The Effect of Pellet Diameter on the Growth Performance, Nutrient Digestibility, and Intestinal Health of Piglets...

This experiment evaluated the effects of pellet diameter on growth performance and intestinal health of piglets during the creep feeding stage. A total of 144 7-day-old suckling piglets (body weight of 2.2 ± 0.3 kg) were randomly assigned to four groups and fed the same formula as meal feed and pellets of 2 mm, 4 mm, and 8 mm in diameter, respectively. Each treatment consisted of six replicates of six piglets. The trial was divided into two phases by weaning time: 7-21 days (breast milk + creep feed) and 21-35 days (creep feed only). After the feeding trial, piglets from the meal feed group and the 8 mm pellet group were selected for slaughter and sampling. The results showed that before weaning, average daily feed intake (ADFI) increased significantly with increasing pellet diameter (p < 0.001). Post-weaning, piglets fed 8 mm pellets presented significantly higher final body weight (FBW) and average daily gain (ADG) than those in the meal group (p < 0.05). Apparent nutrient digestibility (ATTD) in pellet groups was significantly higher than that in the meal feed group and rose with increasing pellet diameter (p < 0.001). The organ indices of the stomach and large intestine in the 8 mm group of piglets were significantly lower than those of the meal group. The jejunal villus height (VH) in the 8 mm group showed a trend toward an increase (p = 0.066), and the ileal crypt depth (CD) was significantly lower (p = 0.004), with significantly higher digestive enzyme activities in the jejunum and ileum (p < 0.05). In the 8 mm group, the relative abundances of Bacteroidetes in the jejunum and Actinobacteriota in the cecum and colon increased, while those of Pseudomonadota decreased; jejunal microbial relative richness increased significantly, while the ileal microbial operational taxonomic unit (OTU) richness decreased obviously. In conclusion, pellets improved the growth performance of creep feeding piglets. Compared with meal, 8 mm pellets can significantly enhance intestinal health level and nutrient digestion and absorption capacity by optimizing intestinal morphology, boosting digestive enzyme activities, and improving flora structure.