Effect of level of feeding on reproductive performance of primiparous sows

Mainly Yorkshire primiparous sows (160) were fed on two energy levels from 25 kg to mating: 1.0-2.7 kg (L) or 1.4-3.0 kg/d (H). In group L the feed (11.8 MJ ME/kg) allowance was 2.4, 3.5 and 6.4 kg during early and late gestation and lactation. The rations of H-sows were 0.3 kg/d larger. Feeding from weaning to oestrus was 3.7 (L) and 6.7 kg/d (H). In comparison with L-sows grew faster (878/720 g/d; p<0.001) before testing (90 kg) and their backfat was thicker (11.7/10.3 mm, p<0.001). The culling rate was higher in the H-group (48.8/37.5 %), the primary cause being leg weakness(H 32.5/L 21.3 %). H-sows were younger at puberty than L-sows (199/225 d; p<0.001). Age at puberty correlated negatively with daily gain (p<0.001) and fat index (FI, backfat/weight) at testing (p<0.01). Age at mating was (H 209/L 232 d; p<0.001). Litter size and piglet performance were similar in both groups. During lactation H-sows consumed 2 kg less feed than L-sows. After weaning they tended to be fatter than L-sows (P2 15.9/14.4 mm), but no differences were found in their returning to oestrus. FI at weaning was positively correlated (p<0.001) with that at testing. Based on these data it is suggested that abundant feeding during the rearing period leads to early puberty and farrowing and exhibits the sow's affinity to leg weakness. The total feed intake (25 kg-weaning) was 5.4 % higher in H-sows.