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Research carried out on gutted and ungutted carps showed changes in physical and dielectrical properties during storage under refrigerated conditions. During the research, quality index scheme for carp was developed. In the conducted experiment, statistically significant (P ≤ 0.05) differences in pH values between the gutted and ungutted fish, and between successive days in both groups, were not observed. Within 10 days of storage of the carps in refrigerated conditions, the Torrymeter values were steadily decreasing. Based on the results, the equations were set. Conductivity and electrical resistance were significantly correlated with Torrymeter readings on the head, tail and belly. Practical Applications This work addresses the evaluation of the freshness of a carp (Cyprinus carpio) meat. Simple, quick and accurate methods have been proposed. Consumers and traders were able to monitor the quality of fish fillets during refrigeration storage using Torrymeter and QIM (quality index method), measurement of electrical resistance.

The major histocompatibility complex in cattle (BoLA) is regulated by genes that are closely related to the development of the immunological response to pathogens. The most polymorphic BoLA-DRB3.2 locus was analysed in 209 black-and-white Holstein-Friesian cows in Poland in order to a better explanation of influence of MHC on immunity to diseases in dairy cattle. A total of 23 alleles were identified, among which the *24, *16 and *22 alleles were observed with the highest frequency. These alleles were analysed in terms of their association with the occurrence of mastitis, ovarian cysts, retained placenta and uterine abscesses as well as their contribution to production traits (milk yield, protein and fat percentage in milk). It was determined that the BoLA-DRB3.2 *22 and *16 alleles were associated with a lower risk of clinical mastitis; however, a statistical significance was observed only for the *22 allele. Clinical mastitis was observed at a frequency lower by 8% in cows with one copy of the *22 allele compared to cows with 0 copies of the allele. The presence of the *22 allele in the genotype was also associated with higher milk yield, although this association was not statistically significant.

Studies into the polymorphism of the bovine osteopontin (OPN) gene have so far been focussed on the association between milk production and milk composition, lactation persistency and the rate of growth and weight gain in young cattle. Results obtained by some authors have shown different associations for various milk parameters. Even though osteopontin is an essential component of immunological response, the relationship between the polymorphism of the osteopontin gene and the incidence of diseases in cows has not been researched as yet. The purpose of this study was to analyse the c.8514 C > T polymorphism and its association with milk parameters such as: average daily yield, average protein and fat percentage and average somatic cell count in Holstein-Friesian cattle. The study also included an analysis of the impact of polymorphism on the incidence of the most frequent cattle diseases such as: clinical mastitis (CM), ovarian cysts (OC), clinical hypocalcaemia (CH) and pyometra (P). The study population of cows was found to have two alleles in the analysed locus of the osteopontin gene: C (0.529) and T (0.471), and three genotypes: CC, CT and TT (0.288, 0.482 and 0.230, respectively). Although the study showed no significant association between the polymorphism of the OPN gene and the incidence of diseases or milk parameters, it is an important contribution to research aimed at identifying the most essential SNPs which could be used for marker-assisted selection in dairy cattle herds. HIGHLIGHTS The study population was found to have two alleles in the locus of the osteopontin gene (c.8514C>T): C and T, and three genotypes: CC, CT and TT. CT was the most frequent genotype of the osteopontin gene (c.8514C>T), identified in about 48% of the study population of cows. No significant differences were focused between the genotypes in the c.8514C>T locus and the milk parameters and the incidence of cattle diseases.