• Korean Journal of Poultry Science
• /
• v.24 no.3
• /
• pp.127-137
• /
• 1997

This study was conducted to estimate the laying performance and heterosis of Korean Native Chicken(KNC), Rhode Island Red(RIR), and KNC x RIR crossbreds A total of 1,274 female pullets were produced from KNC, RIR and RIR crossbreds in National Livestock Research Institute, Korea. The experiment was conducted for 2O~64 weeks from Jan 20. to Nov.25, 1996. The age at first egg of crossbreds were 144.1~148.7 days. The first egg weight of crossbreds was 39. 4~40.3 g, and body weights at first egg of KNC dark brown strain x RlR(DR), KNC light brown strain x RlR(LR) and KNC dark black strain x RlR(BR) were 1,943 g, 1,925 g and 2,044 g, respectively. During the laying period the average viability of crossbreds was 96.6~98.3%. The hen-day egg production of crossbreds were 111.1~113.O eggs at 40 weeks of age, and 223.5~227.5 eggs at 64 weeks of age, respectively. The hen-day egg production peaks were 78.2~80.1% in KNC, and 85.8~87.5% in crossbreds. The heterosis were estimated to be 3.61%, 9.21%, 4.78%, 2.97% and -1.63% for the first egg days, body weights at first egg, layer viability, hen-day egg production, and feed conversion ratio, respectively.

• Korean Journal of Agricultural Science
• /
• v.39 no.1
• /
• pp.53-60
• /
• 2012

This work was conducted to evaluate the laying performance of Korean Native Ducks (KND) Pure-Line (PL). A total of 400 female pullets were hatched from PL to keep in National Institute of Animal Science, Korea. Twenty weeks old PL female ducks were divided into 4 groups (5 replications/group, 20 head/replications). Four groups were compared in a $2{\times}2$ factorial arrangement with strain (White strains, WW; Celadon strains, CC) and house type (flat house, cage house). On first egg laying day, CC strain laid eggs earlier compared to WW strain (P<0.01), but there was no significant difference between flat and cage house. Egg weight (EW) and body weight (BW) at first egg laying day have no difference among strains and houses. BW of CC strain was higher than WW strain at the age of 30 week (P<0.01). Weekly feed intake (FI) have no difference between flat and cage house, but FI of WW strain was high compared to CC strain during 20~30 weeks. There was no significant difference on EW between CC and WW strains, but EW was low at flat house compared to cage house (P<0.05). Weekly egg productions of WW strain and flat house were lower than CC strain and cage house, respectively (P<0.01). Finally, These results can provide the information that needed to introducing new strains.

• Asian-Australasian Journal of Animal Sciences
• /
• v.22 no.5
• /
• pp.694-699
• /
• 2009

The present study was conducted to evaluate the effect of chilled drinking water on the productivity of laying hens under constant high ambient temperature. A total of seventy-two, 123-day-old Hy-line brown layers was divided into two equal groups. The first group (UDWG) was given unchilled water ($23.0{\pm}2.5^{\circ}C$) as a control, and the second group (CDWG) was given chilled water ($16.0{\pm}0.5^{\circ}C$). The laying hens were kept at $30^{\circ}C$ constant temperature with 50% relative humidity and were exposed to 17 h of light per day. Feed intake, egg production, egg quality (egg weight, shell weight, shell thickness, egg color, yolk color, and Haugh unit), and blood samples were collected and analyzed. The results showed that the feed intake of CDWG laying hens was significantly higher (11.64%) than the UDWG counterparts (p<0.01). Egg production of CDWG was also significantly higher (11.27%) than the UDWG counterparts (p<0.001). Furthermore, we observed that the CDWG laying hens had significantly higher (11.72%) levels (p<0.10) of blood calcium, with a corresponding value of 21.92 mg/dl compared to the UDWG hens (19.62 mg/dl). The higher calcium concentration in the CDWG animals may contribute to increased egg production. The CDWG laying hens also contained higher (12.53%) phosphorus concentrations in blood compared to the UDWG (4.22 mg/dl vs. 3.75 mg/dl), although not statistically different (p>0.10). Egg weight and egg quality were not affected by chilled drinking water. In conclusion, providing chilled drinking for laying hens under high ambient temperature improved feed intake and egg production.

