• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1460-1464
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• 2001

This study compared the lipid metabolism of white Leghorn layers between the growing and the laying periods. The study was conducted on thirty layers in the growing period (14 weeks old) and in the initial laying period (36 weeks old; 14 weeks from the onset of laying). Results indicated that all plasma lipid traits were significantly different (p<0.05) between the two periods. The estrogen concentration in the laying period was about 3 fold that in the growing period. Triacylglycerol (TG) concentration in the laying period was about 12 fold that in the growing period. The phospholipids, cholesterol, glycerol and non esterified fatty acid (NEFA) in the laying period were also higher than those in the growing period (p<0.05). Lipogenic enzyme activities in the laying period were higher than in the growing period (p<0.05). High-density lipoprotein (HDL) was the largest lipoprotein portion in growing layers. In laying hens, the major lipoprotein portion was very low-density lipoprotein (VLDL). It was also shown that protein is the primary component of HDL and TG is the largest portion of VLDL in both periods. In laying hens, VLDL contained more TG than that in growing layers (p<0.05). The VLDL particle size in laying hens was larger than that in growing layers (p<0.05). This study indicates that the lipid metabolism traits of a layer in the laying period were different from those in the growing period. The lipogenesis related traits in the laying period were markedly greater than in the growing period.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1090-1095
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• 1999

In order to minimize the occurrence of fatty liver, this study investigated how adding a high level of dietary choline or methionine affected the lipid metabolism of Tsaiya ducks. Feeding trials were conducted with sixty Tsaiya ducks during their growing period, when they were 8-12 weeks old, and during their laying period, 10-14 weeks after the onset of laying when they were 26-30 weeks old. The ducks were randomly assigned to one of three groups: a control group (basal diet), a group in which methionine was added to the basal diet, and a group in which choline was added to the basal diet. The levels of methionine and choline added were twice as high as the levels recommended by the NRC for layer-type chickens. Experimental results indicated that adding choline to the basal diet of growing ducks significantly (p<0.05) increased their body weight, while adding methionine significantly (p<0.05)reduced their body weight. Adding either choline or methionine reduced the ducks' liver fat content in both the growing and the laying periods (p<0.05). Ducks receiving added methionine or choline in their diets displayed enhanced egg production (p<0.05). Adding choline increased serum triacylglycerol (TG) in the laying period (p<0.05). Adding either choline or methionine did not significantly (p>0.05) affect the t-globulin level. Adding methionine increased the activity of liver malic dehydrogenase in both the growing and the laying periods, and increased fatty acid synthetase in the laying period (p<0.05). While adding choline markedly (p>0.05) increased VLDL and apo B in both the growing and the laying periods, it decreased HDL and apo A in the laying period (p<0.05). This study found that adding a high level of choline to the basal diets of Tsaiya ducks in both the growing and the laying periods had beneficial effects. Furthermore, adding methionine affected the lipid metabolism of Tsaiya ducks to a lesser extent than adding choline.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.8
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• pp.1258-1262
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• 1999

With an attempt to elucidating the lipid metabolism of Tsaiya ducks, thirty ducks at growing (8 weeks of age) and laying periods (10 weeks after the onset of laying) were examined, respectively. The ducks were randomly allocated into ad libitum feeding and 3-day fasting groups, to investigate their in vitro hepatocytes lipogenesis capacity and adipocytes lipolysis rate. Results indicate that (1) the capacity of hepatocytes incorporation of glucose and acetate into total lipid and metabolite of $^{14}CO_2$ production during the laying period was greater than during the growing period. Approximately 50% of the glucose or acetate converted into triacylglycerol (TG) by the hepatocytes were recovered as fatty acid during the growing period, while it was 65-70% during the laying period. (2) Acetate used for lipogenesis ability was superior to glucose in both periods. (3) The adipocytes lipolysis rate was increased significantly (p<0.05) by fasting. In contrast, the capacity of incorporated glucose or acetate into total lipid, triacylglycerol, fatty acid and glycerol by hepatocytes was reduced significantly (p<0.05) by fasting.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.403-408
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• 2003

