• Journal of Sericultural and Entomological Science
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• v.42 no.2
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• pp.86-92
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• 2000

Studies were carried out to investigate the phenotypic characteristics of the non-molting mutant (nm-f) which was mapped on the 2nd linkage group. The results obtained were as follows : The nm-f mutant was distinguishable in the 3rd day of hatching. About 80 percentage of the non-molting mutant larvae died at the first instar within 10 days of hatching. The remaining larvae survived to the 2nd ad the 3rd instar but did not live to the final instar. There was no difference in non-molting nutant manifestation between hibernating and artificial hatching eggs. As a result of hemolymph protein analysis, the protein content on nm-f mutant was less than the normal larvae's. Therefore, we conclude that the characterization of nm-f is similar to the already known strains of non-molting mutant and the shortage of hemolymph protein is closely related to the non-molting characteristic in nm-f.

• 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.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.43-51
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• 1998

Studies were carried out to investigate phenotypic expression, mortality and biochemical analysis of haemolymph proteins of nm-d, nm-f, nm-k and nmn bib-molting mutants of the silkworm, Bombyx mori. The non-molting mutants characters were expressed in the homozygote of each mutant genes. All strains of non-molting mutants were similar with each other in physiological characteristics, but the expression varied with each strains. The larvae of nm-d, nm-i and nmn died between day 5 and day 9 after hatching without the first molt. The nm-f and nm-k mutants died between day 5 and day 16 with a slight increase of body weight and, more than 90% of the mutants larvae died before the first molt and a few of them survived to the 2nd and the 3rd instar and died. The haemolymph protein components of nm-d, nm-i, and nmn were rapidly reduced, and on the other hand those of nm-f and nm-k consistently until they died. And there were no distinguishable difference in haemolymph components of non-molting mutants, as compared to those normals.

• Korean Journal of Poultry Science
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• v.34 no.4
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• pp.279-286
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• 2007

This study was conducted to induce molting with DDGS and non-salt diet and compare the effect of feeding molting and fasting molting on the performance, egg quality, and visceral organs in laying hens for animal welfare. One-hundredeight 62-wk-old White Leghorn hens that egg production was over 80% and average weight was $1.8{\pm}0.1kg$ were used in this study. Treatments were control(non-molt treatment), feeding molt treatment(DDGS, non-salt diet), and fasting molt treatment. The four treatments were administered to three replicate group of nine hens wherein each group. All treatment groups were fed the basal diet(CP 15%, ME 2,700 kal/kg) for two weeks as the adaptation period. Test Periods were 28 days at all treatments. Egg production decreased for 18 days to be 0% at feeding molting treatment, and for 17 days to be 0% at non-salt feeding molting treatment. Egg production stopped for 6 days at fasting molting treatment. Egg production restarted after 12 days molt at feeding molting treatment, while after 16 days at fasting molting treatment. On the egg quality was improved at molting treatments (p<0.05) except egg yolk. Egg shell tissue was crowded at molting treatment to compare to control. Liver weights, heart weight, and oviduct weight of laying hens decreased at molting treatments(p<0.05). Finally, feeding molting might could be replaced fasting molting on the welfare and further studies were needed about molting program.

• Journal of Sericultural and Entomological Science
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• v.35 no.2
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• pp.93-99
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• 1993

Studies were carried out to investigate physiological and biochemical analysis of recessive lethal mutant "nmn" and to observe the cuticle formation and dermal gland. All nmn homozygous larvae continued to eat a few mulberry leaves, and died without entering into molt. In case of artificial hatching, eggs had a higher nmn individual segregation ratio than in hibernating eggs. The percentage of nmn individuals with the hatching days was alike during 3days period. As a result of histological observation, nmn mutants dermal gland was different from normal dermal gland in form and size. Normal was formed new cuticle in the middle of the molting, but not in nmn mutant. Total protein content in haemolymph of the normal larva was more than that of nmn smutant and there was a difference between normal and nmn mutant protein components.omponents.

• Journal of Sericultural and Entomological Science
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• v.33 no.2
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• pp.72-74
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• 1991

The recessive lethal mutation 'non-molting of Nho' (symbol, ㎚n) was founded on one preservation stocks. All dwarf larvae continued to eat a few mulberry leaves and very slightly increasing body-size over a 7 days, and then died without entering into molt. Linkage experiments showed that ㎚n was linked with Knob(K) on the 11th linkage group. Precise localization of the gene was performed by mating with ㎚ gene. This mutant was confirmed to be allelic with the ㎚ gene located on the same chromosome.

• Korean Journal of Poultry Science
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• v.34 no.3
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• pp.197-205
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• 2007

This study was conducted to compare the effect of feeding molting and fasting molting on the performance, egg quality, and visceral organs in laying hens for animal welfare. Eighty one 62-wk-old White Leghorn hens that egg production was over 80% and average weight was $1.6{\pm}0.3\;kg$ were used in this study. Treatments were control (non-molt treatment), feeding molt treatment, and fasting molt treatment. The three treatments were administered to three replicate group of nine hens wherein each group. All treatment groups were fed the basal diet (CP 15%, ME 2,700 kal/kg) for two weeks as the adaptation period. Induced molt diets contains low CP (6.7%) and low energy (2,200 kal/kg). Test periods were 14 days for feeding molting and 10 days for fasting molting. Egg production decreased to be 0% at 10 days of feeding molting treatment, but at 2 or 3 days of fasting molting treatment. Egg production restarted after 19 days ending molt at feeding molting treatment, while after 24 days at fasting molting treatment. On the egg quality was improved at molting treatments (p<0.05) except egg yolk. Egg shell tissue was crowded at molting treatment to compare to control. Liver weights, heart weight, and oviduct weight of laying hens decreased at molting treatments (p<0.05). Finally, feeding molting might could be replaced fasting molting on the welfare and further studies were needed about molting program.

• 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.

• 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.

• Korean Journal of Poultry Science
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• v.38 no.3
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• pp.205-211
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• 2011

This work was carried out to investigate the effect of the induced molting diet based on wheat bran on the postmolt performance of layers. Two hundred White Leghorn layers (65-old-wk) with over 80% egg production were used for 8 weeks in this work. Treatments were non-molt control (CO), fasting treatment for 10 days (FW), molt treatment with used molting diet for 4 wk (UM), molt treatment with molting diet based on corn-wheat bran for 4 wk (CW), and molt treatment with molting diet based on wheat bran for 4 wk (WM) as 5 treatments (4 replications/treatment and 10 birds/replication). Feed intake decreased at molting treatments at first weeks and increased after the 3rd week compared to control (P<0.05). Body weight (BW) loss were 18.6% of initial BW at first week in FW treatment, and were 11.4, 14.2 and 17.4% in UM, CW and WM treatments at 4th weeks (P<0.05). Egg production decreased at 1 week in molt treatment and stopped at 2 week in FW, whereas, other molting treatments didn't stop laying eggs. The birds started to lay egg at 4 week in FW and recovered at 5 week in other molting treatments. Egg quality (eggshell thickness, eggshell breaking strength, haugh unit) was high in molting treatments compared with control at 8th weeks (P<0.05). Finally, molting diet based on wheat bran affected BW loss and egg quality such as eggshell thickness, eggshell breaking strength and haugh unit.