• Journal of Sericultural and Entomological Science
• /
• v.3
• /
• pp.23-28
• /
• 1963

The RNA content of fertilized egg of Bombyx mori was shown a continuing great increase reaching peak at the 5th day after egg laying and a slight decrease there after. Such a change of RNA content is considered to be directly associated with the formation and development of egg embryo of silk worm. (2) The RNA content of nonfertilized egg is much less than that of fertilized one at first day of egg laying and it increased slightly until 4 th day after egg laying then decreased. (3) The RNA content of fertilized egg irradiated by gamma-ray (3,000 r) was shown a slight increase until 2nd day after irradiation, but no change was observed there after. This fact shows that irradiation suppressed the biosynthesis of RNA silk worm egg. (4) The RNA content of HCl treated silk worm egg was shown a continuing steep rise until 7 th day after the acid treat, while no change was observed in the non-treated egg. The RNA content of HCl treated egg with irradiation of gamma-ray (1,500 r), decreased until 3 rd day after irradiation in contrast to that of non-irradiated group, but it increased rapidly from 4 th day until 7 th day after acid treating.

• Korean Journal of Poultry Science
• /
• v.50 no.1
• /
• pp.15-22
• /
• 2023

This study was to investigate the relationship between chick weight in the growing period and the laying performance of Korean native chicken (KNC) breeders. We measured the body weights of 1,384 KNC breeders at 1-140 days of age at two-week intervals. The age at first egg laying, hen-day and hen-housed egg production, and the egg weights were investigated. Correlation coefficients between the body weight and egg production traits were analyzed. The results showed that the correlation coefficients between body weight and age at first egg laying were significantly positive before 4 weeks, but negative after 8 weeks of age. The correlation coefficients between body weight and egg production rate were estimated to be negative before 8 weeks and positive after 12 weeks of age. Coefficients of hen-day and hen-housed egg production were similar. There was little correlation between body weight and egg weight at 32 weeks of age, whereas a low positive correlation was with egg weight at 50 weeks. In conclusion, there was little correlation between body weight and laying performance before 8 weeks of age, whereas a significant positive correlation was with body weight after 12 weeks. The results suggest that as the chick's weight increases in the late growing stage, sexual maturity is faster, the egg production rate is higher, and the egg weight increases. Therefore, the weight management of KNC female breeders is very important in the late growing stage, and the body weight of chicks must be maintained above the standard weight.

• Journal of Animal Science and Technology
• /
• v.64 no.4
• /
• pp.717-726
• /
• 2022

The study evaluated different molt-inducing methods to achieve the main goal of molting in commercial layers during molting and post-molting periods. A total of 400 60-week-old Lohmann Brown layers were randomly divided into five groups (eight replicates of 10 birds for each group). Laying hens in the fasting control group received no diet from day 1 to day 10. The second group received a molt-inducing diet recommended by the breeding company. The third group received a wheat bran-based diet. The fourth group received a commercial layer diet with 8,000 ppm zinc (as zinc oxide, ZnO). The fifth group received an induced molting diet given to the second group with 8,000 ppm zinc, respectively. Egg production in the fasting control group and groups fed a diet with ZnO were significantly lower (p < 0.001) than those in groups fed the molt-inducing and wheat bran-based diets without ZnO during molting. Egg laying in the fasting control group was rapidly reduced and stopped on the 5.9th day of molting. In both groups having molt treatment with ZnO, egg production was similarly reduced and ceased on the 6.9th day and 7.0th day of molting, respectively, none of them differed significantly from the control. Layers fed molt-inducing diet or wheat bran-based diet did not reach the cessation of laying even on the 28th d of molting period. Relative weights of the ovary and growing oocytes of layers subjected to fasting or fed diets with ZnO were significantly lower than those of other groups. During the first two weeks of post molting, layers fed molt-inducing diet with ZnO showed higher egg production than the other two groups (p < 0.01). The eggshell strength in the group fed the commercial diet with ZnO was significantly higher than those fed the molt-inducing diet or wheat bran-based diets at 6 weeks of post molting (p < 0.05). These results suggest that the non-feed withdrawal molting using ZnO is more effective in inducing molting and increasing post-molt egg production and egg quality than other methods using a molt-inducing diet alone or wheat bran-based diet without ZnO.

