• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.337-341
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• 2001

Studies were conducted to determine the effects of water temperature on the number of spawning, egg production, spawning intervals and hatching success of Chinese bleak, Aphyocypris chinensis. Adult fish were exposed to water temperatures of 19, 22, 25 and $28{\circ}^C$ for two months in the laboratory. The spawning number, egg productivity, and hatching rate increased as water temperature increased between $19{\circ}^C$ and $25{\circ}^C$. Maximum egg production and hatching rate occurred at $25{\circ}^C$, whereas the spawning intervals decreased as water temperature increased except for the treatment of $28{\circ}^C$. The shortest spawning interval observed at $25{\circ}^C$.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.828-833
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• 2017

Objective: The study was conducted to evaluate the effects of different methionine (Met) sources on production performance, reproduction performance, egg quality and serum biochemical indices in broiler breeders. Methods: After receiving a basal diet (containing 0.25% Met) for a 2-wk pretreatment period, a total of 360 39-wk-old Lingnan yellow broiler breeders were randomly allocated to four treatments with six replicates each (15 birds per replicate). Breeders were fed with basal diets (control) or diets supplemented with DL-methionine (DLM), DL-2-hydroxy-4-methylthio butytric calcium (MHA-Ca) and coated DL-Met (CME) respectively. Results: The results showed that CME supplementation promoted laying rate and decreased feed-to-egg ratio (F/E) (p<0.05), DLM and MHA-Ca supplementation decreased F/E (p<0.05) when compared with control group. The rate of fertility, hatchability and birthrate were higher (p<0.05) in DLM, MHA-Ca, and CME groups than control group. Compared with control group, CME increased the eggshell thickness (p<0.05); MHA-Ca improved the eggshell thickness, shell ratio and eggshell strength (p<0.05). Results also showed that CME elevated the concentration of total protein in serum (p<0.05); MHA-Ca improved the concentration of calcium in serum (p<0.05). The concentration of serum uric acid in DLM, MHA-Ca, and CME groups was lower than that in control group (p<0.05). Besides, CME had higher concentrations of serum taurine, cysteine and cystanthionine (p<0.05) while MHA-Ca and DLM promoted the serum taurine concentration (p<0.05) compared with control group. Conclusion: Based on the results, it was concluded that Met supplementation could enhance the production and reproduction performance as well as the antioxidant status and egg quality of broiler breeders. In terms of improving the production performance, reproduction performance and antioxidant performance, CME was superior to DLM and MHA-Ca; but in regard to the enhancement of eggshell quality and serum Ca concentration, MHA-Ca was superior to DLM and CME.

• 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.48 no.1
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• pp.41-50
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• 2021

Although feather-sexing using sex-linked genes related to feather development is a widely used chick sexing method in the poultry industry, the feather-sexing method has yet to be used for Korean native chickens (KNCs). The purpose of this study was to construct a KNC feather-sexing line using early-feathering (EF) and late-feathering (LF) genes for industrial application. Using 557 reddish-brown KNCs as the basal flock, frequencies of the EF (k) and LF (K) genes were estimated to be 0.814 and 0.186, respectively. This indicating that it would be feasible to construct a feather-sexing line using this chicken group, and we accordingly constructed EF paternal and LF maternal lines. On the basis of test-cross for the selection of LF homozygous (KK) males in the maternal line, we confirmed that three of 40 chickens were homozygous males. The survival rate, body weight, days at first egg-laying, hen-day egg production, and egg weight were analyzed to compare the production performance of EF and LF chickens. The results revealed that EF chickens were characterized by a superior survival rate, whereas LF chickens were superior in terms of egg production rate. However, no differences between LF and EF chickens were detected with respect to other production performance parameters. In addition, assessment of the fitness of sexed chicks produced in the established KNC feather-sexing lines revealed that the accuracy of sexing was 98.6%. Collectively, these findings indicate the feasibility of constructing effective KNC feather-sexing lines with potential industrial application.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.393-405
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• 1983

