• Korean Journal of Poultry Science
• /
• v.9 no.2
• /
• pp.63-101
• /
• 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 Animal Reproduction
• /
• v.27 no.3
• /
• pp.197-206
• /
• 2003

hFSH (human follicle stimulating hormone) is heterodimer consisting of $\alpha$ and $\beta$ subunits. Since assembly of the both subunits in the cell is often the rate-limiting step in production of functional hormone, single-chain hormones have been engineered by genetically linking two different cDNA fragments with a linker sequence. Using retrovirus vector system, the resulting recombinant hFSH gene was transferred in CHO cells and chicken embryos, and the expression of the gene was investigated. In CHO cells, protein synthesis from the single-chain FSH gene was 17 fold higher than that from the heterodimeric counterpart. In the study of transgenic chickens, ten of the eleven chicks hatched from 62 embryos manupulated with recombinant retrovirus stock was determined to carry transgenic genes. RT-PCR analyses confirmed transcription of the single-chain FSH gene, however, no recombinant FSH was detected from the blood samples.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.12
• /
• pp.1686-1695
• /
• 2015

Molecular marker selection has been an acceptable tool in the acceleration of the genetic response of desired traits to improve production performance in chickens. The crossbreds from commercial parent stock (PS) broilers with four Thai synthetic breeds; Kaen Thong (KT), Khai Mook Esarn (KM), Soi Nin (SN), and Soi Pet (SP) were used to study the association among chicken growth hormones (cGH) and the insulin-like growth factor (IGF-I) genes for growth and carcass traits; for the purpose of developing a suitable terminal breeding program for Thai broilers. A total of 408 chickens of four Thai broiler lines were genotyped, using polymerase chain reaction-restriction fragment length polymorphism methods. The cGH gene was significantly associated with body weight at hatching; at 4, 6, 8, 10 weeks of age and with average daily gain (ADG); during 2 to 4, 4 to 6, 0 to 6, 0 to 8, and 0 to 10 weeks of age in $PS{\times}KM$ chickens. For $PS{\times}KT$ populations, cGH gene showed significant association with body weight at hatching, and ADG; during 8 to 10 weeks of age. The single nucleotide polymorphism variant confirmed that allele G has positive effects for body weight and ADG. Within carcass traits, cGH revealed a tentative association within the dressing percentage. For the IGF-I gene polymorphism, there were significant associations with body weight at hatching; at 2, 4, and 6 weeks of age and ADG; during 0 to 2, 4 to 6, and 0 to 6 weeks of age; in all of four Thai broiler populations. There were tentative associations of the IGF-I gene within the percentages of breast muscles and wings. Thus, cGH gene may be used as a candidate gene, to improve growth traits of Thai broilers.

• Journal of Food Hygiene and Safety
• /
• v.29 no.1
• /
• pp.47-52
• /
• 2014

This study was performed to evaluate antimicrobial resistance of food-borne pathogens isolated from retail meat in Korea. A total of 157 samples of beef, pork, and chicken were collected and analyzed for E. coli, Salmonella, Campylobacter. Resistances to tetracycline were declined in accord with reduced usage of tetracycline in live stock production. E. coli stains from chicken meat had higher multi-drug resistance ratio than strains from other meat. One extended spectrum beta lactamase (ESBL) producing E. coli and two ESBL producing Salmonella were identified in this study. ESBL producing Salmonella strains were confirmed to carry CTX-M-1 type genes.

• Korean Journal of Poultry Science
• /
• v.48 no.2
• /
• pp.91-100
• /
• 2021

The study determined the effects of stock density (SD) and energy level (EL) on growth performance, serum biochemistry, and meat quality in Korean native chickens. A total of 240 chickens were randomly assigned to one of the four treatments including two stock density (low, 14, and high, 16 chickens per m²) and two energy level (low, 2,950, 3,000, 3050 ME kcal/kg, and high 3,150, 3,200, 3,250 ME kcal/kg, for starter, grower, and finisher, respectively). During the whole period of the experiment, the chickens were fed ad libitum. The greater final body weight and weight gain were achieved in chickens fed high energy diet, whereas the final body weight and weight gain were significantly reduced in high-density treatment compared with the low density. Chickens in low-density groups had a higher feed intake compared with high-density treatment, however, the energy level did not affect the feed intake. An improved overall feed conversion ratio was detected in the high energy treatment. There was a significant interaction between stock density and energy level on cholesterol concentration. The concentration of aspartate transaminase in serum was increased by higher stock density. There was a significant treatment interaction on IgM levels. Moreover, the carcass rate was significantly increased in the high energy level treatment. Based on the findings, we suggest that rearing chickens in low density with high dietary energy levels could be beneficial by improving the growth performance.

