The aim of this experiment was to estimate possible associations between TG/PsuI genotypes and some milk performance traits (yields of milk, protein and fat and protein and fat content). The study included 180 Polish Jersey cows. The PCR-RFLP method was used to identification genotypes. The TG/PsuI frequencies were as follow: CC – 0.53, CT – 0.44, CC – 0.03 and C – 0.75, T – 0.25. In this study, no statistically significant correlation between TG genotypes and analyzed the traits, however, shown a tendency to maintain a relationship of genotypes with milk production traits.

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