An experiment was carried out to compare the effects of dietary particle size and physical form of the ration on performance and weights of digestive organs of broiler chickens. Nine hundred day-old broiler chicks male of Ross line were used during the 47 days of the trial. The experiment followed a completely randomized 3×2 factorial design: three physical forms of ration (mash, pellet and expanded-pellet) x two methods of grinding (intermediary and coarse), with five replicates of 30 birds. Significant interaction effect of physical form of the ration and method of grinding on body weight was found (P<0.05). In the intermediary grinding rations, broilers grew faster as processing intensity of ration increased (expanded-pellet > pellet > mash). Dietary particle size did not affect feed intake of broilers. Birds fed processed rations had higher feed consumption. Significant interaction effect of the physical form of ration and grinding method on feed conversion and viability (P<0.05) was observed. Within intermediary grinding rations, feed conversion was lower and mortality was higher with the expanded-pellet diet. This pattern did not show up with the coarse grinding rations. The physical form and particle size of rations did not affect carcass yield (% body weight). The relative weight (% body weight) of gizzard was lower and that of liver was higher (P<0.05) with the expanded-pellet and pellet rations.
broiler; grinding; particle size; pellet; expansion
