• 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.15 no.3
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• pp.219-227
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• 1988

This experiment was carried out to evaluate biological availability of Ca and P in 4 different sources of tricalcium phosphate in young chicks. One hundred and twenty five-day-old male Single Comb White Leghorn chicks (10 treatments$\times$3replication$\times$4chicks) were used in trial 1 and 2, respectively, for 12 days of feeding period. Trial I was to evaluate the availability of phosphorus in the supplements, Standard purified diets were prepared to supply 0.07, 0.14 and 0.21％P using a mixture (1 : 1) of NaH$_2$PO$_4$ and KH$_2$PO$_4$ as the reference Phosphorus sources. Bone breaking strength of the tibia determeined by an Instron instrument appeared inadequate to be used as a criterion due to very high variations of the measurement within a treatment. Thus, tibia bone ash content was utilized as a criterion to evaluate th biological avilability of phosphorus in the supplements. The levels of the biological availability of the four different sources of dicalcium phoshate were 77.1, 91.0, 96.4 and 95.5％, respectively, and those of the three tricalcium phosphate sources were 94.1, 95.0 and 99.5％ , respectively. Trial 2 was to determeine the levels of Ca biologically available in the supplements. Standard purified diets were made to supply 0.2, 0.3 and 0.4％ Ca using CaCo$_3$ as the reference calcium source. When bone ash content was utilized as a criterion for the availability, the levels of calcium biologically available to the chicks were 78.3, 234.1, 87.6 and 244.5％, respectively, for the 4 different sources of dicalcium phosphate and 99.5, 84.0 and 101.5％ , respectively, for the 3 different sources of tricalcium phosphate. The observation that two calcium sources appeared to be utilized with an unusual efficiency can hardly be explained at this moment. When they were revaluated on the basis of body weight gain, the availabilities of the four sources of dicalcium phosphate were 89.2, 58.2, 104.1 and 103.1％ and of the three tricalcium phosphate were 112.6, 106.0 and 96.3％ , respectively.

• 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 Poultry Science
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• v.17 no.4
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• pp.255-268
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• 1990

This study was carried out to investigate the time-trends of genetic parameters of the dosed flock population which selected for improving egg production. Data for two layer pure lines, Line-W (Single Comb White Leghorn) and Line-B (brown layer) which have been maintained at the Mani Breeding Farm were collected from 1980 to 1985 during 5 generations. The effective number of parents per generation ranged from 148 to 366 in Line-W and 85 to 355 in Line-B, and the cumulative expected inbreeding coefficients during 5 generations of selection were 15％ and 1.6％. So inbreeding could not be considered a critical factor on estimating the genetic parameters, heritabilities and genetic correlations Heritabilities of EN 300 and EN 400, primary two selected traits were significantly decreased during 5 generations but the estimates of the other 03its not showed the consistent decreasing pattern significantly. No time trends of probable consequence were evident in the genetic correlation coefficients of the traits studied. The reason for that situation was attributed to the fact that selection was conducted for multiple objectives and the relative importance of selection for the studied traits were not consistent by generations.

• Korean Journal of Poultry Science
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• v.17 no.4
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• pp.243-254
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• 1990

This study was carried out to investigate the effectiveness of the selection for commercial populations of layer chickens subjected to multiple objectives. For that purpose, predicted selection responses obtained from estimated genetic parameters and observed values were compared. Data for two layer pure lines, Line-w(Single Comb White Leghorn) and Line-B (brown layer) which have been maintained at the Mani Breeding Farm were collected from 1980 to 1985 during 5 generations. The annual genetic gains were estimated by the moth of selection index in retrospect on the basis of selection differentials, phenotypic and genetic variance-covariance for the traits considered. SM was found to be shorten by 1.67 days and 1.14 days per generation in Line-W and Line-B. EN300 and EN400 were found to be increased by 4.15 and 5.92 per generation in Line-W and 257 and 3.73 per generation in Line-B. The annual gains realized were found to be significantly different from expected gains predicted on the basis of the annual selection differentials and genetic parameters in later generations, but it could not be concluded that the differences were attributed to genetic effects.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.601-605
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• 2005

