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The effects of two different feeding levels, offered in two phases during gestation, on body measurements and litter traits were evaluated in 152 gilts and 551 sows. The treatments consisted of the combination of two gestation phases (phase 1-days 22 to 42; phase 2-days 90 to 110) and two feed amounts (1.8 or 3.5 kg/d). Females were weighed on days 22, 42, 90, and 110 of gestation. Born alive and stillborn piglets were weighed within 12 h of birth. Total placental efficiency (ratio between litter weight and total placental weight) was measured in 518 females. Variables concerning body measurements at days 42 and 90 of gestation were analyzed considering the effects of feed amount, parity order (PO) and its interaction as a 2 × 2 factorial arrangement. Body measurements at day 110 of gestation and litter traits were analyzed considering the effects of feed amounts in phase 1, feed amounts in phase 2, PO and their interactions, as a 2 × 2 × 2 factorial arrangement. As expected, BW, backfat, and caliper units were greater at days 42, 90, and 110 (P ≤ 0.006) for females fed 3.5 kg/d during the previous phase than those fed 1.8 kg. No differences were observed among feed levels in total number of piglets born, mummified fetuses, sum of born alive and stillborn piglets, and within-litter birth weight CV (P ≥ 0.118). The percentage of stillborn piglets was affected by a three-way interaction (feed level at phase 1 × feed level at phase 2 × PO). Gilts fed 1.8 kg/d at phase 1 and 3.5 kg/d at phase 2 had fewer stillborn piglets than the other females (P ≤ 0.004). Birth weight was not affected by feed levels (P ≥ 0.153); however, sows had heavier piglets than gilts (P < 0.001). Females fed 3.5 kg/d during phase 2 tended to have heavier litters (P = 0.054) than those fed 1.8 kg/d. Feeding a high level at phase 2 reduced the occurrence of lightweight piglets in gilts, but not in sows (feed level phase 2 × PO; P = 0.031). Total placental weight, average placental weight, and total placental efficiency were not affected by feed level at phase 1, feed level at phase 2 or interactions (P > 0.14). Sows had total placental weight and average placental weight greater (P ≤ 0.003) than gilts. In conclusion, increasing feed intake during phase 1, phase 2, or both phases resulted in increased maternal BW gain, without expressive effects on litter traits. Feeding 3.5 kg/d to gilts during phase 2 reduced the occurrence of lightweight piglets.

The effect of increasing the feed level (1.8, 2.5, and 3.2 kg/d) during early gestation in parity 1 (PO1) and parity 2 (PO2) sows on maternal growth and litter size was evaluated. A total of 361 sows were group-housed and fed a diet based on a corn-soybean meal (3.15 Mcal Metabolizable Energy (ME) per kg and 0.68% standardized ileal digestible lysine) from day 6 of gestation until day 30. Sows were weighed at weaning and on day 30 of gestation. Farrowing rate, number of total piglets born, piglets born alive, stillborn piglets, and mummified fetuses were recorded at farrowing. The effect of feed level on the total number of piglets born was also evaluated according to classes of body weight (BW), body condition score (BCS), backfat (BF), and caliper unit at weaning for each parity order. There was no evidence for significant effect of the interaction between feed level × parity on the variables related to maternal growth and reproductive performance (P = 0.128). Greater feed levels linearly increased the gains in body condition (i.e., BW, BCS, BF, and caliper unit) between weaning and day 30 of gestation (P < 0.001). Farrowing rate was not influenced by the feed level (P = 0.200) and parity (P = 0.209). The number of total piglets born decreased linearly as the feed level increased (P = 0.041), whereas no evidences for differences were observed on piglets born alive among treatments (P = 0.317), neither between parities (P = 0.904). For PO1 sows, the total piglets born on BW classes (=183 vs. >183 kg) and on classes of BF (=11.5 vs. > 11.5 mm) were quadratically affected by the feed levels (P = 0.041). In contrast, the number of total piglets born was marginally affected (linear; P = 0.094) by the feed level in the different classes of BW, BCS, and caliper unit in PO2 sows. There was no evidence for differences for the interaction of feed level and classes of body condition (P = 0.199) for PO2 sows. Similarly, no interactions between feed level and classes of BW, BCS, and BF at weaning were observed (P = 0.233) for PO1 sows; however, the total piglets born were affected by an interaction between feed level and caliper unit class (P = 0.042). In conclusion, increased feed intake from day 6 of gestation until day 30 resulted in increased maternal BW gain but reduced the number of total piglets born. Furthermore, lighter and in a poor BCS PO1 sows at weaning produced fewer total born piglets with no benefits from greater amounts of feed.