• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.173-178
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• 1986

Data on egg production, egg weight and egg mass were obtained from a sample of the Synthetic White Leghorn population which was raised at Poultry Breeding Farm, Seoul National University. Egg mass was not measured directly, but was calculated from the egg numbers and the average egg weight for same period. Phenotypic means, components of variance and covariance, heritabilities and genetic correlations were computed. Egg mass was estimated to be a lowly heritable trait (0.204-0.270). High heritability estimates were found for age at sexual maturity and egg weight. Genetic correlation estimates were high and positive between egg mass and egg number(combined estimates 0.711). Egg mass and egg weight were moderately correlated genetically (0.431). Genetic correlation estimates was -0.280 between egg number and age at sexual maturity, but was 0.524 between egg weight and age at sexual maturity. Results show that selection for total egg mass based on record from a single period will not be satisfactory unless the single period chosen is one in the latter part of the laying year.

• Korean Journal of Poultry Science
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• v.42 no.4
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• pp.299-305
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• 2015

The production performance and egg quality traits among five strains of Korean native chickens (KNC) were evaluated in conventional cages. A total of 240 KNC were housed in a controlled environment. Each strain had 12 replicates with 4 chickens per cage. Feed intake, body weights, egg production and egg quality were measured at 24, 28 and 32 of weeks. Egg quality parameters were analyzed using 150 eggs. Results indicated significant (P<0.05) difference in average body weights, egg production and egg weight among five strains of KNC. In contrast, KNC strains effect was non-significant (P>0.05) for feed efficiency. The difference among those KNC strains on egg shell color, egg shell strength and egg shell density were not different (P>0.05) at the age of week 24 while it was significant (P<0.05) at the age of week 28 and 32. There was no effect (P>0.05) on egg length and egg shape index from five strains of KNC. The significant difference (P<0.05) was observed in egg width with KNC strains during early ages (week 24 and 28) and it was not significant (P>0.05) at the age of 32 weeks. Regarding internal quality parameters, albumen height and Haugh unit were significantly (P<0.05) affected with KNC strains while the effect on yolk color was not significant (P>0.05). Based on the egg weight and the production performance, GS-10 KNC strain was superior when compared with the other strains.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2002.11a
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• pp.128-129
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• 2002

To evaluate the effect of combined supplementation of both flaxseed and micro additives on fatty acid incoporation in egg yolk, totally 240 of ISA Brown laying hen were alloted into 4 treatments with 3 replication per treatment by completely randomized design. 10% of ground flaxseed was added to the experimental diets of treatment group except control diet. Supplemented micro additives used in this experiments were Vit. A + carnitine for treatment 1, Vit. E + selenium for treatment 2, and probiotics + lecithin for treatment 3. Egg production in flaxseed + Vit. E and selenium supplemented group was lower than those of other treatments. There were no differences in egg weight, feed intake, and feed/egg among treatments. The $\omega$-3 fatty acid content in egg yolk was affacted by flaxseed supplementation with no detection in control group. Especially, The $\omega$-3(Cl8 ：3n3) fatty acid content of egg yolk in probiotics and lecithin supplemented group was higher(P〈0.05) than other flaxseed supplemented groups.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2006.11a
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• pp.62-63
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• 2006

This experiment was conducted to investigate the dietary effect of turmeric powder (TP) on laying performances, egg qualities and its transfer to eggs. A total of two hundred, 60-wk-old, Lohmann Brown layers were divided into 4 groups, placed in to 5 replicates per group (10 layers each) and fed each one of four diets containing 0 % TP(control), 0.1 % TP, 0.25 % TP, or 0.5 % TP for 7 wks, respectively. Egg production and egg mass in groups fed diets containing TP were higher than that of control(p<0.05). No differences in feed intakes, egg and eggshell qualities were observed among the treatments, but egg yolk color was increased significantly as TP was in increased in the diet(p<0.05). In groups fed diets containing TP, Haugh unit after 14 day of storage was significantly higher than that of control(p<0.05). The curcumin content of egg yolk in groups fed diet containing 0.50% TP was significantly higher than those of other groups (p<0.05). The content of egg yolk cholesterol was not influenced by dietary TP.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.399-405
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• 1991

The interaction of 4 dietary crude protein (13, 16, 19 or 22%) and 4 metabolizable energy (2600, 2800, 3000 or 3100 kcal ME/kg) levels on egg quality performances of Starcross layers were assessed between 245 and 275 days of age. The egg weight increased significantly with the increasing dietary protein and energy levels. But egg shape index, albumen index, yolk index, yolk dry matter, yolk protein, yolk fat, albumen protein and shell tickness were similar at all dietary protein and/or energy levels. The egg specific gravity and albumen weight increased but the yolk, weight, Haugh unit and albumen drymatter decreased with the increase of dietary protein levels and showed irregular trend with energy levels. The albumen dry matter and egg shell weight, however, were not affected by energy and protein levels. Simultaneous increase of protein and energy increased specific gravity, albumen index and shell thickness at a greater rate than that increased by the increase of protein or energy alone.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.11a
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• pp.113-114
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• 2003

The observed ranges of genetic and phenotypic changes per generation were as follows, for the body weight at 150 days, -3.66 ∼ -8.99 and -27.07 ∼ -63.61 g ； for the body weight at 270 days, -2.89 ∼ -9.69 and 7.39 ∼ -27.45 g； for the age at first egg, -0.31 ∼ -0.57 and -0.23 ∼ -6.67 g ; for the egg weight at the first egg, -0.02 ∼ -0.06 and 0.65 ∼ 0.26 g ； for the egg weight at 270 days, 0.53 ∼ 0.35 and 1.62 ∼ 0.01, respectively. In general, the genetic and phenotypic change were decreased In body weight and the age at first egg and increased in egg weight and the number of egg production.

