• Journal of Animal Science and Technology
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• v.53 no.5
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• pp.481-487
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• 2011

Rearing density is a major factor in welfare production and health of broiler chicks. An experiment was conducted to investigate the effect of rearing density on the behavioral characteristics of Korean native chicks. In the study, 20, 30, and 40 chicks per pen (3.17 $m^2$) were used in each treatment and randomly allotted to 6.3 bird/$m^2$, 9.5 bird/$m^2$, and 12.6 bird/$m^2$ density, respectively. The broilers' behavior was recorded for 12 hours continuously during 1 to 8 weeks of age. The time budgets (standing, sitting, and walking) and frequencies of certain behaviors (drinking, feeding, preening, scratching, dust bathing, flapping, aggressive pecking, and pecking) in the broilers were checked during the day. The behavioral characteristics in the early period (1 to 4 weeks) were compared to the later period (5 to 8 weeks) to know the changes in each behavior as the chicks matured. It was observed that 40 chicks per pen showed significant decrease in feed intake and body weight. Corticosterone hormone was higher in the order of 12.6 bird/$m^2$ > 9.5 bird/$m^2$ > 6.3 bird/$m^2$ (p<0.05). The behaviors of standing and sitting were the highest in groups of 30 and 40 respectively. The walking behavior was gradually decreased as rearing density increased. The frequencies of the other behaviors also decreased in a high density treatment; especially for feeding, drinking, preening, and pecking. These tendencies widened the gaps of behaviors as time passed. It was concluded that a group of 20 chicks (6.3 bird/$m^2$) was the proper rearing density among these three treatments. Broilers in the lower rearing density showed more activity than that with higher density and therefore this environment may lead to better welfare condition.

• Journal of Environmental Science International
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• v.24 no.3
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• pp.323-328
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• 2015

This study aimed to investigate the effects of dietary supplementation of mixed probiotics on growth performance and fatty acid profiles of Korean native chicken and to provide information regarding producers. Ninety six Korean native chicken (48 males and 48 females, Hanhyup-3-ho) were allocated to 16 wire cages with 4 treatments, 4 replicates and 6 chicks (3 males and 3 females) per wire cage and fed one of four diets containing 0, 0.5, 1 and 1.5% mixed probiotics for 6 weeks. There were no differences among treatments in growth performance of Korean native chicken. For fatty acid profiles, no statistically differences in each fatty acid, total saturated fatty acid and unsaturated fatty acids were observed in all treatments. In the present study, irrespective of statistically differences, inclusion of mixed probiotics tended to improve growth performance, reduce saturated fatty acid and increase unsaturated fatty acids in breast muscles from Korean native chicken compared to controls.

• Journal of Animal Science and Technology
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• v.54 no.4
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• pp.267-274
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• 2012

The method of sexing based on differences in the rate of feather growth provides a convenient and inexpensive approach. The locus of feather development gene (K) is located on the Z chromosome and can be utilized to produce phenotypes that distinguish between the sexes of chicks at hatching. To establish the auto-sexing native chicken strains, this study analyzed the genotype frequency of the feathering in domestic chicken breeds. The method of classification of slow- and rapid-feathering chickens was also investigated. In the slow-feathering chicks, the coverts were either the same length or longer than the primary wing feathers at hatching. However, the rapid-feathering chicks had the primary wing feathers that were longer than the coverts. The growth pattern of tail feather also distinctively differed between the rapid- and slow-feathering chicks after 5-days. The accuracy of wing feather sexing was about 98% compared with tail sexing. In domestic chicken breeds, Korean Black Cornish, Korean Rhode Island Red, and Korean Native Chicken-Red had both dominant (K) and recessive ($k^+$) feathering genes. The other breeds of chickens, Korean Brown Cornish, Ogol, White Leghorn, Korean Native Chicken-Yellow, -Gray, -White and -Black had only the recessive feathering gene ($k^+$). Consequently, feather sexing is available using the domestic chicken breeds. Establishing the maternal stock with dominant gene (K-) and paternal stock with recessive gene ($k^+k^+$), the slow-feathering characteristic is passed from mothers to their sons, and the rapid-feathering characteristic is inherited by daughters from their fathers.

• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.399-405
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• 2009

Two experiments were conducted to establish the basic data of feeding system in cross-bred Korean native chicks. A total of seven hundred twenty chicks were replaced the 36 floor pen for the first five weeks with $3{\times}3$ factorial design in Experiment 1. Four hundred eighty of five weeks old chicks were raised from six to ten weeks of age with $3{\times}2$ factorial design in Experiment 2. Dietary ME and CP were formulated to contain 3,000, 3,050, 3,100 kcal/kg and 21, 22, 23%, respectively in Experiment 1 and 3,050, 3,100, 3,150 kcal/kg and 18, 19% in Experiment 2. Weight gain, feed intake were measured and calculated the feed conversion. Blood were collected and analyzed at the end of experiments. In Experiment 1, weight gain showed significantly higher in 3,050, 3,100 kcal/kg treatments than 3,000 kcal/kg treatment (P<0.05), but was not different in CP treatments. Feed intake was statistically high in 3,000 kcal/kg treatment compared with 3,050 and 3,100 kcal/kg ones (P<0.05), and more increased in 21% CP treatments compared to that of 22 and 23 CP treatment (P<0.05). Feed conversion of birds fed 3,050 and 3,100 kcal/kg diet showed much lower than 3,000 kcal/kg treatments (P<0.05). FCR was signicantly improved (P<0.05) in chicks fed diets containing 21 and 22% CP as compared to that fed 20% CP. Blood protein, glucose, and total cholesterol tended to increase in high energy and diet treatments. Blood HDL was increased as dietary energy increased, whereas LDL increased in low CP treatments. In Experiment 2, weight gain was not consistent between treatments, but more increased in 18% CP treatments compared to that of 19% CP treatment from six to ten weeks old in cross bred chicks (P<0.05). Feed intake was similar to the result of weight gain, but more increased in 19% CP treatment than 18% CP treatment (P<0.05). There were no statistically difference in FCR, but seemed to improve as dietary ME increased. Blood total protein and glucose increased as dietary CP was high, but triglyceride and HDL increased in high versus low ME (P<0.05). The results of these experiments suggested that optimum dietary ME and CP, were 3,050, 3,150kcal/kg and 22, 19% for the first five weeks and second one, respectively.

• Korean Journal of Veterinary Research
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• v.42 no.1
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• pp.7-20
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• 2002

This study deals with the distribution and morphological study of the neurons with the neuropeptide Y (NPY) in developing chick brain. The developing brains of Korean native chicks at embryonic days 8 (E8), E10, E12, E14, E16, E18, and E20 were used. The chicks were perfused with 4% paraformaldehyde through the left ventricle and aorta. The brains were removed and transferred into 30% sucrose, and then cut in a cryostat into $60{\mu}m$ in thickness. The sections were immunostained with free-floating and avidin-biotin complex (ABC) methods. The numerous neurons with NPY were first observed in nucleus rotundus of diencephalon at E8. In particular, neurons in nucleus rotundus had the well-developed processes. At E12, the neurons with NPY were distributed widely in diencephalon; nucleus septalis lateralis, medialis, nucleus magnocelluaris preopticus dorsalis, medialis, ventralis, nucleus preopticus medialis, nucleus dorsolateralis anterior thalami pars magnocellularis, and nucleus paraventricularis magnocellularis (paraventricular nucleus) except nucleus rotundus. From E12 to E20, positive neurons were oval-shaped, changed gradually into the spherical- and multipolar-shaped. The shapes of processes were also omnidirectional and the number of those were less than in telencephalon. As the chicks developed, the morphology of neurons with NPY showed the tendency to increase in their sizes and numbers.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.171-178
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• 2021

A comparative study was conducted to examine the effects of mixed and separate gender feeding on growth performance of Korean native chickens (KNC) against a white semi-broiler (WSB) and a commercial broiler (CB) over five weeks. 576 chicks were used with eight birds per cage in a randomized complete block design with 18 replicates per breed. For the KNC lines, three groups of male (M), female (F) and mixed-gender (FM) were used. Fresh water and feed were supplied on an ad-libitum basis. Birds were fed a standard starter (d 1 - 22) and grower diet (d 23 - 35). Body weight (BW), feed intake, and shank length (SL) were measured weekly. From the BW and feed consumed data, the average daily feed intake (ADFI), average daily gain (ADG), and feed conversion ratio (FCR) were calculated. The commercial broiler showed higher performance (p < 0.05) for all the indices measured for the entire period. The CB group consumed more feed and were more feed-efficient thus grew faster. This group was followed by the white semi-broiler and the KNC, in order. An intra-breed comparison for KNCs revealed that the males showed better growth performance with longer SL (p < 0.05) compared to the female and mixed-gender groups. The results showed that other than the breed type, mixed and separate gender feeding impacted on the growth performance of the two lines of Korean native chickens. Males for both lines of KNC generally performed better for the parameters measured, as determined by a greater BW and reduced FCR.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.1033-1040
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• 2022