The demand for livestock and poultry products including beef, pork, chicken, egg and milk whose income elasticities are relatively higher than other staple foods, has been increased significantly during the past two decades in response to the remarkable increase in per capita GNP. This trend will be continued during the fifth and the sixth five year economic development plan period beginning with 1982. The annual GNP growth rate will be 7.5% on the average during the next 10 years. It is greatly needed to estimate the demand for beef, pork, chicken egg and milk and to study the feasibilities of domestic production of livestock products for the formulation of adequate policies in order to equate the consumption and the production during the 1980s. So this study reviewed the possible changes in the food consumption patterns during the 1980s, estimated the demand for beef, pork, chicken, egg and milk by using empirical demand functions and finally made suggestions for the formulation of long term price stabilization policies for each livestock, poultry and dairy products through the equilibrium of the quantity of demand for and supply of the products. There are many factors affecting the demand for meats, but this study considered own price, prices of supplements and substitutes and per capita income as the independent variables in the demand equations. It was found that it's own price and income were most significantly affecting factors among others and the degree of substitution effects were remarkably different among the products. According to the meat demand derived in this study, per capita consumption of beef, pork and chicken in the base year 1982 was 11.2kg for total meat, 2.5kg beef, 6.0kg pork and 2.5kg chicken, 106 pieces egg, 15.1kg milk respectively, while those in 1991 were 19.3kg for total meat, 4.8kg beef, 9.6kg pork, 4.9kg chicken, 133pieces egg and 44.1kg milk. It is also predicted through this study that, when the level of production costs be maintained, the domestic production of pork and chicken will meet the demand for them during the fifth and sixth five year economic plan period. However, there will be chronic shortage of beef supply during the coming years. The annual import requirement will be 30,000tons to 40,000tons during the period. In order to stabilize the domestic livestock and poultry and dairy products market, the government should introduce measures to curb the increase in beef consumption by encouraging the consumption of pork and chicken. For this, the livestock production policy measures should be concentrated on : 1) the improvement of infrastructures of beef production by introducing advanced feeding and management technology, subsidies for the establishment of facilities and price support programs for farmers : 2) the development of dairy beef : 3) the reinforcement of the forecast systems for pork and chicken production and consumption.

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

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.1
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• pp.13-16
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• 2010

The effect of exogenous administration of tamoxifen (TAM) on hormonal profile and sexual maturity in Indian native Kadaknath (KN) fowl was investigated. Day-old chicks from the same hatch were randomly divided into 15 groups with 20 chicks in each group (5 treatments${\times}$3 replicates). The chicks were placed in battery brooders with wire-mesh floors and reared under uniform husbandry conditions (14 h light/d, 25-32${^{\circ}C}$) on a standard basal diet. At the age of two weeks (wk), birds from the control group ($T_{1}$) were injected with maize oil intramuscularly (I/M), whereas the other four experimental groups $T_{2}$, $T_{3}$, $T_{4}$ and $T_{5}$ were given tamoxifen (I/M) dissolved in maize oil at the rate of 0.5 mg (0.5 TAM), 1.0 mg (1.0 TAM), 2.5 mg (2.5 TAM) and 5.0 mg (5.0 TAM)/kg body weight, respectively, up to 30 wks on every alternate day. At every 6-wk interval, blood samples were collected from nine birds of each treatment group for estimation of estrogen and progesterone. The same birds were sacrificed for determination of the weight of ovary, oviduct, liver and adipose tissue. There was no significant difference in egg production traits except onset of lay and egg number. Low doses of TAM ($T_{3}$) advanced the onset of egg laying by 15 days over the control. Tamoxifen influenced the hormonal profile (estrogen and progesterone) in a dose dependent manner. However, higher doses of TAM suppressed ovary and oviductal growth. From this study, it may be concluded that lower doses of TAM enhanced sexual maturity while higher doses suppressed ovary and oviductal growth.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.561-566
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• 2015

Effect of the addition of egg yolk lecithin at a concentration of 350 mg/kg on iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation of a water/canola oil emulsion (W/O) during storage at $25^{\circ}C$ was studied based on headspace oxygen consumption and hydroperoxide production. Changes in the phospholipid (PL) composition of the emulsion were determined by high performance liquid chromatography. Headspace oxygen consumption and hydroperoxide content of the emulsion increased with storage time, and addition of egg yolk lecithin did not have any significant effect on these parameters during iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation of the emulsion. PL content of the emulsion decreased during both oxidations, and the degradation rate was higher during autoxidation than during photosensitized oxidation. Phosphatidylcholine content ratio tended to increase during autoxidation. The results suggest that egg yolk lecithin in canola oil emulsion behaves differently during iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation.

• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.179-186
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• 1986

A total of 749 Korean native Ogol fowl[Natural Monument No, 265] and 45,340 Ogol eggs were used to investigate the various performances of Ogol, I. e., fertility, hatchability, viability, body weight, and rate of egg production. The studying periods was from May, 1985 to Sept., 1986. The results obtained are summarized as follows. 1. The mean rates of fertility and hatchability were 82.2${\pm}$1.37(X${\pm}$S.E.) and 79.0${\pm}$1.91%, respectively. 2. The mean rates of fertility and hatchability during brooding, growing and laying periods were 90.5${\pm}$1.69, 79.9${\pm}$2.28% and 80.6${\pm}$3.06%, respectively. 3. Average body weight at hatch, at ages of 18, 24, 44 and 72 weeks were 31.5, 0.43, 1209.3${\pm}$17.29, 1646.1${\pm}$25.90, 1975.3${\pm}$40.56 and 2096.7${\pm}$40.83g, respectively. 4. The age of the first egg was 166.5${\pm}$1.69 days old. Egg weights at first egg, at ages of 44 and 72 weeks were 35.7${\pm}$0.49, 48.8${\pm}$0.47 and 502${\pm}$0.44g, respectively. The numbers of egg production age to of 44 and 72 weeks were 69.5${\pm}$3.10 and 129.3${\pm}$5.56 eggs, respectively. 5. Between body weights and age at the first egg showed lower negative correlation. Body weights at ages of 24, 44 and 72 weeks showed highly positive correlation with egg weight, but a significant negative correlation with the number if egg production to ages of 44 and 72 weeks. The age at first egg was positively correlated with egg weight at first egg, but that was negatively correlated with the number of egg production to ages of 44 and 72 weeks.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.12
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• pp.1769-1774
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• 2005

This experiment was carried out to evaluate the effects of feeding green tea powder on laying performance and egg quality in hens. A total 180 'Tetran Brown' laying hens aged 40 weeks were assigned to 6 treatments in a completely randomized design. Each treatment consisted of five replicates accommodating six layers per replication. The experimental diets were a negative control containing no green tea, a positive control diet containing antibiotics (0.05% chlortetracycline) and diets containing 0.5%, 1.0%, 1.5% and 2.0% green tea powder. Egg production rate of layers fed the diets containing green tea powder did not differ significantly from that of the negative and positive controls (p>0.05). Egg weight was decreased significantly in the group fed the diet containing 0.5% green tea powder (p<0.05). Feed intake of layers was significantly higher for the diet containing 1.5% green tea powder compared to that of negative and positive control diets (p<0.05). The eggshell thickness reduced significantly in the layer group fed the diets containing green tea powder regardless of dietary levels (p<0.05). Green tea powder tended to reduce egg yolk cholesterol in this experiment. Particularly, dietary 2% level of green tea powder significantly suppressed the cholesterol contents of the egg yolk (p<0.05). Thiobarbituric acid value (TBA) of egg yolk was significantly reduced by green tea diets (p<0.05). The yellowness of egg yolk was increased in the layers fed the 2.0% green tea diet compared with that of control diet (p<0.005). The Linoleic and $\alpha$-linolenic acids tended to increase in the group fed diets containing 1.5% green tea powder even though there were no significant differences among treatments (p>0.05). The oleic and docosahexaenoic acid contents of the egg yolk were similar among treatments (p>0.05). Based on the results of the experiment, it is concluded that green tea powder inclusion in the diet for layers at 2.0% level can reduce the cholesterol content and TBA value of the egg yolk, implying its potential effect on egg quality parameters.