• Food Science of Animal Resources
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• v.38 no.5
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• pp.1080-1091
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• 2018

The eggshell, which is a complex and highly ordered structure, is very important factor for food safety and egg marketing. This study investigated the changes in eggshell structure and shell components in relationship to hen age. For this study, we examined the histological change of the endometrium of the 30-, 60-, and 72-wk-old commercial layers, and analyzed the ultrastructure and ionic composition of their eggshells. The results showed that histological deformation, fibrosis, atrophy and elimination of micro-villi in the uterus endometrium were found through microscopic observation that was associated with increasing hen age. Concentration of blood-ion components such as $Ca^{2+}$, $Na^+$, $K^+$, and $Cl^-$ ions did not change with age. Along with the results from the ultrastructure analysis of the eggshell, the palisade layer ratio and the density of mammillary knobs were significantly decreased in older hens. In addition, the type B mammillary knobs were frequently observed with increasing hen age. In the mineral element assay from the eggshell, $Ca^{2+}$, $S^{2-}$, and $Co^{2+}$ significantly decreased with increasing hen age, whereas $Na^+$, $K^+$, and $V^{2+}$ significantly increased. Therefore, the damages of endometrial tissue inhibit the processes of ion transmission and the crystallization of eggshell formation, resulting in a large and non-uniform mammillary knob formation. This means the conditions of endometrial cells affect the formation of the eggshell structure. In conclusion, hen aging causes the weakness of the eggshell and degrades the eggshell quality.

• Korean Journal of Poultry Science
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• v.16 no.4
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• pp.239-252
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• 1989

The present study was carried out to investigate the improvement of major production traits with the published data of twenty-two years'random sample tests held in Korea from 1966 to 1988. Eight traits-roaring viability, laying viability, age of sexual maturity, hen day egg production, hen-housed egg production, egg weight, feed requirement, 500 days body weight-were dealt with in this study. The results obtained in this study are summerized as follows； 1. Total mean value for rearing viability was 99.4% in 1980s. Mean value for rearing viability of colored hen was 99.5% and white hen was 99.06% in 1980s. Mean value for laying viability was increased by 0.98%, 0.86% and 0.86% per year in pool data, white hen and colored hen, respectively. 2, Age of sexual maturity was decreased from 171.1 day to 160.8 day in pool data during 1960s- 1910s but increased to 162.4 day in 1980s； and decreased from 160.5 day to 1595 nay in white hen but increased from 163.7 day to 166.1 day in colored hen during 1970s-1980s. 3. Mean values for hen-day egg production were increased by 0.96%, 1.09% and 0.63% per year in pool data, colored hen and white hen, respectively. 4. Mean values for hen housed egg production were increased by 45, 5.37 and 4.23 per year in pool data, colored hen and white hen, respectively. 5. Egg weight were improved by 0.22g and 0.25g per year in pool data and colored hen but decreased by 0.03g in white hen. 6. feed requirement were improved by 0.04, 0.05 and 0.1 per year in pool data, white hen and colored hen, respectively. 7. 500 days body weights were increased by 0.38g per year in pool data but decreased by 14.95g and 10.37g in colored hen and white hen, respectively. 8. Estimate of correlation coefficient between age of sexual maturity and other factors such as hen day egg production. hen housed egg production, egg weight and 500 days body weight were -0.4512, -0.2876, -0.4376 and 0.2045 in pool data； -0.358, -0.1530 0.3475 and 0.1208 in white hen； 0.0989, 0.1181, 0.2885 and 0.2248 in colored hen, respectively. Estimates of correlation coefficient between hen day egg production and egg weight were 0.6233, -0.2259 and 0.2973 in Pool data, white hen and colored hen； between hen day egg production and 500 days body weight, 0.2417, 0.0774, -0.4787 ： between hen-housed egg production and egg weight, 0.6171, -0.2706, 0.4579： between hen housed egg production and 500 days body weight, 0.3082, -0.0792, -0.3368： between egg weight and 500 days body weight, 0.2742, 0.2205, 0.1354, respectively.

• Korean Journal of Poultry Science
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• v.43 no.4
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• pp.253-261
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• 2016