Three lines of White Leghorn (WL) chickens (IWJ, IWG and IWC) maintained at Central Avian Research Institute, Izatnagar (UP), were used for chorioallantoic membrane (CAM) and liver tumour (LT) assay. Eleven-day-old embryos of each line were partitioned into three groups and inoculated with 0.2 ml of subgroup A, subgroup C and an equal mixture of subgroup A and C Rous sarcoma virus (RSV). Subgroup virus receptor on the cell surface membrane for subgroup A is coded for by tumour virus a (tva) locus and for subgroup C by tumour virus c (tvc) locus. The random association of the genes at the tva and tvc loci in IWJ and IWC line was assessed and the $x^2$-values for phenotypic classes were found to be significant, indicating the linkage between the tva and tvc loci. The linkage value was estimated to be 0.09 on pooled sex and pooled line basis. On the basis of four subclass tumour phenotypes a 4-allele model was proposed for tva locus having $a^{s1}$, $a^{s2}$, $a^{r1}$ and $a^{r2}$ alleles and the frequencies were calculated as 0.47, 0.13, 0.13 and 0.27 for IWJ line, 0.31, 0.33, 0.14 and 0.22 for IWG line and 0.44, 0.11, 0.21 and 0.24 for IWC line, respectively. Similarly, for tvc locus the frequencies of four alleles i.e. $c^{s1}$, $c^{s2}$, $c^{r1}$ and $c^{r2}$ were calculated as 0.42, 0.20, 0.21 and 0.17 for IWJ line, 0.42, 0.17, 0.27 and 0.14 for IWG line and 0.30, 0.21, 0.16 and 0.33 for IWC line, respectively. The $x^2$-values for all classes of observations were not significant (p>0.05), indicating a good fit to the 4-allele model for the occurrence of 4-subclass tumour phenotypes for tva and tvc loci. On the basis of the 2-allele model both tva and tvc locus carries three genotypes each. But, on the basis of the 4-allele model tva and tvc locus carries 10 genotypes each. The interaction between A-resistance and C-resistance (both CAM and LT death) was ascertained by taking the 10 genotypes of tva locus and 3 genotypes of tvc locus by pooling the lines and partitioning the observations into 3 classes. The $x^2$-values for the genotypic classes of CAM (-) LT (+) and CAM (-) LT (-) phenotypes to mixed virus (A+C) infection were found to be highly significant (p<0.01), indicating increased resistance, which indicates the joint segregation of $a^r$ and $c^r$ genes, suggesting the existence of close linkage between the tva and tvc loci. Therefore, an indirect selection approach using subgroup C viruses can be employed to generate stocks resistant to subgroup A LLV, obviating contamination with the most common agent causing LL in field condition.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.3
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• pp.414-420
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• 2011

A study was conducted to investigate the effects of the combined stressor induced by high stocking density with feed restriction on immunological parameters such as leukocyte differential counts and cytokine expression in laying hens. A total of forty White Leghorn laying hens were randomly allotted into the control (12 kg of body weight/$m^2$) and the stress (44 kg of body weight/$m^2$) groups, and then birds of the stress group were given 75% of voluntary intake of the control birds for 12-d on a daily basis. There was a significant decrease in body weight without affecting the relative weights of the liver and spleen after 12-d of the combined stressor. In hematological values, no significant difference in leukocyte differential counts including heterophils (H), lymphocytes (L), monocytes and H:L ratio was observed between the two groups. In cytokines, hepatic lipopolysaccharide-induced tumor necrosis factor-${\alpha}$ (LITNF-${\alpha}$) and inducible nitric oxide synthase (iNOS) expression levels in the stress group were significantly (p<0.05) higher compared with those in the control group. However, the expression levels of interleukin (IL)-4 and IL-6 in the liver were not affected by the combined stressor. Splenic LITNF-${\alpha}$ expression in the combined stressor group was significantly (p<0.05) up-regulated compared with that in the control birds. However, the combined stressor did not affect splenic IL-4, IL-6 and iNOS expression. In conclusion, the combined stressor caused by high stocking density with feed restriction enhanced some pro-inflammatory cytokines including LITNF-${\alpha}$ and iNOS in lymphoid and non-lymphoid organs of birds, suggesting that altered cytokine expression to given stressors can be another parameter that can be used in assessing stress responses of birds.