• 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.

• Animal Bioscience
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• v.37 no.3
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• pp.500-508
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• 2024

Objective: Due to current selection practices for increased egg production and peak persistency, the production profile, age at maturity, and body weight criteria for commercial layers are constantly changing. Body weight and age at the time of photostimulation will thus always be the factors that need to be adequately addressed among various production systems. The current study was carried out to determine the effects of pullets' body weight (low, medium, and heavy) on their performance, welfare, physiological response, and hormonal profile. Methods: With regard to live weight, 150 16-week-old pullets were divided into three groups using a completely randomized design (CRD) and held until the 50th week. One-way analysis of variance was used to evaluate the data under the CRD, and the least significant difference test was used to distinguish between treatment means. Results: In comparison to the medium and light birds, the heavy birds had higher body weight at maturity, an earlier age at maturity, and higher egg weight, eggshell weight, eggshell thickness, egg yolk index, breaking strength, egg surface area, egg shape index, egg volume, and hormonal profile except corticosterone. However, the medium and light birds had lower feed consumption rates per dozen eggs and per kilogram of egg mass than the heavy birds. Light birds showed greater body weight gain, egg production, and egg specific gravity than the other categories. At 20 weeks of age, physiological response, welfare aspects, and catalase were non-significant; however, at 50 weeks of age, all these factors-aside from catalase-were extremely significant. Conclusion: The findings of this study indicate that layers can function at lower body weights during photostimulation; hence, dietary regimens that result in lighter pullets may be preferable. Additionally, the welfare of the birds was not compromised by the lighter weight group.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.2
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• pp.206-210
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• 2017

Objective: A study was conducted to test six threonine (Thr) levels (0.39%, 0.44%, 0.49%, 0.54%, 0.59%, and 0.64%) to estimate the optimal dietary Thr requirements for Longyan laying ducks from 17 to 45 wk of age. Methods: Nine hundred Longyan ducks aged 17 wk were assigned randomly to the six dietary treatments, where each treatment comprised six replicate pens with 25 ducks per pen. Results: Increasing the Thr level enhanced egg production, egg weight, egg mass, and the feed conversion ratio (FCR) (linearly or quadratically; p<0.05). The Haugh unit score, yolk color, albumen height, and the weight, percentage, thickness, and breaking strength of the eggshell did not response to increases in the Thr levels, but the albumen weight and its proportion increased significantly (p<0.05), whereas the yolk weight and its proportion decreased significantly as the Thr levels increased. Conclusion: According to a regression model, the optimal Thr requirement for egg production, egg mass, and FCR in Longyan ducks is 0.57%, while 0.58% is the optimal level for egg weight from 17 to 45 wk of age.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2000.04a
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• pp.23-36
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• 2000

Hurdle technique was used to remove cholesterol efficiently from liquid egg yolk. The quality of the low cholesterol egg products from the process were evaluated. From the 75 % cholesterol reduced egg yolk through $\beta$-cyclodextrin treatment. 2 times weight of soy bean oil was added to the egg yolk and homogenized followed by centrifuged to be maximized to remove cholesterol. When the pH of the yolk was adjusted to 9, 92 % of cholesterol was removed while 95.4 % of cholesterol was removed when 3 times weight of soy bean oil was added to the egg yolk. As the results of application of supercritical carbon dioxide extraction to the 75 % cholesterol reduced egg yolk through ${\beta}$-cyclodextrin treatment, 92.5 % of the cholesterol was removed from the egg yolk at $35^{\circ}C$, 4,500 psi, for 4 hours under co-solvent. The quality characteristics of the produced low cholesterol egg products were analysed. The cholesterol reduced egg yolk produced from ${\beta}$-cyclodextrin and soy bean oil treatment showed the lower emulsion capacity compared with control. The fatty acid composition of the cholesterol reduced egg yolk produced from ${\bet}a$-cyclodextrin and soy bean oil treatment showed increased C18:2 and C18:3 compared with control while decreased C16:1 and C18: 1 compared with control. The saponification method with extracting solvent of hexane showed that cholesterol concentration was 28.1 %. The quantity of hydrolysis solution(95 % ethanol : 33 % KOH = 94 : 6) was varied from 40 to 80 times of sample weights and the cholesterol concentration of 35.7 % was the highest result in the 60 times(v/w) hydrolysis solution. Cholesterol concentration of 35.7 % was recovered at the first trial with saponification method. but it could be improved up to 95.7 % after 4 times repetitive purification.