• Asian-Australasian Journal of Animal Sciences
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• v.14 no.7
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• pp.922-928
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• 2001

There exists considerable evidence that steroid hormones are involved in the regulation of ovulation rate and oviductal development in poultry. However, the effect of steroid hormones on egg productivity of Korean Native Ogol Chicken (KNOC) has yet to be studied. Therefore, this study was performed to relate the expression of steroid hormones, especially progesterone ($P_4$) and estradiol ($E_2$), with egg productivity during the laying period. Egg production and egg weight of 70 KNOC were recorded from 20 to 60wk. Blood was taken every 10 wk and serum $P_4$ and $E_2$ were measured by radioimmunoassay. Based on egg productivity and steroid hormones levels up to 60 wk, chickens were divided into two groups, high and low. Compared to the low egg production group, a significantly higher expression of $P_4$ at 30 wk was detected in the high group. Moreover, egg production in the high $P_4$ group significantly differed from that in the low group at 30 wk. On the other hand, a Significant difference (p<0.05) in $E_2$ expression was found between high and low egg weight groups at 30 wk. Although a significant difference in egg weight between two groups by $E_2$ was not detected, the high $E_2$ group showed a higher level of egg weight than the low $E_2$ group except for 25 wk. In the comparison of ovary weight and small yellow follicle number, the group with high egg productivity and steroid concentration showed greater levels than the low group. Taken together, the results indicate that $P_4$ is related to egg productivity whereas expression of $E_2$ is associated with egg weight in KNOC.

• Korean Journal of Animal Reproduction
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• v.6 no.1
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• pp.36-38
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• 1982

For the purpose of identifing the reationship between the first egg day and other economic traits; egg production and egg weight, this experiment was divided 200 birds into four first egg day groups and observed egg number and egg weight every day during 11 months from 2nd December, 1979 to 31st October, 1980 at Animal farm, Yeungnam University. Birds showing 148∼155day in first egg day layed the most eggs among four groups and they produced not only 1.5g heavier eggs than the earlist first egg day group but also similar eggs compared with later matured birds. In egg production above 55g, 148∼155day group showed the best record as a 83.72% of total eggs and also the most egg mass during 11 months.

• Korean Journal of Poultry Science
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• v.14 no.2
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• pp.113-123
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• 1987

This study was carried out to investigate the effects of age of hen and oviposition time on egg weight, egg shell quality and e88 shape index in White Leghorn laying hens. The data were collected from 150 laying hens for about 4 months from September 1, 1986 to January 6, 1987. The results obtained from this study were summarized as follows; The percentage of the eggs produced before noon was decreased and that of the eggs produced after noon was increased as the hen gets older. Egg weight was increased rapidly to 270 days of age but after 270 days of age the rate of egg weight increase was slowly downed. The egg shell thickness became thinner and egg shell breaking strength was reduced and egg shape index was increased as the hen gets older. The egg weight was decreased as the oviposition time was proceeded and the regression coefficients of egg weight on oviposition time were -0.6788--0.4170, which means that the egg weight was decreased 0.4170-0.6788g per one hour delay of oviposition time. Egg shell thickness was increased 0. 0.00377-0.00643mm and egg shell breaking strength improved 0.0287-0.034kg/$\textrm{cm}^2$ per one hour delay of oviposition time. But it seems that there was no relationship between the oviposition time and the egg shape index.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.10
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• pp.1447-1455
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• 2011

