The aim of the research was to establish if there are any statistically significant associations between the polymorphisms of the selected genes (TNF-α, LTF, mLYZ) and natural log-transformed SCC (LnSCC) and search for possible interactions between the genetic variants of the selected genes in determining various SCC values in milk. The study included 171 Jersey cows. Two alternative approaches were compared: the standard simple model accounting for the additive effect of a single locus only, and the full model including both additive and dominance effects of TNF-α, LTF and mLYZ as well as the interactions between them. The results obtained with the full model are different from those obtained with the standard model including only the additive effects of individual genes. The results presented above prove the existence of complex functional interactions between lactoferrin, lysozyme and tumor necrosis factor and suggest that the alleles of the genes that encode them might interact with each other too.

Key words: Mastitis, Epistase, Lactoferrin, Lysozyme, SCC, Tumor necrosis factor