• Korean Journal of Ichthyology
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• v.18 no.4
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• pp.339-346
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• 2006

In this study we conducted artificial hybridization between two sibling species, Rhodeus uyekii and R. notatus, and observed the morphological characteristics in early developmental stage. The two species showed difference in egg shape having rhombus and club respectively. The morphology of yolk of larva just hatched also showed well specific characteristics, that is the bean chaff type for R. uyekii (U type) and anchor type for R. notatus (N type). The rate of fertilization between female R. uyekii and male R. notatus (UN type) and between female R. notatus and male R. uyekii (NU type) were complete and its hatching rate were very high, 71.6% for UN type and 97.5% for NU type. The differences occurred in the yolk shape of hatched larvae for each combination of hybrids. In the group of UN, U type of larvae were found very rarely, but almost all the larvae showed intermediate shape polarized to NN type. Similar phenomenon was observed in the NU having intermediate polarized to UU, but without any NN type. These hybrids will be analyzed for their external morphology, sex ratio, the function of sexual organ and karyology after they grown up to adult.

• Journal of Ecology and Environment
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• v.29 no.3
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• pp.277-286
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• 2006

Population ecology of Cobitis tetralineata was examined at Churyeong Stream, Seomjin River, Korea. C. tetralineata inhabited on the sand bottoms with $10{\sim}20cm/see$ in current velocity, and $30{\sim}150cm$ in water depth. This species was active on the sand during the daylight hours from March to October, but they hibernated in the inside of the sand during the winter season. Sex ratio of female to male was 1:0.57, and female was $20{\sim}30mm$ (TL) larger than male. The age group of C. tetralineata (female) population showed that the $20{\sim}40mm$ group is 0+ years old, the $45{\sim}65mm$ group 1+ years old, the $65{\sim}90mm$ group 2+ years old, and the group longer than 90 mm over 3 years old. Males $13{\sim}14$ months old after hatching had lamina circularis at the base of its pectoral fin as a secondary sexual character. And in its spawning season, lateral color pattern of male was changed as a sexual dimorphism. The spawning season may be from late June to middle July, $22{\sim}26^{\circ}C$ water temperature. The average number of mature eggs in ovary was about $1,288{\pm}583(474{\sim}2,976)$, egg diameter was about $0.98{\pm}0.1mm$. C. tetralineata fed mainly on Chironomidae, Arcellidae, Branchioda and Algae. The feeding rate was the highest in April and September, but they did not fed in the winter.

• Journal of Aquaculture
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• v.21 no.2
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• pp.96-101
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• 2008

To induce of maturation and ovulation, ovary with different development stage of oocytes of sevenband grouper Epinephelus septemfasciatus(n=51, TL $69.1{\pm}1.0$ cm, BW $5.8{\pm}0.3$ kg) rearing indoor-tank in mature and spawning season(June to July) were investigated by cannulation. Female with yolk globule stage oocyte($300{\sim}500{\mu}m$) was injected with human chorionic gonadotropin(HCG, 500 IU/kg BW). Oocytes developed at diameter $300{\sim}700{\mu}m$ in 24 hrs after the HCG injection, and the distribution ratio of over $800{\mu}m$ of oocytes diameter in the cannulated eggs were $91.3{\sim}98.8%(95.1{\pm}3.7%)$ in 48 hrs after the HCG injection. Ovulation was induced from 7 out of 8 female after the HCG injection. The total volume of stripped eggs was 2,480 mL, and the volume of buoyant eggs was 1,360 mL. The fertilization and hatching rates of buoyant eggs were $56.2{\sim}94.9%$ and $70.7{\sim}97.9%$, respectively. These results suggested that HCG 500 IU/kg BW effects on maturation and ovulation of female sevenband grouper with yolk globule stage of oocyte.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.352-360
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• 2005

Acheilognathus signifer is distributed widely in high density in the Naechon-stream. The order of this-stream was 2 ${\sim}$ 4 and the water width is wide but the depth is relatively shallow and the sinuosity is 1.83, which indicates a meandering stream. The water width/stream width ratio is 1.59, which suggests moderate entrenchment. Naechon-stream was classed as B type by Rosgen (1995). The natural habitat of A. signifer is a slow flow velocity pool, like a backwater pool, which is made up of piled up boulders that restricts the flow of water. The stream bed is made up of boulders and sands that enable the spawning host to inhabit. A. signifer selects a microhabitat where the boulders furnish hiding places. The Habitat of A. signifer is strongly affected by the existence or not there of U. douglasiae sinuolatus. After hatching from the mussel, A. signifer inhabits the surface of the water. It then moves to the low layer once it acquires swimming ability. While A. signifer inhabits the river in summer, A. signifer moves to the deeper layers in winter, where there are the refuge like rocks and boulders. In spring A. signifer moves from the deep water to the river line where the mussels reside.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.9
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• pp.1287-1293
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• 2016

