Changes in body weight and fatness of sows during reproductive activity depending on LEPR and MC4R genes polymorphism

• Determined Condition and reproductive performance of sows of known genotype.
• Showed a significant interaction effect (LEPR/MC4R) to change condition of sows
• Showed a significant interaction effect (LEPR/MC4R) on the weight of piglets born.
• Sows LEPRAA/MC4RGG and LEPRAB/MC4RGG produced piglets with higher birth weight.
• Both markers should be used in the marker-assisted selection (MAS) of gilts.

The use of genetic markers in selection of maternal breed gilts for reduced feed intake and fatness of pigs, may impact on their reproductive performance in subsequent breeding. The objective of the study was to analyse changes, over three consecutive lactations, in condition (body weight and fatness) and reproductive performance of Polish Large White (PLW) and Polish Landrace (PL) sows of known genotype at leptin receptor (LEPR) and melanocortin 4 receptor (MC4R) loci. The study involved 58 PLW and 65 PL gilts. Gilts and subsequently sows were monitored for body weight (BW) and backfat thickness (P2) over three reproductive cycles, and their litters were analysed for the number and body weight of the piglets. A total of 168 litters of PLW pigs and 186 litters of PL pigs were evaluated. It is concluded that over the three reproductive cycles, PLW sows exhibited higher weight gains and lower fatness compared to PL sows. The interaction between LEPR and MC4R genes had a significant effect on changes in body weight of the gilts, subsequently on changes in the condition of sows (BW and P2) during consecutive reproductive cycles, and on the average weight of piglets born. Heterozygous sows of LEPRAB/MC4RAG genotype were characterized during that time by the highest weight gains and backfat thickness at P2, and their the piglets born had low birth weight. Over the three reproductive cycles, sows of LEPRAA/MC4RGG and LEPRAB/MC4RGG genotypes produced piglets with significantly higher birth weight compared to sows of LEPRAB/MC4RAG, LEPRBB/MC4RAA and LEPRBB/MC4RGG genotypes.