• Korean Journal of Poultry Science
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• v.26 no.4
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• pp.247-252
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• 1999

This experiment was carried out to investigate the effects of the laying hens on the immune response against bovine serum albumin(BSA) in egg yolk. Total 45 laying hens were divided into three groups according to breeds (White Leghorn, ISA Brown, Native hen). They were fed the experimental diet for 12 weeks. Immune response were examind in egg yolk from three groups of hens injected with BSA. The results obtained from this work were summaried as follows : 1. The weight of egg yolk and the percentage of hen-day production in the ISA Brown hens are greater than those in the Native hens and the White Leghons. 2. IgY concentrations in eggs from hens immunized with BSA were not different among the breeds laying hens. 3. The anti-BSA antibody activities determined by enzyme linked immunosorbent assay (ELISA) in the egg yolk were similar between the White-Leghorn and ISA Brown hens, but Native hens tended to decrease in 20∼50 days respectively. Therefore, the weight of egg yolk and the percentage of hen-day production in the ISA Brown hens are greater than those in the Native hens and the White Leghons will be as important factors for an efficient production of IgY.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1080-1084
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• 1999

Carbon (C) and nitrogen (N) balance technique was used to determine energy balance in Rhode Island Red (RIR) and White Leghorn (WL) laying hens fed maize-and broken rice (BR)- based diets. Carbon and nitrogen intake and outgo were determined for three days on ad libitum fed diets followed by 2/3 of ad libitum intake for next three days. Carbon analysis was done by using four 'U' tubes in which carbon dioxide released during bomb calorimetry was absorbed on drierite in tube 1 and 2 whereas tube 3 and 4 contained sodalime self indicating granule. Carbon in $CO_2$ was determined by an open circuit respiration system. Energy retention (E, kcal) was calculated as E = 12.386 C (g) - 4.631 N (g). By regressing metabolisable energy (ME) intake on energy balance, maintenance ME requirement of RIR was 128 whereas, that of WL hens was $144kcal/kg\;W^{0.75}/d$. Effciency of utilization of ME for maintenance from BR-based diet in RIR hens was equal but in WL hens it was 11% less than maize-based diet.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.686-691
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• 2005

Prolactin is considered to influence the taking of pauses in between ovulatory sequences in White Leghorn hens. Therefore modulating concentrations of prolactin using bromocriptine - a dopamine agonist during early life (17 to 36 weeks of age) could overcome the inhibitory effects of high concentration of prolactin on ovarian activity. The effect of modulation of prolactin concentration on egg production, sequence length and inter sequence pauses were studied by analyzing the oviposition records from 19 to 72 weeks were studied and compared with untreated controls. Bromocriptine administered subcutaneously (100 $\mu$g kg$^{-1}$ body weight or orally through feed (640 $\mu$g day$^{-1}$ bird$^{-1}$) resulted in a steady and sustained decrease in prolactin levels (p<0.01) during and after the withdrawal of treatment up to one reproductive cycle (72 weeks of age). The treated birds had comparatively longer sequences (p<0.01) and fewer pauses (p<0.01). Egg production increased (p<0.01) by fourteen per cent through subcutaneous administration and eleven per cent through oral feeding, over the control birds. It is concluded that the physiological pauses that occur during ovulatory sequences can be disrupted effectively using bromocriptine. Prolactin levels are modulated which may interfere with the follicular recruitment and subsequent oviposition thereby improve egg laying potential of the bird.

• Toxicological Research
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• v.13 no.4
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• pp.317-322
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• 1997

Acute delayed neurotoxicity of KH-502 [O.O-Diethyl O-(1-phenyyl-3-trifluoromethyl-5-pyrazoyl) thiophosphoric acid ester], an insecticide synthesized newly in Korea, was studied in White Leghorn hens. The doses were determined on the basis of preliminary $LD_{50}$ study. High, middle and low doses were determined to be 1123 mg/kg, 762 mg/kg and 518 mg/kg, respectively. The animals were pretreated with atropine (30 mg/kg) prior to administration of KH-502. The chemical was administrated at the first and 21st day of the study. As positive controls, animals were admlnistrated with triorthocresylphosphate (TOCP 1000 mg/kg and 500 mg/kg). Animals administrated with TOCP or KH-502 were sacrificed by perfusion-fixation at 21st and 42nd day of the study, respectively. The central and peripheral nerve tissues were routinely treated for microscopic observation. As results, eight, three, one, and one chickens died within 2 day after adminiatration with signs of cholinergic acute toxicity in high, middle low and TOCP dose-group (500 mg/kg), respectively. No abnormal clinical signs were observed in the survived chickens administrated with KH-502 in the duration of the study. The chickens in positive control groups showed ataxia and incoordination at the 14th day after administration of TOCP. From necropsy, macroscopic changes were not observed in all groups including positive control groups. Histopathologically, oxonal swelling with myelin loss, focal gliosis, distention around axonal space were observed in the spinal cords of the chickens administrated with TOCP 1000 mg/kg. The lesions were distinct in the dorsal and lateral funiculi of cervical spinal cord, in the lateral and ventral funiculi of thoracic spinal cord and in ventral funiculi of lumbosacral spinal cord. Axonal swelling and mlcrogliosis were infrequently observed in the chickens of other groups including negative control one. However, they were nonspecifically distributed in the spinal cords. In this study, we concluded that the new chemical, KH-502 did not have acute delayed neurotoxicity in White Leghorn hens.

• 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.

