• 한국패류학회지
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• 제16권1_2호
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• pp.35-41
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• 2000

1999년 4월부터 2000년 3월까지 서해 금강 하구인 내 초도에 서식하고 있는 가무락조개를 대상으로 자원증식 및 적정 관리를 위해 조직학적 방법에 의해 생식소지수, 생식 소발단단계에 따른 생식주기, 군성숙도를 조사하였다. 가무락조개는 자웅이체로서 난생이다. 가무락조개의 생식주기는 초기활성기(2-4월), 후기활성기(3-6월), 완숙기(4-8월), 부분산란기(7-10월초), 퇴화 및 비활성기(9-2월)의 연속적인 5단계로 구분할 수 있었다. 가무락조개의 산란기는 수온과 밀접한 관계를 가지며 수온이 24$^{\circ}C$이상인 7월부터 산란하기 시작하여 9월 중순까지로 산란성기는 7, 8월이었다. 고창산 가무락조개의 군성숙도는 각장 26.0-30.0 mm 사이에서 암, 수 공히 50% 이상이 재생산에 가담하였고, 각장 41.0 mm 이상에서는 100%가 산란에 참여하고 있다. 전 개체의 50%가 재생산에 가담하기 시작하는 개체들의 연령은 만 2세로 추정된다.

• 한국수산과학회지
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• 제41권4호
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• pp.253-260
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• 2008

Gonadal development, gametogenesis, reproductive cycle, spawning, relative weight of flesh, and onset of sexual maturity of the murex shell, Ceratostoma rorifluum, collected from the rocky intertidal zone of Daehang-ri, Buan-gun, Jeollabuk-do, Korea were investigated monthly from January to December 2005 both cytologically and histologically. The gonads were widely placed on the digestive gland located in the posterior spiral fleshy part in the shell. C. rorifluum had separate sexes, and was an internal fertilizer. The sex ratio of females to males was approximately 1:1. The ovary and testis contained a great number of oogenic follicles and spermatogenic tubules, respectively. The oogonia and fully ripe oocytes were $15-19{\mu}m$ and $150-160{\mu}m$ in diameter, respectively, and the cytoplasm of the ripe oocytes contained a number of yolk granules. The relative weight of flesh reached a maximum in August($39.35{\pm}0.40%$), and then decreased rapidly in November($32.75{\pm}1.20%$). The percentages of female and male snails at first sexual maturity with shell heights ranging from 12.1-14.0 mm were 60.0% and 52.9%, respectively, while 100% of the snails of both sexes with shell heights over 18.1 mm were reproductively active. Based on the gonadal development and histological observations, the reproductive cycle of the snail could be categorized into five successive stages: early active(December to May), late active(March to July), ripe(June to September), spawning(July to October), and recovery(October to March). C. rorifluum spawned once a year between July and October, and the majority of spawning occurred in September when the seawater temperature exceeded $23.5^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• 제23권1호
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• pp.13-16
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• 2010

The effect of exogenous administration of tamoxifen (TAM) on hormonal profile and sexual maturity in Indian native Kadaknath (KN) fowl was investigated. Day-old chicks from the same hatch were randomly divided into 15 groups with 20 chicks in each group (5 treatments${\times}$3 replicates). The chicks were placed in battery brooders with wire-mesh floors and reared under uniform husbandry conditions (14 h light/d, 25-32${^{\circ}C}$) on a standard basal diet. At the age of two weeks (wk), birds from the control group ($T_{1}$) were injected with maize oil intramuscularly (I/M), whereas the other four experimental groups $T_{2}$, $T_{3}$, $T_{4}$ and $T_{5}$ were given tamoxifen (I/M) dissolved in maize oil at the rate of 0.5 mg (0.5 TAM), 1.0 mg (1.0 TAM), 2.5 mg (2.5 TAM) and 5.0 mg (5.0 TAM)/kg body weight, respectively, up to 30 wks on every alternate day. At every 6-wk interval, blood samples were collected from nine birds of each treatment group for estimation of estrogen and progesterone. The same birds were sacrificed for determination of the weight of ovary, oviduct, liver and adipose tissue. There was no significant difference in egg production traits except onset of lay and egg number. Low doses of TAM ($T_{3}$) advanced the onset of egg laying by 15 days over the control. Tamoxifen influenced the hormonal profile (estrogen and progesterone) in a dose dependent manner. However, higher doses of TAM suppressed ovary and oviductal growth. From this study, it may be concluded that lower doses of TAM enhanced sexual maturity while higher doses suppressed ovary and oviductal growth.

