Characterization of Phenotypic Variation in Indigenous Chicken Populations in Lower Northern Thailand to Improve Chicken Breeding

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Introduction
Te Tai government currently prioritizes grassroots economic development by harnessing the biodiversity within communities and localities.Tailand possesses strengths that allow it to compete with other nations, notably in terms of biodiversity and local wisdom [1].Native chickens in Tailand are acknowledged as a valuable biological diversity resource with commercial signifcance, refecting trends seen in other Asian countries.Poultry enthusiasts have raised these chickens for various purposes in roles spanning from food production and aesthetic appeal to exhibition.
Especially, chickens with traits suitable for cockfghting often command higher prices compared to general chickens.Hence, concerted eforts were undertaken to conserve native chicken breeds, preserving them for use in selection processes during breed improvement and development.Te conservation of native chicken breeds not only enabled local communities to achieve self-reliance but also enhanced their income, concurrently creating job opportunities for the people in the area [2].
To enhance the value of native chickens, two main avenues were explored: contests and cockfghting.Contests involved a standardized species selection process aimed at conserving native chicken breeds, with criteria contributing to a potential value addition of 40,000-100,000 Tai baht (THB average exchange rate 36 baht/1 USD).Developing breeds for cockfghting, on the other hand, required extensive knowledge of the advantageous physical characteristics of each breed.Te price of a cockfghting rooster was contingent on fght outcomes, ranging from 10,000 to 100,000 baht, with more victories resulting in higher fnancial gains [3].Tai wisdom defnes the Standard of Perfection, detailing fve crucial traits of exceptional fghting cocks.Tese include a distinguished, long, rounded face reminiscent of a peacock's visage, vibrant feathers enhancing brightness and ferceness, a well-proportioned body conveying balance, legs with neat scales and a strong spur, and adept posture involving standing, walking, running, wingfapping, and fearlessness among other chickens [4,5].
Uttaradit province in northern Tailand is well known for its crucial role in developing local chicken breeds, especially the Khiew Phalee fghting cock [6].Tis region hosts fve additional native chicken breeds, Tao Tong, Lueng Hang Khao, Chee, Pra Dhu Hang Dam, and Jae, serving as valuable economic assets.Each breed possesses distinctive traits: Khiew Phalee, lauded as the epitome of the Tai warrior chicken, distinguished by greenish-black feathers and unique features [7]; Tao Tong, with a tall, slender physique and white feathers, showcased captivating characteristics [4]; Lueng Hang Khao recognized for its white tail and yellow feathers, prominent in cockfghting and conservation eforts [8]; Chee, a visually striking variety with a slender physique and white plumage [4]; Pra Dhu Hang Dam, known for its parrot-like features and seamless integration of black coloring [2]; and fnally, Jae or Kai Tor-Kai Tang, a product of crossbreeding, displaying a tapestry of diversity with distinct phenotypic traits [9].
Moreover, the ongoing practice of crossbreeding has resulted in the emergence of chickens intended for cockfghting in the country, leading to a continuous increase in the number of Burmese and Vietnamese chicken breeds.Consequently, the population of native chickens in Tailand has declined, as well as causing the loss of some native chicken breeds or the unique characteristics of Tailand's Lueng Hang Khao [10].An illustrative example of the renowned Standard of Perfection for Tai fghting cocks is the white-tailed yellow chicken [4].It is worth noting that whitetailed yellow chickens exhibited diverse comb types, sometimes even displaying signs of crossbreeding with Burmese chickens, which underscored the shifts observed in Tai native chicken breeds.Consequently, the genetic merits of native chicken populations have been diluted due to the introduction of exotic breeds, a phenomenon observed in native chicken populations in various regions [11,12].
