In pedegree Charolaise heifers, reared in suckler herd on grasslands, without buildings, and supplemented with bulk feeds (maize silage and grain and papilionaceae mixture silage and straw) polymorphism of miostatin (MSTN) and somatotropin (bGH) was identified. Frequencies of genotypes were as follow: bGH-LL 0,417, bGH-LV 0,517, bGH -VV 0,066 and MSTN-AA 0,817, MSTN-AB 0,183, MSTN-BB 0,00, while frequencies of alleles were consequently: bGH-L 0,765 and bGH-V 0,325, MSTN-A 0,908 and MSTN-B 0,092. The highest body weight at birth and at age of 7 months characte-rized bGH-VV heifers (57,3 kg and 300,6 kg, respectively) –significant superiority in comparison to other genotypes. There were no relations found between MSTN genotypes and body growth traits. Statistically significant differences were stated in body weight due to sire group – the highest body weight of progeny was found for Dimas sire daughters while the lowest for Calin sire daughters (respectively: 51,3 vs 39,6 kg and 295,5 vs 275,2 kg; P≤ 0,01).

45-51