Chicken Plumage Research Articles

A genome-wide association study for eumelanin pigmentation in chicken plumage using a computer vision approach.

Chicken plumage colouration is an important trait related to productivity in poultry industry. Therefore, the genetic basis for pigmentation in chicken plumage is an area of great interest. However, the colour trait is generally regarded as a qualitative trait and representing colour variations is difficult. In this study, we developed a method to quantify and classify colour using an F2 population crossed from two pure lines: White Leghorn and the Korean indigenous breed Yeonsan Ogye. Using red, green, and blue values in the cropped body region, we identified significant genomic regions on chromosomes 33:3 160 480-7 447 197 and Z:78 748 287-79 173 793. Furthermore, we identified two potential candidate genes (PMEL and MTAP) that might have significant effects on melanin-based plumage pigmentation. Our study presents a new phenotyping method using a computer vision approach and provides new insights into the genetic basis of melanin-based feather colouration in chickens.

Candidate pigmentation genes related to feather color variation in an indigenous chicken breed revealed by whole genome data.

Chicken plumage color is an inheritable phenotype that was naturally and artificially selected for during domestication. The Baicheng You chicken is an indigenous Chinese chicken breed presenting three main feather colors, lavender, black, and yellow plumages. To explore the genetic mechanisms underlying the pigmentation in Baicheng You chickens, we re-sequenced the whole genome of Baicheng You chicken with the three plumage colors. By analyzing the divergent regions of the genome among the chickens with different feather colors, we identified some candidate genomic regions associated with the feather colors in Baicheng You chickens. We found that EGR1, MLPH, RAB17, SOX5, and GRM5 genes were the potential genes for black, lavender, and yellow feathers. MLPH, GRM5, and SOX5 genes have been found to be related to plumage colors in birds. Our results showed that EGR1 is a most plausible candidate gene for black plumage, RAB17, MLPH, and SOX5 for lavender plumage, and GRM5 for yellow plumage in Baicheng You chicken.

A Deletion Upstream of SOX10 Causes Light Yellow Plumage Colour in Chicken.

Chicken plumage colour is a complex trait controlled by many genes. Herein, through Rhode Island Red (RIR) and White Leghorn (WL) F1 cross populations, the segregation of plumage color was observed in females, showing white in males, and dark red (DR) and light yellow (LY) in females. The white has been found to be caused by dominant white alleles (I) and the DR phenotype is attributed to a sex-linked recessive silver allele (). LY is a derived feather colour phenotype and the genetic mechanism of this is unclear. In order to explore the genetic basis for LY, we randomly selected 40 DR and 39 LY chickens for paired-end sequencing. Through the use of association analysis, we found the LY phenotype is caused by a 7.6 kb non-coding deletion near the SOX10 gene. This mutation has been reported to be responsible for dark brown plumage in chicken, and subsequent diagnostic PCR tests showed that the length of the long-range non-coding deletion is 7.6 kb instead of 8.3 kb as previously reported.

Genetic basis of chicken plumage color in artificial population of complex epistasis.

Chicken plumage color, the genetic basis of which is often affected by epistasis, has long interested scientists. In the current study, a population of complex epistasis was constructed by crossing dominant White Leghorn chickens with recessive white feather chickens. Through a genome-wide association study, we identified single nucleotide polymorphisms and genes significantly associated with white and colored plumage in hens at different developmental stages. Interestingly, white plumage in adulthood was associated with the recessive white feather gene (TYR), whereas white feathers at birth stage were associated with the dominant white feather gene (PMEL), indicating age-related roles for these genes. TYR was shown to exert an epistatic effect on PMEL in adult hens. Additionally, TYR had an epistatic effect on barred plumage, while barred plumage had an epistatic effect on black plumage. TYR had no epistatic effect on the yellow plumage. We confirmed that the barred plumage gene is CDKN2A, as reported in previous studies. Golgb1 and REEP3, which play important roles in the Golgi network and affect the formation of feather pigments, are important candidate genes for yellow plumage. The candidate genes for black plumage are CAMKK1 and IFT22. Further research is warranted to elucidate the molecular mechanisms underlying these traits.

