There are many genes responsible for the appearance of different coat colours, among which the melanocortin 1 receptor gene (MC1R) plays an important role. The aim of the study was to characterize genetic variation in Central European cattle breeds based on polymorphism of the MC1R gene and factors determining their coat colour. The study was conducted on 290 individuals of the following breeds: Polish White-Backed (PW), Lithuanian White-Backed (LW), Polish Red (PR), Lithuanian Red (LR), Carpathian Brown (CB), Ukrainian Grey (UG), and Slovak Pinzgau (SP). Polymorphism at the MC1R gene locus was analysed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using two restriction enzymes: Cfr10I and SsiI. The proportions of alleles and genotypes in the MC1R locus indicates a strong relationship between polymorphism and the coat colour of cattle: The E^D allele proved to be characteristic for the breeds with a white-backed coat (PW and LW), while the dominant allele in the red breeds (PR and LR) was E⁺. It is noteworthy that coat colour in the SP population was determined only by the recessive e allele, which resulted in the formation of a separate clade in the phylogenetic tree.

Effect of Thermal Stress on Reproductive Performance Parameters of Sows with Defined Genotype at the RYR1 locus: The objective of the present research was to determine the influence of ambient air temperature in the farrowing section of a pig facility on chemical composition, colostrum and milk somatic cell counts (SCC), and rearing efficiency of piglets from Polish Landrace (PL) sows with identified genotype at the RYR1 locus. Subjects were 60 PL sows in the second and third reproductive cycle. Polymorphism at the RYR1 locus was analysed using the PCR-RFLP method. The proportion of RYR1 C/C and RYR1 C/T genotypes in each group was 1:1. Three groups of experimental temperatures were established: I - 22°C, II - 25°C, III - 28°C. The present study demonstrated that sows kept in periodic high ambient temperature (25°C, 28°C) showed a relatively long period of farrowing, more aggressive behaviour and overlying. Variability was also found between the groups with respect to litter size and litter weight, chemical composition and SCC of colostrum and milk. The results indicate that elevated ambient temperature during the perinatal period may adversely affect the utility value of sows.

In view of the threat to local breeds resulting from intensive animal production, many studies are conducted in search of arguments confirming their importance in food production. In the case of milk production, not only is its quantity important, but its quality is as well, including its chemical composition. Particular focus has recently been placed on the casein proteins beta-casein (CSN2) and kappa-casein (CSN3), due to their potential impact on human health or on the suitability of milk for cheese production. The present study analysed the polymorphism of these proteins in 1777 cows belonging to two local cattle breeds, Polish Red and Polish White-Backed, using Illumina Infinium XT SNP technology on a EuroGenomics MD chip. The results indicate that the Polish White-Backed breed is predisposed to produce ‘A2 milk’, as the frequency of the CSN2 A2 allele in the population was 61.2%. The Polish Red breed was characterised by a higher frequency of the CNS3 B allele (35%), which according to extensive scientific literature is associated with better coagulation properties, and increased whey expulsion. The highest yield of milk and its constituents, confirmed at p ≤ 0.01, was obtained for Polish White-Backed cows with the A2A2 genotype in CSN2 and cows with the AA genotype in CSN3. In the Polish Red breed, no statistically significant differences were obtained between means for milk production traits.

Local breeds are the main reservoir of biodiversity of farm animals. According to FAO, they account for 87% of all described breeds in the world. To ensure that they are adequately protected, they should be continually monitored for genetic variation. Another crucial factor is reproduction, which is the most important guarantee of population growth. In the present study, genetic variation in 372 Polish White-Backed cows was determined using DNA microsatellite sequences, taking into account their parentage. Reproductive parameters were analysed as well, based on data from 3658 lactations of 1128 Polish White-Backed cows. The results indicate that despite the small initial population and the implementation of a moderate selection of animals, the existing population of Polish White-Backed cattle has a high level of genetic variation, reflected in the degree of heterozygosity (0.761). Regarding reproductive traits, despite their late age at first calving, Polish White-Backed cows were shown to be distinguished by very good fertility parameters in comparison to other breeds raised in Poland. These findings not only confirm the value of protecting local cattle breeds around the world but may also be of importance in developing selection indices for highly productive breeds, in which reproductive functioning should be one of the most important factors considered.