THE EFFECT OF BACKFAT THICKNESS IN GILTS ON DAY OF MATING ON THEIR REPRODUCTION PERFORMANCE

The present study aimed at determination of the effect of backfat thickness in different measuring points on the body at first mating in pure-bred Polish Large White (PLW) gilts and Polish Large White x Polish Landrace (PLW x PL) hybrid gilts on their reproduction performance. Also an attempt was made to estimate an optimum backfat thickness at which the gilt breeding should be initiated. Backfat thickness measurements were made using a PIGLOG 105 ultrasonic apparatus on the right-hand side of animal body in 6 points. Litter production traits were analysed, expressed by the number and the weight of piglets on day 1 and 21 of life as well as the number of piglets on day of weaning from sow and weaning to first service interval. In order to perform statistical analysis, the gilts examined were divided into groups, taking into account different backfat thickness at mating measured over the shoulder in points P1a and P1b, on the mid-back in points P2a and P2b and on the low back in points P3a and P3b. Measurements of backfat thickness over the shoulder (points P1a and P1b) as well as those on the mid-back in point P2a are particularly important on day of mating in pure-bred PLW gilts. In case when the backfat thickness over the shoulder on day of mating was above 23 mm and on the mid-back was above 15 mm, the sows gave birth and reared significantly more piglets in the first litter (P≤0.05; P≤0.01). It was showed that measurement of backfat thickness in hybrid sows at mating in points P1b and P2a has a significant effect (P≤0.05) on the litter size and the weight of born piglets (point P2a). In the second reproduction cycle, PLW sows showed significant differences (P≤0.01) with respect to the litter weight on day 21 of life (points P1b and P3a), and in point P2a (P≤0.05). When analysing the reproduction performance traits in hybrid gilts according to thinner or thicker backfat on day of mating, it was observed that the number of piglets born in total was significantly larger (P≤0.05) in the group of primiparous sows with thicker backfat over the shoulder in point P1b at mating and with thicker backfat at point P2a. In the second reproduction cycle, sows PLW with thicker backfat at mating reared litters with a larger weight.