Previous data emphasized the morphological importance impacting the economic value and role in breed development of native chicken breeds in Tailand.However, it revealed a noticeable lack of comprehensive studies on both the qualitative and quantitative traits of these breeds.Te lack of information on phenotypic diversity presented a signifcant obstacle to the design of appropriate breeding programs.To address this gap, the primary objective of the study was to conduct a thorough morphological analysis, encompassing both quantitative and qualitative aspects, following the guidelines of the Food and Agricultural Organization (FAO) for the genetic characterization of chicken resources.Te study focused on six native chicken breeds, namely, Khiew Phalee, Tao Tong, Lueng Hang Khao, Chee, Pra Dhu Hang Dam, and Jae, all located in Uttaradit province.Te information gathered from the study raised awareness about the importance of conserving biodiversity and served as valuable data for selecting characteristics to develop breeds of Tai native chicken.

Study Site.
Te study was conducted in Uttaradit province, a historical city situated in the lower northern part of Tailand at coordinates 17 °37′ 23″ north latitude and 100 °5′ 45″ east longitude.Tis region is home to a population of approximately 454,007 people and spans an area of 8,353 square kilometers (Figure 1).Characterized by a tropical savanna climate, Uttaradit is predominantly an agricultural province.Te weather in this area exhibits an average daily temperature of around 27.5 °C [13].According to a 2023 report on livestock production in Tailand, Uttaradit province achieved the third rank in chicken production among nine provinces in the lower northern region.Te province played host to around 4.36 million chickens, cared for by 27,753 farmers.Noteworthy is the cultivation of 1.09 million native chickens, involving 27,515 chicken farmers.Te considerable volume of chickens, particularly the signifcant population of native breeds, and the participation of a substantial number of farmers highlight the economic signifcance of livestock production in Uttaradit [14].Terefore, this province was selected as the study area for examining phenotypic diversity in both qualitative and quantitative traits of these breeds.Tis research employed a mixed-method approach, combining quantitative and qualitative methodologies.Te objective was to gather data on both the quantitative and qualitative characteristics of six native chicken breeds in the study area.Te data collection methods included conducting interviews to gather basic information about chickens in two aspects: the name of the breed of chicken and the age of the chicken.Te collection of data was guided by the FAO [10], encompassing both qualitative and quantitative methods for chicken genetic resource characterization.Qualitative characteristics were observed and recorded by examining the unique shape and color of each external structure of the chicken.Quantitative data collection involved measuring external structures or organs.Data were collected from farms that raised native chickens throughout the period from June 2020 to May 2023.Due to the unpredictability of sample availability and the researcher's lack of knowledge about all farmers' locations, probability sampling was deemed limiting.Terefore, the sample selection in this study employed purposive sampling, a type of nonprobability sampling that enables a targeted approach aligned with the research objectives.Te decision-making process was grounded in the researcher's expertise and experience, with a primary focus on transparency to mitigate potential biases associated with the sample selection.Te application of clear inclusion and exclusion criteria contributes to the transparency of the sampling selection process.Te inclusion criteria for selecting chicken farms required each sample to include a minimum of fve native chickens, specifcally adult chickens aged seven months [15], with farm owners willing to cooperate in studying external morphology.Te exclusion criteria included any afliations between the sample group and the researcher, as well as individuals who were not willing to participate in the study.Te exclusion criteria included any afliations between the sample group and the researcher, as well as individuals who were not willing to participate in the study or were not domiciled in the study area.Data collection from the sample stopped after collecting twenty samples, resulting in a total study population of 134 native chickens (Table 1).qualitative and quantitative parameters adhered to the descriptors outlined by the Food and Agricultural Organization (FAO) for the characterization of chicken genetic resources [10].

