Effect of sorghum particle size on digestibility of nutrients at the terminal ileum and over the total digestive tract of growing-finishing pigs.

The effect of sorghum particle size on nutrient digestibilities at the terminal ileum and over the total digestive tract of growing-finishing pigs were investigated in a replicated 3 X 3 Latin square trial. Sorghum-casein diets were used. Sorghum was dry rolled (C) or ground in a hammer mill through 6.4 mm (M) or 3.2 mm (F) screens, producing particles with a modulus of fineness of 3.57, 2.85 or 2.36, respectively. Each successive reduction in particle size improved (P less than .05) the apparent ileal digestibility of dry matter, starch, gross energy and N. Measured over the total digestive tract, digestibilities of these components were highest (P less than .05) for the F diet but they did not differ (P greater than .10) between diets M and C because of increased (P less than .05) disappearance in the large intestine of dry matter, starch and gross energy from the C diet. N loss in the large intestine was also higher for pigs fed diet C than for those fed diet M, but the difference was not significant. The digestibilities of most amino acids at the terminal ileum were improved (P less than .05) as particle size decreased. Lysine digestibilities were not affected (P greater tha .10). Amino acid digestibilities measured over the total digestive tract were consistently higher (P less than .05) for diet F than diets M and C, which did not differ (P greater than .10) from one another. A comparison of ileal and total tract digestibilities indicated a net disappearance of all measured amino acids except lysine during large intestine transit. These data indicate that increasing fineness of grind will improve digestibility of nutrients in sorghum by growing-finishing pigs.