Effect of Sorghum Particle Size on Digestibility of Nutrients at the Terminal Ileum and over the Total Digestive Tract of Growing-Finishing Pigs

Abstract

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.

Effect of dietary particle size and nutrient supply on energy digestibility and nitrogen excretion in ileal cannulated grower pigs

“…The improved total-tract energy digestibility was consistent with diets based on corn (Wondra et al 1995) and barley (Oryschak et al 2002), although improvements appeared less consistent for diets based on barley or wheat (Laurinen et al 2000). The improved ileal energy digestibility was similar to sorghum-based diets (Owsley et al 1981). In the present study, improvements in energy digestibility by particle size reduction were larger at the ileum than over the total tract, suggesting that the total amount of energy digested was increased and that energy digestion shifted partly towards the small intestine.…”

“…Particle size reduction improved apparent N digestibility more at the ileum than for the total tract, similar to diets based on wheat (Sauer et al 1977) and sorghum (Owsley et al 1981). Increased apparent N digestibility may result from increased true N digestibility or decreased endogenous N excretion (Batterham 1994); however, either hypothesis cannot be proven because endogenous N losses were not measured.…”

Effects of particle size and extrusion of maize and sorghum on ileal digestibility and growth performance in pigs weaned at 14 and 21 days of age

“…But reduced particle sizes of the grains tended to improve the digestibilities of Thr, Val, Leu, and Lys in maize and Thr, Val, and Leu in sorghum. Previous studies showed improved nutrient digestibility when particle sizes of grain were reduced (Owsley et al, 1981;Leibholz, 1982;Ohh et al, 1983;Gieseman et al, 1990;Healy et al, 1994), even though the selected particle sizes and ages of pigs tested were different. Increased surface area of the diet and increased fluidity of digesta contents increases contact with digestive enzymes, and may be involved in the improved digestibility of nutrients (Ohh et al, 1983).…”

“…To minimize the effect of endogenous protein losses, Batterham (1994) recommended that the minimum dietary crude protein (CP) levels of tested diets be at least 105 g CP/kg, while Sauer et al (1989) suggested a range of 150 to 160 g CP/kg. Other experiments were also conducted with diets, fortified with casein, to determine the apparent ileal digestibility of amino acids in cereal grains (Easter, 1972;Cousins, 1979;Purser et al, 1979;Owsley et al 1981;Cho et al, 1997).…”

“…Improved feed efficiency and digestibility of nutrients and energy were reported with fine grinding of major grains such as maize (Reimann et al, 1968;Hedde et al, 1985;Wondra et al, 1995), and sorghum (Owsley et al, 1981). But the optimum particle size is probably dependent on the age of pigs.…”