Results
Te principal objective of this study is to expound upon the morphological traits of diverse native chicken breeds.Tis entails the characterization of both qualitative and quantitative parameters across six native chicken breeds in the Uttaradit province of Tailand, aligning with the descriptors outlined by the FAO for the genetic characterization of chicken resources [10].Te head of native chickens is often adorned with a distinctive comb, varying in both shape and size.Additionally, they possess expressive eyes that refect their alert and active nature.Te beak is typically strong and adapted to their foraging habits.A notable feature of native chickens is the diversity of their plumage colors and patterns.Te size and shape of their wings may vary, providing them with agility in movement.Native chickens exhibit a diverse array of physical characteristics, setting them apart from other poultry breeds.Tey typically possess a robust and compact build, featuring a well-proportioned body.Te diversity of plumage colors and patterns is a notable characteristic of native chickens.Te size and shape of their wings may vary, providing them with agility in movement.Native chickens commonly possess strong and sturdy legs, well-adapted to a free-range lifestyle, possibly in combination with chicken cages.Te color of their legs may vary, and they often have robust claws suitable for scratching the ground in search of food or for defensive purposes.
In this study, each chicken breed examined showcases specifc characteristics, especially in male chickens.Tese specifc traits signifcantly infuence the value of the chickens.Te details of the characteristics and body structure size of each chicken breed can be observed in Figure 2 and are summarized in Table 2. Tis section summarizes the characteristics and the size of the body structure in male chickens for each breed.In the frst breed, Khiew Phalee chickens observed in this study share common features.Tey possess a crest known as a walnut-type comb, locally referred to as "Hin" in Tai.Te beak, neck plumage, back plumage, wing plumage, long curving tail, and back tail in these chickens all exhibit a blackish-green color, while the shanks are black.Tis gives rise to the name of this chicken breed, also known as "Khiew Hang Dam." Tis is because chickens of this breed have feathers that are blackish-green, covering the entire body, and a dark green tail that resembles black."Khiew" means green in Tai, "Hang" means tail, and "Dam" means black.Te average measurements for body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length are as follows: 2.87 ± 0.09 kilograms, 54.76 ± 0.77 cm, 22.22 ± 0.38 cm, 17.98 ± 0.34 cm, 18.27 ± 0.37 cm, 14.36 ± 0.28 cm, 11.37 ± 0.21 cm, and 8.75 ± 0.18 cm, respectively.In the second breed, Tao Tong chickens exhibit shared features across all .57± 0.24 cm, respectively.Te overall appearance of this breed of chicken features a grey base with highlights of golden yellow feathers.Tis characteristic gives rise to the name "Tao Tong," where "Tao" in Tai means grey, and "Tong" in Tai means golden yellow.
Lueng Hang Khao is the third chicken whose external morphology had been studied in detail.It was found that this breed of chicken has a walnut-type comb, similar to the preceding two breeds.Other noteworthy features include an ivory beak, golden yellow neck plumage, and golden yellow or black back and wing plumage.Te long curving tail can be either white or black, with a black back tail and white-yellow shanks.Te average measurements for body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length are 2.83 ± 0.10 kg, 54.43 ± 0.83 cm, 22.86 ± 0.41 cm, 19.85 ± 0.36 cm, 17.56 ± 0.41 cm, 15.70 ± 0.31 cm, 12.44 ± 0.22 cm, and 9.48 ± 0.19 cm, respectively.Te fourth species, the Chee, exhibits a walnut- type comb and ivory beak.Te neck plumage, back plumage, wing plumage, long curving tail, and back tail are white, while the shanks are white-yellow.Chee is a white chicken breed raised for both egg production and meat consumption.Te name of the Chee chicken is inspired by the whiterobed female priestess of Tailand.From the yellow color of the neck plumage, back plumage, and upper wing plumage (referred to as "Lueng" in Tai), and the white fur on the tail (referred to as "Khao" in Tai), the name of this chicken breed originates.Pra Dhu Hang Dam is the ffth breed of chicken that had been studied.Tis chicken breed features a walnut-type comb crest.Te beak is blackish-green, while the neck Te last breed examined in this study is identifed as Jae or bantam breeds.Tis chicken breed is classifed as an ornamental or beautiful breed.Tis chicken breed, known as Jae, boasts a distinctive machine-shaped crest, a greenishblack beak, prominent orange neck plumage, matching back plumage, yellow-gold wing plumage, a black long curving tail, and a black back tail, with grey shanks.Te average measurements for body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length are 1.12 ± 0.19 kg, 32.64 ± 0.97 cm, 13.58 ± 0.51 cm, 12.77 ± 0.42 cm, 11.05 ± 0.48 cm, 8.93 ± 0.36 cm, 6.98 ± 0.26 cm, and 5.81 ± 0.23 cm, respectively.3(a) and 3(b)), beak color (Figures 3(c) and 3(d)), neck plumage color (Figure 4), back plumage color (Figure 5), wing plumage color (Figure 6), long curved tail color (Figure 7), back tail color (Figure 8), and shank color (Figure 9), were meticulously documented across the native chicken population in this area.Signifcantly, there were statistically signifcant diferences observed among the breeds for all qualitative variables (p < 0.01).Variations were evident across all variables within the six distinct breeds based on a Chi-square test with a p value less than 0.001 (Table 2).