A quantitative trait locus on chromosome 2 was identified that accounts for a substantial proportion of phenotypic variance of the yellow plumage color in chicken

Chicken plumage color is an important economical trait in poultry breeding, as triple-yellow indigenous broilers are preferred over western commercial broilers in the Chinese market. However, the studies on the pigmentation of plumage coloration are relatively rare at present. Here, we performed a genome-wide mapping study on an F2 intercross, whose 2 founders were one hybrid commercial line “High Quality chicken Line A” that originated from the Anak red chicken and one indigenous line “Huiyang Beard” chicken that is a classical “triple-yellow” Chinese indigenous breed. Moreover, we used an automatic colorimeter that can quantitatively assess the colorations in L∗, a∗, and b∗ values. One major quantitative trait locus (QTL) on chromosome 2 was thus identified by both genome-wide association and linkage analyses, which could explain 10 to 20% of the total phenotypic variance of the b∗ measurements of the back plumage color. Using linkage analysis, 2 additional QTL on chromosome 1 and 20 were also found to be significantly associated with the plumage coloration in this cross. With additional samples from Anak red and Huiyang Beard chickens as well as pooled resequencing data from the 2 founders of this cross, we then further narrowed down the QTL regions and identified several candidate genes, such as CABLES1, CHST11, BCL2L1, and CHD22. As the effects of QTL found in this study were substantial, quantitatively measuring the coloration rather than the descriptive measurements provides stronger statistical power for the analyses. In addition, this major QTL on chromosome 2 that was associated with feather pigmentation at the genome-wide level will facilitate the future chicken breeding for yellow plumage color. In conclusions, we mapped 3 associated QTL on chromosome 1, 2, and 20. The candidate genes identified in this study shed light in the genetic basis of yellow plumage color in chicken.

Discovery of a new nucleotide substitution in the MC1R gene and haplotype distribution in native and non-Japanese chicken breeds.

Melanocortin 1-receptor (MC1R) is one of the major genes that controls chicken plumage colour. In this study, we investigated the sequence and haplotype distribution of the MC1R gene in native Japanese chickens, along with non-Japanese chicken breeds. In total, 732 and 155 chickens from 30 Japanese and eight non-Japanese breeds respectively were used. Three synonymous and 11 non-synonymous nucleotide substitutions were detected, resulting in 15 haplotypes (H0-H14). Of these, three were newly found haplotypes (H9, H13 and H14), of which one (H9) was composed of known substitutions C69T, T212C, G274A and G636A. The second one (H13) possessed newly found non-synonymous substitution C919G, apart from the known substitutions C69T, G178A, G274A, G636A and T637C. The third one (H14) comprised a newly discovered substitution C919G in addition to the known C69T, G274A and G409A substitutions. The homozygote for this new haplotype exhibited wt like plumage despite the presence of G274A. In addition to discovering a new nucleotide substitution (C919G) and three new haplotypes, we defined the plumage colour of the bird that was homozygous for the A644C substitution (H5 haplotype) as wheaten-like for the first time; although the substitution has been already reported, its effect was not revealed. Besides detecting the new plumage colour, we also confirmed that the A427G and G274A substitutions contribute in expressing brownish and black plumage colour respectively, as reported by the previous studies. Moreover, we confirmed that the buttercup allele does not express black plumage despite possessing a G274A substitution, under the suppression effect of A644C. In contrast, the birds homozygous for the birchen allele presented solid black plumage, which was contradictory to the previous reports. In conclusion, we revealed a large diversity in the MC1R gene of native Japanese chicken breeds, along with the discovery of a new non-synonymous nucleotide substitution (C919G) and three novel haplotypes (H9, H13 and H14).

Endothelins (EDN1, EDN2, EDN3) and their receptors (EDNRA, EDNRB, EDNRB2) in chickens: Functional analysis and tissue distribution

Endothelins (EDNs) and their receptors (EDNRs) are reported to be involved in the regulation of many physiological/pathological processes, such as cardiovascular development and functions, pulmonary hypertension, neural crest cell proliferation, differentiation and migration, pigmentation, and plumage in chickens. However, the functionality, signaling, and tissue expression of avian EDN-EDNRs have not been fully characterized, thus impeding our comprehensive understanding of their roles in this model vertebrate species. Here, we reported the cDNAs of three EDN genes (EDN1, EDN2, EDN3) and examined the functionality and expression of the three EDNs and their receptors (EDNRA, EDNRB and EDNRB2) in chickens. The results showed that: 1) chicken (c-) EDN1, EDN2, and EDN3 cDNAs were predicted to encode bioactive EDN peptides of 21 amino acids, which show remarkable degree of amino acid sequence identities (91–95%) to their respective mammalian orthologs; 2) chicken (c-) EDNRA expressed in HEK293 cells could be preferentially activated by chicken EDN1 and EDN2, monitored by the three cell-based luciferase reporter assays, indicating that cEDNRA is a functional receptor common for both cEDN1 and cEDN2. In contrast, both cEDNRB and cEDNRB2 could be activated by all three EDN peptides with similar potencies, indicating that both receptors can function as common receptors for the three EDNs and share functional similarity. Moreover, activation of three EDNRs could stimulate intracellular calcium, MAPK/ERK, and cAMP/PKA signaling pathways. 3) qPCR assay revealed that cEDNs and cEDNRs are widely, but differentially, expressed in adult chicken tissues. Taken together, our data establishes a clear molecular basis to uncover the physiological/pathological roles of EDN-EDNR system in birds and helps to reveal the conserved actions of EDN-EDNR signaling across vertebrates.

