• Journal of Life Science
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• v.16 no.6
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• pp.942-948
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• 2006

This study was performed to determine whether the length of the feeding of the controlled experimental diet to the dam resulted in changes to the dam milk or pup brain fatty acid composition. As a first method, females have been obtained at 3 weeks of age and fed the experimental diet throughout their growth to adulthood including mating, pregnancy, and lactational periods. As a second method, in order to shorten this long and expensive process, time-pregnant dams were obtained as early as possible from a commercial supplier, on day 3 of gestation, and immediately switched to the experimental diet. At birth, the milk of dams prepared by these two different methods was compared by collecting the stomach contents of the pups. This showed a slight increase in docosahexaenoic acid (DHA) and arachidonic acid (AA) in the pup stomach contents from the time-pregnant dams. There were no significant changes in the brain fatty acid composition of pups between the two different lengths of the experimental diet intake. By the 10 days of age, there were only minor differences in the milk fatty acid composition of pup stomach contents from the two sets of dams. However, the pup brains of the time-pregnant groups at 10 days showed increased AA and DHA due to intake of the chow diet including AA, DHA and eicosapentaenoic acid (EPA). Thus, the history of the maternal feeding could affect the results under these particular circumstances, but the differences were minimal.

• Korean Journal of Poultry Science
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• v.20 no.1
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• pp.1-9
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• 1993

This study carried out to build up new synthetic egg production lines which had sex-linked gene for feather color sexing and also superior combining ability for producing the best commercial chicks. The closed flock breeding method was utilized to improve the general performances in the first experiment and combining ability for heterosis was tested for new synthetic line in the second experimental year. In order to test for the egg production ability in cross breeds synthetic lines, the crossing of B$\times$4 B$\times$C, two imported strains and two domestic strains as controls were compared for the general performances. There was on difference in mortality, body weight to 56 weeks of age. Sexual maturity was delayed about 10 days by comparing with other reports, except 153 days of the Manina White, but no difference among mating systems in this experiment. The hen housed egg production in B$\times$A, B$\times$C was 186.3, 191.3 respectively and it was better than the other controls, except ISA imported lines. The hen-day egg production of B$\times$A, B$\times$C was better than other controls, with 75.7%, 76.8% respectively. In the average egg weight, the B$\times$C cross breed was highest with 64.5g. As the sex of hatching chicks was identified by difference of feather color, the genetic composition of synthetic lines must be homogenized. The feather color of female chicks was brown and that of male was silver (99%), In conclusion, the egg production ability of B$\times$A, B$\times$C cross breeds was superior to the imported and domestic lines. Therefore, it suggest that the synthetic lines with sex-linked gene might be utilized for improving egg production performances.

• Korean Journal of Poultry Science
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• v.15 no.1
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• pp.21-29
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• 1988

This study was conducted to obtain more detailed information on the characteristics of body fat distribution, genetic variation and correlation of fat amount at different location in broiler type chicken. A total of 429 offsprings, produced by mating 13 sires with 52 dams of WPR, were used for this study. All experimental analyses were made on dressed carcasses of 8 weeks of age. The average live body weight was 1,856g in male and 1,483g in female, the proportions of each part to live body weight were higher in male group except skin and abdominal fat pad. The total body fat was more in male (40.76g), but fat rate of total body, skin, and abdomen to live body weight were significantly higher in female group. The fat percentages in each body location were significantly higher in the fatty group and in each sex. The rates of abdominal fat to total body fat were increased by fattening, while subcutaneous fat percentages were lowered. There were high correlations between body weight and fat deposit in each location. The genetic correlation coefficients of body weight to fat percentages of skinned carcass, skin, abdomen, and total body fat to live body weight were negative in both sexes, but those to total body fat, eviscerated carcass fat, and skin fat were positive. In conclusion, the fat weight and fat percentage in individual chickens became higher by fattening however, genetic correlation between live body weight and percentages total body fat to live body weight were so low(negative) that decreasing body fat could be possible without decreasing body weight.

• Korean Journal of Poultry Science
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• v.50 no.3
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• pp.133-141
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• 2023

We conducted a 5 × 5 diallel cross-combination test using 1,060 chickens from pure lines of Korean Rhode-C, -D, Korean Leghorn-F, -K, and Korean Native Yellowish-brown chicken (KNC-Y) to develop a new Korean native chicken layer breeder. The laying performance and combining ability, including livability, body weight, age of first egg-laying, hen-day egg production, and egg weight, were analyzed. The livability from birth to 48 weeks was 72.1±24.0%, with the highest observed in the YC and the lowest in the DK combination (P<0.01). The YC combination exhibited the highest general combining ability (GCA), while the YD combination showed the highest specific combining ability (SCA). Regarding body weight, combinations involving Leghorn showed lighter weights compared to combinations with Rhode and KNC-Y (P<0.01). Additionally, the offspring from the KNC-Y combination reached sexual maturity earlier than those from the Rhode combination. The hen-day egg production was 70.7±12.0%, with the highest seen in the CK combination at 86% (P<0.01). The effects of GCA and SCA on hen-day egg production were similar, with the SCA being highest in the YD combination and the GCA being highest in the Rhode-C. Significant differences in egg weight were observed among the combinations, with the eggs from Rhode and Leghorn combinations being heavier than those from combinations with KNC-Y (P<0.01). In conclusion, the YC and YD combinations, characterized by excellent livability, are highly desirable paternal strains, while the CF and CK combinations, with excellent laying performance and moderate egg weight, are preferred maternal strains for Korean native chicken layer breeders.