The objectives of this experiment was to evaluate the subsequent growth and organ weights, blood profiles and cecal microbiota of broiler chicks fed pre-starter diets containing fermented soybean meal products during early phase. A total of nine hundred 1-d-old chicks were randomly assigned into six groups with six replicates of 25 chicks each. The chicks were fed control pre-starter diet with dehulled soybean meal (SBM) or one of five experimental diets containing fermented SBM products (Bacillus fermented SBM [BF-SBM], yeast by product and Bacillus fermented SBM [YBF-SBM]; Lactobacillus fermented SBM 1 [LF-SBM 1]; Lactobacillus fermented SBM 2 [LF-SBM 2]) or soy protein concentrate (SPC) for 7 d after hatching, followed by 4 wk feeding of commercial diets without fermented SBMs or SPC. The fermented SBMs and SPC were substituted at the expense of dehulled SBM at 3% level on fresh weight basis. The body weight (BW) during the starter period was not affected by dietary treatments, but BW at 14 d onwards was significantly higher (p<0.05) in chicks that had been fed BF-SBM and YBF-SBM during the early phase compared with the control group. The feed intake during grower and finisher phases was not affected (p>0.05) by dietary treatments. During total rearing period, the daily weight gains in six groups were 52.0 (control), 57.7 (BF-SBM), 58.5 (YBF-SBM), 52.0 (LF-SBM 1), 56.7 (LF-SBM 2), and 53.3 g/d (SPC), respectively. The daily weight gain in chicks fed diet containing BF-SBM, YBF-SBM, and LF-SBM 2 were significantly higher values (p<0.001) than that of the control group. Chicks fed BF-SBM, YBF-SBM, and LF-SBM 2 had significantly lower (p<0.01) feed conversion ratio compared with the control group. There were no significant differences in the relative weight of various organs and blood profiles among groups. Cecal microbiota was altered by dietary treatments. At 35 d, chicks fed on the pre-starter diets containing BF-SBM and YBF-SBM had significantly increased (p<0.001) lactic acid bacteria, but lowered Coli-form bacteria in cecal contents compared with those fed the control diet. The number of Bacillus spp. was higher (p<0.001) in all groups except for LF-SBM 1 compared with control diet-fed chicks. At 7 d, jejunal villi were significantly lengthened (p<0.001) in chicks fed the fermented SBMs vs control diet. Collectively, the results indicate that feeding of fermented SBMs during early phase are beneficial to the subsequent growth performance in broiler chicks. BF-SBM and YBF-SBM showed superior overall growth performance as compared with unfermented SBM and SPC.

• Development and Reproduction
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• v.20 no.4
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• pp.331-347
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• 2016

Sexual dimorphism is the most conspicuous difference between the sexes. This study examines possible sexual dimorphism and the relative growth patterns of morphometric characteristics in the marine medaka, Oryzias dancena for their potential to help differentiate between males and females of this species. The von Bertalanffy growth parameters estimated by a non-linear regression method were $L_{\infty}=30.2mm$, K=3.22/year, and ${\tau}_0=-0.05$. All 18 characteristics measured showed a difference between males and females from 70 days after hatching. Each of these characteristics were significantly different between sexes (ANCOVA, P<0.05), and the ratio of standard length between sexes showed that males were larger than females for all five morphometric measurements. Fin length measurements were taken for 21 distances of anal fin and 7 distances of dorsal fin between landmarks. There were all differences for all dorsal fin rays between the males and the females and there is significant difference in 70 days after their hatch when the sexual dimorphism is presented. The significant difference (P<0.05) in fin ray for male and female was more greatly seen as they grow. Male marine medaka showed more rapid growth than females, with longer length, dorsal fins and anal fins. Differences in these characteristics will be useful during experiments when it is necessary to differentiate between sexes of marine medaka.

• Korean Journal of Animal Reproduction
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• v.8 no.1
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• pp.46-55
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• 1984

