Impact of feed intake in early gestation on maternal growth and litter size according to body reserves at weaning of young parity sows.

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 ME per kg and 0.68% SID 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 were 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 x 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 /= 0.200) 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 kg) and on classes of BF ( 11.5 mm) were quadratically affected by the feed levels (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.