• Journal of Nutrition and Health
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• v.25 no.7
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• pp.543-554
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• 1992

True metabolizable energy(TME) is believed a better indicator for animal performance than apparent metabolizable energy (AME) for excluding the endogenous energy losses from excreta, However few researches have been conducted to compare superiority of any energy systems through practical animal feeding tests. Present study was to compare the energy systems in young chicks in terms of predictability of energy intake for the birds performances including body energy retention and of methodological accuracy by evaluating reproducibility and additi-vity of energy values of feed ingredients and compound diets. Five ingredients such as yellow corn wheat soybean meal fish meal and wheat bran were measured for their various biological energy values. in the first feeding trial chicks were restric-ted-fed the basal diet at 80, 60 and 40% on weight basis of the amount of feed ingested by chicks fed ad libitum the same diet. chicks in the second trial were also restricted-fed diets at levels of 80, 70, 60 and 50% on energy basis of the amount consumed by the basak duet group fed ad libitum The diets in the latter trial were however composed of differeent formulations from the basal diet. One-week-old Single Comb White Leghorn male chicks were individually alloted in a cage on 10 cages/treatment basis and fed the diets for 14 days. Individual carcass energy was measured after the feeding trials. Coefficients of variation of energy measurements were lesser for nitrogen-corrected AME and TME(AMEn & TMEn respectively) than AME and TME values suggesting taht reprodu-cibility of energy determinations by former systems could be better than the latters. The coeffi-cients for AME and TME were almkost of the same values. Additivity obtained by the rations between the calculated values and catual measurements appeared quite satisfactory for all the energy systems. Those of AME and TME however were relatively better than the other systems. Regression coefficient ${r}^2$ between energy intake by various systems and chick performances appeared higher for TME, AMEn and TMEn than AME implying that the former systems could provide better predictability for body weight gain and energy retention than the AME. The ${r}^2$ values for TME and AMEn particularly for body weight gain were on the average 0.967 and 0.960 respectively. In conclusion TME or AMEn can be recommended as choice for dietary energy system in terms of performance predictability of the birds and of procedural convenience for the measurements.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.444-449
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• 2006

This study investigated the effects of dietary supplementation of cheese byproduct on performance, egg quality and fatty acid profile of egg yolk lipids from laying hens. One hundred five 30-wk-old White leghorn laying hens were randomly distributed into five groups of twenty one hens each and maintained in individual laying cages for 4 weeks. The hens were assigned to five treatments that consisted of corn-soybean meal based diets containing 0, 1, 3, 5 or 10% of cheese byproduct. Feed intake and rate of egg production of hens were not significantly different across the treatments during the whole experiment (p>0.05). Similarly, egg yolk cholesterol level, egg weight, Haugh's unit, eggshell thickness, color, and strength were not significantly different across the treatments (p>0.05). The amount of C16:0 in egg yolk was not significantly different across the treatments, but that of C18:0 decreased with increased cheese byproduct (p<0.01). Monounsaturated fatty acid (C16:1 and C18:1) content in egg yolk was similar across the treatments. Total CLA and cis-9, trans-11 CLA content increased linearly with increased cheese byproduct (p<0.001), while trans-10, cis-12 CLA amount was not significantly different across the treatments (p>0.05). Total saturated fatty acid (SFA) in the egg yolk was decreased as the level of cheese byproduct including CLA increased (p<0.01). However, the amount of unsaturated fatty acids (UFA) such as monounsaturated fatty acids (MUFA), n-3 polyunsaturated fatty acids (PUFA), n-6 PUFA, and total PUFAs in the egg yolk were not significantly different across the treatments (p>0.05). Therefore, the present results showed that cheese byproduct beneficially improved the fatty acid composition of concern to human health in the egg yolk without adverse effects on egg quality.

• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.173-178
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• 1986

Data on egg production, egg weight and egg mass were obtained from a sample of the Synthetic White Leghorn population which was raised at Poultry Breeding Farm, Seoul National University. Egg mass was not measured directly, but was calculated from the egg numbers and the average egg weight for same period. Phenotypic means, components of variance and covariance, heritabilities and genetic correlations were computed. Egg mass was estimated to be a lowly heritable trait (0.204-0.270). High heritability estimates were found for age at sexual maturity and egg weight. Genetic correlation estimates were high and positive between egg mass and egg number(combined estimates 0.711). Egg mass and egg weight were moderately correlated genetically (0.431). Genetic correlation estimates was -0.280 between egg number and age at sexual maturity, but was 0.524 between egg weight and age at sexual maturity. Results show that selection for total egg mass based on record from a single period will not be satisfactory unless the single period chosen is one in the latter part of the laying year.