Effects of the particle size of barley, wheat, corn or pea based diets on the growth performance of weaned piglets and on nutrient digestibility

The effects of dietary particle size on the growth performance of weaned piglets was studied in five trials. Four particle sizes, ranging from 430 to 900 microns, were compared : very fine (VF), fine (F), medium (M) and coarse (G). In the first four trials, the diets were based on one type of cereal: barley, wheat or corn. In the fifth trial, peas were introduced into the diet at 35 %. The piglets were fed meal ad libitum during the growth performance trial using a feeder. Nutrient digestibility was determined for the VF and G diets.Daily feed intake was not statistically affected by particle size. In the experiments using the cereal based diets, average daily gain (ADG) and food conversion ratio (FCR) were not significantly affected by the treatments VF, F and M. However, coarse grinding (G) reduced ADG in 3 out of 4 trials. The only differences observed for FCR were between treatments VF and G, for 2 out of 4 trials (barley 1 and corn). In the experiment where the diet was based on peas, particle size significantly affected ADG and FCR. Lower nutrient digestibility could explain the decrease in growth performance observed with coarse grinding (except for barley because there was no statistical difference between treatments on digestibility data).Mean diet particle size - between 500 and 600 microns - should be used for piglets receiving cereal based diets whereas, particle size should be smaller for pea based diets.