• 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.26 no.7
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• pp.921-929
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• 2013

Huoyan goose is a Chinese local breed famous for its higher laying performance, but the problems of variety degeneration have emerged recently, especially a decrease in the number of eggs laid. In order to better understand the molecular mechanism that underlies egg laying in Huoyan geese, gene profiles in the pituitary gland of Huoyan geese taken during the laying period and ceased period were investigated using the suppression subtractive hybridization (SSH) method. Total RNA was extracted from pituitary glands of ceased period and laying period geese. The cDNA in the pituitary glands of ceased geese was subtracted from the cDNA in the pituitary glands of laying geese (forward subtraction); the reverse subtraction was also performed. After sequencing and annotation, a total of 30 and 24 up and down-regulated genes were obtained from the forward and reverse SSH libraries, respectively. These genes mostly related to biosynthetic process, cellular nitrogen compound metabolic process, transport, cell differentiation, cellular protein modification process, signal transduction, small molecule metabolic process. Furthermore, eleven genes were selected for further analyses by quantitative real-time PCR (qRT-PCR). The qRT-PCR results for the most part were consistent with the SSH results. Among these genes, Synaptotagmin-1 (SYT1) and Stathmin-2 (STMN2) were substantially over-expressed in laying period compared to ceased period. These results could serve as an important reference for elucidating the molecular mechanism of higher laying performance in Huoyan geese.

• Korean Journal of Poultry Science
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• v.47 no.4
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• pp.237-245
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• 2020

This study investigated the effects of breed, laying age, and egg storage period on hatching performance. Eggs were collected from early laying period (27 to 29 weeks old) and late laying period (50 to 52 weeks old) in Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Eggs laid for each period were stored for 3, 7 and 14 days and then hatched. Fertility, hatchability, and embryonic mortality were observed to determine the hatching performance. The results showed that hatching performance was affected by breed, laying age, and egg storage period with independently or interactively. The Korean Rhode Island Red breed had the lowest hatching performance. Hatchability and early embryonic mortality rate increased in early laying period eggs compared to the late laying period, but the late embryonic mortality rate increased in late laying period eggs. Additionally, hatching performance decreased as the egg storage period increased. Using breed-specific hatching management techniques, avoiding late laying period eggs, and shortening the egg storage period to seven days after laying may improve the hatching performance.

• 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.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.

• Animal Bioscience
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• v.34 no.3_spc
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• pp.457-462
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• 2021

Objective: The aim of this study was to investigate the effects of Enteromorpha powder supplementation on reproduction-related hormones and genes in the late laying period of Zi geese. Methods: A total of 312 (1-year-old) Zi geese with similar laying rate were randomly divided into 2 groups with 6 replicates each, each with 21 female geese and 5 male geese. The control group was fed with a basal diet and the test group was fed with a diet containing 3% Enteromorpha powder. The trial period lasted for 7 weeks. Results: Our results showed that the laying rate was improved in the test group at each week of trial (p<0.01), and the levels of estradiol in serum and prolactin in ovary were increased compared with the control group (p<0.05). Conclusion: Based on above results, Enteromorpha powder supplementation at 3% could promote reproductive performance during the late laying period of Zi geese.

• Korean Journal of Poultry Science
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• v.13 no.1
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• pp.23-30
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• 1986

The Calorimetric experiment was made firstly to measure the difference in energy metabolisms of laying hens among their three different laying periods, secondly to estimate the energy requirements of the layers on their respective laying periods. The laying period was divided into three chronological periods of 25-40, 41-55, and 56-69 weeks old of laying hens, which are refered to as period I, II, and III respectively. 1) The fasting heat production (FHP) of laying hen on the three laying periods were 81.5 Kcal/kg$\^$0.75/ for period I, 72.3 Kcal/kg$\^$0.75/ for perod II, and 97.5 Kcal/kg$\^$0.75/ for perod III. The marked increase in FHP was found in period m, while there was a small difference in FHP between period I and II. The present study have observed among the birds in period in the high degree of plumage defectiveness, and this condition of bird might have accounted for the increase in FHP. 2) The regression equation between ME intake and energy retention (ER) were calculated, and the equations indicated that, for the period I, II, and III, the ME requirements for maintenance (MEm) were 123, 111, and 131 Kcal/kg$\^$0.75/ respectively, and that the Net Availabilities of Metabolizable energy (NAME) were 76, 79, and 74 percent respectively. For the whole laying period measured, MEm was 119 Kcal/kg$\^$0.75/ and NAME was 79 percent. There was a tendancy of higher MEm, and lower NAME during Period III, comparing with period I and II.

