Features of genetic population parameters of Ukrainian local chicken breeds on TLR4 locus

The rational use of the genetic resources of local breeds of farm animals in the framework of the concept of sustainable development is impossible without prior analysis. Now, to assess the genetic characteristics of breeds, lines, and populations, various DNA technologies are widely used, including DNA markers of economically useful traits. The use of target gene mutations as DNA markers, in addition to directly assessing genetic resources, provides the basis for marker-associated selection. One of the promising target genes that can be considered in the context of increasing chicken resistance to bacterial diseases is the toll-like TLR4 receptor gene. The features of the genetic-population parameters of local Ukrainian chicken breeds (Birkivska barvysta and Poltava clay) by the TLR4 locus, namely, by the G3954C mutation, were analyzed using the PCR-RFLP method. As a result, both alternative alleles, A і B, and all possible variants of genotypes were revealed in the experimental populations. In both breeds, the allele B prevailed in frequency (0.90 for the Birkivskaya barvysta; 0.63 for the Poltava clay). The frequency of the allele A was 0.10 for the Birkivskaya barvysta breed; for Poltava clay – 0.37. The frequency of genotypes AA, AB, and BB was as follows: 0.02; 0.16 and 0.82 for the Birkivskaya barvysta; 0.12; 0.50 and 0.38 for Poltava clay, respectively. Certain differences between the breeds in the frequencies of genotypes and alleles are statistically significant (P ≤ 0.01). Both experimental chicken populations at the TLR4 locus are in a state of genetic equilibrium. The Poltava clay breed was characterized by high levels of observed and expected heterozygosity, while for the Birkivska barvysta, these indicators were significantly lower. The levels of the Wright fixation index were low for both breeds, but in the case of the Birkivska barvysta, they indicated a slight deficit of heterozygotes, in the case of the Poltava clay, on the contrary, their “excess”. The values of the indicator of the effective number of alleles were 1.22 (Birkivska barvysta) and 1.87 (Poltava clay). The revealed features of the genetic-population indicators of the studied breeds may be due to the difference in their origin and productivity direction.