• Korean Journal of Poultry Science
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• v.31 no.2
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• pp.79-84
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• 2004

A total of 225 ISA Brown layers, 63-wk-old, were used in a 5-wk feeding trial to measure the effect of dietary canthaxanthin(0, 50, 100, 200, and 300mg/kg feed) on its accumulation in various body parts and the egg yolk. There were three replications per treatment and 15 birds per replication. The redness(a$\^$*/) and yellowness(b$\^$*/) of wing and thigh skin significantly(P＜0.05) increased when canthaxanthin was fed at 2200 and 250mg/kg feed, respectively. However, the color of breast skin was not significantly affected by the canthaxanthin supplementation. Skin lightness(L$\^$*/) was not influenced by the dietary canthaxanthin. The dietary canthaxanthin supplementation did not significantly affect the redness or the yellowness of breast and thigh muscles. However, feeding canthaxanthin at 300mg/kg, compared to the control(0mg/kg feed), significantly(P＜0.05) decreased the lightness of wing and breast muscles. Feeding of canthaxanthin for 1-3d also significantly increased the color of egg yolks. In conclusion, canthaxanthin can be used to improve the color of skin and egg yolks, but it should be used cautiously because too intense egg yolk redness could be rejected by consumers.

• Korean Journal of Poultry Science
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• v.19 no.3
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• pp.113-123
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• 1992

This study was carried out to build up new synthetic egg Production lines which had sex linked gene for feather color sexing and had also superior combining ability for producing the best commercial chicks. In order to make autosexing layer line, the commercial layers which had Z$^{s}$ Z$^{s}$ and Z$^{s}$ W were mated. Among progeny, the chicks which had homozygote of silver gene and non-silver gene were selected for making dam and sire lines. Afterwards the closed flock breeding method was utilized to improve general performances of the each line. The performances of egg production in synthetic line were 161 day for age at sexual maturity, 219 eggs for total egg number to 60 weeks of age, 84% for hen-day egg production and 619 for average egg weight. There was no difference in egg production between new synthetic lines and imported breeds. In the analysis of genetic trends, the estimates of genetic parameter in the autosexing lines were similar to those of the general population of layer breeders. This results indicated the consistency of genetic variation from this selection.

• Korean Journal of Poultry Science
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• v.25 no.4
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• pp.177-183
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• 1998

A feeding trial was conducted to investigate the performance of various Korean Native Chickens (KNC) for 64 weeks. Eight hundreds and ten KNC one-day birds were arranged to three strains, Dark Brown(D), Light Brown(L) and Black(B). Each strain had three replicates of 90 birds a replicate. Birds fed same diet with Korean standard feeding. Data were obtained growing performance to 20 week of age and laying performance from twenty one to sixty four week. During the growing stage from hatch to 20 week of age, there were not significant difference to three strains on viability, body weight and feed intake. L strain tended to be earlier 50％ egg production day than that of other strains, but was not significantly different. Egg production of L strain was the highest of strains. It showed significantly higher egg production compared to that of D strain(P<0.05), but was not statistically different from that of B strain. Laying peak period was between 28 to 32 week of age in all strains, Egg weight was heavier in D strain(P<0.05). Feed intake was the same as 105g, and feed conversion improved in L strain(P<0.05). There were not difference on interior egg and eggshell quality by strains although eggshell thickness improved slightly in D strain. Fertility of D strain was the highest compared to others(P<0.05) regardless laying stages. Hatchability was not influenced by strains at 39 weeks old, but was significantly higher in B strain at 62 week of age(P< 0.05). The results of this experiment indicated that KNC 3 strains were not effect on egg production, feed intake and feed conversion ratio.

• Korean Journal of Poultry Science
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• v.19 no.3
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• pp.125-136
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• 1992

This study was conducted to estimate the effect of dietary alfalfa meal on the contents of egg yolk cholesterol, the levels of egg yolk pigmentation and the performance of laying hens. Alfalfa meal which was alternated wheat bran was supplied 0, 3.5 and 7%, respectively. Total 192 brown laying pullets of 47 weeks old were randomly assigned to the wire cages from July 23 to October 7, 1991 for 10 weeks. The results obtained were summarized as follows ： 1. The egg production was highest at 3.5% alfalfa meal level during the entire period. But there was no significant difference among treatments. 2. Egg weight increased in treatments 3.5 and 7% alfalfa meal supplementation significantly. (P<0.01). 3. Even though there was no significant difference, the daily egg mass was the highest at 3.5% of alfalfa meal level. 4. Daily feed intake was the highest at 3.5% of alfalfa meal level. However, feed conversion rate was the lowest among treatments. 5. The feed cost per kg egg mass in the treatment of 3.5% alfalfa meal was significantly lower than the other treatments. (P<0.05). 6. Shell thickness and shell weight in terms of egg shell quality were increased as the levels of alfalfa meal were increased. But there was no significant difference among treatments. 7, The egg yolk Pigmentation was improved significantly as the level of alfalfa meal was increased (P<0.01). 8.899 yolk cholesterol contents were decreased in the treatments of 3.5 and 7% alfalfa meal supplementation compared with those in the treatment of wheat bran only(P >0.05). The results of this study indicate that 3.5% alfalfa meal level was most effective and economical in laying hen.

