• Asian-Australasian Journal of Animal Sciences
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• v.15 no.5
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• pp.725-731
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• 2002

This experiment was performed to understand the changes in plasma leptin in association with plasma IGF-1, body weight and ADG from early growing to late finishing stages of Holstein steers. Blood collection was performed by arterial vein puncture at selected monthly ages of 1 (54 kg), 2.6 (103 kg), 7.2 (205 kg), 13.5 (314 kg), 16.9 (414 kg), 22.2 (550 kg), 24.9 (626 kg) and 27.4 months (695 kg). The blood was analyzed for leptin using the multi-species leptin RIA with recombinant bovine leptin (rbleptin) as standard, plasma IGF-1 was also measured using RIA. Against the standard rbleptin, the multi-species Leptin RIA system's sensitivity, cross reactivity, slope and recovery of 41.0 ng/ml rbleptin in plasma were 4.9 ng/ml, 11.22%, -1.396 and 97.8%, respectively. Plasma leptin measured were more than 5.0 ng/ml, which enable multi-species RIA system to investigate plasma leptin in normal growing steers. Body weight resulted to a highly significant second-degree polynomial relationship with plasma leptin (q=0.54, p<0.0001) and plasma IGF-1 (q=0.44, p<0.0001) from 1 to 27.4 monthly ages. However, the second-degree polynomial curve of plasma leptin and IGF-1 differs showing a concave and convex curvilinear relationship, respectively. ADG was not significantly associated to plasma leptin (r=0.06, p>0.05) and plasma IGF=1 (r=0.06, p>0.05) from 1 to 27.4 monthly ages. Low coefficient, but significant associated increase of plasma leptin and IGF-1 (r=0.12, p<0.008) from 1 to 27.4 months was observed. The uncoordinated increases of plasma IGF-1 at growing and plasma leptin at fattening period, may indicate (1) indirect involvement of endogenous IGF-1 on leptin secretion, and (2) IGF-1 level may signify lean and bone accretion while plasma leptin may mirror body fatness across the monthly ages of Holstein steers.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.5
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• pp.651-654
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• 2006

An experiment was conducted to investigate amino acid composition of three tropical legumes (Cooper (Glycine wightii), Tinaroo (Neonotonia wightii) and Siratro (Macroptilium atropurpureum)) at two different stages (pre-blooming and blooming stages). Chemical composition and totally 16 amino acids of these plants were analysed for comparison of their composition among species at different growing stages and characterizing the amino acid pattern of these legumes. Crude protein content of the plants ranged from 16% to 27% on a dry matter basis. The total amount of 16 amino acids analyzed in this experiment was highest at 89.7 mg/16 g N in Cooper at pre-blooming and lowest at 80.9 mg/16 g N in Glycine at blooming stage. Total amount of amino acids in each legume species tended to slightly decrease with their maturity but no statistical difference was found. The percentage of aspartic acid, glutamic acid and proline in the total amount of amino acids was dominant at 9% to 13%, and that of methionine was less than 1.6%. In this experiment it was concluded that three tropical legumes were rich in crude protein content and characterized by 16 different amino acids with lower sulfur-containing amino acid as methionine.

• Journal of Ecology and Environment
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• v.33 no.2
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• pp.149-155
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• 2010

This study was conducted to investigate the feeding efficiency of the cattle egret (Bubulcus ibis) and the intermediate egret (Ardea intermedia) in relation to the stage of rice culture during two breeding seasons, 2006 and 2007, in Asan city, Chungcheongnam-do, South Korea. Cattle egrets caught mainly small invertebrate prey (insects and spiders, 98.4%) during all stages of rice cultivation, and had a higher prey capture rate in the plowing stage (14.98 prey/min) than in other stages (2.82-3.51 prey/min). Therefore, the biomass intake rate of cattle egrets was highest in the plowing stage. The intermediate egret captured both loaches (43.4%) and small invertebrates (50.6%). The prey capture rates of intermediate egrets increased gradually from the flooding stage (0.38 prey/min) to the planting stage (1.09 prey/min), and decreased in the growing stage (1.04 prey/min). However, intermediate egrets had the highest biomass intake rates in the plowing stage because more loaches were caught in the plowing stage (0.54 loaches/min) than other stages (0.23-0.36 loaches/min). Consequently, both intermediate egrets and cattle egrets had high energy intakes in the plowing stage and rice fields provided an important feeding habitat for both species.

