Abstract:
The aim of this study was to determine the changes in backfat thickness from mating to weaning in sows, and whether had an effect on the total born (TB), numbers of born alive (BA), the birth weight (BW),the number of piglets weaned (PW), weaning weight (WW) and the weaning to first service interval (WSI). Two pig farms (1 and 2) with Largewhite x Landrace sows were used for this study. The farms had 361 and 422 sows respectively, with normal parity distribution. Backfat thickness was measured using an A-mode ultrasonic detector at the P2 position, at mating, at 4 weeks and 12 weeks of pregnancy, at farrowing and at weaning. The number of sows in each measurement were 361, 345, 330, 318 and 255 respectively, for farm 1 and 422, 360, 333, 318 and 189 sows, for farm 2. Disregarded data (sows) in the experiment occurred when sows were not pregnant or cull. At each measurement, sows were grouped according to their backfat thickness, those less than 11 mm. (BFT 1), 11.5-15 (BFT 2), 15.5-20 (BFT 3), 20.5-25 (BFT 4) and more than 25.5 mm. (BFT 5). The mean backfat thickness at each measurement for farm 1 was 18.8+-3.8 16.0+-3.3, 16.4+-3.2, 17.6+-2.9 and 16.9+-2.9 mm., respectively, and for farm 2 was 17.3+-3.5, 16.8+-3.2, 17.7+-3.0, 19.2+-3.1 and 18.3+-2.6 mm., respectively. The TB in the groups which had good backfat thickness at mating and at 4 weeks of pregnancy was not significantly different from other groups. When comparing the BW of piglets from sows which had backfat measured at 12 weeks of pregnant and at farrowing, the BW of piglets (farm 1) in BFT 3 and BFT4 was heavier than that in BFT1 (p<0.05). Backfat lost from farrowing to weaning (farm 1) had a positive correlation with WSI (r = 0.2; p<0.05). It can be concluded that backfat thickness had an effect on some aspects of the reproductive performance of sows