Effects of grouping at a later age and split-weaning on the performance and nutrients intake of low birthweight piglets during a 7-week lactation in a multi-suckling system

Recently, variation in the BW of piglets in a multi-suckling (MS) system was observed to belarge. The current study investigated two intervention strategies, grouping of litters at alater age and split-weaning. We aimed to improve the BW gain of smaller piglets andthereby reduce the BW variation at weaning on day 49 postpartum (p.p.) by thetwo interventions. Eight batches of 5 sows with their litters were divided into 4 CTRL and 4TREAT batches. In each litter, the second lowest (LBW) and highest (HBW) birthweight(BiW) piglets from both sexes were selected as focal piglets. Piglets in CTRL were groupedon day 8 p.p. and no split-weaning was applied; piglets in TREAT were grouped on day13 p.p. and the three heaviest non-focal piglets per litter were split-weaned on day35 p.p. Individual BW on days 0, 6, 27, 35, 48 p.p., and individual DM intake of nutrients ofpiglets after split-weaning on days 42-43 p.p. were measured. Results showed that: (1)Throughout the lactation there were no differences in BW or BW gain between CTRL andTREAT, and no BiW × treatment interactions were found. (2) On days 42-43, piglets inTREAT tended to have lower DM feed intake than CTRL (439.3 ± 21.5 vs 502.4 ± 20.3g/day, P =0.072). LBW piglets had numerically lower feed intake than HBW piglets in bothCTRL and TREAT, however the mean difference between LBW and HBW was numericallylarger in TREAT than in CTRL; LBW piglets in TREAT had numerically lower feed intake thanthose in CTRL (401.5 ± 26.6 vs 493.4 ± 29.1 g/day). (3) On days 42-43, there was asignificant BiW × treatment interaction in DM milk intake (P =0.038). In CTRL, milk intakewas 168.7 ± 17.6 g/day and 103.1 ± 13.6 g/day in HBW and LBW piglets respectively, and inTREAT milk intake was 197.4 ± 23.3 and 181.9 ± 15.5 g/day in HBW and LBW pigletsrespectively. In addition, fewer LBW piglets had zero milk intake on days 42-43 in TREATcompared to CTRL (4 vs 11). To conclude, the two interventions did not improve the BWgain of low birthweight piglets, however it helps to increase milk intake of low birthweightpiglets in MS system.