Egg quality is a very important factor for both consumers and producers. Factors affecting egg quality include strain and age of hens; egg storage temperature, time, and humidity; laying season; and feeding. This study aimed to determine the effect of hen age and egg storage time on egg quality. A total of 700 eggs obtained from Hyline Brown commercial layers were used for this experiment, and they were separated into two hen age groups (30 vs. 60 weeks) with eight treatments and four storage times (day 0, 10, 20, and 30). The egg weight; shell color, thickness, and density; albumen height; Haugh unit (HU); yolk color; and the yolk and albumen pH and viscosity were measured for the egg quality assessment. The results showed that the age of the hen and egg storage time significantly affected almost all parameters of the internal and external egg quality. The shell thickness, albumen height, HU, yolk color, pH of yolk and albumen, and yolk viscosity significantly decreased with increasing hen age. The egg shell color was significantly lighter in eggs from 60-week-old hens than in those from 30 weeks-old hens. The egg weight; shell weight, thickness, and density; albumen height, HU; and albumen viscosity significantly decreased, but the yolk color and pH of the yolk and albumen increased with increasing egg storage time. The interaction effects between the storage time and hen age were significant in shell thickness, albumen height, yolk color, and yolk and albumen pH and viscosity. The eggs obtained from 60-week-old hens showed significantly lower shell thickness, albumen height, and HU values, which are considered typical egg quality measurements, than values of eggs from 30-week-old hens. Therefore, increasing hen age and egg storage time caused the deterioration of egg quality. In conclusion, this study demonstrated that hen age is the major factor affecting the quality of fresh eggs, whereas the storage time is the determinant factor affecting the quality of stored eggs.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.109-113
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• 2016

This study aimed to examine the nutrient utilization of rump round meat and lotus root using young (32 wk) and aged hens (108 wk) as an animal model. Rump round meat and lotus root were prepared with or without enzymatic treatment. For each age group of laying hens, a total of 24 Hy-Line Brown laying hens were randomly allotted to one of two dietary treatments with six replicates. For rump round meat, the true total tract retention rate (TTTR) of dry matter (DM) and nitrogen (N) were unaffected by either enzymatic treatment or hen age. However, aged hens had greater (p<0.01) TTTR of energy and crude fat than young hens. Enzymatic treatment did not influence the TTTR of energy or crude fat. In addition, we did not observe any significant interaction between the TTTR of DM, energy, N, or crude fat in rump round meat and hen age or enzymatic treatment. The TTTR of DM remained unchanged between controls and enzyme-treated lotus root for young hens. However, enzyme-treated lotus root exhibited greater (p<0.05) TTTR of DM than control lotus root for aged hens, resulting in a significant interaction (p<0.05). The TTTR of energy and N in lotus roots were greater (p<0.01) for aged hens than for young hens. In conclusion, enzymatic treatment exerted beneficial effects on energy and nutrient utilization in aged hens, suggesting the aged hen model is practical for simulation of metabolism of elderly individuals.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.2
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• pp.129-140
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• 2008

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including growth parameters, survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of hen clam, Mactra chinensis, in the Dong-li self-regulatory community of Busan. The von Bertalanffy growth parameters estimated from a non-linear regression were $SH_{\infty}=86.24mm$, K=0.12/year, and = -1.37year. Survival rate(s) of the hen clam was 0.515. The instantaneous coefficients of natural mortality(M) was estimated to be 0.232/year and fishing mortality(F) 0.432/year for hen clam. The current biomass of the hen clam in the study area was estimated to be 713mt and the acceptable biological catch(ABC) was estimated under various harvest strategies based on $F_{0.1}$ and $F_{40%}$.

• Korean Journal of Poultry Science
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• v.13 no.1
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• pp.1-14
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• 1986

The subject of this study was to obtain some genetic information for developing superior layer chickens. Heterosis and combining ability effects were estimated with 5,759 progenies of full diallel crosses of 6 strains in White Leghorn. Fertility, hatchability, brooder-house viability, rearing- house viability, laying-house viability, age at 1st egg laying, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion were investigated and analyzed into heterosis effect, general combining ability, specific combining ability and reciprocal effect by Grilling's model I. The results obtained were summarized as follows; 1. The general performance of each traits was 94.76% in fertility, 74.05% in hatchability, 97.47% in brooder-house viability, 99.72% in rearing-house viability, 93.81% in laying-house viability, 150 day in the age at 1st egg laying, 1,505g in the body weight at 1st egg laying, 60.08g in average egg weight, 77.11% in hen-day egg production, 269.8 eggs in hen-housed egg Production, and 2.44 in feed conversion. 2. The heterosis effects were estimated to -0.66%, 9.58%, 0.26%, 1.83%, -3.87%, 3.63%, 0.96%, 4.23%, 6.4%, and -0.8%, in fertility, hatchability, brooder-house viability, laying-house viability, the age at 1st egg laying, the body weight at 1st egg laying, average egg weight, hen-day egg Production, hen-housed egg production and feed conversion, respectively. 3. The results obtained from analysis of combining ability were as follows ; 1) Estimates of general combining ability, specific combining ability and reciprocal effects were not high in fertility. It was considered that fertility was mainly affected by environmental factors. In the hatchability, the general combining ability was more important than specific combining ability and reciprocal effects, and the superior strains were K and V which the additive genetic effects were very high. 2) In the brooder-house viability and laying-house viability, specific combining ability and reciprocal effects appeared to be important and the combinations of K${\times}$A and A${\times}$K were very superior. 3) In the feed conversion and average egg weight, general combining ability was more important compared with specific combining ability and reciprocal effects. On the basis of combining ability the superior strains were F, K and B in feed conversion, F and B in the average egg weight. 4) General combining ability, specific combining ability and reciprocal effects were important in the age at 1st egg laying and the combination of V ${\times}$F, F${\times}$K and B${\times}$F were very useful on the basis of these effects. In the body weight at 1st egg laying, general combining ability was more important than specific combining ability and reciprocal effects, relatively. The K, F and E strains were recommended to develop the light strain in the body weight at 1st egg laying. 5) General combining ability, specific combining ability and reciprocal effects were important in the hen-day egg production and hen-housed egg production. The combinations of F${\times}$K, A${\times}$K, and K${\times}$A were proper for developing these traits. 4. In general, high general combining ability effects were estimated for hatchability, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion and high specific combining ability effects for brooder-house viability, laying house viability, age at 1st egg laying, hen-day egg production and hen-housed egg production, and high reciprocal effects for the age at 1st egg laying.

