• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.57-63
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• 2024

As global warming worsens, it is feared that higher ambient temperatures and relative humidity might result in a more intense heat stress for livestock animals, especially broilers, which lack sweat glands for thermoregulation and have been selectively bred for rapid growth. Therefore, strategic livestock management is needed to mitigate the adverse effects of heat stress on broilers. In Korea's poultry farming systems, tunnel-ventilated broiler houses and pad cooling systems are commonly installed to lower indoor temperatures during the summer. However, caution is advised with pad cooling systems as they can increase the humidity inside the houses, potentially causing further harm. This study aimed to evaluate the effectiveness of pad cooling systems in tunnel-ventilated broiler house by assessing the reduction in indoor temperature using the Temperature-Humidity Index (THI), which accounts for the impact of relative humidity. Temperature and humidity data were collected during the summer (Jun to Sep) from eight farms with tunnel-ventilated broiler house located in different regions of Korea. The farms were divided into two groups based on the use of pad cooling systems is used, and temperature and humidity data, along with THI values, were analyzed two weeks before the birds were marketed. Meta-analysis results showed that at the hottest time of the day, 14:00, farms with pad cooling systems had significantly lower indoor temperatures compared to the control group, but observed an increase in indoor temperatures by 16:00 (p<0.05). There is no significant difference in relative humidity (p>0.05). The THI values decreased in the treatment group with cooling pads compared to the control group starting from 15:00, suggesting a diminished effect (p<0.05). This study indicates the potential for developing optimal operational guidelines for cooling pads to reduce heat stress in broilers during the summer season.

• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.83-95
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• 2024

This study aimed to assess the performance of laying hens across twelve crossbreed strains (i.e., CFCK, CFYC, CFYD, CKCF, CKYC, CKYD, YCYD, YCCF, YCCK, YDCF, YDCK, and YDYC) of Korean native chicken (KNC) and compare them with Hy-Line Brown layers. A total of 287 18-week-old laying hens were placed in battery cages by strains (2-5 birds per pen). Results indicated that the YCYD and YDYC strains exhibited numerically heavier body weights than Hy-Line Brown at week 18-64. CKYC and YDYC strains demonstrated more than 94% viability by week 64. The CFYC strain had an age of first egg laying of 127 days, and the YDCF strain reached an age of 50% egg production at 140 days, both earlier than their parent stock. The YDCF strain showed over 70% egg production for up to 60 weeks. Regarding egg quality, the CKCF and YCCF strains had numerically higher egg weights among the KNC groups at week 24-64, with the YDYC strain showing a darker (P<0.05) eggshell color compared to CKCF at week 40. Moreover, KNC crossbreeds showed a higher (P<0.05) egg yolk ratio than Hy-Line Brown. In conclusion, the YDCF and YCCF crossbreeds exhibited the most desirable new synthetic Korean native commercial layer based on egg production and quality parameters. Therefore, these strains could be a viable substitute for Hy-Line Brown layers.

• Korean Journal of Poultry Science
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• v.45 no.3
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• pp.219-228
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• 2018

This study was conducted twice to investigate egg purchase behavior and perception on animal welfare of Korean consumers. This study included women, who were the main decision makers and caretakers in the household, and men with one-person household. This survey was conducted with by the Computer Assisted Web Interview and Gang Survey methods. On the key considerations factor, the highest response rate was considered to be 'price', and the response rate of considering 'packing date' increased in the second survey. At a reasonable price based on 10 eggs, the response rate was the highest at 53.8% and 42.9% in both the first and second surveys and the appropriate price averages were 2,482 won and 2,132 won, respectively. The highest rate of purchase of egg consumers from 'Large Mart' followed by 'Medium sized supermarket' and 'Chain supermarket'. As for the awareness about animal welfare, the recognition ratio (73.5%) was higher in the result of the second survey than the first. The cognitive period of animal welfare was 59.0% before the insecticide egg crisis and 41.0% thereafter. Regarding whether or not they have ever seen an animal welfare certification mark and an animal welfare animal farm certification mark, 59.6% of respondents said that they saw it for the first time and 37.6% answered that they knew the animal welfare certification mark. On the animal welfare system, the 'free-range' response rate was the highest at 85.8%. The 'free-range' fit response decreased by 34.2%p, while the 'barn' and 'European type' fit response increased by 13.2%p and 24.1%p, respectively. The number of 'I have never seen' and 'I have ever eaten' responses to the recognition and eating experience of animal welfare certified eggs decreased while the number of those who answered 'Have ever seen' and 'Have eaten' increased. The answer of purchasing animal welfare certified eggs at department stores, organic farming cooperatives, and internet shopping malls was higher than that of buying conventional eggs. Of the total respondents, 92.0% were willing to purchase an animal welfare egg before the price was offered, but after offering the prices of animal welfare eggs, the intention to purchase was 62.7%, which was about 30%p lower than before. The reason for purchasing an animal welfare certified egg was the highest score of 71.0% for 'I think it is likely to be high in food safety', and 38.1% for 'I think the price is high' for lack of intention to purchase. In the sensory evaluation of animal welfare eggs, egg color and skin texture of conventional eggs were significantly higher than those of certified welfare eggs (P<0.05), and boiled eggs showed that egg whites of animal welfare certified eggs were more (P<0.05). As a result, the results of this study will contribute to the activation of the animal welfare certification system for laying hens by providing basic data on consumer awareness to animal welfare certified farmers.

