise, the eggs would not mature perfectly. Scale fall also affects significantly. 2. The amount of pituitary to be injected is preferable to be 2 to 3 times or more in donor's body weight to obtain good results. 3. The eggs should be spawned or stripped and inseminated as soon as mature. If the spawning is delayed the eggs become overmature and the hatching rate decreases significantly. 4. The water once used for the incubation of eggs should not be reused. The eggs under hatching process were melted away when water once used for incubation was reused. 5. A great care must be paid to keep water in quality when the net cage culture system is employed for raising fry or early fingerlings of Chinese carps. The best method to keep water in quality is to supply water in the cage continuously through a pipe or hose. 6. Heavy outbreaks of Spirogyra occured when clear well water was supplied into the cage, and a great number of fry or fingerlings were trapped or entangled resulting in a significant decrease of fish under rearing. It was prevented when moderately bloom-ed pond water was supplied into the cage. 7. Silver carp fry are usually captured and transported in the cool season because they can not be handled in the warm season owing to a high mortality, but cage cultured small size fingerlings ranging from 1.5 to 2 cm in total length are easily handled and transported even in the hot summer season, thus it enables the fish farmers to start growing them one season earlier.

• Journal of Animal Science and Technology
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• v.54 no.4
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• pp.267-274
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• 2012

The method of sexing based on differences in the rate of feather growth provides a convenient and inexpensive approach. The locus of feather development gene (K) is located on the Z chromosome and can be utilized to produce phenotypes that distinguish between the sexes of chicks at hatching. To establish the auto-sexing native chicken strains, this study analyzed the genotype frequency of the feathering in domestic chicken breeds. The method of classification of slow- and rapid-feathering chickens was also investigated. In the slow-feathering chicks, the coverts were either the same length or longer than the primary wing feathers at hatching. However, the rapid-feathering chicks had the primary wing feathers that were longer than the coverts. The growth pattern of tail feather also distinctively differed between the rapid- and slow-feathering chicks after 5-days. The accuracy of wing feather sexing was about 98% compared with tail sexing. In domestic chicken breeds, Korean Black Cornish, Korean Rhode Island Red, and Korean Native Chicken-Red had both dominant (K) and recessive ($k^+$) feathering genes. The other breeds of chickens, Korean Brown Cornish, Ogol, White Leghorn, Korean Native Chicken-Yellow, -Gray, -White and -Black had only the recessive feathering gene ($k^+$). Consequently, feather sexing is available using the domestic chicken breeds. Establishing the maternal stock with dominant gene (K-) and paternal stock with recessive gene ($k^+k^+$), the slow-feathering characteristic is passed from mothers to their sons, and the rapid-feathering characteristic is inherited by daughters from their fathers.

• Journal of Life Science
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• v.29 no.5
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• pp.537-544
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• 2019

Genome editing technology employing gene scissors has generated interest in molecular breeding in various fields, and the development of the third-generation gene scissors of the clustered, regularly interspaced short palindromic repeat (CRISPR) system has accelerated the field of molecular breeding through genome editing. In this study, we analyzed the possibility of silkworm molecular breeding using gene scissors by genomic and phenotypic analysis after editing the biogenesis of lysosome-related organelles (BmBLOS) gene of Bakokjam using the CRISPR/Cas9 system. Three types of guide RNAs (gRNA) were synthesized based on the BmBLOS gene sequence of Bakokjam. Complexes of the prepared gRNA and Cas9 protein were formed and introduced into Bombyx mori BM-N cells by electroporation. Analysis of the gene editing efficiency by T7 endonuclease I analysis revealed that the B4N gRNA showed the best efficiency. The silkworm genome was edited by microinjecting the Cas9/B4N gRNA complex into silkworm early embryos and raising the silkworms after hatching. The hatching rate was as low as 18%, but the incidence of mutation was over 40%. In addition, phenotypic changes were observed in about 70% of the G0 generation silkworms. Sequence analysis showed that the BmBLOS gene appeared to be a heterozygote carrying the wild-type and mutation in most individuals, and the genotype of the BmBLOS gene was also different in all individuals. These results suggest that although the possibility of silkworm molecular breeding using the CRISPR/Cas9 system would be very high, continued research on breeding and screening methods will be necessary to improve gene editing efficiency and to obtain homozygotes.

• Journal of Aquaculture
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• v.4 no.2
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• pp.73-84
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• 1991