• 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.

• Food Science of Animal Resources
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• v.34 no.1
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• pp.127-132
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• 2014

Optimization of carnosine and anserine extraction from chicken breast was performed using response surface methodology (RSM) to obtain the maximized physiological activities for anti-glycation and anti-oxidation. The optimum extraction conditions were water extraction for 1.6 h in the case of the 20-wk laying hen muscle and water extraction for 2.12 h in the case of 90-wk laying hen muscle. Higher carnosine and anserine contents were measured in the 20-wk laying hen muscle, along with higher physiological activities, which increased in direct proportion with the dipeptide contents. The extracts prepared from the 20-wk laying hen under optimum conditions showed 57% inhibition of advanced glycated end-product formation, 64% inhibition of lipid peroxidation, and 61% of DPPH radical scavenging effects. On the other hand, 52% inhibition of AGE formation, 62% inhibition of lipid peroxidation, and 53% of DPPH radical scavenging effect were demonstrated within the 90-wk laying hen. In addition, the ratio of carnosine was a key indicator for the physiological activities of the extracts.

• Korean Journal of Poultry Science
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• v.44 no.1
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• pp.19-28
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• 2017

The eggshell is an intricate and highly ordered structure composed of multiple layers and a calcified matrix. The eggshell is formed at the uterine segment of the chicken oviduct. In this study, histological changes in the uterine endometrium and the expression of the eggshell-related genes were investigated according to hen age. We analyzed the expression of eggshell protein-related genes, such as OCX-32, OCX-36, OC-17, OC-116, and eggshell-ion-related genes, such as CABL-1, SPP1, SCNN1G, ATP2A2, CA2, and CALM1. In chicken uterine endometrium, histological deformation, fibrosis, atrophy and elimination of micro-villi were found with increasing hen age. The concentration of blood-ion components did not significantly change with age. The amount of telomeric DNA in uterine endometrial cells decreased with increasing hen age. The expression of most of the eggshell-related genes changed significantly with increasing hen age. The expression of some ovo-proteins, which play a role in eggshell formation, increased with increasing hen age; however, there were no significant correlations among eggshell protein genes. Eggshell ion-related genes, such as ATP2A2, SCNN1G, CA2, and CALM1, were closely related to each other. The OCX-32 and OCX-36 genes were closely related to some of the eggshell ion genes. Eggshell protein-related genes, such as the OCX-32, OCX-36 genes and ion-related genes such as CALB-1, ATP2A2, SCNN1G, CA2, CALM1, affected eggshell formation, mutually or independently. This study shows that, uterine although endometrial cell damage occurs with increasing hen age, normal eggshells can be formed in old hens. This suggests that eggshell protein-and eggshell ion-related genes also control the homeostasis of eggshell formation.

• Korean Journal of Poultry Science
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• v.50 no.1
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• pp.15-22
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• 2023

This study was to investigate the relationship between chick weight in the growing period and the laying performance of Korean native chicken (KNC) breeders. We measured the body weights of 1,384 KNC breeders at 1-140 days of age at two-week intervals. The age at first egg laying, hen-day and hen-housed egg production, and the egg weights were investigated. Correlation coefficients between the body weight and egg production traits were analyzed. The results showed that the correlation coefficients between body weight and age at first egg laying were significantly positive before 4 weeks, but negative after 8 weeks of age. The correlation coefficients between body weight and egg production rate were estimated to be negative before 8 weeks and positive after 12 weeks of age. Coefficients of hen-day and hen-housed egg production were similar. There was little correlation between body weight and egg weight at 32 weeks of age, whereas a low positive correlation was with egg weight at 50 weeks. In conclusion, there was little correlation between body weight and laying performance before 8 weeks of age, whereas a significant positive correlation was with body weight after 12 weeks. The results suggest that as the chick's weight increases in the late growing stage, sexual maturity is faster, the egg production rate is higher, and the egg weight increases. Therefore, the weight management of KNC female breeders is very important in the late growing stage, and the body weight of chicks must be maintained above the standard weight.