A total of 1,034 pigs produced by breeding PIC sows to 2 different PIC terminal sires were used to create 3 distinct weaning weight populations so that post-weaning growth to 125 kg could be studied. The rearing strategies resulted in BW that ranged from 4.1 to 11.5 kg by 20 d of age. Sows and corresponding litters were allocated to 3 treatments: sow reared (SR; n = 367) for 20 d, sow reared for 14 d (14W; n = 330), and sow reared for 2 d (2W; n = 337). Sows were removed from 2W and 14W groups, but progeny remained in the crates and received milk replacer ad libitum (for 18 and 6 d, respectively) until the contemporary SR pigs were weaned at 20 d of age. The SR pigs (6.49kg) weighed 1.01 kg less than 14W pigs (7.5kg) and 2.26 kg less than 2W pigs (8.75kg). The 14W pigs weighed 1.25 kg less than 2W pigs. Nursery ADG for the 2W group (547 g/d) was 35 g/d less than 14W pigs. The 14W pigs (165 d) required 3 fewer days to reach 125 kg of BW compared with SR pigs. The SR and 14W pigs gained BW 24 and 20 g/d faster in the postnursery period when compared with 2W pigs. The SR and 2W pigs consumed 0.10 and 0.12 kg/d less during this period when compared with 14W pigs (2.32 kg/d). Gain:feed of SR was improved when compared with the 14W and 2W pigs over 167 d of age (0.44 vs. 0.42 and 0.42, respectively). Lean percentage was 0.7% greater in carcasses from SR pigs (55.0%) compared with carcasses from 2W pigs (54.3%) when adjusted to a constant HCW. A study of the effect of weaning weight on days to 125 kg was limited to SR and 14W groups because maternal deprivation compromised the 2W group postweaning growth. Six weaning-weight groups were defined using a normal distribution: 4.6, 5.5, 6.4, 7.3, 8.2, and 9.5 kg. Pigs weighing 5.5 kg at 20 d of age were able to reach 125 kg 8 d sooner (168.8 d) than those weighing 4.6 kg (176.8 d). There was a linear relationship between weaning weight and ADG in the postnursery phase of growth. We conclude that  a weaning weight of less than 5.0 kg imposes the greatest marginal loss in production output for a 20-d weaning and lactation length influences long-term growth, composition of growth, and viability of progeny.

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