Molecular-genetic bases of plumage coloring in chicken

The color of plumage in birds is an important feature, often determining descent to a particular species or breed. It serves as a key factor in the interaction of birds with each other due to their well-developed visual perception of the surrounding world. In poultry including chickens, the color of the plumage can be treated as a genetic marker, useful for identifying breeds, populations and breeding groups with their specific traits. The origin of diverse color plumage is the result of two interrelated physical processes, chemical and optical, due to which pigment and structural colors in the color are formed. The pigment melanin, which is presented in two forms, eumelanin and pheomelanin, is widely spread in birds. The basis for the formation of melanin is the aromatic amino acid tyrosine. The process of melano-genesis involves many loci, part of the complex expression of plumage color genes. In birds, the solid black color locus encodes the melanocortin 1 receptor (MC1R), mutations in which lead to a change in receptor activation and form different variants of the E locus. Using the GWAS analysis, possible genes affecting the formation of color in chickens were detected. The biosynthesis and types of melanin are affected by the activity of the enzyme tyrosine, and mutations in the tyrosinase gene (TYR) cause albinism in different species. The formation mechanism of brown, silver, gold, lavender and a number of other shades is determined by the influence on the work of the MC1R genes and TYR specific modifier genes. Thus, locus I currently associated with the PMEL17 gene inhibits the expression of eumelanin, and the MLPH gene affects tyrosinase function. Research on the mechanisms of formation of the secondary coloring of plumage in chickens is being actively conducted nowadays. The formation of a marble feather pattern is associated with the mutation of the endothelin B2 receptor (EDNRB2), in the coding part of the gene of which a polymorphism is found associated with the mo locus. The molecular base that causes the feather banding (locus B and autosomal recessive banding) is identified. Today, only some genes that determine the color of the plumage of chickens are studied and described. Different genes can produce similar plumage patterns, and different phenotypes can be determined by the polymorphism of a single gene. Using molecular methods, you can more accurately identify these differences. This overview shows the nature of melanin coloration in birds using the example of chickens of various breeds and also attempts to systematize knowledge about the molecular-genetic mechanisms of the appearance of various types of coloration.

Feather colour affects the aggressive behaviour of chickens with the same genotype on the dominant white (I) locus.

Aggression in chickens is a serious economic and animal welfare issue in poultry farming. Pigmentation traits have been documented to be associated with animal behaviour. Chicken pecking behaviour has been found to be related to feather colour, with premelanosome protein 17 (PMEL17) being one of the candidate genes. In the present study, we performed a genotypic and phenotypic association analysis between chicken plumage colour (red and white) and aggressive behaviour in an F1 hybrid group generated by crossing the autosomal dominant white-feathered breed White Leghorn (WL) and the red-feathered breed Rhode Island Red (RIR). In genetic theory, all the progeny should have white feathers because WL is homozygous autosomal dominant for white feathers. However, we found a few red-feathered female chickens. We compared the aggressiveness between the red and white females to determine whether the feather colour alone affected the behaviour, given that the genetic background should be the same except for feather colour. The aggressiveness was recorded 5 days after sexual maturity at 26 weeks. Generally, white plumage hens showed significantly higher aggressiveness compared to the red ones in chasing, attacking, pecking, and threatening behaviour traits. We assessed three candidate feather colour genes—PMEL17, solute carrier family 45 member 2 (SLC45A2), and SRY-box 10 (SOX10)—to determine the genetic basis for the red and white feather colour in our hybrid population; there was no association between the three loci and feather colour. The distinct behavioural findings observed herein provide clues to the mechanisms underlying the association between phenotype and behaviour in chickens. We suggest that mixing red and white chickens together might reduce the occurrence of aggressive behaviours.

