• Korean Journal of Poultry Science
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• v.31 no.4
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• pp.203-212
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• 2004

A total of 1,200 eggs obtained from 312-day-old Hy-line Brown laying breeder hens and 319-day-old Hy-line Brown commercial laying hens (600 eggs obtained from each one) at same day were used to investigate the effects of egg storage, storage temperature, and insemination of hens on the change of albumen height, Haugh unit(HU), albumen pH, shell strength, and yolk color. Eggs were stored up to 14 days after lay at $3^{\circ}C$ or $10^{\circ}C$ and sampled one day after stored and then 24 hours interval. Longer periods of storage resulted in lower albumen height and HU at both storage temperatures, but in higher albumen pH. The eggs stored at $3^{\circ}C$ were significantly (P<0.05) higher in HU and lower in albumen pH than the ones stored at $10^{\circ}C$. The eggs obtained from the non-inseminated-hens were significantly (P<0.05) higher in albumen height, HU, and albumen pH than the eggs obtained from the inseminated-hens. Whereas, the eggs obtained from the non-inseminated-hens in the mean albumen pH of eggs stored at $3^{\circ}C$ were significantly (P<0.05) higher than the ones obtained from the inseminated-hens, but the mean albumen pH of eggs stored at 10^{\circ}C did not differ each other. The mean shell strength of the eggs obtained from the inseminated-hens was significantly (P<0.05) stronger than that of the eggs obtained from the non-inseminated-hens at both storage temperatures. Albumen height and albumen pH were negatively correlated $(P<0.01\~0.001)$ in both inseminated and non-inseminated-hen's egg groups. The degree of yolk colors was not significantly changed overall of the experimental periods in both storage temperatures. The study suggests that the change of egg freshness such as albumen height and HU is relatively more associated with storage period and storage temperature than insemination or non-insemination of hens.

• Korean Journal of Poultry Science
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• v.30 no.1
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• pp.1-10
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• 2003

The objects of this study were to develop a new strain which has resistance to fowl typhoid, high performance in laying, and producing brown shell eggs favored by domestic consumers. Several White Leghorn (WL) breeds known as possessing genetic resistance to fowl typhoid and several brown shell egg breeds such as susceptible to the disease were used to produce the controlled strains with cross mating between the strains within the breeds and the experimental strains with crossbreeding between the breeds. The crossbred strains were Chungnong(CN) 21, 22, 23, 24, 25 and 26. The controlled strains were ISA brown CC, Hyline brown CC and Lohman brown CC. The survival rates were 99.95% for chicks of age 0∼l7 weeks and 91% for adult chickens of age 18∼72 weeks. There was no difference in survival rate between the crossbred and the controlled strains. The means of age of lst egg laying were 147 to 148 days and no difference was observed between the crossbred and the controlled. The egg Production rates of a9e 18∼72 weeks were 83.76% far the crossbred strains and 77.82% for the controlled strains, which is significantly higher in the crossbred than controlled strains by 6%. The numbers of the hen housed egg Production of age 18∼72 weeks were 292.33 eggs for the crossbred strains and 271.31 eggs fur the controlled strains. The difference of 21 eggs more produced by the crossbred than by the controlled was statistically significant. The mean egg weights of age 18∼72 weeks were 64.32g for the crossbred strains and 60.73g for the controlled strains, and the difference of 3.59g was statistically significant. The feed conversion rates during the age of 18 to 72 weeks were 2.297 for the crossbred strains and 2.454 for the controlled strains. The crossbreds were reduced feed consumption by 157g for 1kg of egg Production which was statistically significant. Haugh unit(H$.$u) at the age of 72 weeks were 82.20 for the crossbred strains and 77.82 for the controlled strains. The crossbred strains were superior quality by 4.38 H$.$u. There were no significant differences in the yolk color and the eggshell thickness between the crossbred strains and the controlled strains. The eggshell color of the crossbred strains was light brown which is the medium color of the white eggshell strains and the brown eggshell strains. The body weights at the ages of 8, 12, 18, 42 and 71 weeks were not different between the crossbred strains and the controlled strains.

• Korean Journal of Poultry Science
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• v.43 no.3
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• pp.177-189
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• 2016

This study was conducted to verify the relationships between the expression values of stress-related markers and their production performances in 25 strains of Korean domestic chicken breeds. For stress response markers, the amount of telomeric DNA; expression levels of heat shock protein (HSP)-70, $HSP-90{\alpha}$, and $HSP-90{\beta}$; and comet scores were analyzed. Production performances were measured by the survival rate, body weights, days at first egg laying, egg weight and hen housed egg production. The results showed that the production traits and values of stress-related markers showed significant differences between strains. In general, the stress response of pure bred chickens with heavy weights was relatively high, while that of hybrid chickens with light weights was relatively low. The correlation coefficients between telomere contents and body weights showed that there were weak negative relationships. However, the correlations of telomere content with the survival rate and egg production were weakly positive after 20 weeks old. The expression levels of HSP genes and DNA damage rate (comet scores) were positively correlated to body weight, but were negatively correlated to the survival rate and egg production. The results implied that increasing body weight was associated with increasing HSPs expression and the DNA damage rate was associated with decreasing telomere content. In addition, increasing HSPs expression and the DNA damage rate decreased the survival rate and egg production, but the relationships with the telomere content was the reverse. Correlations among the stress-related markers showed that there were significant correlation coefficients between all of the marker values. HSPs expression was negatively correlated to the telomere content, while it was positively correlated to the DNA damage rate. There was a highly negative correlation between the telomere content and DNA damage rate. In conclusion, increasing the HSP values and DNA damage rate can promote telomere reduction, which led to a decrease in disease resistance and robustness of the chicken. Thus, increasing the stress response was verified to adversely affect the laying performance and viability of chickens.

