• Korean Journal of Poultry Science
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• v.31 no.4
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• pp.299-306
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• 2004

The objective of this study was to investigate the influence of egg storage, broiler breeder age, and the change of egg weight during incubation on growth rate of chicks and 43-day-old dressing percentage. The trials involved hatching eggs obtained from 27-wk-old hens and stored for 6 d for the Young-EXP group, from 28-wk-old hens and stored for 0 d for the Young-CON group, from 51-wk-old hens and stored for 6 d for the Old-EXP group, and from 52-wk-old hens and stored for 0 d for the Old-CON group, The hens were two commercial broiler breeder flocks of the same strain (Cobb) but of different egg producing stages(early and middle stages of egg production). The chicks were grown on floor pens for 6 wks, The differences of setting egg weights between Old-CON and Old-EXP groups were 1 g, but those between Young-CON and Young-EXP groups were 2.9 g(P<0,05). The loss of egg weight during 18 d incubation did not greatly differ among four groups, but the loss of egg weight during 21 d incubation was significantly (P<0.05) more in the middle stage of egg production groups than in the early stage of egg production groups. The mean birth weights of the middle stage of egg production groups were significantly(P<0,05) heavier by 8,7 g than those of the early stage of egg production groups; however, the differences of 6-wk-old body weight were not significant between egg producing stages. The differences of body weights in both egg producing stages were not significantly influenced by egg storage period in overall wks of ages. Egg storage and hen age did not greatly influence to the 43 d dressing percentages, either, The correlations of the setting egg weight with 18 d egg weight during incubation, growth rate of chicks, or 43 d dressing percentage were not significant.

• Korean Journal of Poultry Science
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• v.40 no.4
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• pp.361-368
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• 2013

This experiment was conducted to determine optimum levels of dietary crude protein for productivity and egg quality in laying hens during early stage. A total of seven hundred and twenty 24-wk-old Hy-Line Variety Brown layers were randomly assigned to 4 experimental diets varying with 16%, 17%, 18%, and 19% CP and fed the diets for 12 wks. There were no significant differences in egg production, daily egg mass and feed intake among experimental diets. Although no difference was found on egg weight among experimental diets, decreasing levels of dietary crude protein tended to reduce the egg weight. Haugh unit and egg shell quality were not affected by different levels of dietary crude protein. Although there was no difference on yolk color among experimental diets, increasing levels of dietary crude protein slightly reduced the yolk color. It is concluded that laying hens did not need more than 16% CP to maximize egg production.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.6
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• pp.800-805
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• 2003

The early embryos are obtained in different time after the former egg had been laid, and the aim of the present study was to observe the development law of chicken early embryo.The embryo development has been divided into the two periods according to morphology of blastodisc. Cleavage period, from 5.5 h (0 h uterine age) to 15.5 h (10-10.5 h uterine age) after the former egg had laid, formation blastodisc of 6-7 layers cell. Later blastocyst period, from 17.5 h (12-12.5 h uterine age) to area pellucida formation after the former egg had been laid. The first division took place at 5 h (0 h uterine age), morular at 11.5 h (6-6.5 h uterine age), and blastocyst at 15.5 h (10-10.5 h uterine age) after the former egg had been laid.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.11
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• pp.1514-1517
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• 2000

In chicken, exogenous genes introduced into germinal crescent region (GCR) of the early developmental stage, where primordial germ cells (PGCs) were concentrated, were successfully transferred to the gonads via PGCs. The foreign genes were also confirmed to be successfully incorporated into F1 and F2 generations. We tried to incorporate the exogenous genes into PGCs by lipofection, then the DNA mixture was injected into GCR at stage 3-5 or 9-11 of embryonic development (Hamburger and Hamilton, 1951). The manipulated eggs were incubated, and hatched chicks were reared until sexual maturation. F1 generation was obtained from the DNA-treated chicken (DNA-chicken) mated with normal birds. Furthermore, F2 generation was also obtained from the F1 chicken mated with normal birds. The transfer of introduced foreign genes were confirmed by marker gene detection methods and PCR analysis in the hatched chicks, F1 and F2 generations. However, in our experiments, DNA-chickens showed abnormal characteristics such as low egg production rate, abnormal appearance and decreased number of spermatozoa. In the case of F1 chicken, low egg production and the deterioration of sperm capacity for insemination in male chicken were observed.

• Korean Journal of Poultry Science
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• v.29 no.3
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• pp.171-176
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• 2002

Two experiments were conducted to investigate the effects of taurine supplementation on the egg production and egg quality in laying hen. In experiment 1, 19-wk-old laying hens were allowed one of four taurine supplemented diets (0 (control), 0.4, 0.8, and 1.2% taurine) for 10 weeks. The mean egg weight was lower about 1.2g in the 0.8% diet compared to the control. Egg production rate, egg mass, and feed intake in layers fed with 0.4, 0.8, and 1.2% taurine supplemented diets decreased by 8%∼24%, 3%∼l4% and 11%∼l5%, respectively, relative to the control. However, the feed conversion, parameters of egg quality, and the concentration of triacylglycerol and the level of cholesterol in yolk were not different among the treatments. In experiment 2, 81-wk-old laying hens were allocated one of three taurine supplemented diets(0 (control), 1 and 2% taurine) for 6 weeks. The egg weight, egg production rate, egg mass, feed intake, feed conversion, parameters of egg quality, and level of yolk cholesterol were not different among the treatments, but the concentration of triacylglycerol in yolk was higher by 14%∼19% compared to the control. In conclusion, these results indicated that taurine supplementation in early laying stage of layers decreased hen performance.

