• Korean Journal of Poultry Science
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• v.49 no.3
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• pp.139-144
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• 2022

This study was conducted to investigate the effect of three different photoperiods on growth performance, blood properties, and stress indicators in broiler chicks between 1-7 days after hatching. Two hundred and fifty-two 1-day-old male broiler chicks (57.0±0.12 g) were divided into three treatments, with 4 replicates per treatment and 22 birds per replicate subjected to three different photoperiods of 24L, 22L/2D and 18L/6D. A light-emitting diode bulb served as the light source, with an illuminance of 30 lx. As an experimental diet, a commercial feed based on a corn-soybean meal, with 22% CP and 3,150 kcal/kg ME diet, and water were fed ad libitum. Body weight gain, feed conversion ratio, and liver weight ratio showed a statistically significant difference between the 18L/6D and 24L treatments (P<0.05), but with no significant difference between the 22L/2D treatment and either the 24L or 18L/6D treatment. The breast meat ratio was 5.59% in the 18L/6D treatment group, which was lower than that of other treatment groups (P<0.05). The triglyceride levels were highest (P<0.05) in the 18L/6D treatment among treatments, but alanine aminotransferase levels were significantly higher (P<0.05) in the 22L/2D treatment than in the 24L treatment. Levels of cytokines, i.e., Interleukin-6 and Tumor Necrosis Factor-α did not show a significant difference among the treatments, but corticosterone content was significantly higher (P<0.05) in the 24L treatment than in the 18L/6D treatment. In conclusion, 22 hours of lighting is appropriate between 1~7 days after hatching, considering growth performance and the overall health of broiler chicks.

• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.744-750
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• 2010

This study examined the different polyphenism of larval salamander Hynobius ieechii according to two habitats, pond and stream. We collected salamander's eggs from three regions including Mountain Inwang, Surak and Gwangju. Eggs were treated by four different conditions according to predation level and habitat: high risk - which had a predation risk three times a day; low risk - which had no predation risk, pond and stream habitat. Predation risk was conducted by using chemical cue from Chinese minnows. The chemical cue treatment started from the day of collection and ended one week after the hatching. After the treatment phase, we measured the head width at the level of the eyes(HWE) and the largest head width(LHW) and snout-vent length of the each larva. We calculated the ratio of the head size by dividing HWE by LHW and made a comparison with each of the average ratio of head size according to the predation risk. The results showed that there was a significant difference in the ratio of the head size and snout-vent length according to the predation risk and habitat. From these results we found that predation risk and habitat condition can cause the different polyphenism to the larval salamander and these morphological changes could be affect their mortality.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.410-415
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• 2009

The weekly liveweight gain, growing and stress parameters of quails bred using two different types of lighting for 6 weeks following hatching were examined in this study. The first type of lighting was 23 L:1 D, continuous lighting (CL), widely used in the commercial system and the second was a self-photoperiod (SP) system consisting of a continuously lit chamber and a dark chamber the quails could move to as they wished. On the first 15 days, no difference was found in liveweight gain between the two breeding systems. On the $6^{th}$ week when the trial was completed, the liveweight of the male quails upon which CL lighting was used was 159.03 g while the weight of males in the SP group was 174.43 g; these values in female quails of the CL group were 179.15 g and in the SP group were 200.68 g. The CL group had lower testis volume (TVOM, $cm^{3}$) and testis weight (TW, g) than the SP group, however there was no difference between the groups in testis weight/body weight rate (BWTW %). In female quails, the ovary weight (OW, g) and the ovary weight/body weight rate (BWOW, %) values were higher in the SP group. The CL light regime was concluded to cause stress in male quails (CL, Heterophil/Lymphocyte ratio (H/L): 0.27; SP, H/L: 0.17). In conclusion; the SP system allowing the quails to regulate their light periods increased liveweight gain and enabled sexual maturity to be gained at an earlier period than in quail on the CL system and improved their welfare.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.7-15
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• 2003

Di-2-ethylhexyl phthalate (DEHP), is a widely used plasticizer known to be a suspected endocrine disrupter, but its exact effects on aquatic organisms are not yet known. When Japanese medaka (Oryzias latipes) were exposed from the time of hatching to 3 months of age to an aqueous DEHP solution at nominal concentrations of 1, 10, and 50 $\mu\textrm{g}$/l, DEHP treated female fish showed distinct reproductive effect. And the midge (Chironomus riparius.). an aquatic invertebrate, was exposed to DEHP to evaluate the effects on reproductive processes via sediment toxicity. The test endpoints included emergence, sex ratio, fecundity, and the viability of F1 offspring egg ropes. The result implied that the normal developmental and/or reproductive processes in C. riparius had been disrupted when exposed to DEHP, the effect also being displayed in the next generation. In summary, DEHP hinders the development of reproductive organs in the female Japanese medaka and C. riparius.

