Particle size and heat treatment of barley in diets for early-weaned piglets

One hundred and twenty male piglets weaned at 20 days and weighing 5.7+/-1. 0 kg were used in a 28-day trial to evaluate the effect of dietary particle size and heat treatment of barley on performance and total tract apparent digestibility. There were four dietary treatments: coarsely ground barley ( 4.5 mm screen); finely ground barley (2.5 mm screen); micronized and then f inely ground barley (2.5 mm screen); and finely ground (2.5 mm screen) and then expanded barley. All the diets contained 500 g of barley issued from t he same batch/kg. There were six replicates of five piglets per treatment. Total tract apparent digestibility of organic matter (OMD), energy (ED) and crude protein (CPD) were assessed from samples taken at 14 and 28 days fro m each replicate using chromic oxide as indigestible marker. No differences were found between results associated with screen sizes in the raw barley- based diets. Processing of barley caused an increase in starch gelatinizati on, a decrease in the proportion of large particles (>1.25 mm) and an incre ase in the proportion of fine particles (<0.16 mm; p<0.05), as compared wit h unprocessed barley. Piglets fed processed barley-based diets grew faster than piglets fed raw barley-based diets only in the first 14 days of experi ment (232 vs. 204 g per day; p=0.04). Feed conversion was not modified by b arley processing. Processed barley-based diets showed higher values for OMD , ED and CPD than raw barley-based diets, but only the difference for OMD a pproached significance (0.817 vs. 0.784; p=0.07). It is concluded that proc essing of barley improved piglet performance in the first 14 days post-wean ing, and that no differences exist between processing techniques or grindin g size of barley for any of the traits studied. (C) 2000 Elsevier Science B .V. All rights reserved.