Evaluation of guinea fowls by genetic markers of plumage color

. The work was carried out at LLC "Genofond


Introduction
One of the promising species for the expansion of poultry products is the production of meat and eggs of guinea fowl.This type of poultry, along with the high quality of the products obtained, is characterized by a strong constitution, high viability and resistance to a number of diseases, which distinguishes them favorably from other types of poultry [1][2][3].
Guinea fowls are bred to obtain meat and eggs, which have dietary and excellent taste properties, thanks to these properties, the number of guinea fowls in our country and in the world as a whole increases annually [4][5].In this regard, when carrying out breeding work with guinea fowls, we proposed to take as a basis, first of all, the quality and taste indicators of products obtained from guinea fowls, due to the uniqueness of which this type of bird is bred [6][7].
Known breeding methods used on other types of poultry (chickens, turkeys, geese, ducks) cannot be applied to guinea fowls due to the specific focus of work related to the preservation of their quality and taste indicators of products.Works on the selection of guinea fowl are described in detail in the publications of employees of the Federal Scientific Center "VNITIP" RAS [8][9] and Mari State University [10][11].
One of the limiting factors in the breeding of guinea fowls is the difficulty of determining the sex of the bird before its puberty.Guinea fowl and guinea fowl practically do not differ in live weight and development of the exterior of the main body parts throughout the entire life cycle [12][13].Separate differences in the exterior characteristics of males and females are not clearly expressed, which makes it difficult to form a parent flock, and, accordingly, it becomes necessary to grow "extra males" almost before the beginning of the bird's productivity.The use of well-known methods for separating guinea fowl by sex, based on the opening of the cloaca in order to detect the presence of a penis, also requires certain skills from the operator.Until birds start producing at 20-25 weeks of age, sexing accuracy is typically 85-90%.
In this regard, the purpose of our work was to search for methods for separating guinea fowls by sex at an early age, based on the use of marker genes and their modifiers.

Materials and methods
The studies were carried out at LLC "Genofond" of the Moscow region.For the experiment, 30 guinea fowls and 10 caesars of the following breeds were randomly selected: gray-speckled, Zagorsk white-breasted, blue and cream.
The bird taken for the experiment was bred in itself for a long time and did not give splitting in the color of plumage.The guinea fowls of the experimental groups at the age of 20 weeks were placed in individual cages, 5 breeding nests were completed for each breed.The breeding nest consisted of 6 guinea fowls and 1 caesar.A male of the same type and origin was used as a reserve sire.The assessment of the phenotype of the color of the down color of the cesarean chicks was carried out at the age of one day, and the feathers during the grading of the birds at the age of 12 and 20 weeks, during these age periods, the sex was determined by the cloacal method.
The assessment of economically useful traits of poultry in the experimental groups was carried out according to generally accepted methods.The feeding conditions for guinea fowls corresponded to the VNITIP standards [14] 3 Results and Discussion An analysis of the color of the plumage of guinea fowl showed that it consists of four primary colors: black, white, brown and golden.The manifestation of colors in the form of all possible combinations of them, multiplied by differences in intensity and shades, in the distribution over the body and in the pattern of individual feathers, create a well-known variety of color phenotypes of domestic guinea fowls.The material basis of coloring are the chemical and physical structures of coloring.Chemical coloration directly depends on the pigments contained in the feather.
Analyzing the phenotypes of the plumage color of guinea fowl at Genofond LLC, two main groups of breeds can be distinguished by feather color:  Eumelanin phenotypes with black, gray-speckled and light gray (blue) feather coloration. Pheomelanin phenotypes with cream and white-cream plumage.