Underground sea water is widely utilized for land based aquaculture in Cheju province, Korea nowadays. Salinity of this water($20{\~}30$ ppt) is slightly lower than natural sea water but because of its good water quality and temperature which is maintained at $16{\~}18^{\circ}C$ all year-round, many fish farmers are using this water for finfish culture. To evaluate the possibility of utilizing underground sea water for the seed production of the flounder, Paralichthys olivaeceus, hatching rate of fertilized eggs, survival rate of hatched larvae, and growth rate of the juveniles were tested with various salinity levels ranged from 14.1 ppt to 40.2 ppt. The salinity ranges which showed over $70{\%}$ survival rate for fertilized eggs to hatchout were 33.7 ppt${\~}$40.2 ppt, for hatched larvae to 2-day-old were 20.6 ppt${\~}$40.2 ppt, from 10-day-old to 12-day-old were 27.2 ppt${\~}$40.2 ppt, and from 45-day-old to 47-day-old were 20.6 ppt${\~}$40.2 ppt. Two hundred day old fingerlings showed no mortality when exposured to 7.6 ppt${\~}$40.2 ppt for 2 days. All fish died within 3 days when 45-day-old juveniles were transferred directly from normal sea water to 14.1 ppt sea water. However, they were all survived when transferred first to 20.6 ppt for 3 days then to 14.1 ppt sea water. The highest growth rates of fingerlings reared at 4 different salinities (33.7, 27.0, 31.0, or 15 ppt) were obtained at the 27 ppt group followed by 33.7, 21.0, 15 ppt respectively. The relationship between the days of rearing (X) and the total length of the fingerlings were as follows. $33.7\%$ group : Y=8.8109 + 0.1104X(r=0.999) $27.0{\%}$ group : Y=8.6797 + 0.1208X(r=0.997) $21.0{\%}$ group : Y=8.4081 + 0.1052X(r=0.990) $15.0{\%}$ group : Y=8.4309+ 0.0995X(r=0.990)

• Journal of Aquaculture
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• v.21 no.4
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• pp.272-277
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• 2008

We investigated the growth and survival in seedling production, and growth performance was compared with the different rearing tanks and protein source of formulated feed for juvenile Pacific bluefin tuna Thunnus orientalis (PBT). The survival rate at the end of nursery culture at 30 days after hatching was $0.69{\pm}0.40%$, and total length and mean body weight were $49.83{\pm}2.52\;mm$ and $1.03{\pm}0.09\;g$, respectively. Growth performance has no significant difference in fish reared by different tanks forms for 10 days. In order to develop an artificial diet, we evaluated the dietary utility of enzyme treated fish meal (Bio-CP, BIO) for juvenile PBT. Only diet BIO sustained similar growth and higher feed efficiency, and final carcass lipid content as compared to those of Sand lance (SL) These results revealed that BIO-CP a suitable dietary protein source, could sustain growth of PBT.

• Reproductive and Developmental Biology
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• v.36 no.4
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• pp.269-273
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• 2012

The present study was to assess the in vitro viability and sexing rate of bovine embryos. Blastocysts were harvested on day 7~9 day after insemination(in vitro and in vivo), and the sex of the embryos was examined using the LAMP method. Embryo cell biopsy was carried out in a $80{\mu}l$ drop $Ca^{2+}$, $Mg^{2+}$ free D-PBS and, biopsied embryos viability were evaluated after more 12 h culture in IVMD culture medium. The formation of recovered embryo to expanded and hatching stages had ensued in higher of sexed embryo in vivo than in vitro (100% vs. 89%, p<0.05), and in vitro, the rates of degeneration after sexing were significantly (p<0.05) higher in vitro than in vivo(11% vs. 0.0%). The rates of the predicted sex were female 61% vs. 56%, and male 39% vs. 44% in vivo and in vitro, respectively. The rates of survival following different biopsy methods were seen between punching and bisection method in vivo and in vitro (100% vs. 89% and 100% vs, 78% respectively). Biopsy method by punching was significantly (p<0.05) higher than bisection between produced embryos in vivo and in vitro. The present data indicate that with microblade after punching for embryo sexing results in high incidence of survivability on development after embryo biopsy. It is also suggested that LAMP-based embryo sexing suitable for field applications.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.85-88
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• 1979

The cotton aphid, Aphis gossypii Glover, is known as the most important vectant vector of citrus tristeza virus, cucumber mosaic virus, potato virus Y and potato leafroll virus. This study conducted to investigate the life history of cotton aphid at Suweon, Korea$(Lat.37^{\circ}16'N,\;Long\;126^{\circ}59'E)$. The aphids were reared in small cages placed over twig of hibiscus and on the leaves of cucumber. The results obtained were summarized as follows: 1. Overwintering eggs hatched from mid to late April, with a hatching rate averaging seventy-nine percent. 2. The early-born progeny have 22 generations and the late-born progeny have 6 generations on hibiscus and cucumber from April to October. 3. The fundatrigeniae leave tile the primary host in late May to early June and migrate to the secondary hosts. 4. From early to mid Oct., the gynoparae migrate from the secondary hosts to the primary host. 5. The average length of life was about 29 days and they produced an average of 70 nymphs each. 6. The maximum number of aphids produced per female was 117 in the spring. 7. The developmental period ranged from 6 to 16 days (average 8 days), the reproductive period from 12.2 to 24.6 days (average 19 days). 8. The average number of nymphs produced by a female per dys was about 3.7, with a maximum number of 17.

• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.78-83
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• 2020

This study aimed to investigate the effects of different water temperature (5, 8 and 11℃) on egg hatch and larval growth of walleye pollock Gadus chalcogrammus to improve rearing techniques for this species. Survival of eggs maintained at 5℃ was higher than that of eggs maintained at 8℃ and 11℃. The greatest hatching rate was obtained for larvae maintained at 8℃. However, time to first, 50% and 100% hatch of eggs maintained at 11℃ was shorter than at 5℃ and 8℃. A higher survival was observed in larvae reared at 5℃ compared to 8℃ and 11℃ and the greatest growth was observed in larvae reared at 11℃ compared to 5℃ and 8℃ during the feeding trial. This study demonstrated the importance of water temperature, as it affects culture performance of eggs and larval pollock. The results from this study provides valuable information for further development of pollock aquaculture.