TO STRESS Research Articles

Abstract. The aim of the investigations was to analyse the share of myosin heavy chains (MHC) isoforms (type I, IIa, IIb, and IIx) in the longissimus thoracis et lumborum muscle derived from pigs of different RYR1 genotypes (TT – homozygous negative, CT – heterozygous, CC – homozygous positive). The composition of the MHC isoforms in the muscle tissue of the examined animals was referred to selected meat quality traits. It was revealed that the animals with the CT and TT genotypes were characterized by a significantly (P≤0.05) lower share of the type I and higher share of the type IIb MHC isoform in comparison to homozygotes CC. Inferior tenderness and water holding capacity of meat obtained from pigs susceptible to stress (TT) at 144 h after slaughter could have been associated, among others things, with the increased share of MHC isoform type IIb. The composition of MHC isoforms might be a useful indicator in breeding work in the selection of animals carrying the gene of susceptibility to stress.