Effects of rapeseed particle size and feed form on growth, nutrient digestibility, and gut physiology in weaned piglets*

Full-fat rapeseed (FFRS) has potential as a sustainable ingredient in monogastric animal nutrition requiring no extensive processing. This study evaluated the effects of grinding and pelleting on the growth performance, nutrient digestibility, and intestinal health of pigs fed diets containing FFRS. Forty-eight castrated male weaned piglets were randomly assigned to six dietary treatments in a 2 × 3 factorial design, varying by feed form (mash or cold-pelleted) and rapeseed particle size (whole, coarse, or fine ground). The experiment lasted 28 days, with FFRS included at 5% during the first 14 days and increased to 10% thereafter. Pelleting significantly improved final body weight, daily weight gain, and feed conversion ratio (FCR) during both the first period (0–14 days) and the entire trial (0–28 days) (P<0.001), whereas grinding had no significant impact on performance outcomes. Apparent ileal digestibility (AID) coefficients of dry matter, valine, and most non-essential amino acids were significantly enhanced by pelleting (P≤0.05), excluding cysteine and glutamic acid. Pelleting also increased liver weight, ileal digesta pH, ammonia content, and reduced digesta viscosity (P≤0.05). Grinding alone influenced only the liver weight to body weight gain ratio (P≤0.033) and caused minor changes in ileal histomorphology. Pelleting significantly increased the concentration of acetic acid in the cecal and colon digesta. In conclusion, pelleting of FFRS-based diets improved growth parameters and nutrient utilization of feed mixtures by weaned piglets, with minimal influence from grinding level in terms of particle size. These findings support the strategic use of raw FFRS in pig diets and highlight the role of physical processing in enhancing its nutritional value.