• Korean Journal of Ichthyology
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• v.28 no.2
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• pp.72-78
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• 2016

The age and spawning characteristics of Iksookimia pacifica were investigated in this study to provide baseline data for its ecological characteristics in the Bukcheon (stream), Goseong-gun, Gangwon-do, Korea from January to December, 2013. Age groups of I. pacifica (female) estimated by the frequency distribution of total length in the spawning season indicated that the 30~49 mm group is 1 year old, the 50~74 mm group is 2 years old, the 75~99 mm group is 3 years old, the 100~124 mm group is 4 years old, and the 130~160 mm group is $5{\leq}$years old. The sex ratio (♂/♀) was 0.63, and females were 30~60 mm larger than males. The lamina circularis at the base of pectoral fins in males as a secondary sexual character was created at the 13th month after hatching. The spawning season according to the gonadosomatic index (GSI) was July to August (main spawning season in July) with water temperatures of $20{\sim}25^{\circ}C$. The average number of eggs was $2,503{\pm}1,337$ with a diameter of $1.11{\pm}0.04mm$ in mature eggs.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.11
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• pp.1797-1808
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• 2020

Objective: This study assessed the effects of probiotics on cecal microbiota, gene expression of intestinal tight junction proteins, and immune response in the cecal tonsil of broiler chickens challenged with Salmonella enterica subsp. enterica. Methods: One-day-old broiler chickens (n = 240) were randomly allocated to four treatments: negative control (Cont), multi-strain probiotic-treated group (Pro), Salmonella-infected group (Sal), and multi-strain probiotic-treated and Salmonella-infected group (ProSal). All chickens except those in the Cont and Pro groups were gavaged with 1×10⁸ cfu/mL of S. enterica subsp. enterica 4 days after hatching. Results: Our results indicated that body weight, weight gain, and feed conversion ratio of birds were significantly reduced (p<0.05) by Salmonella challenge. Chickens challenged with Salmonella decreased cecal microbial diversity. Chickens in the Sal group exhibited abundant Proteobacteria than those in the Cont, Pro, and ProSal groups. Salmonella infection downregulated gene expression of Occludin, zonula occludens-1 (ZO1), and Mucin 2 in the jejunum and Occludin and Claudin in the ileum. Moreover, the Sal group increased gene expression of interferon-γ (IFN-γ), interleukin-6 (IL-6), IL-1β, and lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF) and reduced levels of transforming growth factor-β4 and IL-10 compared with the other groups (p<0.05). However, chickens receiving probiotic diets increased Lactobacillaceae abundance and reduced Enterobacteriaceae abundance in the ceca. Moreover, supplementation with probiotics increased the mRNA expression of Occludin, ZO1, and Mucin 2 in the ileum (p<0.05). In addition, probiotic supplementation downregulated the mRNA levels of IFN-γ (p<0.05) and LITAF (p = 0.075) and upregulated IL-10 (p = 0.084) expression in the cecal tonsil. Conclusion: The administration of multi-strain probiotics modulated intestinal microbiota, gene expression of tight junction proteins, and immunomodulatory activity in broiler chickens.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.158-162
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• 2011

Growth and spawning ecology of Cobitis lutheri (Teleoste: Cobitidae) were investigated in the Samcheon Stream, Mangyeong River, Jeollabuk-do, Korea from 2005 to 2006. Age group of C. lutheri estimated from the total length indicated that the 40 ~ 60 mm group is 1 year old, the 60 ~ 80 mm group is 2 years old, and the 80 ~ 110mm group is 3 ${\leq}$ years old. The sex ratio (Male/Female) was 0.78, and the female was 20 ~ 30 mm larger than the male. Lamina circularis at the base of pectoral fins in the males as a secondary sexual character was created 12 months after hatching. A change of lateral coloration of males was observed from April to September. The spawning season was early to middle July with water temperatures of $24{\sim}26^{\circ}C$. The average number of eggs was $1,127{\pm}453$ with the egg diameter of $1.09{\pm}0.02$ mm.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.733-739
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• 2018

