A large pellet size rather than diet complexity increases piglet creep feed disappearance and feeding activity but not growth performance.

The objective of the study was to investigate how creep feed pellet size and diet complexity influenced piglets' pre-weaning feed consumption and eating behavior, as well as pre- and post-weaning (PW) growth performance. In total, 180 litters were allocated to one of six dietary treatments: positive control (commercial crumble feed, PCON; n=30 litters), negative control (no creep feed provided; NCON: n=30 litters), high complexity large pellets (HCLP; n=30 litters), low complexity small pellets (LCSP; n=30 litters), low complexity large pellets (LCLP; n=30 litters), or bakery meal large pellets (BMLP; n=30 litters) offered from day 8 in the lactation period until weaning. Large pellets (LP) had a diameter of 12 mm and a length of 10-40 mm, whereas small pellets (SP) had a diameter of 2 mm and a length of 5-15 mm. The term "high or low complexity" of diets refers to the choice of ingredients included; both diets were wheat-based, but the high-complexity diet included more digestible protein sources and functional additives such as aromas and probiotics. Piglets from 36 litters (PCON; n=6 litters, NCON; n=6 litters, HCLP; n=6 litters, LCSP; n=6 litters, LCLP; n=6 litters, and BMLP; n=6 litters) were recorded individually during the lactation period until 15 days PW. The litters and piglets were weighed on days 0, 8, and 15 of lactation and at weaning on day 21. In addition, the individually monitored piglets were also weighed at days 9 and 15 PW. Creep feed disappearance was measured in litters with individually monitored piglets during the entire creep feeding period, as were behavioral observations (on days 9, 16, and 19 of lactation), to assess how many piglets in each litter had their head in the feeder or feed items in their mouth. Dietary treatment had no effect on pre-weaning BW, BW gain, or ADG (P>0.05). However, piglets fed large pellets (HCLP, LCLP, and BMLP) showed a significantly (P<.0001) higher feed disappearance than piglets fed PCON and LCSP, which was supported by a higher number of piglets observed eating on days 16 and 20 of lactation for these treatments (P=0.001 and <0.001, respectively). Post-weaning, piglets fed PCON had a 40% numerically higher ADG compared with piglets fed NCON. In conclusion, the physical form of the creep feed affected the piglets' feeding activity, although this was not reflected in their growth performance. Also, diet complexity did not seem to impact growth performance when the piglets were weaned on day 21 of lactation.