• Journal of Aquaculture
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• v.20 no.3
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• pp.194-198
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• 2007

Reproductive traits of Palaemon gravieri such as embryo size, number of embryo (fecundity), incubation period, larval development mode, larval development period, larval survival and larval growth were described and compared to analyze the correlation among those traits. Embryo volume is a primary factor determining other ensuing reproductive features. Egg volume was $0.042mm^3$ in the first developmental stage. Embryo volume in P. gravieri was comparatively small which is indicative of great number of embryo (y = 3.0161x + 0.0185 $R^2$ = 0.74 positive isometric relationship) and relatively long incubation period. Larvae survived from zoea 1 to post-larvae and it took 45 days at $22^{\circ}C$. Survival rate of the larvae was rather great in the early stage and thereafter steadily decreased. Daily growth rate of larvae in P. gravieri at $22^{\circ}C$ was 0.0195 mm on average. They grew steadily as time went by. Incubation period was between 10-14 days at $22^{\circ}C$. Larval development mode was almost complete planktotrophic. PNR (point of no return) appeared to be the third day on average. Survival rate of larvae without feeding declined rapidly between 3 and 4 days. Larval development period and stage frequency were 23-30 days and 11 stages which imply prolonged larval period and high mortality. The pattern of brood production followed fast successive parturial pattern. Most ovigerous female had mature ovary when they performed parturial molt soon after hatching (larval release).

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.17-24
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• 2014

The egg development and early life history of Acheilognathus majusculus which is Korean endemic species from Yeong river were observed under the controlled water temperature, $18.0{\pm}1.0^{\circ}C$. Fertilized eggs are opaque yellow in color and round oval shaped measuring 2.12 (2.08~2.18) mm in length and 1.86 (1.80~1.98) mm in breadth. The number of eggs averaged 72 (40~112) per an oviposition. The eggs of this species began to hatch about forty three hours after insemination and the total length of larvae was 4.23 mm mean. S form moving of larvae were not observed during larval development. The larvae reached at the heterotrophic stage about twenty-five days after hatching. It is estimated that the larvae was comming out from freshwater bivalve since that time in nature. A. majusculus was grew up to be adult stage enough which can be join to new production for three hundred days after hatching with over 67.8 mm in total length.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.1-12
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• 2002

Ecophysiologically diapause represents a syndrome of physiological and biochemical characteristics, all of which ensure survival during a long period of dormancy. Since, silkworm enters diapause as embryo at the early embryonic stage, the duration of egg life depends on the duration of embryonic diapause. The nature of diapause in silkworm, Bombyx mori, is primarily determined by genetic characters and endocrinologicnl mechanisms, mediated by environmental factors such as temperature and photoperiod. Hibernating potency value besides nucleic acid and carbohydrate metabolism, production and utilization of sorbitol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Embryonic diapause in Bombyx moir, induced by active secretion of sub-oesophageal ganglion is attributed to hormonal system and metabolic adjustment, which serves to bring about a new physiological state. Metabolic conversion of trehalose to glycogen at induction, glycogen to sorbitol at initiation and sorbitol to glycogen at termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation. An attempt has been made in this review article to discuss briefly the nature of embryonic diapause, influence of various factors on diapause nature, hormonal mechanism of diapause besides biochemical composition of egg, nucleic acid and carbohydrate metabolism, production and utilization of sorbitol in relation to induction, determination, maintenance, initiation and termination of diapause in the silkworm, Bombyx mori.

• Journal of agriculture & life science
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• v.44 no.1
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• pp.43-49
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• 2010

Life history of Gampsocleis sedakovi abscura Walker, an amenity sound producing insect, was investigated in Jinju, Korea from 2005 to 2007. G. sedakovi abscura had a generation per year and could be seen in the field from early March to late September. The peak emergence period of adults was early July. Developmental period from egg to adult was 357 days in average of three years in the field. Egg and nymphal periods, and adult longevity were 269, 88, and 357 days in average, respectively. The average ovipositional period was 63 days, and an adult laid 94 eggs in average throughout her life. The average longevity of adult was 90 days for female and 82 days for male. The sex ratio was 52%. G. sedakovi abscura over-wintered as egg stage in the soil. Circadian rhythm of the adult emergence showed that more than 70% of the adults emerged in the morning.

• Korean Journal of Animal Reproduction
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• v.15 no.3
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• pp.207-220
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• 1991

This study was carried out to investigate the ultrastructural changes of ooplasm and follicular membrane of oocytes, obtained from 150 of 3-year-old female rainbow trout(Oncorhynchus mykiss). All data were collected from March in 1989 to February in 1990, and from August to October in 1991. The size of the nucleoli and number of the yolk granules increased as the oocyte growed. Yolk granules were deposited in the oocyte as crystalline granules. Due to the presence of large early and late maturing oocytes, their ovaires were enlarged, transparent and granular. The lattice was broken down at hydration, leaving the egg transparent. As thepercentages of fish in LPO and EMO stage increased from September to October, Mean GSI values increased. Follicle cells such as granulosa cell and thecal cell change a squamous into cuboid shape in LPO and EMO stage. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in bothgonadosomatic index and macroscopic apearance. Under the natural conditions,t he ovarian follicle influences the histological development and periodical secretion of the hormones, sufficient for a oogenesis and gonadal steroid production. The electrophoretic pattern of major band in mature stage was much thicker(70∼110k dalton) than that in previtellogenic phase.