• Journal of Aquaculture
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• v.10 no.3
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• pp.373-380
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• 1997

The experiments were conducted to improve the mass production of Nile tilapia, Oreochromis niloticus, seed in closed recirculation systems. It was observed that smaller females (340g av. body weight) under lower stocking density (1.2 kg/$m^2$)) group produced 3.6 times more fry than larger females (612g av. body weight) under higher stocking density (2.1kg/$m^2$) group when the fry were collected at 30 days after the broods stocked. The clutch removal method where the eggs and sacfry were collected from female mouth followed by artificial incubation showed improved seed production, when compared to the traditional natural mouth-brooding method by harvesting free swimming fry from brood tanks (P<0.05). Under the clutch removal method, short-term incubatin of brooders (14 days) was proven to be more effective than long-term incubatin (21 days). Hatching success of clutch removed eggs was ranged from 55.7 to 91.5% in 1.8$\ell$ of upwelling incubators depending on the different development stages.

• Journal of Animal Science and Technology
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• v.55 no.2
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• pp.131-139
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• 2013

The aim of this study was to assess the effects of housing systems on physiological and immunological responses as stress indicators in laying hens. A total of 500 White Leghorn aged 16 weeks were allotted into ten conventional cages (10 birds/cage and 810 $cm^2$/bird) and four floor pens (100 birds/pen and 2,800 $cm^2$/bird) for 24 weeks. The hens housed in conventional cages with higher stocking density resulted in a significantly (P<0.05) lower BW compared with those housed in floor pens with lower stocking density without affecting the relative weights of immune organs between housing conditions. In plasma biochemical values, cholesterol and corticosterone were significantly (P<0.05) lower in the hens housed in floor pens compared with those housed in conventional cages. In pro-inflammatory cytokines, hepatic interleukin (IL)-10 and interferon-gamma (IFN-${\gamma}$) levels were significantly (P<0.05) higher in the hens housed in conventional cages compared with those kept in floor pens. Splenic and thymic IFN-${\gamma}$ expression was significantly (P<0.05) up-regulated in the hens kept in conventional cages compared with those kept in floor pens without affecting IL-1, IL-10, lipopolysaccharide- induced tumor necrosis factor-${\alpha}$ factor (LITAF) and inducible nitric oxide synthase (iNOS). In the bursa of Fabricius, IL-10 and iNOS expression of the hens housed in conventional cages were significantly (P<0.05) higher compared with those of the hens housed in floor pens. In conclusion, layers housed in conventional cages enhanced plasma cholesterol, corticosterone and some pro-inflammatory cytokines in the immune organs compared with those in floor pens.

• Journal of Animal Environmental Science
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• v.19 no.1
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• pp.33-38
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• 2013

We conducted investigations of the information and welfare of broiler chickens in Korea. The livestock housing of all broiler chicken farms were windowless type, bell feeder and nipple waterer were used, and stocking density was relatively higher (ranging from 18.2 $birds/m^2$ to 24.2 $birds/m^2$) than RSPCA's welfare standards for chicken hens (less than 19 $birds/m^2$). The ratios of sandwich panel, urethane form, slate, and steel plate in roofing materials were 61%, 21%, 13%, and 5%, respectively. The ratios of sandwich panel, urethane form, brick, and steel plate in wall materials were 61%, 21%, 13%, and 5%, respectively. The ratios of soil and concrete in flooring materials were 10% and 90%. The mist spray, fan, and cooling pad in cooling facilities were 42%, 32%, and 26%, respectively. Thus we believe that present data contribute to develop the animal welfare certification for broiler chickens and to improve animal welfare in Korea.

• Journal of Animal Science and Technology
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• v.53 no.5
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• pp.489-496
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• 2011

This study was carried out to investigate the effects of stocking density on the eating and ruminating behavior of growing Hanwoo steer (Bos taurus coreanae). A total of thirty growing Hanwoo steers were divided into four stocking density groups (G1: 1 head/32 $m^2$, G2: 2 heads/32 $m^2$, G3: 3 heads /32 $m^2$, G4: 4 heads/32 $m^2$) with 3 replicates (12 pens). The results of eating behaviors for 48 hours are summarized as follows: Total intake was higher in 2G, 3G and 4G than in 1G, but not significantly different among thetreatments. Intake of roughage was the highest in 2G (3.32 kg), while 1G (2.85 kg) was the lowest (P<0.05). Eating time of concentrate was highly in the order of 1G > 2G > 3G > 4G (P<0.05). But eating time (concentrate + roughage) and ruminating time were not significantly difference among the treatments. Resting time (standing + lying) was the highest in 4G (P<0.01), and lying time was the highest in 2G. Chewing time (Eating + ruminating) was higher in 3G than in 1G, 2G, and 4G (P<0.05). Number of bolus, number of total chews, ruminating time per bolus and number of bolus per minute were not significantly difference among the treatments. But number of chews per bolus was significantly lower in 1G than those of the other treatments (p<(0.05). Number of urinating was in the order of 1G > 4G > 2G > 3G (P<0.05). However, stocking density had no effect on drinking and defecating. Eating rate and chewing efficiency were the highest in 4G (P<0.01, 0.05), but ruminating efficiency was not significantly difference among the treatments.

