• Asian-Australasian Journal of Animal Sciences
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• v.15 no.3
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• pp.438-444
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• 2002

This study was conducted to investigate the effect of aflatoxin $B_1$ ($AFB_1$) alone or mixed function oxidase (MFO)-activated $AFB_1$ on various functions of mule duck peritoneal macrophages. Duck peritoneal macrophages were incubated with $AFB_1$ 0, 5, 10, 20, 50 and $100 {\mu}g/ml$ for 12 h. The cell viability significantly declined as the concentration of $AFB_1$ increased and more obviously detrimental effects was noticed in MFO-metabolized $AFB_1$ treatments. Either in opsonized or unopsonized Candida albicans, phagocytotic ability of macrophages was decreased with the elevation of the concentration of $AFB_1$. Significantly higher levels of macrophages were damaged in MFO-metabolized $AFB_1$ than $AFB_1$ alone in concentrations above $20{\mu}g/ml$. The cytotoxicity activity was in the range of 41 to 33% after exposure to $AFB_1$ 5 to $100{\mu}g/ml$, and a significant higher TNF-like substance secretion by lipopolysaccharide (LPS) stimulation was obtained. When LPS was present in the medium, the percentage of cytotoxicity was higher than all treatments of $AFB_1$ both with and without MFO-activation in the absence of LPS. The results suggest that MFO-metabolized $AFB_1$ can alter cell viability and morphology of duck macrophages more than $AFB_1$ administered alone. Both with and without MFOactivation, $AFB_1$ has detrimental effects on phagocytotic ability and TNF-like substance secretion, increasing with level of $AFB_1$.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.3
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• pp.331-337
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• 1993

In order to understand the effect of duck hepatitis B virus (DHBV) on the economic performance of ducks, Three groups (DHBV congenitally infected, experimentally infected and DHBV negative) Brown Tsaiya ducks (Anas platyrhyncha) were used for experimental animals. Artificial insemination and pedigree hatching were applied in the propagation of ducklings, and the efficiency of vertical transmission and experimental infection was analyzed through the detection of DHBV DNA in the sera of 8-week-old offspring. The observation of the records of the first year indicated that the persistent infection had no significant effects on the performance of ducks, except the egg number of survival ducks up to 40 week of age. Thus DHBV infection did not appear to give ill effects to the economic performance of ducks in first laying year. A higher infection rate (85.3%) was obtained in congenital transmission than that (75.5%) of experimental infection. Both modes of infection did not reach 100% infectious rate, although some ducks developed transient viraemia in a tracing of DHBV DNA for 24 weeks to 11 challenged ducklings.

• Parasites, Hosts and Diseases
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• v.51 no.6
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• pp.663-667
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• 2013

Free-grazing ducks play a major role in the rural economy of Eastern Asia in the form of egg and meat production. In Thailand, the geographical location, tropical climate conditions and wetland areas of the country are suitable for their husbandry. These environmental factors also favor growth, multiplication, development, survival, and spread of duck parasites. In this study, a total of 90 free-grazing ducks from northern, central, and northeastern regions of Thailand were examined for intestinal helminth parasites, with special emphasis on zoonotic echinostomes. Of these, 51 (56.7%) were infected by one or more species of zoonotic echinostomes, Echinostoma revolutum, Echinoparyphium recurvatum, and Hypoderaeum conoideum. Echinostomes found were identified using morphological criteria when possible. ITS2 sequences were used to identify juvenile and incomplete worms. The prevalence of infection was relatively high in each region, namely, north, central, and northeast region was 63.2%, 54.5%, and 55.3%, respectively. The intensity of infection ranged up to 49 worms/infected duck. Free-grazing ducks clearly play an important role in the life cycle maintenance, spread, and transmission of these medically important echinostomes in Thailand.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.11
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• pp.1587-1593
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• 2009

Duck egg white (DEW) hydrolysates were prepared by five enzymes (papain, trypsin, chymotrypsin, alcalase, and flavourzyme) and their antioxidant activities investigated in this study. DEW hydrolyzed with papain (DEWHP) had the highest peptide content among the five enzymatic treatments. Besides, the peptide content of DEWHP increased when the enzyme to substrate ratio (E/S ratio) increased. It was suggested that higher E/S ratio contributed to elevate the degree of hydrolysis of DEW effectively. Similar results were also obtained by Tricine-SDS-PAGE. In addition, SDS-PAGE patterns indicated papain was the only one amongst all enzymes with the ability to hydrolyze DEW. In antioxidant properties, DEWHP showed more than 70% of inhibitory activity on linoleic acid peroxidation and superoxide anion scavenging. Moreover, the $Fe^{2+}$ chelating effect of DEWHP was greater than 90%, while no significant difference was observed in DPPH radical scavenging and reducing ability. The results of peptide contents, antioxidant activities and electrophoresis suggested that the higher the peptide content, the stronger the antioxidant activities in DEWHP.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1264-1269
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• 2011

