• 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.

• 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.

• 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.

• 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.

• 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.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.953-958
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• 2008

The object of this study was to investigate the immune-enhancing effects of Chlorella vulgaris (CV) on a deteriorated immune function by a protein-energy malnutrition (PEM) diet. Unicellular algae, CV were used as a biological response modifier. Male C57BL/6J mice were fed for 15 days with standard diet or a PEM diet, which is associated with decreased host immune defense. After 8 days, mice in the PEM diet group were orally administered by 0.05, 0.1, and 0.15 g/kg body weight of CV or distilled water. Nutritional parameters, and interferon (IFN)-$\gamma$ levels were significantly increased in the blood serum of the CV (0.15 g/kg)-treated group (29.6$\pm$2.8 pg/mL) compared to the non-treated PEM group (4.1$\pm$0.4 pg/mL, p<0.05). In addition, cell proliferation and production of cytokines were investigated via a CV (0.01, 0.1, and 1 mg/mL) treatment using a human T cell line MOLT-4 cell. The CV treatment (1 mg/mL) significantly increased the production of both IFN-$\gamma$ and interleukin (IL)-2 (51.3$\pm$3.4 and 285.9$\pm$18.8 pg/mL, respectively) compared to the control (51.3$\pm$3.4 and 442.6$\pm$14.3 pg/mL, respectively), but did not affect the production of IL-4. These results suggest that CV may be useful in improving the immune function.

• Korean Journal of Poultry Science
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• v.29 no.4
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• pp.243-247
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• 2002

A study was conducted to investigate the effect of induced molting on the relative weight and hormone levels of thyroid, ovary, and adrenal glands in spent laying hens. Three hundred sixty 77-wk-old, Babcock White hens were divided into 36 experimental units of 10 hens each and induced to molt for seven weeks. A diet containing 16% CP and 2,800 kcal ME/kg was fed ad libitum from 84 to 126 weeks of age. Thirty-six birds were randomly selected for blood collection and slaughtered at Pre-molt, 5% egg Production, Peak, and end Phase of the egg Production. Weights of the thyroid, ovary, adrenal glands, and plasma T3, T4, cortisol, and estradiol contents were measured at each stage. Weight of the thyroid reached its highest level at 5% e99 Production stage. The ovary weight was greatly reduced during molting, but started to increase after induced molting until the end of the egg Production Phase (P<0.05). Plasma T3,T4 and cortisol were found to be the highest at the start of the Post-molt Production stage, but reached their minimum at the end Phase of e99 Production. Plasma estradiol was the lowest at the 5% egg Production stage. The Present study demonstrated that molting is a complex Process that require the involvement of endocrine glands to trigger their specific hormones, which play a key role in molt induction.

• 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 Poultry Science
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• v.36 no.2
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• pp.117-123
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• 2009

This work was conducted to evaluate the effects of induced-molting methods on visceral organs and blood stress indicators in laying hens. One hundred fifty of 63-wk-old White Leghorn hens, with over 85% of egg production and $1.7\;{\pm}0.4\;kg$ of average weight, were used in this study. Treatments were control (non-molt treatment), feeding molt treatment (FM), and starving molt treatment (SM). There were 5 replicates of 10 hens for each treatment. All treatment groups were fed basal diet (15% CP and 2,700 kal/kg of ME) for two weeks as adaptation period. Heart weights were 8.2, 7.9 and 7.5 g in control, FM and SM, respectively. Liver and oviduct weights were decreased in both molting treatments compared with control (P<0.05). Corticosterone (CS) concentrations were 4.48, 4.47 and $4.66\;{\mu}g/mL$ in control, FM and SM at 61 weeks, respectively, but increased to 7.32, 7.11 and $7.71\;{\mu}g/mL$ at 62 weeks, respectively (P<0.05). Heterophil to lymphocyte ratios were 0.27~0.29 in all groups at 61 weeks, but increased to 0.97~1.03 in SM at 62 weeks. Both CS concentrations and H:L ratios in SM were greater compared with those for the other groups. These results suggest that hens in feeding molting program in hens are less stressed than those in starving molting one.