• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.687-694
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• 2018

This study was conducted to investigate the laying performance of six strains of Korean domestic chickens (KDC 1A, 2A, 3A, 1B, 2B and 3B). A total of 288 20-week-old KDC hens were allocated in a completely randomized design to give 12 replicates per each strain (4 chickens per pen). The chickens were fed commercial diets (i.e., week 20 - 32, crude protein [CP] 18.0% and metabolizable energy [ME] 2,850 kcal/kg; week 32 - 40, CP 17.0% and ME 2,800 kcal/kg) ad libitum together with fresh water during the 20-week experiment. Body weight, age of sexual maturity, egg weight, hen-day egg production (HDP) and feed conversion ratio (FCR) were measured during the experiment period (week 20 - 40). Our results show that strain 3B had an improved (p < 0.05) HDP and FCR compared with the other strains on week 24 - 28. However, strain 3A had an improved (p < 0.05) HDP and FCR compared to the other strains on week 28 - 40. Similarly, strain 3A had a higher egg weight (p < 0.05) compared to the other strains on week 28, 32 and 40. In conclusion, the higher laying performance of strain 3A indicates its potential in the development of a KDC strain with improved commercial laying performance.

• Korean Journal of Poultry Science
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• v.36 no.2
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• pp.125-131
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• 2009

This study was conducted to investigate the effects of dietary supplementation of mannan-oligosaccharides (MOS) and fructo-oligosaccharides (FOS) on the performance, immune response and small intestinal microflora in laying hens. A total of 960 Hy-Line $Brown^{(R)}$ laying hens of 27 wks old, housed in 2 bird cages, were assigned in a completely randomized block design into one of the following 6 dietary treatments: control, antibiotic (6 ppm avilamycine), 0.025% MOS, 0.05% MOS, 0.25% FOS, and 0.5% FOS. Each treatment had 4 replicates of 40 birds and was fed ad libitum for 6 wks under 16 h lighting regimen. There were significant differences among treatments in hen-day and hen-housed egg production. Hen-day egg production in 0.025% MOS was significantly higher than that of control. Hen-housed egg production in antibiotic-treated group was significantly higher compared with control. Egg weight, feed intake and feed conversion were not significantly different among treatments. Egg shell thickness was highest in 0.25% FOS, but was not significantly different among the rest of treatments. There were no significant differences among treatments in egg shell strength, egg shell color, egg yolk color and Haugh unit. IgG concentrations in serum were not significantly different among treatments. On the other hand, IgA concentrations of the treated birds tended to be increased compared with control. Dietary treatments tended to decrease Cl. perfringens and E. coli, and to increase Lactobacillus spp. The result of this experiment showed that dietary supplementation of MOS and FOS in laying hens tended to improve egg production comparable to the supplementation of antibiotics. The level of serum IgA and small intestinal microflora were also significantly affected by the treatments.

• Korean Journal of Poultry Science
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• v.23 no.1
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• pp.27-37
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• 1996

This experiment was carried out to study the effects of feeding split diets for a.m. and p.m. on laying hen performance and feed cost with 480 ISA Brown layers for three periods during 32∼36, 52∼56 and 72∼76 wk of age, respectively. The control group(C) was fed a conventional single diet throughout the day and split diet groups (T$_1$, T$_2$, T$_3$, T$_4$ and T$\_$5/) were offered high energy-high protein-low Ca diets, and low energy-low protein-high Ca diets in a.m. and p.m., respectively. In split diet groups, feed intake, ME and CP consumption, and feed cost were significantly reduced(P<0.05) compared to the C, while the hen-day egg production was significantly improved. However, the average egg weight was not influenced by the feeding system. Due to the reduced daily feed, ME, and CP intakes, and the improved egg production, the conversions of feed, ME, CP, and feed cost required per kg egg mass were also significantly improved (P<0.05) in splits diet groups. Among split diet groups, the T$_2$ group fed the diet devoid of Ca supplement from the conventional laying hen diet in a.m., and the diet containing the Ca supplement 2 times the conventional diet in p.m., was superior in conversion of nutrients and feed cost per kg egg mass to the other split diet groups. It was concluded that daily feed and nutrients cousumption and daily feed cost could be reduced 5∼6％ while hen-day egg production could be improved about 4％, so that about 10％ of the feed and nutrients and feed cost per kg egg mass could be spared by introducing the split diet feeding for a.m. and p.m. based on T$_2$ treatment in laying hens.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.5
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• pp.713-719
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• 2006