Qualitative Variables. Phenotypic characteristics, encompassing comb type (Figures
Tis comprehensive examination of the six chicken breeds reveals the variations in their crest types, beak colors, neck plumage colors, back plumage colors, wing plumage colors, long curving tail colors, back tail colors, and shank colors.Specifcally, two types of crests, the walnut comb and the single crest, were observed, with the walnut comb found in Khiew Phalee, Tao Tong, Lueng Hang Khao, Chee, and Pra Dhu Hang Dam, while Jae chickens exhibit the single comb type.Te beak color varies between blackish-green and ivory, with Khiew Phalee, Pra Dhu Hang Dam, and Jae displaying a blackish-green beak, and Tao Tong, Lueng Hang Khao, and Chee showcasing an ivory beak.
In neck plumage color, seven variations were identifed, including blackish-green, brown, grey, orange, Pra Dhu, white, and yellow-gold.Each breed displays unique neck colors, with some maintaining color stability, while others exhibit more than one color.Khiew Phalee has blackishgreen neck plumage, Lueng Hang Khao features yellow-gold, Chee displays white, and Pra Dhu Hang Dam exhibits Pra Dhu.Tao Tong shows variations with brown and grey, and Jae showcases orange and yellow-gold neck plumage.
Back plumage color difers among the breeds, with Tao Tong having both brown and grey, Lueng Hang Khao featuring black and yellow-gold, and the remaining four breeds each showing a single back plumage color: blackishgreen (Khiew Phalee), white (Chee), Pra Dhu (Pra Dhu Hang Dam), and orange (Jae).Wing plumage color varies, with Khiew Phalee featuring black, Tao Tong displaying blackish-green, Lueng Hang Khao showcasing grey and orange, Chee presenting white, and Jae exhibiting yellowgold.
Te long curving tail color difers across breeds: blackish-green (Khiew Phalee), grey and white (Tao Tong), black and white (Lueng Hang Khao), white (Chee), and black (Pra Dhu Hang Dam and Jae).Back tail color is black for Lueng Hang Khao, Pra Dhu Hang Dam, and Jae, blackish-green for Khiew Phalee, grey for Tao Tong, and white for Chee.Shanks exhibit white-yellow for Tao Tong, Lueng Hang Khao, and Chee, black for Khiew Phalee, and grey for Jae.Pra Dhu Hang Dam chickens display both blackish-green and black shanks, with blackish-green being the dominant color.
Tis detailed examination provides a thorough understanding of the unique characteristics of each breed, contributing valuable insights into the diversity of indigenous chicken populations.

Quantitative Variables.
Te study examined eight quantitative variables, encompassing body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length, across six native chicken breeds.Te analysis revealed signifcant diferences in the averages for these variables among diferent chicken breeds and between male and female chickens.Notably, these diferences were statistically signifcant (p < 0.01), with the exception of the variable of sex within each breed (p > 0.05).
