• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.380-386
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• 2009

Molting and growth of the snow crab, Chionoecetes opilio was investigated using samples captured in the East Sea from July 2002 to June 2004. Individuals over 40 mm carapace width (CW) molted once a year from July to October. Annual molt stage of C. opilio can be divided into four stages; premolt stage, molting stage, postmolt stage and intennolt stage. The relationship between CW and chela height (CH) can be expressed as Y=-82lnCW+73.1129lnCH+166. They were separated into two groups based on the equation, that is, one group having a negative value (below 70 mm in CW) and other group having a positive value (over 130 mm in CW). Carapace width at 50% terminal molt ($CW_{50%}$) of males was estimated to be 105 mm. The Gompertz growth equation estimated from a non-linear method was $CW=118.99e^{-6.296e^{-0.3062t}}$ for females and $CW=156368e^{-6.6619e^{-0.2626t}}$ for males.

• Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.115-121
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• 2014

Eyestalk ablation (ESA) is commonly used in aquaculture to stimulate ovarian maturation in crustaceans, and methyl farnesoate (MF) affects crustacean molting and reproduction. To investigate the physiological effects of ESA and MF treatments on the shrimp Litopenaeus vannamei, we compared the effects of single eyestalk removal and MF injections. The ESA group had the lowest survival rate (50%), and individuals in the $0.1{\mu}g$ and $1.0{\mu}g$ MF-treated groups had survival rates of 80 and 73.3%, respectively. Conversely, molting numbers were highest in the ESA group, and similar to those of the 1.0-${\mu}g$ MF group. To investigate shrimp growth, we measured body weight during the experimental period and found that individuals in the ESA and $1.0{\mu}g$ MF groups showed significant increases in body weight. Furthermore, to investigate the effects of ESA and MF treatments on gonadal maturation, the gonad somatic index (GSI) was calculated after the experiment. All treated groups (ESA and MF) had higher GSI values than the control group, but the ESA and $1.0{\mu}g$ MF groups were not significantly different. Using histological ovary analysis, we determined that all treated groups showed indications of the previtellogenic stage, unlike the control group (immature stage). These results suggest that the high-MF-concentration treatment produced effects similar to those of ESA with respect to molting number, growth, and ovarian maturation.

• 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.

• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.375-380
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• 2009

This study was conducted to investigate the effect of feeding induced molting on the visceral organs and blood component profile in laying hens and designed to test 400 flocks of 60 week old Leghorn laying hens for 34 weeks. A total of four molting treatment methods by including the molted with customary molting by fasting method (c), feeding single diet of corn (T1), feeding single diet of wheat bran (T2) and feeding single diet of alfalfa meal (T3) were tested, and each treatment was repeated for 5 times, and 20 laying hens were randomly assigned in an cage for each repeat. As the result of the experiment, ovary was $2.03{\sim}6%$ and oviduct was $2.51{\sim}3.47%$ in visceral organs for body weight at pre-molting term, but there was no significant difference. At post-molting, no significant difference was found, ovary was $0.25{\sim}0.41%$, uterus of control, T1, T2 and T3 was 1.12%, 0.82%, 0.48% and 0.90%, respectively. T2 was significantly lower than control, T3 (p<0.05) at the 50% of egg production. Ovary was $2.20{\sim}2.60%$ and oviduct was $2.98{\sim}3.45%$. In addition, ovary was $2.65{\sim}3.01%$, oviduct was $3.23{\sim}3.64%$ at the peak egg production, but there was no significant difference by non-feeding and feeding molting treatments. In blood component profile, cholesterol was $179.8{\sim}245.7\;mg/dL$ at pre-molting, but there was no significant difference and at post-molting, concentration of cholestrol in control, T1, T2 and T3 was 353.6, 229.1, 261.8 and 300.6 mg/dL, respectively. T1 was significantly lower than control and T3 (p<0.05). In addition, first laying day was $228.1{\sim}271.8\;mg/dL$, 50% of egg production was $236.5{\sim}284.8\;mg/dL$, there was no significant difference. Concentration of cholestrol in control, T1, T2 and T3 was 324.1, 591.6, 363.0 and 315.6 mg/dL, respectively, at the peak egg production period. T1 was significantly higher than other treatment (p<0.05).