• Korean Journal of Poultry Science
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• v.12 no.1
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• pp.7-16
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• 1985

Present experiment was undertaken to compare the effects of two dietary fats whose free fatty acid content was quite different on performances and on meat quality of broilers. Yellow grease or animal fat (trade name) containing 15 or 38.6% free fatty acid, respectively, was added to the broiler starter and finisher diets at levels of 3.0 and 5,0%, respectively. A total of 108, day old, male Maniker(Chunho) broiler chicks was alloted to 3 dietary treatments with 3 replications per treatment and 12 chicks per replication Though control diet was not supplemented with fat, the three dietary groups were made isocaloric and isonitrogenous. All the chicks were ad libitum fed the test diets for 8 weeks. Feed intake and body weight were measured every other week. Shank color was measured at the end of feeding trial by Roche Color Fan. To evaluate meat quality, 7 chicks of mean body weight were selected from each treatment group after the trial. Measurements were made for abdominal fat content, organoleptic scores for thigh and breast, and for contents of total lipids, free fatty acids, iodine values and peroxide values of the breasts. During the period from 0 to 4 weeks of age, the broilers fed the diets added with fats performed the same as those fed the control diet. However, the body weight gam (25%), feed intake (10.8%) and feed efficiency (11.3%) of chicks fed the fat-supplemented diets, during the finisher period (5-8 weeks), appeared significantly improved compared to those of control group (p＜0.05). During overall period of 8 weeks, body weight gain, feed intake, and feed efficiency of chicks fed the diets added with fats were, on the average, 16.2. 8.8 and 6.8%, respectively, better than, those of control Monwhile the performance between the chicks fed diets added with the two different fat sources appeared to be of the same tendency. Though the shank pigmentation was not statistically different among the treatments, the chicks fed the fat-supple ented diets tended to have slightly less pigments than the control. Organoleptic scores of thigh or breast of chicks fed the animal fat diet were of the same range as those of the other two groups. The contents of total lipids, free fatty acids, iodine values and peroxide values of breasts from broilers fed the various diets appeared to be in the same ranges among the treatments. The values for control, yellow grease and animal fat groups were 7.77, 6.66 and 6.32% for total lipids, 9.23, 9.7 and 9.31mg oleic acid/g fat for free fatty acids, 65.36, 63.89 and 59.25g/ 100g fat for iodine values, and 9.62, 10.46 and 8.79 meq/kg fat for peroxide values, respect vely. Changes of free fatty acids contents of breast during a storage for 10 da s at 4$^{\circ}C$ were also not different among the dietary groups. From the observations n. this experiment, it seems possible to conclude that the animal fat containing 38.6% free fatty acid can be used as efficiently as yellow grease in broiler diets without any adverse effects on meat quality.

