The effect of backfat thickness determined in vivo in breeding gilts on their reproductive performance and longevity

The aim of this study was to determine the effects of backfat thickness (mean standardised measurement from in vivo assessment) of Polish Large White (PLW) gilts on their reproductive performance and productive lifespan. The study included 5,122 PLW gilts from 160 breeding herds in Poland, which reproductive performance was analysed on the basis of the rearing results of 20,662 litters. The gilts were divided into two groups differing in mean standardised backfat thickness (P2+P4/2) on the performance test day: I≤10 mm, II>10 mm. Sows in group I vs II had a three month shorter herd life (P≤0.001), gave birth to fewer litters and piglets (P≤0.001), but the average number of piglets born alive and reared to 21 days of age/litter was higher in them (P≤0.001). The number of live-born piglets per 100 days of reproductive life in group I was greater than in group II (P≤0.001). When culling sows in cycles 1–8 and later, there was more intensive culling in group I vs II from cycle 1 to 6 and a lower percentage of sows remaining in the herd. In group I vs II, the proportion of sows with a lifetime productivity of fewer than 30 piglets was 5.5 percentage points higher and that with a production of more than 100 piglets was 1.9 percentage points lower. Our results indicate that the level of fat reserves determined in vivo in breeding gilts can be a preliminary information about the reproductive potential of sows and their predisposition to longevity.