• Korean Journal of Medicinal Crop Science
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• v.15 no.4
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• pp.276-284
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• 2007

To investigate the influence of shading materials with growing stages in Panax Ginseng C. A. Meyer, the diurnal change of photosynthesis, stomatal conductance, transpiration and its any correlation were measured. The net photosynthetic rate and stomatal conductance of ginseng were higher in the morning than in the broad day. The net photosynthetic rate was increased as the PAR (Photosynthetically Action Radiation) was increased and it was reached the maximum at the $200\;{\mu}mol/m^2/s$ of PAR in overall leaves. Transpiration rate was increased in the afternoon compared to in the morning. The transpiration rate was higher in rain shelter shading plate than in polyethylene net. A linear equation was obtained between net photosynthetic rate and stomatal conductance in the morning. SPAD was higher in rain shelter shading plate than in polyethylene net through all growth stages. It may result from the decrease of growth progress. From investigating photosynthetic characteristics, we concluded that shading plate of rain shelter was more an efficient material to ginseng growth.

• Development and Reproduction
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• v.4 no.2
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• pp.175-180
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• 2000

The reproductive cycle of ovoviviparous melania snail, Semisulcospira libeytina libertina was studied in the valley near Naewon Temple in Yangsan, Korea. Water temperature (WT) of the habitat ranged from 1.3$^{\circ}C$ to 22.5$^{\circ}C$ The meat weight rate (MWR) reached the maximum with the beginning of WT increase in March and the minimum in August. Monthly changes in average oocyte diameter showed the maximum (249.6$\pm$2.6 ${\mu}{\textrm}{m}$) in July and the minimum (134.3$\pm$2.8 ${\mu}{\textrm}{m}$) in December S. libertina libertina seemed to be a year-round breeder except for mid-summer and mid-winter. Two main reproductive cycle of the species could be divided into five successive stages: multiplicative (March, October), growing (April and May, November), mature (June and July, December), ovulation (August, January), parturition (September and October, March to May) and resting (September, February) stages in female and multiplicative (March, October), growing (April, November), mature (March to June, December), copulatory (July and August, January), resting (September, February) stages in male.

• Development and Reproduction
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• v.21 no.3
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• pp.297-305
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• 2017

An experiment was conducted to investigate the annual reproductive cycle of a Korean endemic species, Acheilognathus majusculus, from Jeokseong-myeon located in Seomjin River. The reproductive cycle is examined histologically regarding water temperature and day length of the habitat, the gonadosomatic index (GSI), the female ovipositor length index (OLI), monthly variation in egg diameter distribution, and developmental characteristics of female and male gonads. The maximum GSI was found in $19.21{\pm}2.32$ and $6.90{\pm}0.53$ for female and male respectively when water temperature ($14^{\circ}C$) and day length (11.1hr) began to rise. On the other hand, the minimum level was reached during August ($1.87{\pm}0.67$ for female and $0.88{\pm}0.50$ for male). No samples represent with measurable ovipositor between September and November, while the longest ovipositor length index was in April ($79.68{\pm}4.69%$). We compared and calculated the stages of testis and ovary development process in order to determine the germ cell development characteristics and the reproductive cycle. According to the result, we classified the female Acheilognathus majusculus reproductive cycle into four stages: Ripe (April) and spawning phase (May to June), degenerative phase (July), growing phase (August to December), and mature phase (January to March). The annual reproductive cycle of male Acheilognathus majusculus was categorized into five stages viz. Ripe and spawning phase (May to June), degenerative phase (July to August), resting phase (September to November), growing phase (December to February), and mature phase (March to April).

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.2
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• pp.117-122
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• 1997

