Background and Aim: Kalmyk cattle represent a resilient indigenous beef breed of Russia, valued for their exceptional adaptation to harsh continental climates and growing importance in sustainable beef production. Despite their economic and ecological relevance, genetic determinants underlying meat productivity and quality in this breed remain fragmented across largely regional studies. This systematic review aimed to synthesize available evidence on polymorphisms in four major candidate genes, growth hormone (GH), Thyroglobulin (TG), Leptin (LEP), and Calpain 1 (CAPN1), and to evaluate their distribution, associations with productive traits, and relevance for marker-assisted selection in Kalmyk cattle. Materials and Methods: The review was conducted in accordance with PRISMA 2020 guidelines. A comprehensive literature search covering January 2004 to December 2024 was performed using international (PubMed, Scopus, Google Scholar) and Russian (eLibrary.ru) databases. Eligible studies included peer-reviewed articles, dissertations, and conference proceedings reporting primary genotyping data for GH, TG, LEP, and CAPN1 polymorphisms in purebred or crossbred Kalmyk cattle. Data extracted included sample size, geographical origin, genotyping methods, allele and genotype frequencies, and reported genotype–phenotype associations. Due to methodological heterogeneity, a qualitative narrative synthesis was applied. Results: The synthesis revealed pronounced inter-herd and regional heterogeneity in the frequency of favorable alleles. The GH c.2141C>G polymorphism showed extreme variability, with the desirable VV genotype ranging from 0% to 78.3% across herds. Substantial contrasts were also observed for LEP polymorphisms, where favorable genotypes varied from near absence to dominance within specific populations. For meat quality markers, the TG c.-422C>T and CAPN1 c.4568G>C polymorphisms displayed generally low but highly uneven frequencies. Evidence from selected breeding programs demonstrated that targeted selection can substantially increase the prevalence of desirable alleles and improve growth and carcass traits. Conclusion: Kalmyk cattle exhibit marked genetic heterogeneity for key meat productivity and quality markers, reflecting founder effects, localized selection, and breeding history. While GH and LEP polymorphisms show strong potential for marker-assisted selection, the low baseline frequency of favorable TG and CAPN1 alleles highlights the need for structured, large-scale genomic strategies. This review provides the first consolidated genetic landscape of meat-related polymorphisms in Kalmyk cattle and establishes a foundation for sustainable, climate-resilient breeding programs. Keywords: beef cattle genetics, CAPN1 polymorphism, GH gene, Kalmyk cattle, LEP gene, meat quality traits, molecular markers, TG gene.
Chimidova et al. (Tue,) studied this question.