• Korean Journal of Poultry Science
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• v.8 no.2
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• pp.55-68
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• 1981

Calcium and phosphorus are not only indispensable for the bone formation and body fluids equilibrium but also are major components of egg shell. It is nutritionally important, therefore, to investigate the metabolism of calcium and phosphorus and to search for optimum requirement of calcium and phosphorus and the availability of various sources of calcium an4 phosphorus by poultry. An attempt was made to review the nutrition of calcium and phosphorus in poultry diets. 1, Calcium and phosphorus have great interrelationship with vitamin D in their metabolisms. 2. Most of the plant-origin phosphorus are existing in phytic form and it leads to low availability when used in poultry rations, although calcium and phosphorus present in animal-origin or mineral supplements are highly available in general. 3. Calcium and phosphorus requirement from existing information indicated that 1.0% calcium and 0.7% phosphorus for broiler and egg-type chicks, and 3.5% calcium and 0.4% phosphorus for laying hen. 4. It has been recommended that calcium and phosphorus level should be increased when the feed intake was decreased or when the egg Production rate was higher or when the hens are old. 5. Mono-, ci-, tri-, calcium phosphate, calcium carbonate, bone meal, limestone and oyster shell u the most readily available among various sources of calcium phosphorus supplements. Soft rock phosphate, deflourinated phosphate and gypsum are somewhat inferior to the previous ones in bioavailability. 6. The effect of particle size of calcium supplements on egg shell quality and egg production rate is not yet clearly defined but recent works showed that oyster shell is more available when it was coarse and limestone is more available when it was fine in panicle. size. 7. Present data indicated that mixed feeding of oyster shell and limestone is superior to the single feeding of each on laying performance. 8. Significant interaction between phosphorus and sodium was observed, that is, excessive sodium decreased egg production in layer and body weight growth in broiler in the low phosphorus diets but increased them in the high phosphorus diets.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.391-398
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• 2010

This study was conducted to investigate the effects of feeding probiotics(gene modified yeast) on the egg quality in laying hens. The laboratory method of this study is as follow: In hens, 300, 36 weeks old ISA brown commercial layer, were employed in 13weeks feeding trial with a 7 days adjustment period. Dietary treatments are 1) control (basal diet) 2) Y0.3 (basal diet+0.3% probiotics), 3) Y0.5% (basal diet+0.5% probiotics), 4) PY0.3% (basal diet+0.3% plasmid modified probiotics), 5) PY0.5% (basal diet+0.5% plasmid modified probiotics). For overall period, hen-day egg production, egg weight (p<0.05) by dietary probiotic supplementation were recorded. Eggs were collected and weighed every day. Egg production number and egg production rate, egg weight, failure egg ratio and trouble egg ratio were recorded for 13weeks days. Diets PY0.3 and PY0.5 improved Egg production rate, egg production number and egg weight, compared to control diet (linear effect. p<0.05). And, diets PY0.3 and PY0.5 improved Egg production rate, egg production number, compared to Y0.3 and Y0.5 (linear effect. p<0.05). But, in Inferior egg and cracked egg, diets PY0.3 and PY0.5 did not tended to increase by dietary probiotic supplementation compared to control diet and Y group (0.3, 0.5) (linear effect. p<0.05). The productivity enhance on the egg quality in laying hens is considered from the effects of feeding probiotics(gene modified yeast).

• Korean Journal of Poultry Science
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• v.35 no.2
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• pp.143-151
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• 2008

