To adjust breeding programs for local, commercial, and fancy breeds, and to implement molecular (marker-assisted) breeding, a proper comprehension of phenotypic and genotypic variation is a sine qua non for breeding progress in animal production. Here, we investigated an evolutionary subdivision of domestic chickens based on their phenotypic and genotypic variability using a wide sample of 49 different breeds/populations. These represent a significant proportion of the global chicken gene pool and all major purposes of breed use (according to their traditional classification model), with many of them being characterized by a synthetic genetic structure and notable admixture. We assessed their phenotypic variability in terms of body weight, body measurements, and egg production. From this, we proposed a phenotypic clustering model (PCM) including six evolutionary lineages of breed formation: egg-type, meat-type, dual purpose (egg-meat and meat-egg), game, fancy, and Bantam. Estimation of genotypic variability was carried out using the analysis of five SNPs, i.e., at the level of genomic variation at the NCAPG-LCORL locus. Based on these data, two generally similar genotypic clustering models (GCM1 and GCM2) were inferred that also had several overlaps with PCM. Further research for SNPs associated with economically important traits can be instrumental in marker-assisted breeding programs.
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.
Divergently selected chicken breeds are of great interest not only from an economic point of view, but also in terms of sustaining diversity of the global poultry gene pool. In this regard, it is essential to evaluate the classification (clustering) of varied chicken breeds using methods and models based on phenotypic and genotypic breed differences. It is also important to implement new mathematical indicators and approaches. Accordingly, we set the objectives to test and improve clustering algorithms and models to discriminate between various chicken breeds. A representative portion of the global chicken gene pool including 39 different breeds was examined in terms of an integral performance index, i.e., specific egg mass yield relative to body weight of females. The generated dataset was evaluated within the traditional, phenotypic and genotypic classification/clustering models using the k-means method, inflection points clustering, and admixture analysis. The latter embraced SNP genotype datasets including a specific one focused on the performance-associated NCAPG-LCORL locus. The k-means and inflection points analyses showed certain discrepancies between the tested models/submodels and flaws in the produced cluster configurations. On the other hand, 11 core breeds were identified that were shared between the examined models and demonstrated more adequate clustering and admixture patterns. These findings will lay the foundation for future research to improve methods for clustering as well as genome- and phenome-wide association/mediation analyses.
Relevance. The demand for organic meat products is constantly increasing. Organic agriculture is the leading global trend. The organic market for 2020 is estimated at $ 130 billion with an annual growth of 13–15 %. During the pandemic, sales of organic products in developed countries increased by 30–40 %. Methods. The object of the study were chickens of the Pushkin breed and the Ross 308 cross (broiler). The birds were grown up to 85 days of age under the same conditions, the stocking density was 10 birds/m2. At the age of slaughter in industrial production (48 days – broiler) and organic production (85 days) according to the methodology of the All-Russian Research and Technological Institute of Poultry (2001), anatomical cutting of 9 heads was carried out. Analysis of quality indicators of meat by high performance liquid chromatography (M02-902-142-07) was carried out in the certified laboratory «Leningradskaya MVL». Dry matter was determined by the express method according to the Rygalova E. A. and the water binding capacity of meat was determined by the Grau – Hamm method in the Volovinskaya – Kelman modification. Results. Extending the fattening period of broilers to 85 days to meet the requirements of organic poultry farming does not sufficiently improve the quality of their meat. Low livestock safety (58.16 %) reduces the profitability of organic broiler production. An increase in the total protein content from 20.44 % to 24.41 % and amino acids (tryptophan and prolin), as well as a decrease in fat content from 5.1% to 1.35 % in the pec-toral muscle of broiler chickens from 45th to 85th day improves the dietary qualities of broiler meat. However, a decrease from 51.46 % to 48.54 % of the water-binding capacity of meat reduces its taste and techno-logical qualities. In chicken of the Pushkin breed this figure is 51.35 %. Thus, using the example of the Pushkin breed of chickens, it is shown that breeds of the combined direction of productivity are more suitable for long-term cultivation in organic poultry farming for obtaining meat products.
Relevance. Recently, the number of many breeds and lines of chickens has significantly decreased, while others are under threat of extinction. Reducing the genetic resources of chicken’s worldwide limits the possibilities of future breeding programs. The study of the genetic diversity of the species allows you to more accurately manage the productive and potential of chicken breeds, the possibilities of its use for obtaining Biosafety and full-fledged food. Adding exterior estimation data to the bird breeding value forecast increases its accuracy and is relevant.Methods. The study was conducted on chickens of two experimental populations «Experimental CS» meat-egg of productivity and «Experimental LZS» egg-meat productivity from the Genetic collection of rare and endangered chicken breeds Russian Research Institute of Farm Animal Genetics and Breeding — Branch of the L.K. Ernst Federal Science Center for Animal Husbandry.Results. The highest absolute increase in live weight of chickens is observed in the period of 4-8 weeks, and the relative increase at the age of 4 weeks, regardless of the type of productivity of chickens. The results of cultivation largely depend on the intensity of growth of the bird in the early period, up to four weeks of age. The superiority of the meat-egg population in comparison with the egg-meat population was revealed in terms of breast circumference (5.0–7.7%).
The article presents experimental data on the development of interior features in the offspring of chickens of the experimental Tsarskosel’skaya (CS) population in ontogenesis from 2 to 16 weeks of life.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.