• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8_spc
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• pp.1284-1295
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• 2019

Considerable progress in reproduction of dairy goats has been made, with advances in reproductive technology accelerating dairy goat production since the 1980s. Reproduction in goats is described as seasonal. The onset and length of the breeding season is dependent on various factors such as breed, climate, physiological stage, male effect, breeding system, and photoperiod. The reproductive physiology of goats was investigated extensively, including hypothalamic and pituitary control of the ovary related to estrus behavior and cyclicity etc. Photoperiodic treatments coupled with the male effect allow hormone-free synchronization of ovulation, but the kidding rate is still less than for hormonal treatments. Different protocols have been developed to meet the needs and expectations of producers; dairy industries are subject to growing demands for year round production. Hormonal treatments for synchronization of estrus and ovulation in combination with artificial insemination (AI) or natural mating facilitate out-of-season breeding and the grouping of the kidding period. The AI with fresh or frozen semen has been increasingly adopted in the intensive production system, this is perhaps the most powerful tool that reproductive physiologists and geneticists have provided the dairy goat industry with for improving reproductive efficiency, genetic progress and genetic materials transportation. One of the most exciting developments in the reproduction of dairy animals is embryo transfer (ET), the so-called second generation reproductive biotechnology following AI. Multiple ovulation and ET (MOET) program in dairy goats combining with estrus synchronization (ES) and AI significantly increase annual genetic improvement by decreasing the generation interval. Based on the advances in reproduction technologies that have been utilized through experiments and investigation, this review will focus on the application of these technologies and how they can be used to promote the dairy goat research and industry development in the future.

• Journal of Environmental Science International
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• v.31 no.10
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• pp.861-868
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• 2022

The Namdae stream in Gangneung-si is one of the rivers where salmon stock is mainly maintained by natural spawning rather than artificial seedlings. There are structures including weir, and fish distribution and movement characteristics can be different by these structures. In this study, we investigated the distribution and behavioral characteristics of salmon by sighting survey within 12 km immediately upstream of the river mouth between October 2021 and February 2022. As a result, salmon distributed within 9 km from rivermouth. There were more salmon in the lower reaches of Doosan weir than in the upper reaches of that. The main spawning ground for salmon was between 7-9 km from rivermouth and around the lower part of Doosan weir. Salmon behaved for spawning in the gravel-bed area and undercut slope of the mainstream, such as mating, digging the riverbed, and competition among males. Salmon moved more slowly in the gravel-bed area than sand-bed area. Doosan weir hinders the spawning migration of salmon by frequent flow changes and terraced fishway. This study provides primary information to understand the ecological changes of salmon by environmental changes in the Namdae stream.

• Korean Journal of Agricultural Science
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• v.49 no.1
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• pp.19-29
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• 2022

The present experiment was conducted to evaluate the effects of single-sex or mixed rearing on the growth and laying performance, blood parameters, egg quality, and feather scores of laying hens in an aviary system. A total of 2,928 (females, 2,856; males, 72), Hy-Line Brown chickens at 20 weeks were evenly assigned to two treatments: termed here the single-sex (only female) and mixed-sex (female to male 20 : 1) conditions. They were allowed an ad libitum diet for 20 weeks in an aviary system. There were eight replicates of each treatment, each consisting of 12.42 m²·birds^-1 (n=183), respectively. The body weight and uniformity in the mixed-sex condition were higher than those in the single-sex condition, but egg production did not show any significant differences between the two types of treatment for 20 weeks. The mixed-sex group showed an effect through stress parameters (corticosterone), whereas the feather score on the back was low at the end of the experiment. These results suggest that the presence of males affect corticosterone level for mating but can reduce the vigilance and aggressive behavior of laying hens.