This study was conducted to investigate the growth performance between six different Korean crossbred native chickens. A total of 312 one-day-old male chickens from the same paternal line with six different maternal lines were allocated into six groups (1A, 2A, 3A, 4A, 5A, and 6A) to give four replicate cages (13 birds per cage). Corn soybean meal based diets were provided as a starter (0 - 5 weeks: 20% crude protein [CP] and 3,050 kcal/kg metabolizable energy [ME]), grower (5 - 8 weeks: 18% CP, 3 and 100 kcal/kg ME) and finisher (8 - 12 weeks: 17% CP and 3,150 kcal/kg ME) diet. Chickens were able to access their respective feed and water ad libitum. In week 2, 2A had a lower body weight (p < 0.05) than that of the other groups. In contrast, in weeks 4 and 8, 2A had a higher body weight (p < 0.05). Similarly, in week 6, 2A had a higher body weight (p = 0.76) than that of the others. However, no difference (p > 0.05) was observed in the body weight after week 10. Meanwhile, 2A had a lower feed conversion ratio (FCR) than that of the other groups (p < 0.05) and a higher average daily feed intake (ADFI; p < 0.05) compared to the other groups in week 6. In conclusion, crossbred 2A had a lower growth performance in week 2; however, in weeks 4 and 6, 2A had a higher growth performance than that of the other groups. Based on this conclusion, we can use those results as a basis for further study.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.69-72
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• 2018

A new silkworm variety 'Chilseongjam' was bred for special purpose as educational learning and festivals. Their breeding history and major characteristics are as follows. The Chilseongjam variety was selected and succeeded from the F1 of Galwon ${\times}$ C721 in 2009 autumn. They are showing 94% (spring & autumn) of high practical hatching ratio. The larval period of Chilseongjam (spring: 23 d, autumn: 24 d 3 h) was shorter than that of Daebakjam (spring: 24 d, autumn: 25 d 23 h). In the pupation percentage, Chilseongjam (spring: 96.6%, autumn: 86.1%) is similar to Daebakjam Daebakjam (spring: 96.3%) in spring, but autumn is lower than Daebakjam (autumn: 94.9%). Single cocoon weight (spring: 1.57 g, autumn: 1.29 g) and Cocoon yield (spring: 14.2 kg, autumn: 11.1 kg) were lower than those of Daebakjam (spring: 2.76 g, 25.4 kg, autumn: 2.19g, 20.2 kg), respectively. The new silkworm variety, Chilseongjam showed higher pupation rate than control variety. This variety can be used as a educational learning and festivals.

• Journal of Animal Science and Technology
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• v.62 no.6
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• pp.840-853
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• 2020

The present study was conducted to investigate the effect of a multi-protease on production indicators of broiler chickens fed a crude protein and amino acid deficient-diets for 35 days immediately after hatch. A total of 448 one-day-old Ross 308 male broiler chicks were allocated in a completely randomized design into one of eight dietary treatments (positive control [PC], negative control [NC: minus 0.5% from PC, and minus 2% of lysine, methionine, threonine and methionine plus cysteine], extreme negative control [ENC: minus 1% from PC, minus 4% of lysine, methionine, threonine and methionine plus cysteine], and plus multi-protease 150 or 300 g per ton [e. g., PC-150]; PC, PC-150, NC, NC-150, NC-300, ENC, ENC-150, ENC-300) to give eight replicates with seven birds in a battery cage. Body weight, average daily gain, average daily feed intake, feed conversion ratio, and mortality were measured every week. Carcass traits, proximate analysis of breast meat, and ileum digestibility were analyzed on day 21 and 35. Feeding a multi-protease (i.e., more than 150 g/ton) for 35 days immediately after hatching improved feed efficiency and ileum digestibility (i.e., dry matter, crude protein, and energy) compared to their counterparts (i.e., diets without multi-protease: PC, NC, and ENC). In conclusion, our results indicated that broiler chickens fed nutrients deficient-diet (i.e., crude protein and amino acids) supplemented a multi-protease had an ability to compensate and (or) improve their growth performance commensurate with increased ileal digestibility for 35 days immediately after hatch.