• Korean Journal of Poultry Science
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• v.48 no.1
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• pp.1-12
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• 2021

We investigated the effects of breed, laying age, and egg storage period on the vitality of chicks using the Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Their eggs were collected during the early laying period (27~29 weeks) and late laying period (50~52 weeks) and were stored for 3 days, 7 days and 14 days. After the eggs hatched, the hatching time, production performance, and organ weight of chicks were investigated. IL-6 gene expression level and relative length of telomeres were analyzed to determine the physiological activity of the chicks. HSP gene expression level and heterophil to lymphocytes ratio were also analyzed to examine the degree of stress response in the chicks. The results showed that breed and laying age influenced the vitality of chicks, but the egg storage period did not. Korean Leghorn chicks were considered the weakest breed in terms of vitality owing to their low survival rate, small heart size, low physiological activity, and high stress response level. Although the survival rate of chicks produced in the early laying period was low, their high physiological activity and low stress response indicated that they had a high vitality than the chicks produced in the late laying period. In conclusion, to obtain chicks with high vitality, it would be desirable to select a high vitality breed and avoid the use of chicks produced in the late laying period.

• Korean Journal of Poultry Science
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• v.22 no.2
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• pp.77-84
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• 1995

In order to investigate the effect of feeding live yeast culture on the performance of laying hens, a feeding trial was conducted with 96 20-wk-old Hy4ine brown layers during their laying period of 60 wk. The live yeast culture used was a product from Saccharomyces cerevisiae that was cultured on the corn-based substrate followed by careful drying of whole material not to lose the viability of yeast. Three levels of yeast culture as 0.5, 1.0, and 2.0% for three treatments and 0% for the control were included in the experimental diets. The feeding trial was carried out for 60 wk from August 26, 1992 to October 26, 1993. To evaluate the performance of layers during cold or hot periods as affected by the yeast culture feeding, data from the 12-wk winter period and 12-wk summer period were separated and analyzed accordingly. During 60 wk of laying period hen-day egg production was slightly but significantly(P<.05) improved by feeding the yeast culture. The average egg weight and daily egg weight(g /day) were also increased by the yeast culture. Feeding the yeast culture did not increase feed intake but feed efficiency was improved significantly (P<.05). No significant difference was detected in egg or eggshell qualities between control and yeast culture-treated groups. Feed intake and egg weight were not affected by the yeast culture feeding under both cold and hot period, but egg production and feed efficiency during hot summer improved significantly by its feeding. This result indicates that the effectiveness of the yeast culture feeding is greater during summer than winter for laying hens.

• Korean Journal of Organic Agriculture
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• v.12 no.2
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• pp.171-181
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• 2004

A study was conducted to investigate the effect of supplementing earthworm meal (EWM) on the performance of spent laying hens after induced molting, and fatty acid composition in egg yolks. A total of 90 laying hens at 73 weeks of age were fed the experimental diets containing 0.0% (Control) and 0.2% of EWM for 4 weeks. Eggs were collected and weighted every day and Egg production and feed conversion were recorded every week during the experimental period. However fatty acid composition of egg yolk were measured at last week of experimental period. An amount of feed intake increased by supplemental with EMW except for Erst week experimental period (P<0.05). When 76 and 77 week of age, egg production and daily egg mass were improved by the supplemented with EWM (P<0.01), but average egg weight was not different when fed a EWM, therefore feed/egg mass was significantly decreased when fed a EWM. The ratio of egg yolk n-6/n-3 fatty acids contents was significantly improved fed a EMW (P<0.05). It is concluded that supplementing 0.2% of earthworm meal in the spent laying hens after induced molting was fast in recover of physical strength, therefore improves laying performance.