This study was conducted to identify the correlation of bacterial phytase ($Transphos^{(R)}$) to the calcium level in feed. Of all 21-week-old 720 HyLine brown laying hens, 2 birds of similar weight were placed on each individual cage. The experiment was conducted by $3{\times}2{\times}3$ factorial design with including 3 different levels of phytase (0, 300, and 1,000 DPU/kg), 2 different levels of calcium (3.5% and 4.0%), and 3 different levels of no NPP addition 0% (0.095 NPP), 0.5% (0.185% NPP), and 1.0% (0.275% NPP). The feeding trial maintained the ME level of 2,800 kcal/kg and 16% for crude protein. The diet was fed ad libitum and 17 hours of lighting was provided throughout the experimental period. Egg production seemed to increase, in the 300 DPU of bacterial phytase added group and the cracked egg tended to reduce in Transphos added group. The egg productivity between treatment groups did not show significant difference by dietary calcium level, whereas non NPP added group (0.095% NPP) was found to be low compared to NPP added groups (P<0.05). The highest mean egg weight and the highest daily egg mass were detected in 300 DPU phytase added group. Although the mean egg weight was significantly higher in treatment groups fed with 3.5% calcium containing feeds (P<0.05), daily egg mass was no among treatment groups. The mean egg weight and daily egg mass were the lowest in non NPP added group (0.095% NPP) compared to other treatment groups (P<0.05). The feed intake showed similar pattern regardless of the bacterial phytase and calcium levels in the diet. However, the treatment groups fed diets containing NPP level of 0.275% and 0.165% showed significantly higher feed intake than the group fed with 0.095% NPP (P<0.05). Although the feed conversion was not affected by calcium and NPP levels in the diet, the most improved result was obtained from 300 DPU phytase added group (P<0.05). The eggshell breaking strength and thickness increased as dietary calcium level increase the level of calcium increases in diet. The treatment groups fed diet containing 0.275% and 0.165% NPP revealed to show improvement in eggshell breaking strength and yolk color index compared to the NPP non added (0.095% NPP) treatment group. The result of the present study suggests that the appropriate level of microbial phytase is 300 DPU and at this level, tricalciumphosphate supplementation in feed can be reduced to 40% of NRC recommendation. Higher calcium level in feed fail to show synergistic effect by adding microbial phytase.

• Korean Journal of Poultry Science
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• v.15 no.3
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• pp.229-246
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• 1988

These studies were conducted to investigate the effects of dietary protein and metabolizable energy(ME) levels on layer performance during summer period. Total 480 ISA Brown egg-type layers ageing 49 weeks housed 2 birds per cage with 4 replictes of 20 birds were employed in this study. Mean environmental temperature over experimental period ranged from 22.3$^{\circ}$to 29.5$^{\circ}C$. The treatments consisted of dietary ME levels of 2500, 2700, 2900kcal/kg of diet containing 15% and 17% protein, respectively, to provide $3{\times}2$factorial design. As metabolizable energy level increased form 2500 to 2900 kcal/kg of diet, daily feed and protein intake, egg production. egg weight, egg mass decreased, but the reverse was true for the daily energy intake, energy requirement and feed costs per kg egg. Feed conversion(kg feed/kg egg) and viability were not affected by the dietary energy levels. However, there were no significant difference in egg production, protein requirement per kg egg, and egg weight between those hens fed 2500 kcal ME/kg diets and those fed 2700 kcal ME/kg diets, and no difference was found in egg weight between those fed 2700 kcal ME/kg and those fed 2900 kcal ME/kg, either. In addition, no specific trend was observed in protein requirement per egg by the different level of metabolizable energy in diets. On the other hand, as dietary protein level increased from 15 to 17%, daily protein in-take, egg production, egg weight, egg mass, and protein requirement and feed costs per kg egg increased, but feed and energy requirement per kg egg decreased, and no significant difference in the daily feed and energy intake and viability were observed among dietary protein levels. It was concluded that metabolizable energy level of 2500 kcal/kg of diet and 17% dietary protein level were considered to be adequate to support the optimum productivity of layers during summer period.

• Korean Journal of Poultry Science
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• v.17 no.3
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• pp.167-177
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• 1990

In order to investigate an effect of the feed restriction on the laying performance, 208 White Leghorn strain layer of 36 week-old were divided to 4 groups of 52 birds each and raised for 1 week of previous feeding and for the subsequent 3 weeks of experimental restricted feeding. The egg production, daily egg mass and feed efficiency of four groups of birds fed daily 100g, 95g, 90f and 85g of a commercial diet, respectively, which were compared with those of the original 2879 birds fed l13g of diet per day as control. During 3 weeks of experimental restricted feeding, period, daily body weight nam was decreased linearly as the degree of restriction increased in birds fed 100, 95, 90 and 85g of diet. Hen day egg production, egg weight and daily egg mass was linearly related to the diet intake level. then feed intake(x, g day$^{-1}$ ) showed a positive regression equations with the henday egg production(y, % ), egg weight(y, g egg$^{-1}$ ) and egg mass(y, g bird$^{-1}$ ) as y＝38.75＋0.3753$\times$(r＝0.503, n＝15), y＝48.2＋0.08868$\times$(r＝0.835, n＝ 15) and y＝15.69＋0.2786$\times$(r＝0.597, n＝15), respectively. Feed efficiency was increased to a plateau in birds fed 95g of diet. The estimated energy utilization for egg production was reached to a plateau in birds fed 95g of diet and the highst protein utilization was shown in birds fed 90g of diet anions birds fed graded levels of diet. And the feed restriction did not affect on the egg shell contents, while protein contents of egg were shown a trend to be increased and lipids and cholesterol contents of eggs was decreased according to the diet intake lowered. The results suggested that the improved feed efficiencies of birds restricted under 16% of diet(above 95g of diet) will be due to increased energy and protein utilization for egg production and feed restriction above 16% will be aboided. In the range from 113g to 95g of diet feeding, the crude profit was increased as the feed restricted in the case of egg price 600 won kg$^{-1}$ and feed price 200 won kg$^{-1}$ .