• Journal of Food Hygiene and Safety
• /
• v.25 no.3
• /
• pp.226-231
• /
• 2010

We aimed at the monitoring medroxyprogesterone acetate (MPA) residue amount in meats and confirmed the safety of its residue in meats. Optimized condition for analytical and instrumental methods was obtained by method validation. The limit of detection (LOD) and limit of quantification (LOQ) were validated at 1.5 and 5.0 ug/kg, respectively. The calibration curve showed good linearity ($r^2$ = 0.9968) within the concentration range of 5.0~50.0 ug/kg. We selected progesterone-d9 for internal standard, The recoveries in fortified meat ranged from 67.5 to 109.56% at the 3 spiking levels. As the regulation of MPA analysis method used by LC-MS/MS on other products have established. We selected 3 species of farm stock products (cattle, pig, chicken) and purchased at the markets of seven major cities. The total 196 of meat including 46 of domestic beef, 43 of import beef, 60 of domestic pork, 12 of import pork and 35 of domestic chicken. No residue of synthetic growth hormones were detected in cattle, pig and chicken samples tested.

• Korean Journal of Poultry Science
• /
• v.48 no.2
• /
• pp.69-80
• /
• 2021

We conducted a 4 × 4 diallel cross-mating test using 934 chickens from four grandparent stock lines to develop a new synthetic breed of Korean native chicken. The mean values, combining ability, and reciprocal effects on survival rate, body weight, and hen-day egg production were analyzed. In phenotypes, most chickens have yellowish-brown, reddish-brown and mixed color feathers. The average survival rate was 86.8±12.3%, with the highest in YH combination. Specific combining ability (SCA) had a greater effect on survival rate than general combining ability (GCA), and the SCA of HY combination was the highest. The 16 cross-combinations were distinctly divided into three weight groups according to their genetic characteristics. At 12 weeks of age, GCA showed a greater effect on weight than SCA, and the SCA of FH combination was the highest. The age at first egg laying was 157 days, and the crosses reached sexual maturity faster than the pure lines. The egg production rate was highest in SY at 79.5±2.1%. The GCA and SCA for hen-day egg production were similar, and the SCA was highest in the HS and FY combinations. The reciprocal effect showed that the offspring's egg production rate was high when S and Y were maternal parents in almost all combinations. In conclusion, FH and HF combinations, which have excellent growth performance, are the most desirable paternal parent stock strains, and FY, FS, HY, and SY combinations, which have excellent laying performance with moderate weight, are the preferred maternal strains.

• Korean Journal of Poultry Science
• /
• v.42 no.2
• /
• pp.157-167
• /
• 2015

We compared the degrees of stress response of 12 domestic purebred chicken strains that have been bred at National Institute of Animal Science, RDA, Korea since 1980. As a physiological marker of stress response, the expression levels of heat shock protein (HSP)-70, HSP-$90{\alpha}$, HSP-$90{\beta}$, hydroxyl-3-methyl-glutaryl coenzyme A reductase (HMGCR) genes and telomere length were measured by quantitative real-time polymerase chain reaction using the lymphocytes of 1,101 chickens. There was significant difference in HSP-70, HSP-$90{\alpha}$, HMGCR expression and telomere length among the strains. There was also significant difference in HSP-$90{\alpha}$, HSP-$90{\beta}$, and HMGCR expression between male and female chickens. Different age groups of chicken exhibited different expression levels of HSP-70, HSP-$90{\alpha}$ and telomere length. The results of the HSPs expression level suggested that, the strains of R, L and Y were highly resistant to stress, whereas the strains of S, O and W were susceptible to stress. Although the statistical differences in some of HSPs gene expression existed between genders, the HSP expression results varied in different strains that some opposed to the others, and there might be interaction between strains and genders, which conclude that there was no difference in stress response between male and female chickens. Moreover, despite of significant difference in some of HSPs expression level, it was considered that there was no difference in stress response between ages due to the inconsistent trends among HSP markers.

