The effects of extrusion processing of carbohydrate sources on weanling pig performance

Three experiments were conducted to study the effects of extrusion processing on growth performance of weanling pigs. In Exp. 1, 350 weanling pigs (initially 4.4 +/- 1.0 kg BW and 10 +/- 2 d of age) were used to study the effects of various carbohydrate sources (corn, cornstarch, broken rice, wheat flour, and grain sorghum), with or without moist extrusion processing, on growth performance in a 5 x 2 factorial arrangement of treatments. No carbohydrate source x extrusion processing interactions were observed (P > .10). Growth performance was not affected by extrusion processing; however, pigs fed corn had poorer growth performance (P < .05) than those fed other carbohydrate sources. In Exp. 2, 360 weanling pigs (initially 5.0 +/- .5 kg BW and 10 +/- 2 d of age) were used to determine the interactive effects of ingredient processing and diet complexity on growth performance. Three processing combinations were used with either a simple or complex diet formulation in a 3 x 2 factorial arrangement of treatments. The three processing conditions were 1) pelleted only (control); 2) corn that was moist-extruded and then the complete diet was pelleted (extruded); or 3) the complete diet was expanded and then pelleted (expanded). Pigs fed extruded diets had a greater improvement in ADG as diet complexity increased than those fed other diets (processing x diet complexity interaction, P < .10). Pigs fed moist-extruded corn had the best growth performance (P < .01). In Exp. 3, 210 weanling pigs (initially 6.8 +/- 1.5 kg BW and 21 +/- 2 d of age) were fed pelleted diets containing nonextruded corn (14.5% gelatinization; control) or corn extruded to provide 38.7, 52.7, 64.4, or 89.3% gelatinization. Average daily gain and ADFI decreased and then increased (P < .05), but apparent digestibility of DM, CP, and energy (P < .01) increased and then decreased with increasing gelatinization. These results indicate that moist extrusion processing of carbohydrate sources has variable effects on growth performance of early-weaned pigs and that the degree of gelatinization does not seem to be a major factor in explaining this variation.