Interleukin-2 (IL-2) is a vital cytokine secreted by activated T lymphocytes, and plays an important role in the regulation of cellular functions and immunity of animals. In this study, the recombinant duck IL-2 (rduIL-2) was secretory expressed in Pichia pastoris (P. pastoris). The recombinant P. pastoris strain was cultured in shake flasks and then scaled up in a 5.0-l bioreactor. The result showed that the maximal fresh-cell-weight of 594.1 g/l and the maximal $OD_{600}$ of 408 were achieved in the bioreactor. The rduIL-2 was purified by two steps of purification procedures, and approximately 311 mg of rduIL-2/L fermentation supernatant was obtained. SDS-PAGE showed that the purified rduIL-2 constituted a homogeneous band of ~16 kDa or ~14 kDa corresponding to the glycosylated or non-glycosylated duIL-2 protein in size, respectively. The bioactivity of rduIL-2 was determined by lymphocyte proliferation assay. The result indicated that the rduIL-2 greatly promoted the proliferation of ConA-stimulated lymphocytes in vitro. The P. pastoris expression system described here could provide promising, inexpensive, and large-scale production of the rduIL-2, which lays the foundation for development of novel immunoadjuvants to enhance both the immunity of ducks against various infectious pathogens and vaccine efficacy.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.2
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• pp.225-228
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• 1992

The study was undertaken to determine the effect of various levels of dietary magnesium on the metabolizability of magnesium in laying Tsaiya ducks and Leghorn hens. Twenty-five Tsaiya ducks and 25 Leghorn hens were raised in individual cages. The basal diet was mainly consisted of corn starch and isolated soybean protein. At the beginning of the experiments, birds were fed the basal diet added with 500 mg/kg Mg (1070 mg/kg in total by analysis) for 10 days in order to make the birds adapt to the new diet. Then, they were randomly divided into five treatments with five birds for each treatment and fed the experimental diets containing 690, 1070, 1690, 2150 or 2380 mg/kg Mg for 21 days and during the last five days excreta were collected. The experiment was repeated three times each at the age of 25, 31 and 36 weeks. The metabolizability of magnesium in the diet was determined by the indicator method. The metabolizabilities of magnesium for Tsaiya duck and Leghorn hen were 59.9% and 62.5%, respectively as the diet contained 690 mg/kg magnesium, and were significantly decreased (p<0.05) to 39.7 and 30.7%, respectively when the dietary magnesium content was increased to 2380 mg/kg.

• Journal of Veterinary Clinics
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• v.35 no.1
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• pp.7-9
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• 2018

Mycobacterium avium subspecies paratuberculosis (MAP) causes a significant economic burden in the animal production industry. The purpose of this study was to investigate the prevalence of MAP in the feces of wild duck populations residing along a riverside close to farms in the center of Korea. From wild Spot-billed (Anas poecilorhyncha) and Mallard (Anas platyrhynchos) ducks, 128 fecal samples were collected and analyzed using multiplex real-time PCR, sequencing, and nested PCR to confirm the presence of the organism. The molecular analyses showed that 44 samples (34.4%) were positive for MAP, suggesting a high prevalence of MAP in the wild duck population. Considering the nature and habitat of wild ducks, this result suggests that the organism was introduced from contaminated water from waste of nearby farms, and that the wild ducks may act as a transmitter of the organism to other wild birds or livestock.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1115-1119
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• 2007

As in many of the vehicle NVH issues, blower motor noise has been improved over the years through intensive R&D and production process improvement. Durability of motors, however, still has room for improvement according to customer surveys such as VDS. To investigate the noise issues of blower motors in view of durability, current production motors along with major competitor motors are tested. The noise after accelerated durability test shows that production motors are competitive in noise level with similar noise performance compared to initial measurement. The test result also provided guidelines to the durability development process.

• Journal of Microbiology and Biotechnology
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• v.7 no.4
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• pp.278-281
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• 1997

Streptomyces sp. MCY-846 selected by in vitro cytotoxicity assay produced elaiophylin. Individual characteristics of the strains such as spore morphology, and physiological characteristics indicated that the strain is resembled to Streptomyces hygroscopicus. The time course of cell growth and antibiotic production was observed in the medium containing 0.5% trehalose and 0.5% soybean meal as carbon and nitrogen sources, respectively. The optimum production of elaiophylin was tested with different combinations of carbon and nitrogen sources and reached a maxima of $470{\mu}$/ml in the PC-II medium.

• Korean Journal of Veterinary Service
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• v.38 no.1
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• pp.61-64
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• 2015

Highly pathogenic avian influenza (HPAI) occurred in the breeder duck farms in Jeonbuk of in Korea on January to February 2014. Clinically, the most ducks showed various signs from depression, dropped egg production and feed consumption to even, death. The most commonly gross changes were hepatomegaly, splenomegaly, petechial and ecchymotic hemorrhage on the liver surface, a white stripe on the cardiac muscle, multifocal hemorrhagic foci in pancreas, and severely hemorrhagic embryos. The most significant signs of H5N8 virus was supposed to specific on ducks. The viral antigen was mainly detected in the endothelium of blood vessels of various organs and tissues, peripheral nerves, and neuronal cells. Based on the above results, we identified that HPAI H5N8 induced systemic infection in the adult breeder ducks.