The effect of dietary iodine and selenium supplementation, alone or in combination, on peripheral blood lymphocyte function was determined in laying hens. Eight-hundred-and-sixty-four New-Loman laying hens were randomly allotted into 12 dietary treatments with different inclusion levels of iodine (0, 0.1 and 0.2 mg/kg), selenium (0, 0.05, 0.1 and 0.2 mg/kg) or their combinations for 24 weeks. The lipopolysaccharide (LPS) stimulation index, concanavalin A (ConA) stimulation index, peroxide enzyme activity and phagocytosis to neutral red particles were tested. There were significant differences in LPS stimulation index, ConA stimulation index, peroxide enzyme activity and phagocytosis to neutral red particles in different iodine or selenium supplementation levels (p<0.05). The highest iodine and selenium supplementation both resulted in highest LPS-/ConA-stimulation indices (p<0.05). However, when iodine was lower than 0.2 mg/kg, the additional effect of different levels of selenium did not always result in significant differences in these indices. The results indicated that iodine and selenium may affect immunity in laying hens and, when the iodine level in the laying hen is lower than 0.2 mg/kg, a selenium allowance higher than 0.1 mg/kg may be necessary to improve immunity.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.203-212
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• 2023

This study conducted a diallel-crossbreeding test using four Korean native chicken parent stock lines (YC, YD, CK, and CF) to develop a native commercial layer with high egg-laying performance. A total of 312 chickens in six combinations were examined for various traits, including livability, body weight, age at first egg-laying, hen-day, and hen-housed egg production, egg weight, and egg quality, from hatching to 60 weeks of age. The results showed that the average survival rate was 77.1±18.8% with the YDYC combination having the highest survival rate along with excellent specific combining ability. The YDYC combination exhibited significantly higher body weight compared to the other combinations (P<0.01). The average age at first egg-laying was 121.3±2.5 days, with no significant difference between the combinations. The average hen-day egg production was 74.0±6.4%, and the hen-housed egg production was 181.4±33.8 eggs with the YDCF and YCCK combinations demonstrating the highest laying performance, while the YDYC and CKCF combinations had the lowest (P<0.05). Laying performance was more influenced by specific combining ability than general combining ability. The eggs from the YDYC combination were significantly lighter and had the darkest shell color (P<0.01), whereas the YDCF combination exhibited the thickest eggshells. There was no difference in internal egg quality among combinations, except the YDCF combination had the darkest yolk color. Overall, we concluded that the YCCK combination, characterized by high laying performance and livability, and the YDCF combination with high laying performance and good egg quality are the most desirable combinations for Korean native commercial layers.

• Korean Journal of Poultry Science
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• v.42 no.1
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• pp.61-67
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• 2015

The objective of this experiment was to investigate the effect of dietary supplementation of herbal medication (HM) on laying performance, blood parameter, and immune response in laying hens. A total of 800 Hy-Line Brown laying hens of 60 weeks of age were randomly allotted to one of four dietary treatments with four replicates per treatment. Three additional diets were prepared by adding 0.5, 1.0 or 1.5 % of HM to the basal diet. Feeding trial lasted 7 weeks under 16L:8D lighting regimen. The diet and water were available ad libitum. Hen-day egg production in groups fed diets with 0.5% and 1.5% HM was significantly (P<0.05) higher than that of control. Feed conversion ratio in group fed diet with 0.5% HM showed the lowest value (P<0.05). Egg weight, feed intake, broken and shell-less egg production were not affected HM supplementation levels. Egg yolk color was significantly greater in all HM supplemented groups than basal treatment. However, eggshell strength, eggshell thickness, eggshell color, and Haugh units were not affected by HM supplementation level. There were no differences in leukocyte counts among the treatments. Plamsa IgM concentration was (P<0.05) higher in all HM treated groups. In conclusion, dietary HM improved egg production, and IgM of laying hens.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.151-156
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• 2012