Identification and Characterisation of Alternative Splice Variants of Hoxb9 and Their Correlation with Melanogenesis in the Black-Boned Chicken

ABSTRACT Homeobox B9 (HOXB9) gene has been demonstrated to be associated with melanogenesis in chicken plumage by high-throughput RNA sequencing. In this study, we cloned and characterised HOXB9 in black-boned chickens. Two alternative splice variants (HOXB9-1 and HOXB9-2) were identified in chicken feather bulbs. Expression analysis of HOXB9 in 11 different chicken tissues by RT-PCR indicated that the two transcripts were only expressed in the kidney, abdominal fat, feather bulbs, skin, and small intestine. No HOXB9-1 or HOXB9-2 transcripts were detected in the breast muscle or the ovary. The two HOXB9 variants were expressed at significantly different levels in black feather bulbs and white feather bulbs (p<0.01), and in black skin compared with white skin (p<0.01). The results indicate that HOXB9-1 and HOXB9-2 may be involved in melanin formation in the plumage and skin. The expression of HOXB9-2 was higher in white than in black muscles (p<0.05), HOXB9-2 may play a role in muscle melanogenesis. Our results suggest that HOXB9, which is partially regulated by alternative splicing, may be involved in the process of melanogenesis in the black-boned chicken.

Feather follicles transcriptome profiles in Bashang long-tailed chickens with different plumage colors.

Despite the rich variety in plumage color found in nature, genetic studies on how feather follicles affect pigmentation are often limited to animals that have black and white pigment. To test how gene expression influences plumage color, transcriptomes of chicken feather follicles with white, black, hemp, reed catkins, silvery grey, and landscape plumage colors were generated using Illumina sequencing. We generated six RNA-Seq libraries with over 25million paired-end clean reads per library with percentage of paired-end clean reads ranging from 96.73 to 96.98%. 78% of the reads mapped to the chicken genome, and approximately 70% of the reads were mapped to exons and 6% mapped to introns. Transcriptomes of feather follicles producing hemp and land plumage were similar, but these two showed moderate differences compared with gray and reed colored plumage. The black and white follicle transcriptomes were most divergent from the other colors. We identified several candidate genes, including GPNMB, PMEL, TYRP1, GPR143, OCA2, SOX10, SLC45A2, KRT75, and TYR. All of these genes are known to induce pigment formation in mice. White feathers result from the lack of pigment formation, and our results suggest that the white chickens due to the recessive insertion mutation of TYR. The formation of black area size and color depth may be due to the expression levels of GPNMB, PMEL, TYRP1, GPR143, OCA2, SOX10, SLC45A2, KRT75, and TYR. The GO analysis of the differentially expressed genes (DEGs) revealed that DEGs in our transcriptome analysis were enriched in cytoskeleton and cell structure related pathways. The black plumage transcriptome showed significant differences in melanogenesis, tyrosine metabolism, and riboflavin metabolism compared with transcriptomes of other plumage colors. The transcriptome profiles of the different chicken plumage colors provide a valuable resource to understand how gene expression influences plumage color, and will be an important resource for identifying candidate genes in breeding programs.

Transcriptome Profile Analysis of Mechanisms of Black and White Plumage Determination in Black-Bone Chicken

Background/Aims: Melanin is a major and ubiquitous component of plumage colouration, and patterns of melanin pigmentation in birds are extremely varied. However, the molecular mechanism of pigmentation in avian plumage is still largely unknown. Methods: To elucidate the molecular mechanisms involved in the formation of black and white plumage, this study takes advantage of high-throughput sequencing technology to compare differences in the transcriptome between black and white chicken feather bulbs. In total, we constructed six cDNA libraries from black (Group B) and white (Group W) feather bulbs in the dorsal plumage of Muchuan black-boned chickens. Results: A comparison between Groups B and W revealed 61 differentially expressed genes, with 47 displaying higher, and 14 displaying lower, levels of expression in white feather bulbs. Our results revealed a set of candidate genes and two potential metabolic pathways involved in black-bone chicken plumage melanogenesis. These include four homeobox genes (HOXB9, HOXC8, HOXA9, and HOXC 9), two glutathione (GSH) metabolism-related genes (CHAC1 and GPX3), and the transforming growth factor beta (TGF-β) signalling pathway. Two known genes, TYR and MITF, were also shown to play a role in melanin formation. Conclusion: our data provide a valuable resource for discovering genes important in plumage melanin formation and will help further elucidate the molecular mechanisms for black and white plumage.