• Korean Journal of Poultry Science
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• v.29 no.4
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• pp.237-241
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• 2002

To observe the effect of Induced molting on the recovery patterns of abdominal fat, visceral organs, and muscle tissues in spent laying hens after induced molting, three hundred sixty 77-wk-old, Babcock White hens were divided into 36 experimental units of 10 hens each and subjected to molt induction for seven wk. The post-molt production phase was spread over 84 to 126 wks of age. Thirty-six birds were randomly slaughtered and dressed at the pre-molt, 5% egg production, Peak, and end Phases of e99 Production. The body weight, abdominal fat, relative weight and length of visceral organs were measured. Proximate compositions of breast and thigh muscles were analyzed at each stage. The body weight was found to be minimal at the 5% egg Production stage, but increased as the egg Production increased for the rest of production. The pattern of abdominal fat change was very similar to that of body weight. The relative weight of the liver decreased to the lowest at the start of Post molting stage, but Peaked at the end Phase of egg Production (P<0.05). However, he heart and gizzard were observed to reach their maximum weight at the 5% egg Production (P<0.05), whereas they were, similar to those of the pre-molt phase for the rest of the production stages. Both intestine and reproductive tracts were found o be significantly smaller at 5% egg Production than at the other stages; however, their sizes increased gradually, reaching leak at the end Phase of e99 Production (P<0.05). Fat contents in breast and thigh muscles decreased significantly to the lowest at the start of the Post-molt stage, but increased to the highest at the end Phase of e99 Production (P<0.05). Thus, he Present study indicated that the molting process reduced body weight by decreasing the weights of abdominal fat and other visceral organs. Molting also influenced the breast and thigh muscle composition by decreasing fat content.

• Korean Journal of Poultry Science
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• v.35 no.1
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• pp.15-20
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• 2008

This study aimed at evaluating the effects of a molting diet method in molt induction and post-molt performance of laying hens. Eighty-one ISA Brown hens at 62 wk of age were randomly divided into three groups. After a 4-wk preliminary period, a control group was fed a corn-soybean-based layer diet, and for the other groups, molting was induced by starvation (MS) or feeding a molting diet (MD). For the MS group, feed was withdrawn for 2 wk; this was followed by feeding a layer diet every other day for 1 wk and then the control diet. The MD group was fed a molting diet containing low-protein and low-energy diet based for 4 wk; this was followed by feeding a layer diet. They had a free access to their diet and water. Egg production, egg quality, feed intake, and ovary and oviduct weights were measured throughout the experimental period. During molting, the feed intake in the MD group was lower than that of the control. Body weight of the molted groups was significantly reduced. The MS group feeding totally ceased egg production within 4d; after the initiation of feeding and decreased; in the MD group, egg production to 9.3% by d 10. On d 14, the ovaries and oviducts of the molted groups were distinctly lighter than those of the control. Throughout the post-molt period, egg production and egg shell thickness of the molted group improved; but there were no significant differences. Eggs from the MD-fed or control group were heavier than those of the MS-fed or control group. Finally, feeding of a low-protein and low-energy diet effectively induces molting and increase post-molt production, but further research will be conducted to determine the effects of the molt diet with other ingredients and to reduce the energy level of the molt diet for maximizing molt induction and post-molt egg quality.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.202-209
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• 2014

RNA interference (RNAi) is the method which controls phenotypes of gene in live cells. Chitinase is the enzyme helping digestion and absorption of old cuticles during the ecdysis of insects. In order to investigate molting-inhibition effect with the chitinase related gene in Spodoptera litura, RNA was extracted from the $5^{th}$ instars. cDNA was synthesized and then we obtained about 700 bp size chitinase. After PCR products were cloned into a pGEM T-easy vector, colonies were picked. DNA was extracted from the colony cultures. EcoR I enzyme was used to check whether PCR products were inserted or not. And then we confirmed vector band of about 3 kb and insert band of about 700 bp. To synthesize the dsRNA, each DNA was cut with Spe I and Nco I enzymes (Circular DNA became lineared DNA). After synthesis of dsRNA, approximately 5 ul dsRNA was injected into the $3^{rd}$ abdominal segment of S. litura $4^{th}$ larvae. The concentration of dsRNA was about $10{\mu}g/{\mu}l$. We confirmed larval-larval molting : there were phenotypically abnormal individuals - for instance malformation, molting inhibition and change of integument color. Pupaadult molting : there were phenotypically abnormal individuals - for instance molting inhibition, change of wings and malformation. Also we could investigate the pupation, emergence and variation about noninjection, treated with DW and dsRNA. Each pupation was non-injection 83.3%, DW 78.3% and dsRNA 66.7%. Each emergence was non-injection 90.0%, DW 72.3% and dsRNA 65.0%. So we considered that chitinase dsRNA induced molting inhibition effect. But each variation was non-injection 8.9%, DW 2.9% and dsRNA 19.2%. Therefore dsRNA group showed the highest variation value. When 18 hours after injecting dsRNA, we could obtain abnormal individual.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.78-84
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• 1999