• Korean Journal of Poultry Science
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• v.47 no.1
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• pp.1-7
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• 2020

The effect of stocking density on the growth and meat quality of native Korean chickens was investigated. A total of 364 one-day-old native Korean chickens were randomly assigned to one of 5 treatments, each of which was replicated 4 times. Five distinct stocking densities-14, 15, 16, 18, and 22 birds/㎡-were compared. The diet was fed ad libitum for 10 weeks. Results indicated that the final body weight, body weight gain, and feed intake were lower (P<0.05) for the 22 birds/㎡ stock density as compared to the other stock densities. There was no significant difference in the feed conversion ratio, proximate analysis (DM, crude protein, crude fat, and crude ash), water-holding capacity, and cooking loss among the different stock densities. These results indicate that increasing the stock density to 22 birds/㎡ elicits some negative effects on the growth performance and meat quality of Korean-native chickens.

• Journal of Aquaculture
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• v.13 no.4
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• pp.339-351
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• 2000

Optimal environmental conditions, that sustained fastest growth, lowest mortality and abnormality of the scallop Patinopecten yessoensis, were identified from field experiments undertaken at Chumunjin during 1991-1998. Temperature within the water column 10~30 m depth ranged between 5 and 23$^{\circ}C$; high temperature and daily fluctuation resulted in growth retardation and heavy mortality of the scallop. Optimal salinity range was between 31.5 and 34.5%0 and water transparency 6.0 and 18.1 m, which was significantly affected by phytoplankton density. Chlorophyll concentration ranged between 0.04 and 3.51 f.lgfL. Low temperature and high chlorophyll concentration appear to support faster growth of the scallop. Optimal periods of transplantation for intermediate culture were between mid July and early November: cultured under high density during July-August as a first step and under low density during mid September through early November as a second step. Optimal stocking density in square net cage (<35${\times}$35 em) for intermediate culture was 30-40 individuals per cage for main culture using lantern net and 80 -100 individuals of the size of 1.5 ~ 3.0 em shell height per cage for sowing culture. During the intermediate culture, the highest growth was realized, when the cage was held at water depth between 10 and 15 m. Water depth below 25 m, however, was best to avoid mass mortality during the periods of abnormally high water temperature and high variation of water temperature. The daily growth rate during the intermediate culture was between 0.019~0.381 mm; low in January and February but high in March and April. It is suggested that the main culture is commenced before June under low stocking density to avoid the possibility of mass mortality during summer by high water temperature.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.83-91
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• 2015

This study is measured the change of chlorophyll-${\alpha}$ concentration and phytoplankton density, the grazing rates (GR) and pseudofaeces production (PFP), by grazing of freshwater apple snail, Pomacea canaliculata, to investigated that the snails are able to control of phytoplankton bloom. The experiments are performed to evaluate the GR and PFP at different conditions such as incubation time (0, 2, 4, 6, 8, 10 and 12 hr), shell height (1.0 to 4.0 cm, n=108), snail density (1, 1.5, 2.5, 3.5 and 5 indiv. $L^{-1}$) and food concentration (200, 400, 600, 800 and $1000{\mu}g$ $L^{-1}$). Regarding feeding time, the highest GR (2.5 L. $gAFDW^{-1}h^{-1}$) and PFP (15.3 mg $AFDW^{-1}$) showed at 4 hr after snail stocking, respectively. The snail, smaller than 1.5 cm in body size, showed the highest of GRs (2.54 L. $gAFDW^{-1}h^{-1}$) for the initial period (2 hr of stocking), compared to those greater than 1.5 cm, which showed a stable FR, higher than 0.099 L. $gAFDW^{-1}h^{-1}$. Upon snail density effect, the density of 5 indiv. $L^{-1}$ induced the most effective inhibition on phytoplankton biomass with the highest PFP. On the food concentration, the highest GR (0.54 L. $gAFDW^{-1}h^{-1}$) and PFP (8.5 mg $gAFDW^{-1}$) were induced at the level of $600{\mu}g$ $L^{-1}$, respectively. We checked that it is possible to control of phytoplankton bloom by the grazing of apple snail as well as Reeve. However, it required a through research for the remove of pseudofaeces and 2nd problem by the decomposition of the organic materals.

