• Korean Journal of Poultry Science
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• v.35 no.2
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• pp.171-176
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• 2008

Animal welfare advocates, claim that the induced molting by fasting be avoided. This study was conducted to evaluate the effect of molting induced by various feeding methods on productivity and egg quality in laying hens. We used 400 flocks of 60-week-old leghorn laying hens in four treatments(five replicates of 20 hens each): fasting method (C), feeding single corn grain diet (T1), feeding single wheat bran diet (T2) and feeding single alfalfa meal diet (T3). As the result of the experiment, egg production and daily egg mass significantly decreased only in T1 compared with the control during the $1{\sim}4th$ week after the secondary egg laying (P<0.05). Although the amount of feed intake was significantly less in T1 group during the $1{\sim}4th$ week compared to the control, no significant difference was detected during the total period (P>0.05). In addition, no significant difference of feed conversion was observed between treatment groups. In terms of egg quality, the egg shell thickness was significantly improved in T1 group than the control group by feeding only corn at the 10th and 14th week after the secondary egg laying (P<0.05), but the significant decrease was observed at the corn (T1) and wheat bran (T2) fed treatment groups than the control group at the 26th week of the experiment (P<0.05). The eggshell strength and haugh unit did not show any difference by the molting methods. Egg yolk color was significantly decreased in T1 and T2 group than the control group at the 6th week (P<0.05). However, T1 and T2 group resulted to show significantly high egg yolk color at the 18th week of the experiment (P<0.05). As the result of the experiment, no large difference was observed in the productivity by the feeding molting method and by the fasting induced molting method. In addition, the single diet fed feeding induced molting method by using alfalfa revealed to show more satisfactory trend than the corn or wheat bran single diet fed feeding induced molting methods even if no statistically significant difference was found in terms of egg productivity.

• Korean Journal of Poultry Science
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• v.42 no.4
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• pp.335-345
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• 2015

This study was conducted to compare carcass yield and meat quality among four lines of Korean native chickens (Yeonsan Ogye, Hyunin Black, Hoengseong Yakdak and Hwangbong) and White Leghorn as control. Chickens (N=23, male) were grown under same conditions and slaughtered at 56 weeks old to observe the physicochemical differences in breast and leg meats. The live and carcass weights of Hwangbong were significantly higher than other chickens (p<0.05). Four lines of Korean native chickens, regardless of the part, had higher shear force value than White Leghorn (p<0.05). In addition, the breast meat of Korean native chickens had higher cooking loss and lower water holding capacity than that of White Leghorn. The cooked meat of Hwangbong particularly were more chewy, gummy and cohesive with lower tenderness than other chickens (p<0.05). Oleic acid content which is related to meat flavor was significantly higher in the breast meat of Hoengseong Yakdak (39.6%). The meat of Korean native chickens had lower n6/n3 ratio, in which the breast and leg meat of Hoengseong Yakdak contained the lowest ratio (p<0.05). The meat of Hwangbong and Hoengseong Yakdak were more acceptable than the others according to sensory test (p<0.05).

• Korean Journal of Poultry Science
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• v.16 no.1
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• pp.9-15
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• 1989

This study was conducted to estimate genetic parameters for egg yolk cholesterol. Content of egg yok cholesterol was measured for a total of 473 hens of White Leghorn line. Cholesterol values were obtained from tee consecutively laid eggs when hens were 53 weeks of age. The yolk of each egg was weighted and freeze dried. Dried egg yolks were stored at -2$0^{\circ}C$ until analyzed. The results obtained from this study were as follows; 1. Yolk cholesterol content was measured in average $56.00\pm$0.194 mg/g dry yolk. 2. Heritability from the sire component of variance was $0.522\pm$0.215 and from the sire＋dam component of variance $0.33\pm$0.209. 3. Estimates of phenotypic correlation between your cholesterol and other factors such as body weight at 20 weeks of age, age at first egg, 40-week total egg number, egg Production rate: 53-week egg weight and 53-week yolk weight were -0.0208, -0.0321, -0.0378, -0.0834, 0.0790 and 0.1624, respectively. And genetic correlation coefficients for each item in the order were -0.5293, 0.7105, -0.4062, -0.0254, 0.2164 and 0.5027, respectively. 4. These results suggest the possibility that egg Yolk cholesterol should be reduced through selecting of sire families. To breed for low egg yolk cholesterol, it makes age at first egg earlier and enhances total egg number so that we can obtain the high rate of egg Production.