• Journal of Aquaculture
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• v.4 no.1
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• pp.31-66
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• 1991

This paper deals with the reproductive ecology e.g., number of the pre-spawning moults, morphological characteristics of the pre-spawning moult the common moult, daily ration druing a molting cycle mating behavior, structures of spermatozoa and spermatophore, structure of vas deferens, mechanisms of the oviposition and brooding into the egg-chambers, a suitable time for the artificial mating and fertilization, time sequence of the oviposition and brooding into egg-chambers from the copulation, responses to temperature and chlorinity on the egg development and hatching, effect of temperatures on duration of egg development, physical mechanism of the egg hatching, to make an attempt for the artificial spawning and brooding to establish a suitable system of the artificial seedling-production for the aquaculture. 1. Females molted commonly $8{\~}10$ times at an interval of $17{\~}18$ days at $28^{\circ}C,\;3.26\~4.35\%_{\circ}$ while the prespawning moltings were $4{\~}5$ times at an interval of $13{\~}14$ days. The suitable state for artificial copulation was within 14 hours elapsed from the prespawning moltings (most suitable state was within 8 hours). Males discharged a gelatinous spermatophore and placed it on the females sternum during copulation. Oviposition was seen $6{\~}17$ hours after copulation. External fertilization was considered to take place at oviposition. Fertilized eggs held in egg-chambers forming between pleopods were about $5000{\~}6000$ in females those sizes about 6.5 cm in body length. 2. Eggs immediately after oviposition were elliptic shape, measuring $0.58{\times}0.48$ mm up to hatching. Their sizes increased with egg development and finally reached $0.85{\times}0.54$ mm up to hatching. The relationship between the long axis of the egg(Y in U) and days elapsed(X) was expressed as Y= 5.60194 + 0.007358X. The eggs performed superficial cleavage and their cleavage furrows became visible at the 4-daughter-nucleus stage. The eggs showed normal development up to hatching at water temperature range of $22{\~}30^{\circ}C$ (optimum temperature : $26{\~}28^{\circ}C$) and at chlorinity range of $0.00\~6.64\%_{\circ}$ (optimun chlorinity : $2.21{\%}_{\circ}$). The relationship between incubation period (Y in days) and water temperature(X in $^{\circ}C$) could be expressed as Y= 50.803-1.3555X. The eggs hatched $12{\~}13$ days after oviposition at $28.0{\~}28.6^{\circ}C$ 3. The pre-spawning moltings were appreciably different in the morphologic structure from those of common moltings. Breeding setae and dresses were formed on the thoracic regions, abdominal epimerae and the bases of the first to fourth pleopods in order to prepare and support oviposition, transfering and supporting eggs in egg-chambers up to hatching. These supplementary breeding organs were observed only at reproductive seasons.

• Korean Journal of Heritage: History & Science
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• v.56 no.1
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• pp.132-140
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• 2023

In this study, a total of 21 parts of the head, carapace, and plastron of 21 tortoises were examined to investigate the characteristics of male and female sexual dimorphism of the Reeve's turtle (Mauremys reevesii), a natural monument in Korea. The ratio values of a total of 19 areas were derived from Head Length (HL) and Carapace Length (CL). As a result of comparing the ratio values, it was found that male tortoises had larger head length, head width, and head height than females compared to the size of the carapace. Since females grow eggs inside the body through internal fertilization after mating, female carapaces are judged to be larger than males overall. As a result of statistical analysis of the ratio values of the measured values, Plastron Length (PL), Bridge Length (BL), Gular Length (GL), Interhumeral Length (IH), Interanal Length (IAN), Femoral-Anal seam (FA) and Head Height (HH) showed statistically significant differences. Statistically significant in the part of the plastron, it is judged that the tortoise acts directly on each deck of the plastron as it grows. In addition, the head size of male tortoises was smaller than that of females, but it was found to be larger in proportion. It is considered that the tortoise has a rather large head compared to the body due to the male's habit of shaking his head and courtship behavior before mating. This study, we were able to identify the characteristics of sexual dimorphism in Reeve's turtle. However, since most of them were rescued, it was not possible to accurately determine habitat and age. In the future, if additional studies are conducted on individuals with clear habitats and ages, it is expected that the characteristics of the physical differences that develop as they grow can be identified.