Sixty four, 30-week-old, Lohmann Brown-Lite laying hens were randomly allocated to one of four treatments with eight replicates per treatment and two hens per replicate for a 10 week study. The control diet was a high energy (11.81 MJ/kg) diet and the moderate energy (11.39 MJ/kg) diets were formulated dropping the level of animal fat. The three moderate energy diets were fed either unsupplemented (0.0%) or supplemented with 0.05 or 0.10% glycine. There were no significant differences (p>0.05) in hen-day egg production, egg weight, feed intake or feed conversion between birds fed the unsupplemented moderate energy and high energy diets. Significant differences were detected concerning egg components and quality measurements as assessed by albumen percentage (p = 0.02), yolk weight (p = 0.02), yolk percentage (p<0.01), yolk to albumen ratio (p<0.01) and yolk color (p = 0.01) between birds fed the unsupplemented moderate and high energy diets. Glycine supplementation of the moderate energy diet linearly increased (p<0.01) egg weight and feed intake with no significant (p>0.05) effects on egg production or feed conversion. Glycine supplementation significantly increased egg content (p<0.01), albumen weight (p<0.01) and percentage (p<0.01) as well as yolk weight (p<0.01) while yolk percentage (p = 0.04), yolk to albumen ratio (p = 0.01) and egg shell percentage (p<0.01) were linearly decreased. Supplementation with glycine produced a tendency (p = 0.09) towards an increase in the percentage of large eggs (63-72.9 g) produced with a concomitant decrease in the percentage of small (below 53 g) eggs (p = 0.09). The overall results of this study indicate that glycine supplementation of laying hen rations has the potential to increase egg production and weight. These increases appeared to be mediated through increases in feed intake and the ileal digestibility of fat and energy.

• Korean Journal of Poultry Science
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• v.10 no.2
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• pp.75-81
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• 1983

The records on 787 white Leghorn hens from two different strains, A and K were wed in this study to find out the pattern of increase in egg weight with age and the optimum age of early selection for maximizing the genetic gain. The pattern of increase in egg weight with age in two lines which was expressed on graph showed that the amount of increase was larger in the early part of the laying year and it decreased gradually. Regression equations suggested that egg weight increased linearly with age at the rate of 0.46 gram per week for line A and 0.83 gram for line K. And in the regression analyses of each period mean egg weight on annual mean egg weight, the coefficients of EW 30 that is mean egg weight from 29 weeks of age to 32 weeks of age were 0.86 for line A, 0.88 for line K, and those were the highest figures among the all regression coefficients of each mean egg weight on annual mean egg weight. In estimating the relative selection efficiency of each period mean egg weight on annual mean egg weight in EW 46, selection on EW 34 for line A and on EW 30 for line K was the most efficient for improving egg weight. These results suggested that one periods from 29 weeks of age to 36 weeks of age could be used for the best predictable time for improving annual mean egg weight.

• Korean Journal of Poultry Science
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• v.43 no.1
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• pp.31-38
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• 2016

Consumers demand fresh and high-quality eggs. Egg quality may be represented by shell color, shell weight, egg weight, shell thickness, shell density, albumen height, yolk color, albumen pH and viscosity. Various factors such as strain, age of hen, storage temperature, humidity, the presence of $CO_2$ and storage time affect egg quality. Therefore, we investigated the effects of storage time and temperature on egg quality to define the freshness of Korean market eggs. A total of 1,800 eggs were used for this experiment and were separated into 45 treatments with 40 eggs in each. The treatments were consisted of 15 storage periods (2 d to 30 d) and 3 storage temperatures ($2^{\circ}C$, $12^{\circ}C$, $25^{\circ}C$). Each egg was weighed and broken, and the height of the thick albumen, Haugh units (HU), egg shell color and yolk color were measured by a QCM+system. We also observed the physiochemical properties of eggs such as yolk pH, albumen pH and albumen viscosity. The egg weight, shell weight, albumen height, HU and albumen viscosity significantly decreased with increasing storage time and temperature. However, the albumen and yolk pH significantly increased with increasing storage period and temperature. The interaction effects between the storage period and temperature were significant for shell weight, shell density, egg weight, albumen height, HU, yolk color, yolk pH, albumen pH and albumen viscosity. In the analysis of the correlation with egg quality, the storage temperature exhibited a higher correlation coefficient than the storage period. In conclusion, storage time and temperature are the major factors affecting egg quality, but the storage temperature is a more sensitive determinant of egg quality deterioration compared with the storage period.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.4
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• pp.538-543
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• 2015