• Korean Journal of Poultry Science
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• v.9 no.2
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• pp.63-101
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• 1982

A study was conducted to investigate the possibility of improving the effectiveness of the existing method(s) to estimate the edible meat weight in live broiler chicken. Four. breeds of chicken, white Cornish broiler chicks(parent stock), Single Comb White Leghorn(SCWL) egg strain chicks (parent stock), and two reciprocal cross breds of these parent stocks were employed in this study. A total of 480 birds, 60 male and 60 female chicks for each breed, were used. Ten male and 10 female chicks from each breed were randomly sacrificed at 0, 2, 4, 6, 8 and 10 weeks of ages in order to measure the body weight, edible meat weight of breast and 1eg(thigh and drum-stick), various components of body weight and various body shape measurements. In addition, chemical analyses of edible meat were carried out. Results obtained from this sturd were summarized as follows. 1. The average body weights of White Cornish broiler chicks and SCWL egg strain chicks were 1.82${\pm}$0.048kg(X${\pm}$S.E.) and 0.67${\pm}$0.029 kg. respectively, at 8 weeks of age. The feed to gain ratio for White Cornish and SCWL chicks were 2.24 and 3.28, respectively, for 0 to 8 weeks of age. The reciprocal cross bred chicks (White Cornish ${\times}$ SCWL) showed intermediate values in both parameters.

• Korean Journal of Poultry Science
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• v.19 no.4
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• pp.187-195
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• 1992

This study carried out to investigate selection response of pure line population of layer chicken. Data for two layer pure line of Single Comb White Leghorn were collected from 1986 to 1991. Primary selection criteria were egg number to 270 days of age (EN270), egg weight(BW270), body weight (BW270) at 270 days of age and the days of the 1st egg(SM). The results obtained in this study are summarized as follows ; 1. Mean phenotypic values of two strains were decreased by 1.94 day(K), 1.320ay(F) for SM and increased by 0.09g(K), -0.05g(F) for EW 270 and 0.56(K), -0.78(F) for EN270. 2. The ratio of a realized selection differential to expected selection differentials for SM (sexual maturity), EW 270, and BW 270 were not significantly decreased during 5 generations. 3. Heritability were estimated from sib analysis. The means of estimates were 0.28(F), 0.39(K) for BW270, and 0.25(F), 0.29(K) for EN270 and 0.51(F), 0.48(K) for EW270. 4. The genetic gains were estimated by method of selection index in retrospect on the basis of selection differentials. EN270 and EW270 were found to increase by 2.01(F), 2.25(K) and 0.54 (F), 0.65(K) per generation.

• Korean Journal of Poultry Science
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• v.34 no.2
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• pp.119-128
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• 2007

The effects of microbial phytase on laying performance, egg quality, and ileal digestibility of nutrients and amino acids were examined at three levels of phytase (0, 300, 600 unit/kg) in 55-wk-old White Leghorn for 4 weeks. Egg productivity tended to increase with supplemental phytase compared to that of control. Daily feed intake of hens fed phytase also increased. Egg shell thickness was not significantly different among the treatments. Haugh unit and yolk color were not statistically different. However, egg shell breaking strength was high at phytase treatment. Excretion and absorption of nitrogen were no difference among all treatments, but those of phosphorus was higher in the phytase treatment than control. The digestibility was high at crude fiber, crude ash, calcium and phosphorus in nutrients, at lysine, methionine and phenylalanine in essential amino acids, and alanine, cystine, glutamic acid, glycine and tyrosine in non-essential amino acids. In conclusion, supplemental microbial phytase in laying hens diet may help to improve egg production and to decrease P of feces. But, further studies were needed to investigate on the digestibility.