Genome-wide association analysis identifies potential regulatory genes for eumelanin pigmentation in chicken plumage.

Plumage color in chicken is determined by the proportion of eumelanin and pheomelanin pigmentation. As the main ingredient in plumage melanin, eumelanin plays a key role in the dark black, brown and grey coloration. However, very few studies have been performed to identify the related genes and mutations on a genome-wide scale. Herein, a resource family consisting of one backcross population and two F2 cross populations between a black roster and Yukou Brown I parent stockbreed was constructed for identification of genes related to eumelanin pigmentation. Chickens with eumelanin in their plumage were classified as the case group, and the rest were considered the control group. A genome-wide association study of this phenotype and genotypes using Affymetrix 600K HD SNP arrays in this F2 family revealed 13 significantly associated SNPs and in 10 separate genes on chromosomes 1, 2, 3 and 5. Based on previous studies in model species, we inferred that genes, including NUAK family kinase 1 (NUAK1) and sonic hedgehog (SHH), may play roles in the development of neural crest cells or melanoblasts during the embryonic period, which may also affect the eumelanin pigmentation. Our results facilitate the understanding of the genetic basis of eumelanin pigmentation in chicken plumage.

Foot-pad dermatitis in commercial broilers

In the present experiment, the presence of mycological agents in chickens with skin lesions on foot pads was investigated, in order to improve the health of broiler chickens. Foot-pad dermatitis (FPD) is described in the literature as dermatitis caused by multifactor causes. The presence of irritating chemical substances in the litter, genetic predispositions of hybrids, immune suppressive diseases of chickens, as well as the composition of commercial broiler diets that influence the occurrence of wet litter, are proven factors that contribute to a more intensive incidence of foot-pad dermatitis. Foot-pad dermatitis is a condition characterized by lesions on metatarsal and digital ventral skin of poultry feet. It is type of contact dermatitis which in severe cases shows slower weight gain, poor health condition and welfare. Taking into consideration the literature data, chickens reared in closed facilities where the bacterial and mycological agents are present partly in the litter if not properly disinfected, but also in the food or the chicken plumage, we wanted to investigate their presence in the skin of foot pads. The study was focused on incidence of foot-pad dermatitis in 500 one day old broiler chickens of Hubbard genotype, in two feeding (standard/economical) programs for broilers available on our market. Chopped straw was used as litter. At the end of fattening, all chickens were examined for the presence of lesions on the skin of the feet. Total of 39 chickens were allocated to the intensity of the lesion on foot pads rated as 2 (mild) and 3 (severe). In the mycological examination of the 9 samples of autoclaved chicken legs with lesions on the feet, we have isolated and identified the presence of fungi /mould Aspergillus fumigatus. The histopathology investigation, during which the tissue section from mild and severe skin foot pads was collected and stained using Hematoxylin and eosin, revealed the hyperkeratosis, panniculitis, ballooning degeneration and dermis inflammation. No fungal elements were observed in the sections of pads stained with Gomori methenamine silver. Birds are especially susceptible to infection with Aspergillus fumigatus. That species of fungus is also classified as allergenic factor.

Developmental phenotypic-genotypic associations of tyrosinase and melanocortin 1 receptor genes with changing profiles in chicken plumage pigmentation

The tyrosinase (TYR) and melanocortin 1 receptor (MC1R) genes have been accepted as major genes involved in the plumage pigmentation of chickens. The co-segregation of plumage coloration and sequence polymorphism in TYR and MC1R genes were investigated using an intercross between black and white plumage color types of the Dongxiang blue-shelled chicken. Profiles of plumage color changing and genes expression levels of TYR and MC1R were observed from hatch to 112 d of age using quantitative real-time reverse transcription-PCR. Intercrossed offspring were classified by phenotypes of plumage colors. The phenotypes of black and amber chicks with genotypes of E_C_ exhibited a black feather pattern, whereas white, gray, and buff chicks with genotypes of E_cc and eecc belonged to the white feather pattern. Although TYR in cooperation with MC1R determined the coloration feather patterns, the different phenotypes did not correspond completely with the genotypes. During the period studied, plumage phenotype changed dramatically, and the buff and gray down were gradually replaced by whiteness feathers. Real-time reverse transcription-PCR studies showed that 1) expression levels of TYR declined dramatically with age, and expression at hatch was highest (P<0.01) during the ages studied; 2) expression level of MC1R was higher at 28 d than at younger and older ages; and 3) expression of TYR in chickens carrying E/E and E/e alleles on MC1R loci were higher than those carrying e/e alleles from hatch to 28 d.

