Basic statistical characteristics of backfat thickness and numbers of all, born alive and
weaned piglets estimated within the framework of performance control of Large White
sows on the base of different ranks of parturitions are presented in Table 1. These
means enable indicate that the backfat thickness showed an increasing tendency from
10.99 mm at the first farrowing to 12.21 mm at the seventh and subsequent
parturitions. The difference between the backfat thickness at the 1st and the 7th (and
subsequent) farrowing was 1.22 mm (10,00 %).
The character of these changes in measured values is linear (Fig.). The increasing
backfat thickness of sows with a higher number of parturitions indicates that sows with
a higher percentage of fat remain in the herd for a longer period and that they show a
positive effect on the average longevity. The analysis of numbers of all, alive-born and
weaned piglets again corroborated the fact that the fertility increased with the
increasing rank of the litter. The obtained results indicate that the lowest number of all
piglets (10.5) was in the first litter while the highest one (12.09) in the fifth litter. A
similar trend was observed also in numbers of piglets alive-born, viz. 9.81 vs. 11.05 on
the first and the fifth parturition, resp.; as far as the weaned piglets were concerned,
their lowest and highest numbers were recorded in the 1st and the 3rd litter: 8.77 vs.
9.65, respectively. In this case it is necessary to consider a great effect of exogenous
factors on the rearing of piglets.