Effect Of Cereal Extrusion On Performance, Nutrient Digestibility, And Cecal Fermentation In Weanling Pigs

A trial was conducted to evaluate the effects of extrusion of different cereals on the performance, nutrient digestion, and VFA concentrations in the cecal digestive contents of weanling pigs. Ninety-six weaned piglets (allocated in 48 pens) were fed 12 different cereal-based diets, consisting of 6 cereals (rice, barley, wheat, corn, oats, and sorghum; 55% inclusion) with or without extrusion processing. Piglets' performance (for 26 d) and nutrient apparent total tract digestibility (ATTD; at d 13) were evaluated. At the end of the trial, the 32 piglets fed the rice and barley diets (with low and high contents of nonstarch polysaccharides, respectively) were slaughtered and samples were obtained to measure apparent digestibility (AD) of nutrients and digesta viscosity in the proximal two-thirds of the small intestine (pSI) and the distal one-third of the small intestine (dSI) and the concentrations of VFA in the cecal contents. Cereal source (CS) or extrusion did not affect piglet performance. Cereal source affected ATTD for all nutrients, whereas extrusion improved ATTD of only GE (86.5 vs. 85.1%) and starch (99.9 vs. 99.8%; P < 0.05). There was a CS x extrusion interaction for ATTD of CP, which was reduced by extrusion but only for rice and oats (84.0 and 84.4 vs. 77.4 and 78.8%, respectively). Extrusion reduced AD of fat in the pSI, whereas a CS x extrusion interaction was observed for AD of starch that was improved by extrusion in barley (88.5 vs. 80.0%) but not rice. Greater AD of DM (72.2 vs. 63.3%) and GE (72.0 vs. 62.7%) in the dSI was observed in rice than in barley, whereas extrusion improved AD of starch (98.6 vs. 96.6%). Interactions (CS x extrusion) were also observed for digesta viscosity in the pSI and dSI (extrusion increased viscosity for barley but not rice). Finally, extrusion reduced (P < 0.05) the concentrations of propionic (20.0 vs. 13.2 mu mol/g) and butyric acids (11.0 vs. 4.4 mu mol/g) in the cecum. It is concluded that both CS and extrusion affect nutrient digestibility but not performance. Cereal source effects are evident over the whole digestive tract, but the effects of extrusion depend on the nature of the cereal and are more evident in the small intestine.