The "silver" Japanese quail and the MITF gene: causal mutation, associated traits and homology with the "blue" chicken plumage

BackgroundThe MITF (microphthalmia-associated transcription factor) gene has been investigated in mice and various vertebrates but its variations and associated effects have not yet been explored much in birds. The present study describes the causal mutation B at the MITF gene responsible for the "silver" plumage colour in the Japanese quail (Coturnix japonica), and its associated effects on growth and body composition, and tests its allelism with the "blue" plumage colour mutation Bl in Gallus gallus.ResultsThe semi dominant B mutation results from a premature stop codon caused by a 2 bp deletion in exon 11 of MITF. Homozygous "white" (B/B) quail which have a white plumage also show a slightly lower growth, lower body temperature, smaller heart, and lighter pectoralis muscles but more abdominal adipose tissue than the recessive homozygous "wild-type" (+/+) and heterozygous "silver" (B/+) quail. Similar observations on cardiac and body growth were made on mice (Mus musculus) homozygous for mutations at MITF. The production of chicken-quail hybrids with a white plumage obtained by crossing Bl/+ chicken heterozygous for the blue mutation with B/B white quail indicated that the mutations were allelic.ConclusionThe "silver" Japanese quail is an interesting model for the comparative study of the effects of MITF in birds and mammals. Further investigation using a chicken family segregating for the "blue" plumage and molecular data will be needed to confirm if the "blue" plumage in chicken results from a mutation in MITF.

Body Weights of Gold and Silver Segregates in Chicken Broilers

Abstract It is known that certain genes affecting color of plumage in chickens are associated with a depression of body growth rate. Jerome et al. (1956) demonstrated that dominant white depressed growth and feed efficiency up to 10 weeks of age in a strain of Barred Rocks. Jaap and Grimes (1956) presented evidence that three mutant genes, the dominant white gene I (inhibition of black), E (extension of black) and B (rhythmic failure of pigment in the feather) interact to produce a suppression of body growth rate in the chicken. Body weight was suppressed through the interaction of I and E by .03 to .04 pounds in 2 to 2½ pound chickens at eight weeks of age and was further reduced by B to .06 to .07 pounds. Evidence was also presented by Jaap and Grimes (1956) that S (silver) which suppresses red plumage pigmentation, or K which delays chick feather…

Segregation of Hypostatic Colour Genes Within Inbred Lines of Chicken

THE two forms of white plumage in chickens, dominant (I) and recessive (c) white, are (with some qualifications in the case of I) epistatic to most other colours and patterns. The phenotypic uniformity of a white breed or strain may thus conceal a considerable amount of genetic diversity at loci affecting plumage colour and pattern. The mere examination of the F1 of a cross with a suitable coloured breed will suffice to determine the constitution at some loci. Data have been collected in this way on the constitution of inbred lines of two breeds: White Leghorn (W.L.) and White Plymouth Rock (W.P.R.).Attention is directed mainly to whether segregation is occurring within a particular line, or whether it is uniform (isozygous). The frequency with which segregation is found may be compared with calculations based on the coefficients of inbreeding of the lines; calculations which assume that all genotypes have an …

Raça em formação de galinhas de plumagem azul e ovos azuis - II. Teste de cruzamento

The data reported in this paper are in accordance with the hypothesis previously established (2) of the interaction of a main pair of alleles as controlling the inheritance of black, blue and blue-splashed plumage in chickens received from the State of Goias, Brazil. The black plumage is relatively uniform but the blue and blue splashed plumages indicate the action of other genes regulating the lack of uniformity.

Plumage Development in Chickens

GLOSSY, highly-colored plumage in chickens is a characteristic of a well-conditioned bird. Rough, split, faulty barred, or faded feathers, or the absence of feathers, is usually the outward evidence of faulty metabolism, injury, or a pathological condition, the exact cause of which is often unknown. It is a common belief that the best plumage is found on the chicken which is growing the most rapidly. However, results of experiments conducted at this station provide evidence to indicate that feather development does not always parallel rapidity of body growth.Wilcke and Hammond (1940) state that feather development aids sales and inhibits cannibalism. They report that corn-fed chicks produce a “curled, frizzled” feather and that the addition of oats, oat hulls, or hulled oats improves the condition.Graham (1941) states that “feather faults are a sure indication of poor growth, feeding, confinement, or lack of vigor,” and that “smooth, close-fitting plumage that .