Studies of non-cage or alternative systems have been discussing in EU because the EU has banned use of conventional cages for laying hens since 2012. This survey was carried out the information related to laying hens' welfare in Korea. Laying hens' breeding systems divided into deep litter, free range and alternative system, and livestock housings divided into windowless housing and open-type housing. The ratios of trough and bell feeder types were 37.5% and 62.5%, respectively. The ratios of nipple, trough, and bucket in waterer types 75%, 12.5%, and 12.5%, respectively. What stocking density is the most appropriate for production and welfare has been aroused. All laying hen farms met the required standards of stocking density ranged from 3.4 birds/$m^2$ to 7.6 birds/$m^2$ in this survey. According to welfare standards for laying hens, perch length should not be less than 15 cm. However, most laying hen farms did not satisfied the standards. We believe that presentdata contribute to develop alternative systems and to improve animal welfare in Korea.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.8
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• pp.1174-1178
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• 2006

An experiment was conducted to investigate the effects of dietary supplementation of copper chelates in the form of methionine, chitosan and yeast on the performance of laying hens. Four hundred ISA Brown layers, 84 wks old, were assigned to 4 treatments: control, 100 ppm Cu in methionine chelate (Met-Cu), 100 ppm Cu as chitosan chelate (Chitosan-Cu) and 100 ppm Cu as yeast chelate (Yeast-Cu). Each treatment had five replicates of 20 hens. Hen-day and hen-housed egg production and egg weight were significantly (p<0.05) increased by Met-Cu supplementation. The increase by Chitosan-Cu and Yeast-Cu supplementation was not significant. Contrast of the control vs. Cu chelates showed egg weight was significantly (p<0.05) increased by Cu chelate supplementation. Soft-shell egg production was significantly (p<0.05) reduced by supplementation of Cu chelates. Met-Cu treatment showed the lowest incidence of soft egg production. Gizzard erosion index was increased by Cu chelate supplementation. Crude fat in liver, total cholesterol in yolk and Cu content in liver and yolk were not significantly influenced by Cu chelate supplementation. It was concluded that dietary supplementation of 100 ppm Cu as Met-Cu significantly increased egg production and egg weight. Cu-Met chelate was also effective in reducing soft-shell egg production but increased gizzard erosion index.

• Korean Journal of Veterinary Service
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• v.29 no.1
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• pp.65-70
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• 2006

In order to detection of the intestinal parasites, fecal samples were taken from broiler (n=290), parent stock (n=168) and laying hen (n=114) in Jeonbuk province. The prevalence and identification of intestinal parasites were determined by the fecal examination using the floatation method and microscopical examination, respectively. The detection rate of parasite-eggs from 3 flocks (total=572) was 44.9%. In the breed and type of breeding, infection rate of parasite-eggs was detected 65.5% as broiler (floor breeding, 290 chickens), 20.2% as parent stock (floor breeding, 168 chickens) and 28.9% as laying hen (cage breeding, 114 chickens), in order. In the concern of mixed infection such as single and double, the rate were 40.7% and 4.2%, respectively. Six kinds of infective eggs were isolated 257 fecal sample from 3 flock. They were classified 74.7% as Eimeria spp, 18.1% as Ascaridia galli and 6.0% as Capillaria spp and 0.4% as Heteratkis gallinarum, Railleina spp or Trichostrongylus spp, single or in combination.

• Korean Journal of Veterinary Service
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• v.16 no.1
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• pp.82-89
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• 1993

In order to detection of the intestinal parasites, fecal samples were taken from broiler (n=262), laying hen(n=244), parent stock(n=207) and native stock(n=287) in Chonbuk province. The prevalence and identification of intestinal parasites were determined by the fecal examination using the floatation and /or sedimentation methods and microscopical examination, respectively. The results were obtained as follows : 1. The detection rate of parasite-eggs from 4 flocks(total=1,000) was 65.7%. 2. In the breed and type of breeding, infection rate of parasite-eggs was detected 84.0％ as native stock (floor breeding, 241 chicken), 79.7％ as parent stock (floor breeding, 165 chickens), 73.3% as broiler(floor breeding, 192 chicken) and 24.2% as laying hen(cage breeding, 59 chicken), in order. 3. In the concern of mixed infection such as single, double and triple, the rate was 55.1%, 8.7% and 1.9%, respectively. 4. Ten kinds of infective eggs were isolated from 657 fecal sample of 4 flock. They were classified 51.l% as Eimeria spp., 12.7% as Ascaridia galli, 5.1% as Capillaria spp., 4.1% as Strongyloides avium, 2.3% as Heterakis gallinarum, 0.5% as Hymenolepis spp., 0.3% as Railleina spp. and 0.2% as Syngamus spp., Trichostrongilus spp., or Choanoteania spp., single or in combination.