Detailed data in Table 3 present the least square means of the quantitative variables for each of the six native chicken breeds.Chee chickens distinguished themselves by having the highest average body weight (2.97 ± 0.14 kg), body height (54.85 ± 1.15 cm), and body width (20.35 ± 0.51 cm).On the other hand, Lueng Hang Khao chickens displayed the longest body length (22.86 ± 0.41 cm), upper shank length (15.70 ± 0.31 cm), and lower shank length (12.44 ± 0.22 cm).Khiew Phalee and Tao Tong chickens showcased unique features, with the former having the longest wing length (18.27 ± 0.37 cm) and the latter possessing the longest toe length (9.57± 0.24 cm).
Jae chickens, in contrast, demonstrated relatively lower average values for all variables when compared to the other breeds.Furthermore, across all breeds, male chickens consistently exhibited superior performance in all variables compared to females, although these diferences were not statistically signifcant (p > 0.05).Male chickens were observed to exhibit a larger body size compared to females.Tis diference in size encompasses body weight, width, length, International Journal of Zoology   International Journal of Zoology and height, as well as the length of the wing, upper shank, lower shank, and toe, with males consistently found to be longer than females in these aspects.

Correlation between Quantitative
Variables.Te fndings from the study on the correlation between quantitative characteristics of native chickens reveal a high and statistically signifcant correlation (p < 0.05), all pointing in the same direction.Tis correlation serves as an indicator that improvement in one characteristic within these six native chicken breeds is likely to result in an improvement in another characteristic (Table 4).Te observed correlation underscores the interconnected nature of these quantitative traits and suggests that eforts to enhance any one trait will result in desirable efects on chicken traits.Concerning chicken body weight, the study observed positive correlations with body height, body length, body width, wing length, upper shank length, lower shank length, and feet length across all breeds.Exceptions included the absence of correlation between body weight and body length for Khiew Phalee and Kai Lueng Hang Khao chickens, as well as between body weight and body width for Tao Tong chickens.Additionally, the body height of the chickens exhibited positive relationships with body length, body width, wing length, upper shank length, lower shank length, and feet length across all breeds.Notably, exceptions encompassed the lack of correlation between body height and body length for Lueng Hang Khao chickens, between body height and body width for Tao Tong chickens, and between body height and feet length for Jae chickens.Signifcant positive correlations between body length and all other variables were solely discerned in Pra Dhu Hang Dam chickens (Table 4).
Regarding body width, the study found signifcant correlations with wing length, upper shank length, lower shank length, and feet length for Lueng Hang Khao, Chee, and Pra Dhu Hang Dam chickens.Correlations were also

Discussion
Based on the investigation into the diversity of phenotypic characteristics of Tai native chickens within lower northern Tailand, the outcomes of the study can be elucidated as follows.
Tis study classifes two native chicken comb types: the walnut comb and the single comb.Te walnut comb proves to be the dominant type across six breed species, namely, Khiew Phalee, Tao Tong, Lueng Hang Khao, Chee, and Pra Dhu Hang Dam chickens.Notably, only the single comb type is observed in Jae chickens.Tese fndings are consistent with previous studies that investigated the characteristics of cockscombs in fve chicken breeds (Pra Dhu  [4,17,18].According to earlier reports from studies on the comb of Jae chickens across six provinces in the lower northern region of Tailand: Phetchabun, Phitsanulok, Phichit, Sukhothai, Uthai Tani, and Uttaradit, it was noted that Jae chickens showed the single comb type [9].No diversity in comb types was noted in each chicken breed.Tis uniformity is maintained by each studied chicken breed possessing only one comb phenotypic trait.Tis contrasts with previous research, where Pea-type combs were observed in the Lueng Hang Khao population in Northeast Tailand, the Chee population in the East and Central regions of Tailand, and the Pra Dhu Hang Dam population in the Central regions of Tailand [19].Tese chickens, therefore, display a genetic trait of a comparatively consistent comb, which varies uniquely across distinct regions. Regarding beak color, Tao Tong, Lueng Hang Khao, and Chee chickens exhibited only ivory beak color and whiteyellow shank color.Tis is consistent with the previous fndings [17,20], which noted that Tao Tong and Lueng Hang Khao chickens displayed white-yellow beak and shank colors.On the other hand, the predominant beak and shank