• 한국패류학회지
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• 제21권1호
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• pp.1-11
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• 2005

Reproductive cycle, first sexual maturity, spawning amount related with the size and spawning interval in female Ruditapes philippinarum were investigated by histological observation and the analysis of morphometric data during artificial spawning induction. Ruditapes philippinarum is dioecious and oviparous. The reproductive cycle of this species can be subdivided into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (May to October), and spent/inactive stage (August to February). The spawning period was once a year between May and early October, and the main spawning occurred between July and August when seawater temperature was approximately $20^{\circ}C$. Percentages of first sexual maturity of female clam of 15.1-20.0 mm in shell length were 56.3%, and 100% for the clams > 25.1 mm. The mean number of the spawned eggs increased with the increase of size classes (shell length). In case of spawning induction by the same size class, the number of spawned eggs were gradually decreased with the increase of spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-17 days (average 16.5 days).

• 대한수의학회지
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• 제33권2호
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• pp.277-283
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• 1993

In the present study, observations were made on the life-history of Lymnaea viridis under laboratory conditions, involving incubation period of the eggs and their hatching rate, shell length of the newly hatched snails, sexual maturity, size of the snails when the snail produced the first egg-mass, the number of eggs in each egg-mass, egg-laying, ovipostion, growth rate of the snails, and longevity of the snail. At temperatures between $19.8^{\circ}C$ to $22.5^{\circ}C$, incubation period of the eggs occupied 10~12 days, and after beginning of hatching, all young snails emerged completely from the egg-mass within 5 days. The hatching rate was 88%. The average shell length of the newly hatched snails was about 0.064cm. The rate of growth was extraordinarily rapid under good laboratory conditions. When two snails were reared in one culture vessel($20{\times}15{\times}5cm$) with blue-green algae at about $22^{\circ}C$, snail growth was optimal, taking 37 days to reach 1.2cm in shell length. Sexual maturity reached in about 19 days. The size of the snails at sexual maturity was $0.78{\pm}0.05cm$ in length and $0.47{\pm}0.04cm$ in width. The first egg-masses produced were $0.59{\pm}0.22cm$ in length and $0.34{\pm}0.08cm$ in width, and contained 7~38 eggs. The eggs are usually laid in water. The egg-laying was affected by food and temperature. Snails fed with blue-green algae at about $22^{\circ}C$ produced larger egg-masses than the snails fed with fish food at about $26^{\circ}C$. Under conditions of continuous activity and growth, the maximum expectation of life appears to be 109~350(mean 230) days. And the shell length of snails at death were 1.39~1.64cm.

• 한국수산과학회지
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• 제35권4호
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• pp.380-385
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• 2002

본 연구에 사용되어진 마루자주새우 (Crangon hakodatei)는 거제도 주변 해역에서 2000년 10월부터 2001년 10월까지 새우조망을 이용하여 매월 채집하였다. 이들 개체군의 구조, 성장, 사망 및 성 성숙에 관한 분석은 갑각장을 이용한 체장빈도 데이터를 이용 ELEFAN 프로그램에 의해 분석하였다. 성장계수의 추정은 변형된 von Bertalanffy 성장식을 이용하였다. 암컷이 수컷보다 성장이 빨라 성숙개체에 빨리 도달하는 것으로 나타났다. 체장변환 어획 곡선에 의해 구해진 전 사망계수는 $3.10yr^{-1}$로 나타났고, Pauly 식에 의해 산출된 자연사망계수는 $2.48yr^{-1}$로 나타났다. 또한 어획사망계수는 $0.62yr^{-1}$인 것으로 나타났다. 암컷의 성 성숙 개체의 크기는 갑각장 $11.00\~11.50$ mm 사이인 것으로 나타났다.

• 한국양식학회지
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• 제22권1호
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• pp.92-99
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• 2009

대하새우 양식장에 서식하는 곤쟁이 Neomysis japonica (Ishikawa and Oshima, 1951)의 개체군 역학과 성 성숙에 관한 전반적인 생물학적 정보를 밝히기 위해 2002년 10월부터 2003년 9월까지 12개월 동안 매월 1회씩 충남 태안군 남면 당암리에 소재한 순천향대학교 해양수산연구소의 대하새우 양식장에서 표본을 채집하였다. 개체군의 특성을 알기 위해 성비, 성 성숙도, 포란수 그리고 성장계수 등을 조사하였다. 암컷이 수컷에 비해 월별 성비가 높았고, 평균 갑각장은 수컷($2.42\;mm{\pm}0.52$)이 암컷($2.31\;mm{\pm}0.48$)보다 높았으나 모두 오차 범위내에서 차이를 보여 갑각장의 크기는 통계학적으로 유의하지는 않았다. 암컷은 성체의 크기가 큰 개체가 많은 난을 포란하였으며, 암컷의 50%가 포란하는 체장은 4.48 mm였다. von Bertalanffy, 성장 매개변수를 바탕으로 한 계절별 성장 속도는 암컷이 수컷보다 빨랐으며, 양식장내에 서식하는 개체군은 일년 중 2회의 가입을 하는 것으로 나타났다. 암컷과 숫컷의 상대성장을 회귀직선 방식으로 비교한 결과수컷의 성장속도가 암컷보다 조금 빨랐다.