• Korean Journal of Poultry Science
• /
• v.40 no.1
• /
• pp.17-23
• /
• 2013

This work was carried out to investigate the performance of early laying period of large-type Korean native ducks. One hundred sixty eight ducks were used in this work and divided into A and B strains (6 replications/strain, 14 birds/replication). The days at first egg of A and B strains were the age of 154.5 and 154.7 days, egg weights were 69.1 g and 65.5 g, and body weights were 3,187 g and 3,105 g at the period of laying the first egg, respectively. The days at sexual maturity of A and B strains were the age of 175.8 and 171.5 days, egg weights were 75.2 g and 74.9 g, and body weights were 3,245 g and 3,225 g at the period of laying the first egg, respectively. There were no significant differences on the day of first egg, the day of sexual maturity, egg weight and body weight at first egg and the sexual maturity, average body weight, and daily feed intake between A and B strains (P>0.05). The day of the sexual maturity of B strain was earlier than that of A strain (P<0.05). However, weekly body weight was the highest at the age of 28 weeks (P<0.05), and weekly feed intake increased after 26 weeks old (P<0.05). Egg production (%) of B strain was higher than that of A strain at the age of 22~24 weeks (P<0.05), but there was no significant difference on egg production (%) the other weeks. A number of egg laid of B strain was higher than A strain at 22~24 weeks old (P<0.05). Feed conversion ratio of A and B strains were 10.7 and 6.53 at 24~24 weeks old, respectively, so feed conversion ratio of A strain was higher than that of B strain (P<0.05). Weekly feed conversion ratio wes the highest at 20~22 weeks old, and significantly decreased until 24~24 weeks old, but were lowly maintained from the age of 24 weeks to the age of 30 weeks. These results provided the basic data on the record of early laying period of large-type Korean native ducks.

• Korean Journal of Poultry Science
• /
• v.40 no.1
• /
• pp.67-73
• /
• 2013

With an increasing concern on laying hen welfare, barn system has appeared as one of the alternatives to replace the conventional cage. This study was conducted to compare the early laying performance and egg quality at the barn system with those at the conventional cage. A total of 288 shaver-579 brown layers were used for 9 weeks ($21^{st}$ to $30^{th}$ weeks of age) feeding study. Feed consumption and egg weight were significantly (P<0.01) higher at barn than at cage. However, there were no significant differences between two housing systems on hen day egg production (HDEP), egg mass, body weight, feed efficiency and livability. In case of egg quality parameters, shell thickness, albumen height and Haugh unit were significantly (P<0.05) different between two systems. Haugh unit and albumen height were significantly higher in eggs produced at cage (88.97 and 8.16 mm) compared than those produced at barn (83.11 and 6.87 mm), whereas shell thickness was thicker in eggs produced at barn than those produced at cage. Shape index, breaking strength, blood spots and yolk index data were not influenced significantly by the types of housing system. To implement welfare bestowing production, this study showed that the barn system can replace the conventional cage without serious sacrifices on starting phase egg production. In addition, this study suggested that the barn system need to be optimized in view of daily feed consumption.

• Korean Journal of Poultry Science
• /
• v.50 no.4
• /
• pp.203-212
• /
• 2023

This study conducted a diallel-crossbreeding test using four Korean native chicken parent stock lines (YC, YD, CK, and CF) to develop a native commercial layer with high egg-laying performance. A total of 312 chickens in six combinations were examined for various traits, including livability, body weight, age at first egg-laying, hen-day, and hen-housed egg production, egg weight, and egg quality, from hatching to 60 weeks of age. The results showed that the average survival rate was 77.1±18.8% with the YDYC combination having the highest survival rate along with excellent specific combining ability. The YDYC combination exhibited significantly higher body weight compared to the other combinations (P<0.01). The average age at first egg-laying was 121.3±2.5 days, with no significant difference between the combinations. The average hen-day egg production was 74.0±6.4%, and the hen-housed egg production was 181.4±33.8 eggs with the YDCF and YCCK combinations demonstrating the highest laying performance, while the YDYC and CKCF combinations had the lowest (P<0.05). Laying performance was more influenced by specific combining ability than general combining ability. The eggs from the YDYC combination were significantly lighter and had the darkest shell color (P<0.01), whereas the YDCF combination exhibited the thickest eggshells. There was no difference in internal egg quality among combinations, except the YDCF combination had the darkest yolk color. Overall, we concluded that the YCCK combination, characterized by high laying performance and livability, and the YDCF combination with high laying performance and good egg quality are the most desirable combinations for Korean native commercial layers.

• 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.