color for Khiew Phalee, Pra Dhu Hang Dam, and Jae chickens was blackish-green.Several researchers [4,8,9,17] have previously reported similar beak and shank coloration in various Tai native chicken breeds.Additionally, only blackish-green plumage and white tail colors were observed in Khiew Phalee and Chee chickens, respectively.Tese results align with previous fndings, providing descriptive information about the colors of the beak, plumage, and tail in Khiew Phalee chickens, which exhibited blackish-green tones [21].In contrast, observations indicated that Jae chickens had a grey shank but a brown beak color [9].However, the plumage color of the six breeds did not correspond with the results of other studies that reported black as the predominant plumage color in Tai native chickens [22][23][24].Tis discrepancy may have been because the studied samples had their coat color controlled by genes that mainly utilized black color.Previous studies have described the regulation of fur color by three genes: melanocortin 1 receptor (MC1R), tyrosinase (TYR), and agouti signaling protein (ASIP) genes.Each gene gives a diferent coat color.Tree SNPs in the MC1R gene resulted in six haplotypes, notably H5 and H6 associated with white and grey feathers.TYR gene variations yielded six haplotypes, excluding P2, P3, and P6 in black chicken plumage.Te single SNP (T168C) in the ASIP gene favored the homozygous dominant genotype across various plumage color groups [25].
Furthermore, evidence from several studies had explained that signifcant variations in the color of all characters observed in native chickens could primarily be attributed to the geographic situation, encompassing factors such as isolation, natural selection, and artifcial selection.Consequently, distinct characteristics emerged in various native chicken groups, and their names were often designated based on their niche areas [26,27].Te study examined the impact of geographic factors on village chickens in Jordan's Karak Governorate, covering six regions in Karak, Taflah, Madaba, Aqaba, and Al-Mafraq.Findings revealed disparities in phenotypic features between sexes and regions.Traditional rearing practices without genetic improvement or gene fow from distant regions maintained a resemblance to ancestral traits.Predominant traits included pink color, a single comb, a beige beak, orange eyes, and red earlobes with white speckling.Regional diferences and elevation signifcantly infuenced trait variations in both sexes [26].
Hence, the varied physical characteristics observed in local chickens suggested substantial genetic potential as a genetic resource for use in future breeding.Tese results increased knowledge and could have helped in the development of conservation plans for chicken breeds.Safeguarding this extensive gene pool from genetic erosion was crucial [28].
Te results indicated that female chickens exhibited lower quantitative values for all variables compared to male chickens' counterparts.Our fndings align with previous studies that investigated the weight and structural size of other native chicken breeds in the upper northern and lower northern regions of the country, where males tended to exhibit greater weight or larger size compared to females [22,24].Te diference in size could be attributed to sexual dimorphism, where males and females displayed diferential growth rates.Previous research explained this diference as a result of the actions of hormones [29].Tis aligns with the research on sexual dimorphism in terms of quantitative variables, which is expected due to difering growth rates between males and females.Tis phenomenon is explained by variations in the levels of male sex hormones, responsible for greater muscle development in males compared to females [30,31].Various investigations of Tai native chickens have reported body weight ranges from 1.25 to 2.42 kg [22,24,28], which were lower than the average body weight of the six breeds (2.59 ± 0.87 kg) observed in the present study.Te average body weight of Jae chickens in this study closely matched the previous fndings, which reported an average body weight of 1.07 ± 0.20 kg for Jae in the lower northern region of Tailand [9].Tese variations in quantitative variables could be attributed to difering genetic backgrounds, chicken maturity (including animal age), agroclimatic conditions, or environmental factors, including farm management and the nutritional status of the chickens [24].Terefore, genetic factors and environmental conditions of diferent breeds and rearing environments could have caused variations in body size in native chickens.Nafu et al. explained that the quantitative properties of native Indonesian chickens, including head length, chest length, wings length, shank length, back length, neck circumference, and chest circumference, indicated that the observed differences were infuenced by a combination of genetic factors and environmental conditions [25].