Ultrastructural changes in the cuticle of Paleamon serrifer associated with the intermolt cycle were examined and quantified as changes in the cuticular thickness. The cuticular thickness in each zoea stage increased with time elapsed after molting. The cuticle in the premolt stage was about 1.5 and 3 times thicker than that in the postmolt and intermolt stage, respectively. The cuticle in the premolt stage, including the molting space, was more than 5 times as thick as in the postmolt stage. In addition, newly hatched larvae were individually reared in the laboratory and body length for each specimen was measured frequently until the end of zoea VI. An average increase in body length between one zoea stage and the next is about $10\%$ of the length of the previous stage. Within individual zoea stages, the premolt stage had a body length some 0.3% longer than that of the postmolt stage, indicating a growth rate of about 0.03 mm/d.

• Korean Journal of Poultry Science
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• v.37 no.2
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• pp.117-123
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• 2010

This work was carried out to investigate the effect of the induced molting with low-protein and energy diet on the postmolt performance of layers. Eighty White Leghorn layers (61-old-wk) with over 80% egg production were used for 12 weeks in this work. Treatments were non-molt control (CO), fasting treatment for 10 days (FW), molt treatment with low-protein and low-energy molting diet for 3 weeks (LO), and molt treatment with standard molting diet for 3 weeks (ST) as 4 treatments (2 replications/treatment and 10 birds/replication). Body weight (BW) loss was 26.5% of initial BW at 2 week in FW treatment, and was 17.3% and 14.2% in both LO and ST treatments (P<0.05). Layers in molting treatments were fed with commercial layer diet after completion of molting since BW of layers was recovered for 7 weeks. Heart weight ratio was shown as 0.47, 0.43, 0.46 and 0.46% at CO, FW, LO and ST treatments, respectively, and liver weight ration of body weight was shown as 2.56, 1.30, 1.47 and 1.52%, respectively. Thus, those of molting treatments decreased compared to non-molt control (P<0.05). Oviduct weight ratio were shown as 3.95, 1.17, 1.54 and 1.67%, respectively, and similar with the results of liver (P<0.05). Feed intake decreased at LO and ST treatments during molting period and increased from the 5th week compared to control. Egg production decreased at 1 week in molt treatment and stopped at 2 week in FW, 3 week in LO, and 4 week in ST treatments. The birds started to lay egg at 4 week in FW and at 5 week in LO and ST treatments. Egg production was recovered until 50% at 6 week in FW and was recovered as 66.1 and 71.6% at 8 week in LO and ST treatment, respectively. Egg weights were similar among all treatments. Eggshell thicknesses were 0.41, 0.47, 0.46 and 0.46 mm at CO, FW, LO and ST treatment, respectively, but the higher in molt treatments than control (P<0.05). Eggshell breaking strength was 3.83 and 3.81 kg/$cm^2$ in FW and LO treatment, respectively, and high compared to control. However, eggshell breaking strengths were 3.54 and 3.78 kg/$cm^2$ and were not statistically different. Haugh units were 75.6, 81.1, 80.6 and 79.9 in 4 treatments and high in molt treatment. Finally, dietary low-protein and low-energy may induce molt as few effect on performance of layers.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.2
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• pp.341-347
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• 1992

Eggs used in this study were obtained from Saudi Arabian Baladi laying hens which were divided into four experimental groups and subjected to the following treatments: Commercial laying ration (17% CP, 3.6% Ca and 0.343%, available P) fed ad libitum as a control (C); Conventional force molting, feed removal for 10 days followed by 18 days full-feed of cracked corn (F); 15 days ad libitum intake of the control ration supplemented, to initiate forced-molt, with 0.35% aluminum as the sulfate (ALS) or the chloride (ALC). The hens were in production for 52 weeks and 17 months of age at the start of the trial and the post-treatment period lasted 36 weeks. During the treatment period F and AL treated groups had similar egg and shell weight, egg surface area, shell thickness and shell weight per unit of surface area but significantly (p<0.05) lower than the control. F had significantly (p<0.05) the highest and the control the lowest Haugh unit values whereas AL fed groups had significantly (p<0.05) lower meat spot incidence compared with the control which tended to have higher value than F group. ALC and F had significantly (p<0.05) the lowest yolk color grade whereas ALC had significantly (p<0.05) lower egg index than ALS and the control. During the post-treatment period the control had significantly (p<0.05) the highest egg index and blood spots incidence and ALS the lowest shell diensity compared with other groups. ALS had significantly (p<0.05) lower shell weight than ALC and the control whereas F and AL treated hens had significantly (p<0.05) the highest Haugh unit values and yolk color grades respectively. F had significantly (p<0.05) lower meat spots incidence than ALC and the control. The same results were observed for ALS compared with the control.