• The Korean Journal of Zoology
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• v.31 no.4
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• pp.327-333
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• 1988

계절에 따른 초파리 집단내 역위다형 현상의 변동상을 알기 위하여 전주근교의 과수원에서 1983년 1월부터 11월까지 격월로 여섯번 채집한 집단 표본을 분석하였다. 총 1071마리에서 얻은 15개형의 역위는 모두 편동원체역위(paracentric inversion)였으며, 이 중 7개형은 세계형91위(cosmopolitan inversion)였고, 나머지 8개형은 지역형역위(endemic inversion)였다. 개체당 역위의 평균 보유수는 0.639이고 역위를 보유한 개체의 빈도는 0.465였다. 7개의 세계형역위에 대한 표본집단을 분석한 결과 격월 집단간에서 유의한 차이를 보이는 반면 1월과 1 1월 표본간에서는 그 성황이 오히려 비숫해짐으로서 집단내 총역위빈도는 주기적으로 변동하고 있음이 암시된다. 역위와 환경변수와의 다중상관분석에서는 기온, 습도, 강수량이 역위빈도에 유의한 영향을 미치는 것으로 나타났고 역위 중 In(2L)t가 상기한 환경변수 모두에 대하여 유의한 상관관계를 보인 반면, In(3R)C와 In(3R)P는 어느 것과도 상관성을 보이지 않았다. 염색체내 그리고 염색체간의 연관 또는 조합의 검정결과 연관불평형혈상을 1월, 5월, 그리고 7월 표본의 제3염색체에서, 그리고 비균일조합은 1월과 7월 표본에서 역시 제3염색체에서만 산출 되었다. Seasonal changes of inversion frequencies in Chonju 0. melanogaster populations were studied. A total of 1071 males were collected six times with ho months intewal from January through November in 1983. to analyse diploid sets of chromosomes carried by males, each male was mated to several virgin females homoBvgous for cytologically standard sequence in all chromo-somes. From each mating, more than seven FL larvae were selected in random and tested to find chromosomal aberrations. In the present study, 15 different inversions were found and identified to be paracentric only In both second and third chromosomes; seven were cosmopolitan and the rest eight endemic types. The average frequency of inversions was 0.465 and the mean number of inversions carried by a single male was 0.639. The linkage disequilibria were detected between the leK and right arms of third chromosomes from the samples of January, May and Julv, Whereas nonrandom associations appeared also in the third chromosomes only in January and Julv samples. In multiple regression analysis among frequencies of inversions and environ-mental variables it appeared that mean temperature, relative humidity and total precipitation for a month skipped over 30 days before collected affect to change to frequencies of particular inver-sions. With respect to the behavior of inversions in the present samples, it is suggested, with the Friedman's analysis of variance by ranks of inversion frequency orders, that the frequencies of inversions change cyclically year to year.

• Korean journal of applied entomology
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• v.43 no.3 s.136
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• pp.225-231
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• 2004

An endoparasitoid wasp, Cotesia plutellae, has been used for a biological control agent against the diamondback moth, Plutellae xylostella. It has a symbiotic polydnavirus in their reproductive tract, which is required for its successful parasitization. Here, we measured a specific replication time of the polydnavirus during female development of C. plutellae. We, also, analyzed the reproductive potentials of female C. plutellae under mating or different host conditions. At $25^{\circ}C$, pupal C. plutellae began to develop adult tissues such as compound eyes and wings since day 2. At day 5, all adult tissues including antennae were developed and were ready to emerge. With polyclonal antibody raised against C. plutellae polydnavirus, an immunobloting could confirm virus replication at day 4 during pupal stage. Virus particles could be visualized by transmission electron microscope in the oviduct lumen of day 5 pupae. After adult eclosion, venom gland and ovarian calyx increased in size, though ovarioles did not. Mated females layed large number of eggs (over $60\%$) at first 4 days during their mean longevity of ca. 8 days at $25^{\circ}C$. Unmated females showed less active ovipositional behavior, where all the eggs developed into males. C. Plutellae parasitized both P. xylostella and fall webworm, Hyphantria cunea. However, C. Plutellae developed faster and showed higher successful paarasitization in P. xylostella than in H. cunea.