• Korean Journal of Poultry Science
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• v.29 no.3
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• pp.195-204
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• 2002

Two experiments were conducted to study the effects of nutrient level and feeding method of split diets for a.m. and p.m. on laying hen performance, feed cost and eggshell quality. In experiment 1, 384 ISA Brown layers of 30∼38wk of age were assigned to four treatments which comprise of three replicates each containing 32 birds. The control(C) was fed a conventional single diet throughout the day and split diet groups(T1, T2 and T3) were offered high energy/protein-low Ca diets, and low energy/protein-high Ca diets in a.m.(04:00∼15:00) and p.m.(15:00∼21:00), respectively. In the split diet groups, daily ME and CP consumption, and feed cost were significantly reduced(P<0.05) compared to the C, while the hen-day egg production, average egg weight and daily feed intake were not different among treatments. Due to the reduced daily ME and CP intakes and feed cost, the conversions of feed, ME, CP and feed cost required per day and per kg egg mass were also significantly improved(P<0.05) in the split diet groups. Eggshell qualities (egg specific gravity, egg breaking strength and eggshell thickness) were improved(P<0.05) by split diet feeding. As the Ca level of the p.m. diet increased. In Experiment 2, 384 ISA Brown layers of 50∼58 wk of age were used in three treatments and each treatment was represented by four replicates each containing 32 birds. The control(C) was fed a conventional single diet throughout the day and split diet group(T1) was offered high energy/protein-low Ca diets, and low energy/protein-high Ca diets in a.m.(04:00∼l5:00) and p.m.(15:00∼21:00), respectively. T2 group was fed the diet mixed (50:50) with the a.m. diets in mash and p.m. diet in pellet used T1 group. In T1 and T2 groups, daily feed intake and average egg weight were significantly reduced(P<0.05) compared to the C, while the hen-day egg production was not influenced by the feeding system. Daily ME and CP consumption, and feed cost were reduced(p.0.05), and the conversions of ME, CP and feed cost required per egg were also significantly improved(P<0.05) in T1 and T2, while the conversions of feed, ME, CP and feed cost required per kg egg mass were not different to the C. Eggshell qualities of T1 and T2 were improved(P<0.05) compared to the others. It was concluded the feed and nutrients consumption, feed cost per day or per kg egg mass could be reduced by introducing split diets for a.m. and p.m. and the feeding method of mixed diet of split diets were also convenient and effective for sparing feed cost and improvement of eggshell quality.

• 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.18 no.3
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• pp.197-208
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• 1991

This study was conducted to estimated the genetic and phenotypic correlations between economic traits and certain other traits in Korean Native Ogol fowl The data analysis were the record of 450 pullets bred from 150 dams and 20 sires of Korean Native Ogol fowl at Chungnam National University from June 18, 1987 to April 6, 1989. The results obtained are summarized as follows ： 1 The genetic correlation coefficients of the economic traits and body shape components were as follows ： between body weight and shank length, breast width. breast girth, tibia length were 0.210~0.788, 0.231~0.826, 0.610~0.995 and 0.096~0.503 between age at first egg and shank length, breast width, breast girth, tibia length were 0.555~0.626, 0.149~0.270, 0.370~0.445 and 0.014-0.124. between number of egg production and shank length, breast girth, tibia length were -0.446~-0.167, -0.162~-0.320, 0.076~0.336 and 0.203~0.312 ： between egg weight and shank length, breast width, breast girth, tibia length were 0.132~0.498, 0.236~0.410, 0.148~0.775 and -0.019~0.593, respectively. 2. The genetic correlation coefficients of the economic traits and egg components were as follows ： between body weight and albumen weight, yolk weight, shell weight were 0.083~0.591, 0 110~0.541 and 0.336~0.782 between age at the first egg and albumen weight, yolk weight, shell weight were 0.476-0.692, 0.265~0.631 and 0.420~0.519 between number of egg Production and albumen weight, yolk weight, shell weight were -0.578~-0.240, -0.255~-0.060, -0.477~-0.313. between egg weight and albumen weight, yolk weight, shell weight were 0.825~0.939, 0.382~0.564, 0.374~0.337, respectively. 3. The genetic correlation coefficients of the economic traits and egg qualifies were as follows ： between body weight and egg shape index, shell thickness, albumen height, Haugh units were 0.215~0.367, 0.248~0.650, 0.161~0.624, 0.157~0.449. between number of egg production and egg shape index, shell thickness, albumen height, Haugh units were -0.384~-0.207, -0.557~-0.306, -0.555~-0.198, -0.582~-0.074 between egg weight and egg shape index, shell thickness, albumen height, Haugh units were 0.276~0.697, 0.290~0.627, 0.238~0.538, -0.207-0.020, respectively. 4. The genetic correlation coefficients of egg compositions and egg qualities were as follows ： between albumen weight and egg shape index, shell thickness, albumen height and Haugh units were 0.110~0.584, -0.380~-0.002, 0.239~0.887 and -0.195~0.279 ： between yolk weight and egg shape index, shell thickness, albumen height and Haugh units were -0.204~0.160, 0.294~0.133, -0.049~0.133 and -0.196~-0 136 ： between shell weight and egg shape index, shell thickness, albumen height and Haugh units were 0.127~0.503, 0.127~0.476, 0.140~0.273 and -0.172~0.233, respectively.