• Journal of Animal Science and Technology
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• v.61 no.5
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• pp.260-271
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• 2019

The objective of this study was to determine the effect of different stocker management programs on skeletal muscle development and growth characteristics, satellite cell (SC) activity in growing-finishing beef cattle as well as the effects of SC-conditioned media on preadipocyte gene expression and differentiation. Fall-weaned Angus steers (n = 76; $258{\pm}28kg$) were randomly assigned to 1 of 4 stocker production systems: 1) grazing dormant native range (NR) supplemented with a 40% CP cottonseed meal-based supplement ($1.02kg{\cdot}steer^{-1}{\cdot}d^{-1}$) followed by long-season summer grazing (CON, 0.46 kg/d); 2) grazing dormant NR supplemented with a ground corn and soybean meal-based supplement fed at 1% of BW followed by short-season summer grazing (CORN, 0.61 kg/d); 3) grazing winter wheat pasture (WP) at high stocking density (3.21 steers/ha) to achieve a moderate rate of gain (LGWP, 0.83 kg/d); and 4) grazing winter WP at low stocking density (0.99 steers/ha) to achieve a high rate of gain (HGWP, 1.29 kg/d). At the end of the stocker (intermediate harvest, IH) and finishing (final harvest, FH) phases, 4 steers / treatment were harvested and longissimus muscles (LM) sampled for cryohistological immunofluorescence analysis and SC culture assays. At IH, WP steers had greater LM fiber cross-sectional area than NR steers; however, at FH, the opposite was observed (p < 0.0001). At IH, CORN steers had the lowest Myf-5+:Pax7+ SC density (p = 0.020), while LGWP steers had the most Pax7+ SC (p = 0.043). At FH, CON steers had the highest LM capillary density (p = 0.003) and their cultured SC differentiated more readily than all other treatments (p = 0.017). At FH, Pax7 mRNA was more abundant in 14 d-old SC cultures from HGWP cattle (p = 0.03). Preadipocytes exposed to culture media from proliferating SC cultures from WP cattle isolated at FH had more $PPAR{\gamma}$ (p = 0.037) and less FABP4 (p = 0.030) mRNA expression compared with NR cattle. These data suggest that different stocker management strategies can impact skeletal muscle growth, SC function, and potentially impact marbling development in growing-finishing beef cattle.

• Development and Reproduction
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• v.27 no.2
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• pp.67-75
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• 2023

Polymeric immunoglobulin receptor (pIgR) mediates the transfer of polymeric immunoglobulin to protect organisms and is one of the most important mucosal effectors. In this study, the developmental stage- and tissue-specific expression of pIgR were observed before virus inoculation in olive flounder. pIgR was gradually expressed until the formation of immune tissue, exhibiting high expression in the late juvenile period; thereafter, pIgR expression gradually decreased and exhibited high expression in the spleen and skin. Moreover, pIgR expression after viral hemorrhagic septicemia virus infection was high in the kidney and spleen tissues at high density and low at low density. The results of this study can provide a basis for future studies on breeding density, virus expression, and immune system studies in fish.

• Journal of Forest and Environmental Science
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• v.38 no.3
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• pp.174-183
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• 2022

The study aims to examine population indices of mature trees in Jebel Elgarrie forest, Blue Nile State, Sudan. We used remote sensing techniques to stratify the forest into vegetation classes depending on tree density. We distributed 97 circular sample plots (0.1 ha) proportionally to the area of the vegetation classes. In each sample plot we identified, counted and recorded all mature trees (DBH ≥10 cm). We calculated frequency, density, abundance, richness, evenness and diversity for each species and we drew abundance rank curve of mature trees. We used One-Way ANOVA to test for differences (α=0.05) in mean density (No./ha) of mature trees between vegetation classes. Results revealed that the forest was conveniently sub-divided into high density (C1), medium density (C2), low density (C3) and bare farm land (C4) classes. We identified fifteen tree species that belong to 10 families and 14 genera. Combretaceae and Fabaceae were the common families while Anogeissus leiocarpa was the most frequently occurring species. While species diversity varied between vegetation classes, diversity of the forest as a whole is low. While mean density of mature trees in C1, C2, C3 and C4 it was 100, 74, 10, and 0, respectively, it was 54 for the whole forest indicating low stocking, Following One-Way ANOVA, multiple comparisons revealed significant differences in mean density of mature trees between C1 & C3 and C2 & C3. The study provided empirical results on population indices of mature tree species, which would be of importance for successful management and conservation of the forest.