• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.391-398
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• 2009

The objective of the present study was to compare of the effects of four molting methods on performance of laying hens. In total, 120 White Leghorn layers (62 weeks of age) were used. The four molting methods consisted of 10 days of feeding and the first 3 days of water withdrawal (FW1, 2) followed by ad libitum access to a layer diet 1 and 2 from day 11; 28 days of restricted feeding (NFW1); 28 days without withdrawing their feed (NFW2). Egg production of postmolt decreased until $3{\sim}4$ days at FW1 and FW2 treatments and until $16{\sim}18$ days at NFW1 and NFW2. 50% recovery of egg production were 7, 6, 7 and 5 week at FW1, FW2, NFW1, and NFW2 treatments, respectively. At day 14 of postmolt, the weight of livers, hearts, and oviducts decreased at molting treatments (P<0.05). Egg quality was improved on egg weight, eggshell thickness, eggshell break strength, and Haugh unit except egg yolk color (P<0.05).

• Korean Journal of Poultry Science
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• v.18 no.2
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• pp.85-95
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• 1991

The investigation concerned an effect of the ground charcoal powder and organic acids on the digestibilities of protein and energy or the contents of uric acid, ammonia, creatine and urea in excreta of 113 week-old White Leghorn strain layers. Birds were fed basal (control) diet composed of mainly corn-soybean meal during a week of previous feeding and subsequent experimental diets during 12 weeks of experimental feeding . The experimental diets were the control diet(CON). diet(CPD) substituted 0.5% of the ground charcoal powder with the defatted rice bran of the CON, diet(PWV) added 0.1mM(based on the acetic acid) wood vinegar in the CPD and diet(PFA) added 0.1mM (based on the acetic acid) fermented acetic acid in the CPD. Birds fed CPD excreted significantly(P＜0.05) more fecal nitrogen(FN) and lower urinary nitrogen (UN) than those of birds fed CON. Digestibility of protein was lower significantly (P＜ 0.05) in CPB-fed bird than in bird fed CON. while birds fed CON. PWV and PFA showed similar values. Also urinary nitrogen per nitrogen intake (UN/NI) or absorbed nitrogen (UN/AN) was significantly (P＜0.05) lower in birds fed CPD compared with those in birds fed CON. And birds fed PWV tended to increase UN/NI and UN/AN, while PFA-fed birds excreted significantly (P＜0.05) higher UN/Nl and UN/Ah than those of birds fed CPD diet. The uric acid nitrogen (UAN) per nitrogen intake (UAN/NI) or absorbed nitrogen (UAN/AN) were lower significantly(P＜0.05) in CPD-fed birds and were tended to decrease in birds fed PWV compared with those in birds fed CON and PFA The ammoniacal nitrogen(AMN) per nitrogen intake (AMN/NI) or absorbed nitrogen (AMN/NI) was tended to increase in birds fed experimental diets and was increased significantly(P＜0.05) in birds fed PFA compared with those of birds fed CON. The excretion of creatine and urea nitrogen per nitrogen intake or absorbed nitrogen was shown similar values among birds fed experimental diets Digestibility of energy (DE/GE) was not shown any significant effect of experimental diet and were in the range of 80~84%. But metabolizability (ME/GE or MEn/GE) was increased in birds fed CPD and PWV and was decreased in birds fed PFA compared with those in birds fed CON. Although birds fed PWV showed significantly(P＜0.05) higher ME/GE than bird fed PFA, the MEn/GE were higher significantly (P＜0.05) in birds fed CON and CPD compared with that in birds fed PFA. Fecal energy affects 10~23% in the change of metabolizability though significant effect of fecal energy on the metabolizability were not found. But the effect of urinary energy on the metabolizability of diet was lowered as 2.3~3, 0% and the effect of experimental diets on the metabolizability of diets was due to change of urinary energy which also was originated from the change of uric acid energy.

