• 한국발생생물학회지:발생과생식
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• 제16권1호
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• pp.1-8
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• 2012

The reproduction of animals is a way to maintain their species and demands a large amount of energy. The golden hamsters are seasonal breeders whose reproductive activities are regulated by photoperiod (length of day time in a day). The photic information received is transported to the pineal gland via many steps. Melatonin produced by the pineal gland affects the reproductive neuroendocrine system to manage reproductive activities. The major regulator neurons, secreting gonadotropin-releasing hormone, integrate all kinds of information to govern the reproductive frame hypothalamuspituitary-gonad axis. The elements impinging on the neurons are recently outspread. Thus the present review is to briefly survey the elements discovered newly and subjected to the active research realm and their correlations, focusing on the regulation of reproduction in mainly male golden hamsters as a representative animal.

• 대한수의학회지
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• 제36권4호
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• pp.1007-1012
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• 1996

The purpose of the survey was to understand the field situation on the occurrence of enteric diseases in poultry farms in Korea. During the period from January of 1991 to December, 1992, 279(35.8%) out of 779 farms surveyed experienced the cases of enteritis in their chickens. The farms with diarrheal problems consisted of 157(45.1%) of 348 broiler flock, 28(32.6%) of 86 breeder flock, and 94(27.2%) of 345 layer flock. The main diseases causing enteritis were frequently appeared as infectious bursal disease(27.3%), colibacillosis(22.6%), and coccidiosis(8.6%). Necrotic enteritis(NE) in chicken occurred in 21 farms(2.7%) among 779 farms examined. The outbreaks of NE were divided 4.7% in breeders, 4.0% in broilers, and 0.9% in layers, respectively. NE occurred mainly in the age(71.4%) of 20~30 days and the mortality was varying from 1.4% to 10.0% for broilers, 3.0% for layers and 0.8% for breeders. Seasonal prevalence of NE showed the highest as 52.4% in summer and followed by 33.3% in autumn, 9.5% in spring and 4.5% in winter.

• 한국가금학회지
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• 제23권3호
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• pp.153-160
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• 1996

Though pheasants (Korean ring-necked pheasant) have been raised for several decades, their behavior and wild nature are far from domestication. The pheasant is a seasonal breeding species and lays a limited number of eggs in a breeding season. The growth rate and feed efficiency of pheasants are very low as compaired with those of chicken for meat purpose. In addition, the breeder's access to one's herd for care is not easy. From these reasons, pheasants seem to be unsuitable for meat production in a large flock at present. However, pheasant raising is expected to increase slowly in accordance with rising demand for special poultry meat. Therefore, it is necessary to improve techniques about raising, feeding and rnanagement, so that the consumer price of pheasant meat can be lowered down reasonably.

• 대한수의학회지
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• 제34권1호
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• pp.9-18
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• 1994

The morphological changes of Sertoli cells of the Korean native pheasant were studied in the active and inactive spermatogenic phases. Twenty-four male of the pheasants were studied in the active (April~June) and inactive(August~March) phase. These data are useful in studying the male genital organs of the Korean native pheasant. Light microscopic morphological changes of the Sertoli cells were studied on paraffin-embedded sections stained with hematoxylin-eosin stain. Ultrastructural changes of Sertoli cells were investigated of ultrathin section using electron microscope. Results are summarized as follows: During the active phase, the average diameter of seminiferous tubule was $245.33{\pm}29.93{\mu}m$ and was largely decreased by $94.50{\pm}14.10{\mu}m$, and the thickness of interstitial tissue was comparatively increased during the inactive phase. During the active phase, in the cytoplasmic process of Sertoli cell and lipid droplets appeared disperse. Well-developed smooth Endoplasmic Reticulum and microtuble were observed in the cytoplasmic process. The nuclei of Sertoli cells were adjacent to the basement membrane. The size of nuclei was reduced and nuclei of Sertoli cells were densely packed within the tubule. Few collagen fibers, fibroblast and various sizes of lipid droplets were observed in the interstitial cell of the seminiferous tubule.

• International Journal of Industrial Entomology and Biomaterials
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• 제45권1호
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• pp.22-28
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• 2022

Silkworms are very sensitive to changes in temperature and humidity, and unless it is a suitable temperature and humidity to grow, the productivity and quality of silkworms are greatly reduced. Therefore, it is very important to manage temperature and humidity for silkworm feeding facilities. In particular, it is essential to install heating facilities in Asian countries with distinct seasonal changes. During the feeding period, many farms manage the temperature and humidity of feeding facilities by installing and using electric heaters inside the facilities. However, it is very difficult to manage the room temperature stably by the heaters. In addition, unlike the temperature inside the facility, silkworms could undergo severe temperature changes as the inside of the rearing tray could not be warm enough. In this study, in order to improve the previous heating method, the new rearing method that directly heats the bottom of the rearing tray was developed. Compared to the previous room-heating system, the novel heater-installed tray (HIT) system significantly reduced the change in temperature during the experimental period. In addition, the number of days of silkworm growth up to harvest was shortened, which was effective in growth performance, and it was also found that silkworms grew more uniformly in HIT system than in previous system. Moreover, as the heater tubes were installed directly under the rearing tray, it quickly dried mulberry leaves and silkworm feces after feeding, and as a result, the environment in the tray was greatly improved with decrease the labor of breeder. In conclusion, these results suggest that the heater-installed rearing tray method greatly improves silkworm quality, increases weight of silkworms, and final profits compared to the previous room heating system with electric heaters.

• 한국산학기술학회논문지
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• 제21권10호
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• pp.433-439
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• 2020

본 연구는 초음파 유래 OPU (Ovum Pick-Up) 기술을 이용하여 엘크 암사슴의 개량 및 활용성 증진을 위해 엘크 암사슴 난자를 채취하였다. 비번식 계절시기에도 체외 수정란이 생산 가능한지 확인하기 위하여 OPU 초음파 진단기를 이용하여 사슴 난소에서 난포를 흡입한 후 난자를 회수 하였다. 총 85개의 난포를 흡입 한 결과 57개의 난자가 회수되어 67.1%의 회수율을 나타내었다. 난자의 등급을 평가한 결과 A 등급 14.0%, B 등급 19.2%, C 등급 15.7% 및 D 등급 50.8%로 조사되었다. 본 연구에서는 A~C 등급의 난자를 이용하여 체외성숙, 체외수정 및 체외배양을 실시하였다. 총 28개의 난자를 이용하여 67.9% (19/28)의 수정율을 보였으며 배반포 발달율은 14.3% (4/28)로 나타났다. 본 연구 결과를 토대로 하여 볼 때, 계절번식을 하는 것으로 알려져 있는 엘크에 초음파 유래 OPU 방법이 적용 가능한 것으로 확인하였다. 따라서, 향후 추가적인 연구를 통해 체외수정과 체외배양 효율을 보다 향상시킨다면 엘크 수정란 이식을 통해 사슴의 개량기반 구축과 암사슴의 활용성 향상에 기여 할 수 있을 것으로 사료된다.