• Korean Journal of Poultry Science
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• v.13 no.1
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• pp.1-14
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• 1986

The subject of this study was to obtain some genetic information for developing superior layer chickens. Heterosis and combining ability effects were estimated with 5,759 progenies of full diallel crosses of 6 strains in White Leghorn. Fertility, hatchability, brooder-house viability, rearing- house viability, laying-house viability, age at 1st egg laying, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion were investigated and analyzed into heterosis effect, general combining ability, specific combining ability and reciprocal effect by Grilling's model I. The results obtained were summarized as follows; 1. The general performance of each traits was 94.76% in fertility, 74.05% in hatchability, 97.47% in brooder-house viability, 99.72% in rearing-house viability, 93.81% in laying-house viability, 150 day in the age at 1st egg laying, 1,505g in the body weight at 1st egg laying, 60.08g in average egg weight, 77.11% in hen-day egg production, 269.8 eggs in hen-housed egg Production, and 2.44 in feed conversion. 2. The heterosis effects were estimated to -0.66%, 9.58%, 0.26%, 1.83%, -3.87%, 3.63%, 0.96%, 4.23%, 6.4%, and -0.8%, in fertility, hatchability, brooder-house viability, laying-house viability, the age at 1st egg laying, the body weight at 1st egg laying, average egg weight, hen-day egg Production, hen-housed egg production and feed conversion, respectively. 3. The results obtained from analysis of combining ability were as follows ; 1) Estimates of general combining ability, specific combining ability and reciprocal effects were not high in fertility. It was considered that fertility was mainly affected by environmental factors. In the hatchability, the general combining ability was more important than specific combining ability and reciprocal effects, and the superior strains were K and V which the additive genetic effects were very high. 2) In the brooder-house viability and laying-house viability, specific combining ability and reciprocal effects appeared to be important and the combinations of K${\times}$A and A${\times}$K were very superior. 3) In the feed conversion and average egg weight, general combining ability was more important compared with specific combining ability and reciprocal effects. On the basis of combining ability the superior strains were F, K and B in feed conversion, F and B in the average egg weight. 4) General combining ability, specific combining ability and reciprocal effects were important in the age at 1st egg laying and the combination of V ${\times}$F, F${\times}$K and B${\times}$F were very useful on the basis of these effects. In the body weight at 1st egg laying, general combining ability was more important than specific combining ability and reciprocal effects, relatively. The K, F and E strains were recommended to develop the light strain in the body weight at 1st egg laying. 5) General combining ability, specific combining ability and reciprocal effects were important in the hen-day egg production and hen-housed egg production. The combinations of F${\times}$K, A${\times}$K, and K${\times}$A were proper for developing these traits. 4. In general, high general combining ability effects were estimated for hatchability, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion and high specific combining ability effects for brooder-house viability, laying house viability, age at 1st egg laying, hen-day egg production and hen-housed egg production, and high reciprocal effects for the age at 1st egg laying.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.171-179
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• 2006

