Use of feed technology to improve the nutritional value of feed ingredients

Two experiments were conducted to test the hypothesis that reduced particle size of corn will improve the caloric utilisation of corn fed to weanling pigs and to determine effects of pelleting, extrusion and extrusion and pelleting on energy and nutrient digestibility in diets containing low, medium or high levels of fibre. In Experiment 1, 128 pigs were used (initial bodyweight (BW) of 9.41 ± 1.54 kg). Pigs were randomly allotted to four diets in a randomised complete block design. There were four pigs per pen and eight replicate pens per treatment. The corn used was ground to different particle sizes (i.e. 865, 677, 485 or 339 µm). In Experiment 2, three diets were formulated, including a low-fibre diet, a medium-fibre diet-, and a high-fibre diet. Each diet was divided into four batches after mixing and either fed in a meal form without further processing or pelleted, extruded, or extruded and pelleted. In total, 24 growing pigs (initial BW: 26.5 ± 1.5 kg) with a T-cannula installed in the distal ileum were allotted to the diets in a split-plot design, with eight pigs allotted to each level of fibre. Ileal digesta and faecal samples were collected and the apparent ileal digestibility of energy, crude protein and dry matter were calculated as was the metabolisable energy in each diet. Results of Experiment 1 indicated that final BW and average daily gain were not affected by corn particle size. However, average daily feed intake decreased (linear, P < 0.05) as mean particle size decreased from 865 to 677, 485 and 339 µm. Likewise, gain to feed ratio increased (linear, P < 0.05) from 0.65 to 0.66, 0.70 and 0.69 for pigs fed diets containing corn ground to a mean particle size of 865, 677, 485 and 339 µm, respectively. In Experiment 2, results indicated that pelleting, extrusion, or pelleting and extrusion improved (P < 0.05) the apparent ileal digestibility of energy and dry matter, but in most cases, there were no differences among the pelleted, the extruded, and the extruded and pelleted diets. Medium- and high-fibre diets that were extruded had greater metabolisable energy (P < 0.05) than the meal diets. In conclusion, results indicated that gain to feed of pigs fed diets containing corn with the smaller particle size was increased compared with diets containing corn with a greater particle size. In addition, energy utilisation may be improved by pelleting or extrusion or by a combination of the two technologies, but the response seems to be greater for extrusion in diets that are relatively high in fibre.