Identification of the potential to increasthe agricultural production of farm animals has become possible through the use of genomic selection methods. It is advisable to improve breeding and pedigree qualities of local breeds, since these have the best adaptability to the features of the natural and geographical conditions in a given area. He controlled slaughter of animals with different genotypes allowed us to determine their meat qualities, such as biological value, slaughter yield and slaughter weight. The ratio of slaughter weight and pre‐slaughter weight gives the slaughter yield in percent.PCR (polyamino acid chain reaction) using specific synthesised sets of oligonucleotides in the genotyping of experimental sheep populations was carried out in order to study the allelic variants of the CAST and GH genes.When studying the indices characterising body weight in sheep which have different genotypes, significant increases in the indices could be observed before the periods of driving to summer pastures (17.2 kg) and during lambing (25.8 kg). The lowest indices were noted during driving both from winter pastures to summer pastures and from summer pastures to winter pastures (30.5 kg).In the period before driving, the live weight index was higher in the CASTMM genotype by 5.8 %; upon arrival in the mountains the difference was 6.1 %; during lambing — 4.7 %; before leaving for winter pastures — 8.4 % and upon arrival at winter pastures — 9.5 %.