• Korean Journal of Poultry Science
• /
• v.44 no.2
• /
• pp.123-134
• /
• 2017

This study was conducted to establish new synthetic lines of Korean Native Chicken. We performed $5{\times}5$ diallel crossings with GPS lines of Korean Native Chicken for the selection of parent stock. The production traits including viability, body weight, age at first egg laying, egg weight, hen-day egg production, and hen-housed egg production were measured and analyzed for 25 crosses with 1,157 hens. The heterosis effects of these traits were also estimated. The results showed that the average survival rate during laying periods was 67.7% in the pure lines and 77.1% in the crosses. The 25 cross combinations were shown to be distinctly divided into three groups according to body weight; nine crosses in the high-weight group, 12 crosses in the medium-weight group and four crosses in the light-weight group. The average body weight at 12 weeks of age was $1,873.8{\pm}43.0g$ in the high group, $1,595.4{\pm}56.6g$ in the medium group and $1,152.7{\pm}24.7g$ in the light group, and $1,560.2{\pm}339.3g$ in the pure lines and $1,640.9{\pm}213.7g$ in the crosses. In terms of egg production performance, the age at first egg laying was $139.7{\pm}4.9$ days in the pure lines and $135.8{\pm}5.1$ days in the crosses. The average egg weight was $52.3{\pm}1.6g$ in the pure line and $53.0{\pm}1.6g$ in the crosses. The average hen-housed egg production from 20 to 40 weeks was $58.3{\pm}12.9$ eggs in the pure line and $69.2{\pm}10.4$ eggs in the crosses. The average heterosis effect was 16.9% for survival rate, 5.4% for body weight at 12 weeks, -2.7% for age at first egg laying, 1.3% for egg weight, and 14.3% for hen-day egg production. Generally, the heterosis effect for viability and egg production traits was higher than that for growth trait. On the basis of these results, it is expected that the selection of the HF combination, which had excellent growth performance, is the most desirable as the paternal strain, and the selection of GW and FW combinations, which had excellent laying performance, are preferable as the maternal strain.

• Korean Journal of Poultry Science
• /
• v.43 no.4
• /
• pp.219-228
• /
• 2016

A total of 720 slow-growing Korean meat-type (Hanhyop 3) chicken were used to evaluate the effect of stocking densities and dietary protein levels on growth performance, meat quality, bone mineral composition, and serum corticosterone. Three (6.3, 9.5, and $12.6birds/m^2$) stocking densities and two dietary protein levels (19% and 18%) were factorially ($3{\times}2$) arranged for six treatments. Overall body weight gain (BWG) was highest (p<0.001) at the lowest stocking density ($6.3birds/m^2$). The feed intake (FI) of birds at the highest density ($12.6birds/m^2$) was lower than that of birds at the other densities, but resulted in better feed/gain (F/G). Among 18% protein groups, the overall FI of birds at $9.5birds/m^2$ was higher than that at the lowest density; therefore, birds at $9.5birds/m^2$ had poorer F/G than birds at the lowest density during days 61~75. Difference in F/G among densities was only significant (p<0.05) during days 61~75 but not significant (p>0.05) during days 41~60. Although there were no significant differences (p>0.05) in BWG and F/G between 19% and 18% dietary protein levels, FI of the 18% protein diet was less (p<0.05) than that of the 19% diet. Although there was no difference (p>0.05) in meat TBARS values, meat color differed (p<0.05) with stocking density and dietary protein levels. There was no effect (p>0.05) of stocking density and dietary protein levels on bone mineral composition. Serum corticosterone concentration increased (p<0.05) with increasing stock density but was not affected (p>0.05) by dietary protein levels. This study indicated that a density of $12.6birds/m^2$ is not recommended for slow-growing chickens. Between 19% and 18% dietary protein levels, 18% would be recommended for the Korean Hanhyop 3 chicken in the finishing stage.