This experiment was conducted to measure the effects of olive leaf powder on performance, egg yield, egg quality and yolk cholesterol level of laying hens. A total of 120 Lohmann Brown laying hens of 22 weeks old were used in this experiment. The birds were fed on standard layer diets containing 0, 1%, 2%, or 3% olive leaf powder for 8 weeks. Egg weight and yield were recorded daily; feed intake weekly; egg quality and cholesterol content at the end of the trial. Olive leaf powder had no effect on feed intake, egg weight, egg yield and feed conversion ratio (p>0.05) while olive leaf powder increased final body weight of hens (p<0.05). Dietary olive leaf powder increased yellowness in yolk color (p<0.01) without affecting other quality parameters. Yolk cholesterol content was tended to decrease about 10% (p>0.05). To conclude, olive leaf powder can be used for reducing egg yolk cholesterol content and egg yolk coloring agent in layer diets.

• Korean Journal of Poultry Science
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• v.22 no.3
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• pp.161-166
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• 1995

To evaluate the nutritional values of Spirulina platensis as the protein supplement for laying heo diet, two experimental diets (Control, Spirulina platensis 2%) were prepared. Total 120, 40-wk old ISA Brown layer hens were randomly employed with 15 hens per replicate and 4 replicates per treatment. Hen-day egg production, egg weight, feed intake, intake /egg weight, egg shell thickness, yolk color score and yolk cholesterol content were examined during 6 weeks of experimental period. Hen-day egg production and feed conversion ratio (intake /egg weight) were significantly (P<0.01) improved by the 2% Spirulina plalensis supplementation. However, there were no differences in egg weight and feed intake between hens fed two experimental diets. Egg from hens fed Spirulina platensis 2% diet have more yellowish yolk color than the control egg although there was no difference in egg shell thickness. Yolk cholesterol content was significantly (P

• Proceedings of the Korea Society of Poultry Science Conference
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• 2002.11a
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• pp.140-142
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• 2002

This study was conducted to obtain some genetic information for developing superior Korean native chickens. Heterosis and combining ability effects were estimated with 1,080 progenies of full diallel crosses of 3 strains in Korean Native Chicken. The traits of egg productivity were Investigated, and heterosis effect, general combining ability, specific combining ability and reciprocal effect were analyzed model I of the Griffing's method 1. The general performance were 147.0 days in age at first egg laying, 71.8 eggs in egg numbers to 270 days, 50.1g in egg weight at 270 days, 75.6 in egg shape index, 356$\mu\textrm{m}$ in egg shell thickness, and 4.27kg/$\textrm{cm}^2$ in egg shell strength, respectively. According to result, heterosis effect revealed comparatively high in age at first egg laying, egg numbers, egg weight, and egg shell strength. The effects estimated highly in general combining ability for age at first egg laying, egg numbers, egg weight, egg shape Index and egg shell thickness, and in specific combining ability were egg numbers, egg weight and egg shell thickness, and in reciprocal effects for egg numbers, egg shape index, and egg shell thickness. This result could be used for developing Korean native chicken.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.4
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• pp.455-459
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• 1996

The genetic parameters for various economic traits were estimated in a White Leghorn population selected for part period egg production over 16 generations. In early part of selection, egg number had moderate to high heritability (0.26 to 0.51) while age at sexual maturity, egg weight and body weight at 20 and 40 weeks of age had high heritability (0.54 to 0.83). The sire component heritability for all the traits except 20 week body weight declined in later periods of selection. Sex linked gene effects for egg number and age at sexual maturity were more important in early periods of selection in comparison to the later periods, while maternal effects remained important for 20 week body weight in all the periods. Egg number was negatively correlated with egg weight ($r_{G(S)}=-0.36$), age at sexual maturity ($r_{G(S)}=-0.84$) and 40 week body weight ($r_{G(S)}=-0.84$), while it was positively correlated with 20 week body weight ($r_{G(S)}=-0.34$) in base generation. The genetic association between egg number and 40 week body weight changed not only in magnitude but also in direction in later periods. The genetic correlation of egg number with egg weight as well as with age at sexual maturity also decreased in magnitude in later periods of selection.