Eumelanin phenotype
Grey-speckled guinea fowls are the parent breed of all domestic guinea fowls and are characterized by a wild phenotype.As you know, wild populations of guinea fowls are characterized by gray-mottled plumage.It can be assumed that the intensity of eumelanin deposition in the color of the down and feathers of these guinea fowls is due to the action of the gene locus E.
The E color genes interact with other forms of color in a rather complicated way; the E gene is part of the genotype of all black birds.In a latent state or with modified phenotypic manifestations, the E gene is contained in most variegated breeds.The effect of limited feather pigmentation in gray-speckled guinea fowl (white pearls) is explained by the phenotypic expression of the Sp/sp gene located in a separate locus.The action of this gene is manifested in the restriction of the spread of black pigment in the areas of the feather.
There were no differences in the color of down and feathers in males and females.The white-breasted guinea fowl plumage of this breed is characterized by a darkcolored (gray-speckled) back, upper part of the wings and tail.The sides of the body, the lower part of the wings, the underbelly and the chest are white without beads.The white plumage of the white-breasted guinea fowl occupies from 1/3 to 2/3 of the feathered body area.The phenotype of these guinea fowls is determined by the action of the Zn (Zonal) gene locus, which determines the restriction of pigment deposition in the feather in certain areas of the body (zonal color restriction gene (Zn)).There were no differences in the color and structure of the plumage of males and females.
Blue guinea fowl plumage blue guinea fowl have a light gray color.This plumage color is manifested in guinea fowls under the influence of the eumelanin color weakening genes BL / bl (Blokator) diluting the extreme degree of eumelanin deposition: to gray and light gray.The BL/bl genes act on the E/e genes, which are responsible for the deposition of the eumelanin pigment in plumage.
There were no differences in plumage color between males and females.

Phaeomelanin phenotype
Cream guinea fowls are characterized by the presence of pheomelanin in the feather: the gene for silver S and golden s.The "gold" gene s is involved in the formation of brown and cream plumage.Its dominant allelomorph, the "silvery" gene S, causes the appearance of individuals with lighter, almost white plumage, without visible pearls.The difference in the degree of feather pigmentation can be explained by the action of the Ig (Inhibitor) gene, which blocks the deposition of the pigment pheomelanin in down and feather.The location of the Ig gene on the Z chromosome in males (ZZ) will have a twofold effect of the inhibitor gene.In this regard, males have the weakest degree of feather pigmentation, females have a darker one.The group with intermediate plumage color is 20-25%.Thus, white-and-cream guinea fowls, carriers of the S/s and Ig genes, are autosex for colormarking feather genes.At this stage of the work, the accuracy of sexing this bird on average for the population is 86-88.0%.
As follows from the above descriptions, each breed has a peculiar genotype, which has developed as a result of selection and crosses used in its creation.Based on this, the phenotypic manifestation of the same color genes differs in different breeds.It should be noted that the color phenotype is often changed by directed selection of special modifier genes.Modifier genes affect the intensity and color of plumage in a bird.
The main productive indicators of guinea fowl breeds in Genofond LLC are shown in Table 2.As follows from the data on the productivity of guinea fowls of the gene pool herd of the studied breeds given in Table 2, it is approximately at the same level.The birds of the studied groups are characterized by satisfactory productivity.At the same time, cream guinea fowls differ from grey-speckled, white-breasted and blue guinea fowls by the presence of silver S and golden s genes, on the basis of which an autosex cross of guinea fowls can be created in the future.

Conclusion
It has been established that by the color of the plumage of gray-speckled, blue and Zagorsk white-breasted guinea fowl can be attributed to the eumelanin phenotype.The deposition of eumelanin pigment in down and feathers of guinea fowls is controlled by the gene alleles of the E/e locus.Restriction of pigment deposition in the feathers of certain parts of the body of Zagorsk white-breasteds is determined by the action of the Zn/zn (Zonal) gene, the manifestation of pearl spots is determined by the action of the Sp/sp gene, the autosomal gene Bl (Blokator) determines the saturation of eumelanin colors, and Ig (Inhibitor) blocks the deposition of the pheomelanin pigment.
Cream guinea fowl assigned to the pheomelanin phenotype are characterized by a white-cream color of the feather.The presence in the feather of pheomelanin controlled by the genes for silverness "S" and goldenness "s" and the presence of the Ig (Inhibitor) gene blocking the deposition of the pigment pheomelanin in the down and re-determines the presence of autosex color of the plumage.
In this regard, in the future, on the basis of this breed, it will be possible to create an autosex cross of guinea fowls.

Table 2 .
The productivity of guinea fowls of the conserved gene pool.