The study investigated the lipid metabolism of Tsaiya ducks under fasting and ad libitum feeding conditions. Sixty Tsaiya ducks in their growing period (8-12 wk-old) and sixty Tsaiya ducks in their laying period (26-30 wk-old, 10-14 weeks after the onset of laying) were randomly divided into ad libitum feeding and 3-day fasting groups. The activities of lipid metabolism related enzymes were determined. Experimental results indicated that fasting depressed the activities of lipogenesis related enzymes such as fatty acid synthetase and NADP-malic dehydrogenase in both periods (p<0.05). Fasting also increased the activities of liver fatty acid $\beta$-oxidation enzymes (p<0.05). However, the activities of lipoprotein lipase in adipose tissue, heart and ovarian follicle in both periods and the hormone-sensitive lipase of adipose tissue in the growing period were decreased by fasting (p<0.01).

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.2
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• pp.254-265
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• 2002

Soybean meal (SBM) is a major protein source in poultry feeds and one of the best quality ingredients because of the relatively high protein content, good amino acid profile and bioavailability. But soybean meal quality is largely dependent on the processing technology and origins. In this experiment, effects of three different soybean meals were evaluated in layer (experiment 1) and broiler (experiment 2). Soybean meal sources used in the experiments were the US-originated dehulled soybean meal (USDHSBM), India-originated non-dehulled soybean meal (India SBM) and Brazil-originated non-dehulled soybean meal (Brazil SBM). Experiment 1 was conducted during growing and laying periods and evaluated the interactive effects of soybean meal sources according to feeding periods on growth performance and egg quality. Experiment 2 was conducted during growing period (day 1-35) and finishing period (day 35-42). The growth performance was measured for the same periods and any possible interaction between soybean meal origins and crude protein levels was also studied. In experiment 1, chicks fed India SBM utilized feed more efficiently (p<0.05) than those fed Brazil SBM from day 29 to day 42. The body weights of layers during the laying period had no relation to egg production. But egg weights were significantly heavier in all the USDHSBM fed groups than other groups (p<0.001) and depended on feed protein source during growing period (p<0.001). The average egg weight of the USDHSBM fed group scored the highest value (65.4 g), followed by the Brazil SBM fed group (62.1 g) and India SBM fed group (62.1 g). There was an effect of interaction between origins of soybean meal fed group in growing and laying period on eggshell color (p<0.01). Eggshell was significantly stronger in the USDHSBM fed (for growing period) groups than other groups (p<0.05) on $31^{st}$ week. Haugh's unit (HU), albumin index and yolk index of the USDHSBM fed group in growing stage were significantly superior (p<0.001) to other groups. In experiment 2, for the 7-week, chicks on the India SBM group gained less (p<0.001) weight than other groups. While daily gain of India SBM chicks was not affected by dietary crude protein level, those of the USDHSBM and Brazil SBM chicks were linearly increased as dietary crude protein level increased from 18% to 20%. The gain per feed ratio of the USDHSBM group was the highest (0.585), followed by the Brazil SBM group (0.568) and India SBM group (0.550) (p<0.01). Therefore, in this experiment, the use of USDHSBM with excellent protein quality and amino acid digestibility could be of advantage to the economic production of layer and broiler.

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

• The Korean Journal of Ecology
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• v.26 no.6
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• pp.341-347
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• 2003

Historical Documents on Proper Tree Selection System of Korea were collected in Japan and introduced in this review. Products of some pine species and fruit were used for laying a tribute to Kings in the Chosun dynasty. In this review, some case studies and implementation of proper tree selection system during the period of Japanese rule, the atlas of climatically favourable regions for the species of trees and bamboos in Korean peninsular, and the test results on regional afforestation, tree selection and proper tree selection of fast growing trees were introduced. Of these documents, especially, the atlas of climatically favourable regions of trees and bamboos growing in Korean peninsular is considered as a valuable document. It tis expected that these historical documents on proper tree selection system might be use as references for the researches on indigenous forest, forest resources development, afforestation of fire damaged areas, and the restoration project of North Korea by the time of reunification of Korea.

• 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.