• Journal of Life Science
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• v.20 no.7
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• pp.1086-1092
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• 2010

To estimate the genetic characteristics and cumulative power of discrimination (CPD) within Korean native commercial chicken, we used a total of 395 genomic DNAs from six breeds population (Korean Native Red chicken: R, Korean Native Yellow chicken: Y, Korean native Commercial Chicken: C, Ogal chicken: S, Hy-Line Brown: H, White Leghorn: W). Genetic diversity indices including mean allele number among loci, unbiased heterozygosity ($h_i$) within locus, effective number of alleles ($N_e$) and polymorphism information content (PIC) as well as the unbiased average heterozygosity (H) among loci in the populations were calculated using the generated allele frequencies by each marker. Frequencies of microsatellites markers were used to estimate heterozygosities and genetic distances. The nearest distance (0.119) was observed between the C and Y strains. The generated unbiased average heterozygosity among loci in each population was integrated to the global formula of CPD and the result demonstrated that the CPD within the six chicken populations was 99.461%.

• Korean Journal of Poultry Science
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• v.20 no.4
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• pp.209-216
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• 1993

This study was conducted to classify Korean native chicken(KNC) and imported chicken by phenotypic performances and DNA fingerprinting. Two lines, KNC and White Leghorn(WL) , of chicken were maintained in the laboratory of Yeungnam University. Economic traits (body weight, sexual maturity, hen-day egg production, egg weight) and phenotypic characteristics (body-type, head, feather, shank) were checked. The DNA fingerprinting was analyzed for both breeds. The growth rate of the KNC was similar to WLS and sexual maturity of the KNC came later than WL. Hen-day egg production of the KNC was also slightly lower than the WL. The egg weight was about 10g lighter than WL. There was no difference in body weight of female KNC compared to the WL after 28 weeks. The study confirms difference between KNC and WL in DNA fingerprinting as well as its outlook. Thus, we suggest that these should be tested in nationwide districts about chickens known as the KNC using DNA fingerprinting. Then, the confirmed KNC populations should be maintained and used for the genetic improvement. Finally, only confirmed KNC should be in market which induce consumer to seek the KNC by its favorite.

• Korean Journal of Poultry Science
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• v.48 no.1
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• pp.1-12
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• 2021

We investigated the effects of breed, laying age, and egg storage period on the vitality of chicks using the Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Their eggs were collected during the early laying period (27~29 weeks) and late laying period (50~52 weeks) and were stored for 3 days, 7 days and 14 days. After the eggs hatched, the hatching time, production performance, and organ weight of chicks were investigated. IL-6 gene expression level and relative length of telomeres were analyzed to determine the physiological activity of the chicks. HSP gene expression level and heterophil to lymphocytes ratio were also analyzed to examine the degree of stress response in the chicks. The results showed that breed and laying age influenced the vitality of chicks, but the egg storage period did not. Korean Leghorn chicks were considered the weakest breed in terms of vitality owing to their low survival rate, small heart size, low physiological activity, and high stress response level. Although the survival rate of chicks produced in the early laying period was low, their high physiological activity and low stress response indicated that they had a high vitality than the chicks produced in the late laying period. In conclusion, to obtain chicks with high vitality, it would be desirable to select a high vitality breed and avoid the use of chicks produced in the late laying period.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.10
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• pp.1406-1410
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• 2003

The studies were based on the RAPD fingerprinting for the species identification of animals. The genomic DNA samples of ostriches, Taiwan local chickens, Aboracres broilers, Leghorn chickens, quails, doves, emus, Beltville small white turkeys, pheasants, Chinese geese, mule ducks, Holstein cattle and Landrace pigs were amplified with random primers by RAPD-PCR for fingerprinting. The results showed that the varied band patterns of DNA fingerprints were generated from templates depending on the kinds of primers or animal species. The same primer applied to the same breed, all of the main bands are similar, but which were different among species. In order to try to identify the species from the mixture of meat by RAPD fingerprinting, the meat of ostrich and cattle was mixed in different ratios for this study. The results showed that it could be easily and precisely distinguished according to the band distribution of RAPD patterns.