• Korean Journal of Poultry Science
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• v.36 no.4
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• pp.293-300
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• 2009

The rate of fetus with abnormal chromosomes increase with maternal age. Nondisjunction of aging oocyte chromosome is a major reason for the increased rate of abnormalities. Telomeres are the ends of eukaryotic chromosome, which are essential for chromosome stability and are related in cell senescence. This study was carried out to analyze the chromosome aberration rate and amount of telomeric DNA in chick embryo along with maternal age. Fertilized eggs and blood were sampled from White Leghorn layers starting at 20 weeks through to 70 weeks age at 10 weeks interval. Chromosome aberration rate was analyzed by karyotyping. The amounts of telomeric DNA in embryonic cells and lymphocytes were quantified by Quantitative Fluorescence in situ Hybridization method. The chromosome aberration rate in chick embryos significantly differed with maternal age. The chromosome aberration rate increased at early laying period and beyond 70 weeks of maternal age. Therefore, chromosome aberration rate was affected by maternal age due to ovulated oocytes state. However, the amount of telomeric DNA on embryonic cells did not differ significantly with maternal age. Thus, maternal age does not affects telomere quantity in their embryos due to cellular reprograming at early embryonic stage after fertilization.

• Korean Journal of Poultry Science
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• v.13 no.1
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• pp.23-30
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• 1986

The Calorimetric experiment was made firstly to measure the difference in energy metabolisms of laying hens among their three different laying periods, secondly to estimate the energy requirements of the layers on their respective laying periods. The laying period was divided into three chronological periods of 25-40, 41-55, and 56-69 weeks old of laying hens, which are refered to as period I, II, and III respectively. 1) The fasting heat production (FHP) of laying hen on the three laying periods were 81.5 Kcal/kg$\^$0.75/ for period I, 72.3 Kcal/kg$\^$0.75/ for perod II, and 97.5 Kcal/kg$\^$0.75/ for perod III. The marked increase in FHP was found in period m, while there was a small difference in FHP between period I and II. The present study have observed among the birds in period in the high degree of plumage defectiveness, and this condition of bird might have accounted for the increase in FHP. 2) The regression equation between ME intake and energy retention (ER) were calculated, and the equations indicated that, for the period I, II, and III, the ME requirements for maintenance (MEm) were 123, 111, and 131 Kcal/kg$\^$0.75/ respectively, and that the Net Availabilities of Metabolizable energy (NAME) were 76, 79, and 74 percent respectively. For the whole laying period measured, MEm was 119 Kcal/kg$\^$0.75/ and NAME was 79 percent. There was a tendancy of higher MEm, and lower NAME during Period III, comparing with period I and II.

• Korean Journal of Veterinary Research
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• v.37 no.3
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• pp.569-576
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• 1997

Fowl typhoid(FT) caused by Salmonella gallinarum is an infectious, egg-transmitted disease and characterized by swollen bronze liver, greenish-yellow diarrhea and high mortality in growing and adult chickens. Since 1992 the outbreak of FT has been increased. Several problems have been occurred such as absence of appropriate vaccines and lack of useful therapeutic methods. In these studies we investigated the pathogenicity of S gallinarum isolated in chickens. To compare the pathogenicity among the species of chickens, all chickens were challenged intramuscularly or orally with $1{\times}10^7$ CFU of S gallinarum. The brown-colored layers were more susceptible and white leghone chickens were more resistant than other species. In the brown layer chickens orally challenged, lethal doses ($LD_{50}$) of the isolates were inoculated at 1 day, 2 weeks, 4 weeks and 8 weeks old chickens with amount of $10^{4.2}$, $10^{4.7}$, $10^{7.0}$ and $10^{7.6}$ CFU, respectively. The chickens which were intramuscularly challenged with the less amount than $10^2$ CFU showed higher mortality than that of the chickens orally inoculated with same dose. Also, we investigated the recovery rates of bacteria from various organs of survival chickens which were challenged orally with $5{\times}l0^7$ CFU of S gallinarum. The bacteria was more frequently and isolated earlier from the liver and spleen than from any other ogans. In the pathogenicity test, the white-leghorn chickens which were known as resistant-strain against Salmonella were artificially immunosuppressed using bursectomy and/or dexamethasone treatment. Mortality of chickens with both bursectomized and treated with dexamethasone was higher(90%) than that of the control group(10%), the bursectomized chickens(10%) and the dexamethasone only treated group(20%). It was suggested that the protective mechanism in chickens against S gallinarum may be required both the functions of B-cells and T-cells.