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.