Dietary fat during pregnancy and lactation increases milk fat and insulin-like growth factor I concentrations and improves neonatal growth rates in swine

Primiparous (n = 24) and multiparous (n = 24) sows were used to examine the effects of supplemental dietary fat and induction of parturition (d 112) o n colostrum and milk composition and suckling piglet growth. Sows were assi gned to one of eight treatments on d 90 of gestation that included variable s such as parity (1 vs. greater than or equal to 3), dietary fat (0 vs. 10% ), and farrowing (natural vs. induction via lutalyse on d 112). Piglets suc kling fat-supplemented dams grew up to 25% faster than control pigs nursing unsupplemented sows (250 vs. 200 g/d; P < 0.01). Improved growth was corre lated with elevated milk fat and insulin-like growth factor (IGF) concentra tions associated with fat supplementation. Dietary fat elevated milk fat co ncentration at 48 and 72 h postfarrowing by 21.6 and 22.6%, respectively (P < 0.05). Compared with nonfat-fed controls, multiparous sows fed 10% fat s howed a more consistent rise in milk fat concentration, with 26% and 41% el evations for induced or naturally farrowing sows, respectively, vs. a 19% r eduction or a 1% elevation in induced or naturally farrowing gilts (P < 0.0 1). The concentration of milk IGF-I tended to be lower in gilts than in mul tiparous sows (P < 0.2, 95.7 vs. 117.4 mu g/L), and levels were particularl y low in milk from induced gilts receiving no additional dietary fat (44.7 mu g/L). However, fat supplementation elevated IGF-I to levels (110.6 mu g/ L) exceeding those measured in unsupplemented, naturally farrowing control sows and gilts (95.8 mu g/L). In conclusion, supplemental dietary fat eleva tes milk fat in multiparous sows more than primiparous gilts regardless of farrowing treatment (induced vs. natural farrowing) and improves piglet gro wth throughout lactation irrespective of parity or farrowing treatment. The potential of supplemental dietary fat to reverse the reductions in milk IG F-I observed in first-parity females and in dams induced to farrow merits f urther investigation.