In examining relationships among diferent chicken breeds, positive correlations were observed among various physical characteristics.Tey identifed relationships International Journal of Zoology between body weight and body measurements, including the length of wings, shanks, and feet, both within and between species of chickens (p < 0.05).For instance, Chee's fndings indicated within-species correlations (r) between body weight and body measurements ranging from 0.54 to 0.75.Additionally, interspecies correlations varied from 0.69 to 0.85.Tese results align with prior research, confrming the existence of noteworthy correlations in these traits both within chickens of the same breed and across diverse chicken species [8,24,[32][33][34][35].Tese correlations imply the potential for estimating a chicken's body weight based on its linear body measurements.While other correlations generally showed positivity, their strengths exhibited variations (p < 0.05).Te phenotypic correlation between body weight and various linear body parameters was not only positive but also statistically signifcant, suggesting that alterations in one body trait are likely to be associated with changes in others.
From this study, a database on the diversity of external structural characteristics has been established for all six native chicken breeds in Uttaradit province.Tis was carried out in accordance with the study guidelines of the FAO for the genetic characterization of chicken resources [10] and the Standard of Perfection, outlining the fve characteristics of exceptional fghting cocks.Tis database serves as a guide for conservation and improvement planning, facilitating the selection of appropriate characteristics within each breed.Ultimately, this contributes to fostering a sustainable and efcient career in raising native chickens.Te conclusion drawn was that existing variations in size and aesthetic characteristics of chickens can be improved through selective breeding tailored to the specifc needs of farmers.Tis aligns with several previous reports, which have explained that existing variations in size and aesthetic characteristics of indigenous chickens can be improved through selective breeding customized to the specifc needs of farmers.Furthermore, it was highlighted that farmers would beneft economically from support in the husbandry and management of indigenous chickens [35][36][37].For example, the potential development of broiler chicken breeds utilizing Pelung chickens highlighted the local chicken's capability to evolve into a broiler chicken.A study conducted in Indonesia investigated the crossbreeding of Pelung and broiler chickens, revealing distinct characteristics in the second generation.Although the average body weight of the second-generation chickens surpassed that of Pelung, it did not exceed the average weight of broilers.Tese chickens exhibited a variety of coat colors, including white, black, brown, and black with white patterns (dotted).In addition, the second generation exhibited a distinctive inheritance pattern of foot colors, encompassing black, white, and yellow, while maintaining a notable level of phenotypic uniformity amid considerable variation [38].

Conclusions
In conclusion, this study contributes to a comprehensive database on the external structural characteristics of six native chicken breeds in Uttaradit province, aligning with FAO guidelines and the Standard of Perfection for the genetic characterization of chicken resources.Tis database serves as a valuable resource for conservation and improvement planning, aiding in the selection of desirable characteristics within each breed.Importantly, the conclusion drawn emphasizes the potential for improving existing variations in size and aesthetic characteristics through selective breeding tailored to the specifc needs of farmers, aligning with previous reports advocating for economic support in the husbandry and management of indigenous chickens.Te study's insights into the potential development of broiler chicken breeds utilizing local chickens, as demonstrated in the Pelung breed in Indonesia, further highlighting the adaptability and potential economic benefts of indigenous chicken breeds.
Our discoveries ease concerns of invasion from nonnative chickens, directly threatening Tailand's standard of perfection for native breeds.Tis intrusion jeopardizes the preservation of unique traits, casting doubt on the long-term viability of conserving the distinctive features defning Tai native poultry.By seamlessly integrating our fndings into the broader context of past research, this study enriches our comprehension of phenotypic diversity in Tai native chickens.In the future, research should delve into the complexities of native chicken breeds.Molecular genetic techniques should be employed to examine genetic diversity, identifying pure and hybrid chicken lines.Tis enhanced understanding will signifcantly contribute to the conservation and sustainable development of native chicken populations, aligning with the evolving needs of the market.Tis holistic approach ensures the preservation of valuable genetic resources and upholds the cultural and historical signifcance of the country.