• 한국어류학회지
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• 제29권3호
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• pp.176-189
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• 2017

경기도 가평군의 가평천 일대에서 2016년 9월과 2017년 2, 4월에 쉬리 245개체를 채집하여 이석과 전장빈도분포법을 이용한 연령추정과 23가지의 계측형질을 이용하여 연령에 따른 성적이형을 조사하였다. 연령추정 결과 만 2년생부터 만 4년생의 비율이 높았고 만 5년생이 최대연령이었다. 23개의 계측형질 중 9개의 형질에서 성별 간에 유의한 차이가 있었다. 이중 뒷지느러미에서 나타나는 성적이형은 수컷의 뒷지느러미 연조가 길게 신장되어 뒷지느러미 폭과 길이가 암컷에 비해 넓고 긴 특징을 보이는 주요한 성적이형으로 나타났다. 또한 산란기에 수컷개체는 뒷지느러미의 연조에 추성이 발달하는 성적이형을 나타내었으나 뒷지느러미를 제외한 다른 계측형질과 외부형질에서 성별에 따른 성적이형이 나타나지 않았다. 성적으로 성숙하는 만 2년생 개체부터 성적이형이 나타났으며, 당년생 치어와 만 1년생 개체에서는 성적이형이 나타나지 않았다. 산란기는 4월에서 5월이었으며, 만 2세부터 산란에 참여하였다. 주요 산란 연령은 만 3세부터였으며, 최대 생식소 도지수(GSI)는 만 5세에서 암컷 14.91, 수컷 8.96으로 나타났다.

• 한국가금학회지
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• 제44권4호
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• pp.245-251
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• 2017

A dose-response experiment was conducted to determine the lysine requirement for broiler breeder hens during pre-peak production. Totally, one hundred and twenty-six flock 23-week-old Ross 308 broiler breeder hens with similar body weight were selected ($2,188{\pm}32g$) for a 6-week experiment. Hens were fed with a basal diet of corn-wheat-soybean meal formulated to achieve the Ross 308 breeder nutrient specifications (2016), except for lysine. The 7 graded, daily lysine intake levels used in this experiment were 732, 785, 838, 891, 944, 997, and 1,050 mg, and hens were restricted to 133 g of feed throughout this experiment. Pen based egg production were recorded once a day and all eggs were weighed daily. Age at sexual maturity was determined when the hens attained age at 25% production. Body weight at 23~29 weeks of age was not affected (P>0.05) by lysine levels. By fitting a linear-plateau model, the daily lysine requirements for feed conversion ratio, total produced egg weight, and age at sexual maturity at 23~29 weeks of age were estimated as 865, 907, and 891 mg, respectively. Using a quadratic-plateau model, the daily lysine requirement at 23~29 weeks of age were estimated as 974, 964, and 950 mg for feed conversion ratio, total produced egg weight, and age at sexual maturity, respectively. These results suggested that the daily lysine requirement for modern broiler breeder hens according to the National Research Council (1994) are insufficient for higher total produced egg weight, sexual maturity, and feed efficiency, and 120% of the NRC recommendation level would improve hen productivity when data are fitted under linear- and quadratic-plateau models.

• 한국발생생물학회지:발생과생식
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• 제6권1호
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• pp.37-44
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• 2002

자연 생물자원 관리를 위해, 광양만내 인공적으로 폐쇄된 슬라그 적재장내에 서식하는 암컷 피뿔고둥 Rapana venose(Valenciennes)를 대상으로 조직학적, 육안적 관찰에 의해 군성숙도, 성비, 산란빈도, 난낭 산출 및 포란수를 조사하였다. 암컷 개체들의 군성숙도(%)는 각고 7.1~8.0 cm의 경우 51.6%이었고, 9.1 cm 이상인 개체들의 경우는 100%이었다. 개체당 총난낭수 및 난낭내의 평균 난수는 각각 192~382개와 500개이었는데, 저염분이나 먹이가 부족한 환경조건을 갖추고 있는 폐쇄된 슬러그 적재장내에 서식하는 피뿔고둥들은 최적 염분농도 및 충분한 먹이조건을 갖추고 있는 개방된 지역의 것보다 개체당 총난낭수 및 난낭내 평균 난수가 적었으며,난낭의 크기도 작았다. 본 종의 포란수는 대략 개체당 96,000~191,000이었고, 산란기 중 적어도 2~4회의 산란빈도를 갖는다. 난낭내에서의 발생기간은 약 18~2$0^{\circ}C$에서 18~19일이었다. 피뿔고둥의 배는 어린 고둥이 아닌, 피면자유생으로 부화하였다. 암컷 : 수컷의 성비는 1 : 1로 유의한 차를 보이지 않았다($\chi$$^2$= 0.23, p>0.05)