Changes in the chicken testis from hatching to adulthood were studied in Korean native chickens of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 21, 24, 28, 32, 44, 52 and 64 weeks (n=13 chickens per group) of age. The present study was to investigate in more detail the post-hatching development of testis in Korean native chickens. Testes of chickens were fixed by whole body perfusion using a fixative containing 2.5% glutaraldehyde in cacodylate buffer, processed and embedded in Epon-araldite. Using $1{\mu}m$ sections stained with methylene blue-azure II, qualitative and quantitative(stereological) morphological studies were performed. Sperm production was measured by routine technique. The average volume of a testis of 1 week old Korean native chickens was determined as 0.015 g and the parameter increased linearly from 1 week to 21 weeks days (28.9 g), and did not change from 21 weeks to 64 weeks. The volume density of the seminiferous tubules increased with age from 32.6% at week 1 to 92.89% at week 64. The volume density of the interstitium represents 67.4% of the testicular parenchyma at week 1. This proportion progressively diminished during development to reach a value of 7.11% at week 64. Total sperm production per testis increased significantly from 18 weeks to 28 weeks and remained unchanged. Sperm production per 1 g testis increased significantly from 18 weeks to 28 weeks, did not change significantly from 28 weeks to 52 weeks, and declined significantly at 64 weeks of age. The average diameter of the seminiferous tubules gradually increased with age from 1 week $(42.4{\mu}m)$ to 21 weeks $(412.8{\mu}m)$. The length of the seminiferous tubules was 0.34 m at 1 week, increased significantly in subsequent age groups and reached 72.2 m by weeks 64. The stage of germ cell development in seminiferous tubules was classified as 1) spermatogonia $(1\sim8\;weeks)$, 2) spermatogonia and spermatocytes $(10\sim12\;weeks)$, 3) spermatogonia, spermatocytes and round spermatids $(14\sim16\;weeks)$, and 4) speramatogonia, spermatocytes, spermatids and spermatozoa $(18\sim64\;weeks)$. These results clarified the pattern of changes in the testicular development in Korean native chickens from hatching to adulthood as 1) neonatal-prepubertal $(1\sim12\;weeks)$, 2) puberty$(14\sim18\;weeks)$, and adult$(21\sim64\;weeks)$.

• Korean Journal of Poultry Science
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• v.37 no.1
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• pp.51-62
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• 2010

This study was conducted to investigate the effects of dietary supplementation of multiple probiotics on the performance, small intestinal microflora and immune response in laying hens and broilers. In Exp.1, a total of 800, 82 wk old Hy-line Brown$^{(R)}$ laying hens were assigned to one of the following five dietary treatment; Control, Antibiotics (avilamycin 6 ppm), Probiotics; PB-M (Micro-ferm$^{(R)}$ 0.2%), PB-L (Lacto-sacc$^{(R)}$ 0.1%), PB-Y (Y University probiotics 0.2%). Each treatment was replicated eight times with 20 birds in each replicate and two birds were housed in each cage. Twenty birds units were arranged according to completely randomized block design. Feeding trial lasted 6 wk under 16 h lighting regimen. The Exp. 2, was conducted with a total of 1,000 broilers chicks (Ross$^{(R)}$). They were divided into five treatments, same as those of Exp. 1. Birds were fed starter (0~3 wk) and grower (4~5 wk) diets. Each treatment was replicated four times with 50 birds per pen comprising of deep litter. In Exp. 1, egg production parameters, such as hen-day and hen-house egg production, egg weight, broken and soft shell egg production, feed intake and feed conversion were not significantly different among treatments. However, strength and thickness of eggshell were significantly (P<0.05) different. Among the probiotics, PB-Y showed the highest strength and thickness of eggshell. Eggshell color, egg yolk color and Haugh unit were not significantly influenced. In Exp. 2, overall weight gain (0~5 wk) and mortality were not significantly different among treatments. However, weight gain of birds from PB-Y treatment during starter (0~3 wk) was significantly lower than the birds from Control and Antibiotic treatment. During the whole period (0~5 wk), birds from Antibiotics treatment had higher feed intake and Production Index (PI) and lower feed conversion than birds from Control treatment. Probiotics treatments were not significantly different from the Control on feed intake and feed conversion. In Exp.1, there were significant (P<0.05) differences in leukocytes parameters, such as white blood cell (WBC), hetrophil (HE), lymphocytes (LY), monocyte (MO), eosinophil (EO) and stress index (SI; HE/LY) in the blood of layers. Birds from Antibiotics and probiotics treatments tended to increase these parameters. In Exp. 2, however, only SI was significantly (P<0.05) decreased in Antibiotics treatments. Concentration of serum immunoglobulin (IgG) were higher (P<0.05) in PB-M and PB-Y treatments when compared with Control treatment in Exp. 1. The population of E. coli significantly (P<0.05) decreased in birds from Antibiotics, PB-L and PB-Y treatments when compared with birds from Control treatment in Exp. 1. Metalbolizability of crude fat decreased significantly (P<0.05) in birds from probiotic treatments in Exp. 2. It was concluded that the response of probiotics on the productivity of layers and broilers were different. Probiotics increased strength and thickness of eggshell in layers, and decreased feed conversion and increased PI in broilers. Leukocytes and IgG tended to increase by supplementation of antibiotics and probiotics in layers. Intestinal E. coli tended to decrease in layers. Digestibility of crude fat of diet decreased in probiotics treatments broilers. Parameters of blood and microbial were more sensitive in layers than broilers.