The effects of food level during lactation and early gestation on the reproductive performance of mature sows

Abstract

AbstractSeventy-six Large White × Landrace sows from parities 2 to 6 were allocated to one of four treatments at day 110 of gestation on a parity and live-weight basis. The four treatments involved food levels of either 3 or 6 kg/day during a 28-day lactation followed by either 1·75 or 3·50 kg/day during the first 28 days of gestation. Litter size suckled was standardized at 10 piglets wherever possible. Live weight and backfat changes were monitored in all sows and litter growth and survival rates were recorded. Post weaning all sows were given daily boar contact and mated twice at the first observed oestrus. A single blood sample was collected from each sow at days 7, 14, 21 and 28 of gestation for determination of plasma progesterone concentration. Data on litter size and piglet birth weights were collected at the subsequent parturition. Sows low-fed during lactation lost significantly more live weight (31·2v.5·8 kg,P< 0·01) and P2 backfat (3·6v.1·9 mm,P< 0·05) in lactation than did high-fed sows. Underfeeding the lactating sow also significantly reduced the weaning weight of the litter (62·3v.68·7 kg for low-v.high-fed sows,P< 0·05), but did not significantly change either creep food intake by the litter or pre-weaning mortality rate. Parity 2 sows weaned significantly heavier piglets and litters than did sows from parities 3 to 6 (7·48 and 74·9 kgv.6·72 and 63·8 kg respectively,P< 0·01). Food level in lactation did not significantly influence the length of the rebreeding interval (6·3v.7·3 days for high-v.low-fed sows) and although there was a two-fold difference in the proportion of sows failing to exhibit oestrus post weaning (0·08v.0·16 for high-v.low-fed sows) this difference was also not significant. Lactation food level did not significantly influence either sow live-weight or backfat change in gestation, plasma progesterone concentrations during early gestation or subsequent litter size. However, sows low-fed in lactation did tend to produce fewer piglets in the subsequent litter (9·54v.10·75 piglets born alive for low- and high-fed sows respectively,P= 0·062). Post-weaning reproductive performance was significantly affected by sow live weight (P< 0·05) and backfat (P< 0·01) at parturition, and live weight (P< 0·01) and backfat (P< 0·05) at weaning, but not by changes in these parameters during lactation. Food level in early gestation did not significantly influence either plasma progesterone concentrations, the size of the subsequent litter (10·09v.20·29 piglets born alive for high- and low-fed sows respectively) or mean piglet birth weight (1·27v.2·22 kg for high- and low-fed sows respectively). It is concluded that (1) both lactation food level and parity may alter pre-weaning piglet growth, and (2) the effects of lactation food level on the subsequent reproductive performance of mature sows appear to be different from those seen in parity 1 sows.