The current experiment was conducted to evaluate the effect of diallel crossbreeding on the body weight and laying performance of Korean native chicken from hatch to week 40. A total of 1,000 one-day-old chicks were allotted to 10 cages per crossbreeding treatment with 10 birds per cage on a random basis and then raised until 16 weeks and subsequently moved to layer battery cages and raised until 40 weeks. Ten crossbred treatments (YC, YD, YF, YK, CD, CF, CK, DF, DK, FK) that were obtained from the diallel crossbred of five pure lines were used in the current experiment. The body weight and mortality were measured biweekly from hatching to week 20 and every four weeks from week 20 to week 40. The number of eggs was measured daily. YC and YD crossbreeds showed a higher body weight (p < 0.05) and FK crossbreed showed a lower body weight (p < 0.05) during the whole xperimental period. The week 20 weight range was 1,501 to 1,729 g and the week 40 weight range was from 1,829 to 2,179 g. Earlier onset of egg-laying was noted in the YC and YD groups whereas late onset was observed for the DF and DK groups. YK reached its peak earliest at week 25 with 89.15% while the DK crossbreed attained its peak at week 36 with 89.69%. The YC and YD crossbreeds showed the improved body and egg-laying performance. Conclusively, there are variations in the body weight and laying performance of Korean native chickens with diallel crossing.

• Korean Journal of Poultry Science
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• v.45 no.3
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• pp.175-182
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• 2018

The carcass and meat quality of new native chicken strains (A, C, and D) being developed in the Golden Seed Project for Samgyetang were compared with a commercial native chicken (Hanhyup No. 3, H) and Baeksemi (white semi broiler, W) strains. In total, 250 male chicks were raised under the same feeding and raising conditions for 5 weeks. After slaughter, the carcass weight and percentage yield of parts from each strain were measured and the physicochemical quality traits (general composition, color values, fatty acid composition, and sensory evaluation) of breast muscles were comparatively analyzed. The carcass weight (875.10 g) of the W strain was significantly heavier than that of the other native chicken strains, while that of A strain (537.54 g) was the lowest. The percentage yield of breast meat was also higher in the W strain than in the other strains. The fat content of W strain was higher than that of the other native chicken strains. The new native chicken strains (A, C, D) had higher contents of linoleic acid (C18:2) than the H strain. The A and D strains especially showed relatively high content of arachidonic acid (C20:4), a characteristic fatty acid in native chicken meats. On the other hand, the fatty acid composition of C strain was similar to that of the W strain. This study provides important information on specific quality characteristics than can be used to select new native chicken lines for breeding program.

• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.65-71
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• 2024

The feather-sexing method is widely used commercially for chick sex identification. However, for feather-sexing to be industrially practical, the early-feathering (EF) and late-feathering (LF) genes must existed within the foundation stock, a suitable feather-sexing lines must be established, and the accuracy of sex identification by feather-sexing must be ensured. Therefore, this study introduces the method of constructing the Korean native chickens (KNC) feather-sexing lines using EF and LF genes and evaluates the effectiveness of feather sex determination on commercial chicks produced from the constructed KNC lines. The results showed that both EF and LF chickens existed within the foundation stock, with the frequency of LF genes ranging from 0 to 0.205. In feather-sexing line establishment, the paternal strain of the grandparent stock (GPS) was fixed as EF (kk) for both sexes, while the maternal strain was composed of males with LF homozygotes (Z^KZ^K) and females with EF (Z^kW). Thus, in the parent stock (PS), male breeder had EF (Z^kZ^k) and female breeder had LF (Z^KW), resulting in chicks produced from their crosses having LF (Z^KZ^k) for males and EF (Z^kW) for females, allowing sex determination based on feather development. Additionally, to evaluate the effectiveness of feather-sexing for the produced commercial chicks, a study was conducted on 1,000 samples of the produced chicks to investigate the concordance between vent-sexing and feather-sexing, showing a matching rate of 93.1%.

• Korean Journal of Agricultural Science
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• v.44 no.4
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• pp.566-573
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• 2017

The study was conducted to evaluate the growth performance, viability, and uniformity of female crossbred Korean native chickens (KNC) for the first twelve weeks after hatching. Six crossbreed lines of chickens (1B, 2B, 3B, 4B, 5B, and 6B) bred from 1 paternal line and 6 maternal lines of KNC were compared in this study. Sixty newly hatched 1-day old chicks from each crossbreed, for a total of 360 chickens, were allocated into 6 replicates (10 birds per replicate) in a complete randomized design. Experimental diets used in this study consisted of 3 phases: 1) week 0 to 5, crude protein 20.3% and metabolizable energy 3,059 kcal/kg; 2) week 5 to 8, crude protein 18.6% and metabolizable energy 3,123 kcal/kg; and 3) week 8 to 12, crude protein 16.7% and metabolizable energy 3,187 kcal/kg. Body weight and feed intake were measured bi-weekly during the experiment. The 4B crossbreed had a higher body weight, average daily gain, and average daily feed intake on week 12 (p < 0.05) than the other groups. The 4B crossbreed had a lower (p < 0.05) uniformity during weeks 10 to 12 than crossbreeds 1B and 5B. However, a lower viability was observed (p > 0.05) in 4B in weeks 2 to 12 than those in the other groups. Results of the current study indicate that the 4B crossbreed had a higher growth performance in week 12 but had a lower viability for weeks 2 to 12 than the other crossbreeds.