The purpose of the experiment was to clarify morphologically normal growth pattern of the ductus deference in accordance with the sex maturity of meat-type cockerels. 1. Diameter of lumens in u, pp.r, mid and lower parts of ductus deferens, the most conspicuous enlargement of lumen was observed in the lower part. Heights of epithelial layers of ductus deferens showed abrupt growth at 12 weeks of age with subsequent gradual growth in all the part of u, pp.r, mid and lower, and heights of those at 30 weeks were a, pp.oximately 4 times as large in the u, pp.r and mid parts and 5 times as large in the lower part in contrast to those at 4 weeks of age. Thickness of muscular layer of ductus showed gradual growth in contrast with the diameter of lumen and height of epithelial layer, showing 1.3 times as large in the u, pp.r part, 1.6 times in the mid part and 1.9 times in the lower part at 30 weeks of age in contrast to the thickness at 4 weeks of age. 2. Within 10 weeks after hatching, lining cells of ductus deferens were mainly composed of round cells and columnar cells in simple columnar epithelium. During 10th to 20th week, the lining cells were mainly composed of high columnar cells and round cells in pseudostratified epithelium. From 22nd week, the lining cells were composed of pseudostratified columnar cells. Whereas round cells disa, pp.ared gradually. Enlargement of lumen and pooling of sperms in ductus deferens coincided with the maturation of seminiferous tubules. 3. In simple correlation between the values of testis weight and the values from various measurements in the ductus deferens, there was significant correlation coefficient with each other. 4. In the India ink absorption test, India ink granules were not absorbed on the epithelium of the ductus deferens, but the granules reactive to acid phosphatase a, pp.ared in a line on the free border of each parts of the ductus deferens. The granules reactive to alkaline phosphatase were noted on the luminal border of ductus deferens mainly, but weak reaction showed than acid phophatase were a, pp.ared. The granules reactive to PAS were a, pp.ared mostly near on the free border of hte epithelial cells of ductus deferens. 5. Number of sperm, Indes of sperm vitality and MRT in the different parts of ductus deferens were tended to be somewhat dominant in the mid and lower parts than in u, pp.r part, even though not significant in the statistical analysis. Ratio of sperm abnormality was tended to be relatively high in the u, pp.r part too, and in the sperm of abnormality blunted head was less in number significantly in the mid and lower part than in the u, pp.r part.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.421-426
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• 2017

These experiments were conducted to investigate the morphological characteristics, occurrence ecology, host preference, and oviposition of Locusta migratoria to create a forecasting manual in preparation for outbreaks of this species. The sex ratio (female:male) of 274 adult of L. migratoria which occurred naturally in the Muan region of Jeollanam-do was 18.2 : 81.8, 60.9% individuals were of the green type and 39.1% were of the brown type. Body length and body weight were 6.5 cm and 2.8 g for females and 5.0 cm and 1.5 g for males, respectively; body size did not differ between differently colored individuals. Spawning activity in the field was observed from late August to late October. Eggs laid between late September and early October hatched in late May the following year. Female adults fed 3.5 g of corn leaf and male adult was 1.6 g for a day. The host preference of L. migratoria was in the order corn > foxtail millet > millet > silver grass > rice, and preference for silver grass and rice was very low. Pure sand was most favorable for the spawning of L. migratoria, and the cumulative amount of hatching was higher when the soil moisture content was higher after spawning began.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.239-248
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• 2016

The habitat, age and spawning characteristics of the Korean eastern spined loach, Iksookimia yongdokensis, were investigated to obtain baseline data for its ecological characteristics in the Chuksancheon (stream), Yeongdeok-gun, Gyeongsangbuk-do, Korea. The difference between the habitats of juveniles (0+) and 1~4 year old loaches was that juveniles mainly inhabited sandy bottoms (substratum particle size $0.6{\pm}1.44\;cm$) with very slow velocities of water current ($2.4{\pm}2.09\;cm/sec$) and low depths ($29.2{\pm}7.57\;cm$), whereas 1~4 year old loaches inhabited pebble and cobble bottoms (substratum particle size 5.5~6.1 cm) with relatively fast velocities of water current (3.8~4.6 cm/sec) and deep depths (50~70 cm). The age groups for I. yongdokensis (female) estimated by the frequency distribution of total length in the spawning season (July) indicated that the 35~64 mm is 1-year old, the 65~94 mm group is 2-year old, the 95~119 mm is 3-year old, and the 120~145 mm is more than 4-year old. The sex ratio (♂/♀) was 0.69, and females were 10~30 mm larger than males. The lamina circularis at the base of the pectoral fins in males, a secondary sexual characteristic, formed at the 13th month after hatching. The spawning season according to the gonadosomatic index (GSI) was June to July with water temperatures of $20{\sim}25^{\circ}C$. The average number of eggs was $2,292{\pm}618$, with a diameter of $1.46{\pm}0.02\;mm$ for mature eggs.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.177-184
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• 2021

Sex identification in day-old chicks is essential in the poultry industry. Currently, the feather-sexing using a sex-linked inheritance is a chick sexing method used extensively in the poultry industry. For chicks produced by feather-sexing, all females are early-feathering (EF) chicks and all males are late-feathering (LF) chicks. Therefore, investigating the effects of EF and LF phenotypes on production traits of chickens is critical. The purpose of this study was to analyze and compare the production performance between EF and LF chickens in Korean native commercial chickens. The results showed that the survival rate of the EF chickens was significantly higher than that of the LF chickens, from hatching to 12 weeks of age (P<0.05), with the highest difference observed in females. However, no significant difference was observed in body weight between the EF and LF chickens at almost all ages. In addition, no significant difference was observed between in feed utility, such as average daily feed intake and feed conversion ratio, between the EF and LF groups. In conclusion, although the survival rate of early-feathering chickens was superior to that of late-feathering chickens, no significant difference was observed in growth performance and feed utility among Korean native chickens. The results suggest that production capacity is not influenced by feathering type in the establishment of a breeder structure and production system for feather-sexing Korean native chickens, which is valuable for the practical application of feather-sexing in the poultry industry.