Processed cereals in diets for early-weaned piglets

Two trials were carried out to study the influence of cereal processing in diets for early-weaned piglets. Six diets were formulated on an alternate base of two cereals: barley or maize, and three types of processing: control (raw), extrusion and micronization according to a factorial arrangement. In Trial 1, 120 male piglets weaned at 23 days and weighing an average of 6.4 kg, were randomly affected by litter in successive blocks and used in a 25-days performance trial. In Trial 2, 18 piglets, three animals per treatment, were used to measure apparent faecal digestibility of dry matter (DMD), organic matter (OMD), energy (ED), crude protein (CPD) and neutral detergent fibre (NDFD). Ileal viscosity, and pH of stomach, caecum and colon were also performed. In Trial 1, piglets fed barley-based diets grew faster than piglets fed diets based on maize (423 versus 404 g/d; P = 0.04. Heat processing of the cereal improved daily gain (423 versus 396 g/d, P = 0.01) and feed conversion ratio (1.18 versus 1.25 g/g, P = 0.02) with respect to diets based on raw cereal. An interaction between type of cereal and heat processing was observed for the first 2 weeks of the experiment: the improvement in daily gain associated with heat treatment was higher for barley than for maize (13.7 versus -4.3%; P = 0.08). The same occurred for feed efficiency (-14.5 versus 3%; P = 0.06). No differences were detected between types of processing for growth or feed efficiency. In Trial 2, maize-based diets had higher DMD (0.908 versus 0.871; P < 0.001), OMD (0.921 versus 0.880; P < 0.001), ED (0.905 versus 0.863; P < 0.001), CPD (0.886 versus 0.860; P = 0.04) and NDFD (0.795 versus 0.708; P = 0.03), than barley-based diets. Processing of cereals increased digestibility of nutrients but only OMD was improved significantly (0.908 versus 0.886; P = 0.05). Neither ileal viscosity nor pH of stomach and caecum contents were affected by the experimental treatment. Maize-based diets reduced colon pH compared to barley-based diets (6.18 versus 7.00; P < 0.01). It is concluded that processing of cereals improves performance and OMD of diets for piglets and that this improvement is higher for barley than for maize. (C) 1999 Elsevier Science B.V. All rights reserved.