• Korean Journal of Poultry Science
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• v.21 no.3
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• pp.183-193
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• 1994

White Leghorn hens were fed a commercial formula feeds as a basal diet, which was supplemented with 3 types of plant oil safflower, evening primrose and pine seed, at the 10% level for 3 weeks. No significant changes was found between the basal diet and the oil feeding trials in the egg yolk cholesterol content, the laying rate, the egg weight, and the yolk weight, except the feed intake. In the fatty acid composition of the egg yolk lipid, however, the plant oil feedings to hens resulted in considerable increase of $C_{18:2}$ acid with a simultaneous decrease of $C_{18:2}$ acid ,and, consequently, followed by the improvement of balance with P /S and P /M /S ratio close to 1.0 and 1:1:1, which is known a desirable ratio for human health in lipid nutrition, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.11
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• pp.1617-1621
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• 2002

Two hundred and sixteen single comb white egg layers of the White Leghorn hens of 24 weeks of age were randomly allocated to 12 groups with three replications of six hens in each. Hens were fed in a factorial arrangement 2${\times}3{\times}$2, on diets containing either 16 or 18% crude protein with 0, 3 or 6% fish meal, replacing groundnut meal with soybean meal. Soybean meal incorporation improved (p<0.05) egg production, feed intake, feed conversion efficiency and egg weights. Egg quality traits of specific gravity, shape index, albumen index, yolk index and shell thickness remained unchanged. Laying performance was significantly (p<0.05) better at 18% than on 16% dietary protein level. Use of fish meal linearly improved egg production and feed conversion efficiency on diets supplemented with groundnut meal and fish meal incorporation showed quadratic improvement on feed conversion efficiency with SBM diets at 16% dietary protein level. Therefore, use of soybean meal as substitute of groundnut meal is recommended in layer diets, at 16% dietary protein level and fish meal incorporation could be beneficial for layers.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.4
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• pp.524-530
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• 2012

Laying hens were fed commercial diets added with supplemented fat (SFAT) at 0.6, 1.2, and 1.8% in order to study the long term dietary effects - on - their productive performance from 22 to 75 wk of age. Five hundred and seventy six Single Comb White Leghorn hens were assigned to one of the four dietary treatments. The experimental phase consisted of three periods of 18 wk each. The final body weight and gain of hens fed on diets with SFAT at 1.2% and 1.8% were lower (p<0.05) than those hens given no SFAT. The SFAT at the 1.2% and 1.8% levels improved egg production rate, egg weight and mass, as well as FCR. Mortality and feed consumption were not affected by dietary SFAT. Administration of a diet with SFAT significantly decreased the cracked-broken egg ratio (p<0.01). The beneficial effects of SFAT on egg production performance were particularly more pronounced at intermediate and later ages. Hence, SFAT by period interactions were significant for all traits studied except feed intake. Hens fed SFAT deposited significantly higher abdominal fat than those on the no-SFAT diet. As a result, SFAT at 1.2% and 1.8% inclusion levels provided benefits in terms of efficient table egg production.

• Journal of Animal Science and Technology
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• v.55 no.2
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• pp.131-139
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• 2013

The aim of this study was to assess the effects of housing systems on physiological and immunological responses as stress indicators in laying hens. A total of 500 White Leghorn aged 16 weeks were allotted into ten conventional cages (10 birds/cage and 810 $cm^2$/bird) and four floor pens (100 birds/pen and 2,800 $cm^2$/bird) for 24 weeks. The hens housed in conventional cages with higher stocking density resulted in a significantly (P<0.05) lower BW compared with those housed in floor pens with lower stocking density without affecting the relative weights of immune organs between housing conditions. In plasma biochemical values, cholesterol and corticosterone were significantly (P<0.05) lower in the hens housed in floor pens compared with those housed in conventional cages. In pro-inflammatory cytokines, hepatic interleukin (IL)-10 and interferon-gamma (IFN-${\gamma}$) levels were significantly (P<0.05) higher in the hens housed in conventional cages compared with those kept in floor pens. Splenic and thymic IFN-${\gamma}$ expression was significantly (P<0.05) up-regulated in the hens kept in conventional cages compared with those kept in floor pens without affecting IL-1, IL-10, lipopolysaccharide- induced tumor necrosis factor-${\alpha}$ factor (LITAF) and inducible nitric oxide synthase (iNOS). In the bursa of Fabricius, IL-10 and iNOS expression of the hens housed in conventional cages were significantly (P<0.05) higher compared with those of the hens housed in floor pens. In conclusion, layers housed in conventional cages enhanced plasma cholesterol, corticosterone and some pro-inflammatory cytokines in the immune organs compared with those in floor pens.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.3
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• pp.173-178
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• 1988

To study the effects of utilizing extruded full fat soybean (FFS) in layer diets, 300 White Leghorn pullets were put in trial divided into 5 treatments; control (commercial soybean meal as protein source), FFS 50% (replacing 50% of soybean meal with FFS), FFS 100% (replacing all amount of soybean meal with FFS), soybean oil and tallow added treatment. Each treatment consisted of 5 replicates of 12 birds. Egg production and feed efficiency from hens fed control diet were significantly lower than from hens fed the other diets. Significant differences in egg production and feed efficiency were found between the control and the other treatments. Cholesterol concentration of serum and egg yolk were not affected by any dietary treatment. Feeding extruded full fat soybean did not cause pancreatic hypertrophy nor change in mortality. There was an indication that linoleic acid (C18:2), linolenic acid (C18:3) and iodine contents increased in the thigh and egg yolk lipid of the groups fed FFS or soybean soybean can serve as effective protein source for layer diets if economically justified.