This experiment was conducted to evaluate the forage yield and quality and the possibility to provide Festulolium bmunii(Festuca pratensis $Huds{\times}Lolium$ mult~jlotum Lam.) as forage source in Korea. The Festuloliurn braunii were harvested at boot, heading and anthesis stage, respectively. The field trials were performed 6om 1994 to 1996 at the forage experimental field, College of agriculture, Chunpam National University. The results obtained were summarized as follows: 1. The date of boot, heading and anthesis stage of Festulolium bmunii observed in Taejon were May 12, May 23 and June 1 in 1995, and June 1, June 4 and June 9 in 1996, respectively. Winter survival percentage of Festulolium bmunii war ranged 6om 96% to 98% and summer survival percentage were 75-86%. It would suggest that Festulolium brawlii persisted well in the aspect of overwintering, while it wasn' t widely adapted to drought and high temperature in Taejon regions. 2. The CP content and DMD of Festulolium bmunii tended to decline as the growth stage advanced. The CP content and DMD of Festulolium bmunii were high at the boot stage and those at the anthesis stage were low. But fiber contents at the boot stage were lower than those at anthesis stage(P< 0.05). The yields of the DM and DDM with advancing the growing stage tended to increase, while there was no difference in the CPDM yields among stages. On the otherhand, the yields of DM and DDM at the anthesis stage were the highest (P< 0.05), but there was no difference in CPDM yield among stages. Based on the results mentioned above, it is suggested that Festulolium b m n i i has a possibility to use until the anthesis stage under the cutting regimes and that it has a potentiality to provide one of a good forage sources. %'ifqqiZ 43q *(College of Agriculture, Chungnam National Un~versity, Taejon 305-764, Korea)

• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.391-401
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• 2014

Ten feeding trials were conducted to determine and to make the guideline for the optimum feeding rates in olive flounder Paralichthys olivaceus fed extruded pellets at various growth stages at the optimum rearing water temperature. The entire trials were grouped into four growth stages, namely the first stage of juvenile (5 and 9 g), the second stage of juvenile (20, 30, 40 and 50 g), growing (240 and 317 g) and sub-adult (384 and 525 g) stages with 2, 4, 2 and 2 feeding trials, respectively. In the first and second experiments, results indicated that the optimum feeding rates for the first stage of juvenile olive flounder weighing 5 and 9 g could be >5.17 but <5.52% and >4.44 but <4.64% body weight (BW)/day, respectively. In the third, fourth, fifth and sixth experiments, results suggested that the optimum feeding rates for the second stage of juvenile olive flounder weighing 20, 30, 40 and 50 g could be >3.47 but <3.50, >2.85 but <3.53, >2.58 but <3.04 and >2.36 but <2.50% BW/day, respectively. In the seventh and eighth experiments, results showed the optimum feeding rates for growing olive flounder weighing 240 and 317 g to be >1.03 but <1.25 and >0.85 but <1.0 % BW/day, respectively. In the ninth and tenth experiments, the optimum feeding rates in sub-adult olive flounder weighing 384 and 525 g were shown to be >0.69 but <0.7 and >0.55 but <0.8% BW/day, respectively. We will compare these results with the previous studies done by other research groups.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.474-481
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• 2010

The sperm collection time, sex steroid hormones, and gonadal development of protandrous black porgy, Acanthopagrus schlegeli, acclimated in freshwater for more than 2 years were investigated to evaluate its reproductive capability. The gonadal development of black porgy reared in seawater and freshwater could each be classified into four successive stages. For black porgy reared in seawater (BSW) as the control, these were the growing (December to February), mature (February to March), spent (March to June), and degeneration and resting (July to December) stages; for black porgy reared in freshwater (BFW), these were the growing (November to January), mature (January to February), spent (February to May), degeneration and resting (June to November) stages. In both BSW and BFW, the plasma cortisol levels were the highest in March. The plasma testosterone (T) levels of BSW and BFW were the highest in March and February, respectively. The plasma estradiol-$17{\beta}$ ($E_2$) levels did not differ significantly between BSW and BFW. The 11-ketotestosterone (11-KT) levels in the plasma of BSW and BFW were the highest in April. Sperm was collectible from March to June in BSW and from February to May in BFW. The results indicated that the gonadal maturation of BFW was about 1 month faster than that of BSW.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.633-641
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• 2009

Maturity and spawning of the atka mackerel, Pleurogrammus azonus, was investigated based on the samples collected by gill net and set net in the East Sea from January 2006 to March 2009. Gonadosomatic index (GSI) began to increase in October, and reached a maximum between November and December. After spawning GSI began to decrease from January. The spawning period was from October to January, and main spawning period was from November to December. Annual reproductive cycles of this species could be divided into five successive stages in females; early growing stage (June), late growing stage (July to August), mature stage (September to October), ripe and spent stage (November to January), and recovery and resting stage (January to May). Males showed four successive stages: growing stage (June to August), mature stage (September to October), ripe and spent stage (October to December), and recovery and resting stage (January to May). P. azonus could be one of polycyclic species spawning two times or more during one spawning season. Number of total and mature eggs in the fecundity were proportional to fork length. The fork length at 50% group maturity was estimated to be 26.9 cm.