• 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.

• 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.49 no.2
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• pp.53-60
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• 2022

This study investigated correlations between egg quality indicators to identify external egg quality traits to predict internal egg quality using non-destructive and convenient measurements. Thirteen indicators, including Haugh unit, albumen height, eggshell breaking strength, eggshell thickness, eggshell color (CIE L^*, CIE a^*, CIE b^*), and reflectivity value, egg weight, egg length, egg width, shape index, and yolk color, were investigated. A total of 180 brown eggs were obtained from one 27-week-old flock of Hy-line brown-laying hens raised in a cage system. Correlations were evaluated using Pearson's correlation coefficient (r). The results showed strong correlations between Haugh unit and albumen height, eggshell color CIE L^* and reflectivity, egg weight and width, egg weight and length, eggshell color CIE L^* and CIE a^*, eggshell color CIE a^* and reflectivity, and shape index and egg length (P<0.001). Moderate correlations were observed between eggshell breaking strength and eggshell thickness, eggshell color CIE a^* and CIE b^*, and shape index and egg width (P<0.001). Eggshell color CIE L^* was correlated with eggshell breaking strength (P<0.01), and eggshell color CIE a^* was correlated with Haugh unit, albumen height (P<0.01), and eggshell breaking strength (P<0.001). The present study showed significant correlations between eggshell color and other quality indicators. Thus, this study suggests that eggshell colors based on reflectiveness and the CIE L^*a^*b^* value can be used to estimate the Haugh unit, albumen height, eggshell breaking strength, and thickness.

• Korean Journal of Poultry Science
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• v.38 no.3
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• pp.173-179
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• 2011

This experiment was conducted to evaluate the dietary effects of multiple mixture of probiotics on laying performance and the faecal examination in laying hens (Hy-line Brown) at the early (21~40 wk) and middle (41~65 wk) laying term. Multiple probiotics were produced by developing products and the properties of microorganisms were examined for detecting of acid-resistance, bile salt-resistance and antibacterial activity against pathogenic enteric bacteria. Probiotics produced to the fermenting cultures of four selected organisms and soybean meal substrates by nine steps of NK proliferating system. The most microorganisms were shown higher resistance of acidity and bile salt. High antibacterial activities against Bacillus subtilis, Lactobacillus plantarum and Enterococcus faecium were observed, but was not against Saccharomyces cerevisiae. Total egg production of the treatment was significantly higher than control group but was not statistically different between 0.1% and 0.2% treatments (P>0.05). Average egg weight of the treatment in early laying term was also significantly higher than control but was not significantly different between 0.1% and 0.2% treatments (P>0.05). But the egg weight of the treatment in middle laying term was significantly higher than control and between 0.1% and 0.2% treatments (P>0.05). The mortality of 0.2% treatment was significantly lower than control (P<0.05), and 0.2% treatment in the early laying term was tended to decreased than 0.1% treatment and control. But there was not significantly between 0.1% and 0.2% treatments in middle laying term. In feed intake, 0.2% treatment in middle laying term was significantly increased than control and 0.1% treatment (P<0.05) but not in early laying term. In faecal examination, the total number of Lactobacillus of 0.1% treatment was significantly increased than control in whole laying term (P<0.05), but Coli form of the treatment was decreased than control in middle laying term. In conclusion, dietary long term supplementation of multiple probiotics improved performance of lay hens, egg weight and mortality drop by regulating enteric bacteria.

• Korean Journal of Poultry Science
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• v.35 no.1
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• pp.63-69
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• 2008

The objective of this study was to investigate the effect of restricted feeding to laying performance and egg quality in brown layers. A total of 1,080 brown layer chicks were divided into three treatments; conventional feeding (ad libitum) and two restricted feedings (80% of conventional diet) for 70 weeks. One of restricted feeding started from six to eighteen weeks of age, and the other started from twelve to eighteen weeks of age. Diets were formulated by NRC (1994) recommendation. Overall laying performance and feed intake were the highest in $6{\sim}18 wk$ restricted group. But there was no significant difference among treatment group (P>0.05). Feed intake was higher in $6{\sim}18 wk$ restricted group during maximum production (P<0.05), but there was no difference between treatments after the peak. Egg quality tended to decreased by aging, but there was no significant difference among the treatments (P>0.05). The result of present study indicated that restricted feeding in rearing period of layers is beneficial to improve egg productivity and to reduce feed cost.