The myostatin gene (MSTN) in cattle has a number of polymorphisms associated with increased muscle mass. The aim of the current study was to determine the haplotype frequencies of F94L and nt821(del11) MSTN polymorphisms among cattle bred for meat in Russia, using DNA analysis. Using the earlier created test systems based on the AS-PCR and PCR-RFLP methods, six populations of Aberdeen Angus (n = 684), two populations of Limousin (n = 54), one population of Simmental (n = 55), and one population of Belgian Blue (n = 137) belonging to Russian farms were genotyped on nt821(del11) and F94L MSTN polymorphisms. The animal carriers of the mutant allele of nt821(del11) MSTN associated with the double-muscling genetic defect were found in one Aberdeen Angus population at a frequency of 2.18%, but were not found in the Limousin and Simmental populations. However, 100% of the Belgian Blue population were heterozygous carriers of nt821(del11) MSTN. The frequencies of the A allele F94L MSTN desirable for productivity traits in the Limousin populations were the highest and accounted for 0.97 and 1 in populations one and two, while in the Aberdeen Angus, Simmental, and Belgian Blue populations, these figures were considerably lower at 0.04–0.08, depending on the population. The obtained data show the high genetic potential of Russian beef cattle, and facilitate an improvement in meat productivity by preserving the health of animals.

Abstract. The use of specialized meat breeds in cattle breeding programs is considered very promising for improving herds' productivity. However, in animal genotype, along with genes that positively affect the productivity signs, there are genes whose mutations, known as genetic defects, negatively affect the health of animals. The aim of the study was the screening of the Russian populations of Aberdeen Angus, Hereford and Belgian Blue cattle on gene mutations associated with the genetic defects of arthrogryposis multiplex (AM), osteopetrosis (OS), developmental duplication (DD), double muscling (M1), hypotrichosis (HY) and maple syrup urine disease (MSUD) as well as the F94L polymorphism of myostatin gene (MSTN) linked with the gene responsible for less fat content in the carcass by means of DNA analysis. In the article, test systems based on the polymerase chain reaction method are presented. The analysis of the Aberdeen Angus (n=4480) population has revealed 0.19 ± 0.09 % animal M1 carriers, 0.53 ± 0.03 % OS carriers, 1.92 ± 0.09 % AM carriers and 9.00 ± 0.20 % DD carriers. The genotyping of Hereford cattle of Russian populations (n=525) has not revealed any individual carriers of MSUD or HY genetic defects. All of the Belgian Blue population (n=92) animals were heterozygous M1 carriers. The study of the F94L MSTN polymorphism has demonstrated extremely high frequencies of the desirable A allele (0.93 and 0.90) in two Aberdeen Angus populations with an average mean of 0.63 ± 0.08, which was 32 % higher compared to the Belgian Blue population. The results suggest the high genetic potential of the Aberdeen Angus and Belgian Blue cattle, but the existence in the genotypes of the mutant alleles associated with hereditary diseases indicates the risk of uncontrolled use of these breeds.

In the paper have been described the inherited diseases AH1 and FMO3 charactering for Ayrshire cattle breed and AM, OS and DD, charactering for Aberdeen Angus one, particularly, the clinical signs and causing gene mutations. The aim of the study was a genotyping of Ayrshire and Aberdeen Angus breeds cattle of Russian populations by earlier developed DNA tests and the evaluation of the spread of animal carriers. The analysis of two populations of Ayrshire cows (n=268) and three populations of Aberdeen Angus (n=772) sire bulls has shown the presence of animals carriers of the genetic defect of AH1 and FMO3 among the Russian Ayrshire populations in 6.33-15.79% and 7.69-46.15% frequencies, respectively. In addition, in Subpopulation 5b three FMO-affected animals were found (3.03%). The animals carriers of AM and DD genetic defects have been found in Russian Aberdeen Angus populations in the frequencies of 0.63-2.73 and 1.13-9.49% dependently from the populations, respectively. In addition, we have observed the increasing of the frequencies of AMC- and DDC-animals in the subpopulations of descendants of populations 1 and 2. The increasing of AMC-animals in Subpopulation 2b comparing with 2a was statistically significant.

The article highlighted the problem of meat cattle genetic defects. The aim was the development of DNA tests for some genetic defects diagnostics, the determination of the animal carriers and their frequencies tracking in time. The 1490 DNA samples from the Aberdeen Angus (n = 701), Hereford (n = 385), Simmental (n = 286) and Belgian Blue (n = 118) cattle have been genotyped on the genetic defects by newly created and earlier developed DNA tests based on AS-PCR and PCR-RFLP methods. The Aberdeen Angus cattle genotyping has revealed 2.38 ± 0.31% AMC-cows and 1.67 ± 0.19 % AMC-bulls, 0.65 ± 0.07% DDC-cows and 0.90 ± 0.10% DDC-bulls. The single animals among the Hereford cattle were carriers of MSUD and CWH (on 0.27 ± 0.05%), ICM and HY (on 0.16 ± 0.03%). The Simmental cattle were free from OS. All Belgian Blue livestock were M1- and 0.84%-CMD1-carriers. The different ages Aberdeen Angus cattle genotyping has shown the tendency of the AMC- and DDC frequencies to increase in the later generations. The statistically significant increase of DDC of 1.17% in the cows’ population born in 2019 compared to those born in 2015 allows concluding the further development of the DNA analysis-based measures preventing the manifestation of the genetic anomalies in meat cattle herds is necessary.

The article highlighted the problem of genetic defect of Aberdeen Angus cattle. Previous investigation showed the presence in Russian population of Aberdeen Angus cattle of animals carrying in their genotypes the mutant alleles associated with Arthrogriposis multiplex, Developmental Duplication and Osteopetrosis. In some populations, the frequencies of the animals-genetic defects carriers were sufficiently high. The aim of the study was to evaluate the risk of spread of the mutant alleles causing the genetic disorders by their transfer from parents to offspring under absence of control over the genetic defects in the farm, breeding Aberdeen Angus cattle. The analysis has shown increasing of the frequency of animals-Arthrogriposis multiplex carriers about on 10.3% in the population of heifers comparing with population of their mothers and the raising of the mutant allele frequency in six times in F2 generation.