Figure 1 :
Figure 1: Illustration of a map of Tailand, generated using free and open-source software (QGIS), with a focus on highlighting the geographical positioning of Uttaradit province in the lower northern region.

Figure 3 :Figure 4 :
Figure 3: Variation in qualitative traits of comb type and beak color in the native chicken breeds.Note.(a) Single comb, (b) walnut comb, (c) blackish-green beak, and (d) ivory beak.
Te experimental procedures undertaken in this study received approval and were conducted in accordance with the guidelines set forth by the Animal Ethics Committee of Pibulsongkram Rajabhat University (approval reference number: PSRU-(AG)-2021-007.
Tis sample included 31 individuals of Khiew Phalee, 18 individuals of Tao Tong, 26 individuals of Lueng Hang Khao, 26 individuals of Chee, 21 individuals of Pra Dhu Hang Dam, and 23 individuals of Jae.3.1.Description of the Morphological Characteristics.Te study results involved the observation and measurement of chicken structures or organs to delineate the morphological attributes of various native chicken breeds.It was discovered that native chickens exhibit physical characteristics, distinguishing them from other poultry breeds.Tey typically display a sturdy and compact build, featuring a wellproportioned body.Teir feathers showcase a variety of colors and patterns, highlighting the breed's rich diversity.
Te study involved the examination of the qualitative and quantitative external structure of native chickens, with a sample of 134 individuals from 6 breeds.

Table 1 :
Te number of chickens of each breed used in the quantitative and qualitative characteristics study.
individuals, including a walnut-type comb, ivory beak, neck plumage in brown or orange, back plumage in orange or grey, wing plumage in brown or grey, a long curving tail in white or grey, a grey back tail, and shanks in white-yellow.Te mean values of body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length are 2.65 ± 0.12 kg, 54.17 ± 1.02 cm, 21.33 ± 0.51 cm, 19.46 ± 0.45 cm, 17.57 ± 0.49 cm, 15.06 ± 0.38 cm, 11.65 ± 0.27 cm, and 9

Table 2 :
6ata and information about the qualitative variables used in Chi-square analysis for the six native chicken breeds under study.Note.Te Chi-square test indicated a statistically signifcant diference with a p value <0.001 for all the data.6InternationalJournal of Zoology plumage, back plumage, and wing plumage are distinctively colored in a shade of olive green, but with a brighter appearance.In Tai folk wisdom, this color is referred to as "Pra Dhu," and it is said to resemble the color of old leaves from the Pterocarpus tree.Tis color is distinctive and is used to name this particular chicken breed.Te name of the tail, called "Hang Dam," comes from the color of the long curving tail and back tail, which is black.Te word "tail" means "Hang" in Tai, and the word "black" means "Dam" in Tai.Te shanks are black and blackish-green.Te average measurements for body weight, body height, body length, body width, wing length, upper and lower shank length, and toe length are 2.93 ± 0.12 kg, 53.47 ± 0.95 cm, 22.32 ± 0.49 cm, 19.95 ± 0.41 cm, 17.34 ± 0.45 cm, 15.35 ± 0.35 cm, 12.13 ± 0.25 cm, and 9.52 ± 0.22 cm, respectively.

Table 4 :
Data and information on the correlation between quantitative variables for the six native chicken breeds studied.and** exhibited statistically signifcant diferences in Pearson correlation, with p values of less than 0.05 and 0.01, respectively.Te study investigated even quantitative variables, including body weight (in kg), body height, body length, body width, wing length, upper and lower shank length, and toe length (all in cm), across six native chicken breeds.International Journal of ZoologyHang Dam, Khiew Phalee, Tao Tong, Chee, and Lueng Hang Khao) within the study area and in the neighboring Phitsanulok Province.Tese studies revealed that Pra Dhu Hang Dam, Khiew Phalee, and Lueng Hang Khao chickens displayed the walnut comb type *