1. Twelve sets of 3 litter-sister Large White gilts were mated at first oestrus after reaching 250 lb. live-weight and given daily during 3 successive pregnancies either 6 lb. (A), 3 lb. (B) or 3 lb. for 76 days then 6 lb. until parturition (C) of the same meal mixture. During an 8-week lactation all were given 4 lb. meal plus 0·8 lb. per piglet suckled.2. There was a significant linear increase in numbers born with successive parities (P<0·05) but no significant differences between treatment or sister groups. There was a highly significant difference between treatment groups in mean piglet birth weight (P< 0·001) but no parity effect; mean birth weights were 2·76, 2·40 and 2·58 Ib. for Groups A, B and C respectively. Differences between sister groups in mean piglet birth weight were also significant (P<0·05).3. Post-natal litter performance was poor for all groups, probably because of the presence of E. coli, but there was no evidence of treatment effects other than on 3-week weight of third litters, which was significantly greater in Group C than in A or B (P<0·05). There were no significant effects on either number or weight of piglets at 8 weeks.
Superconducting parity effect across the Anderson limit
