Dietary roller-milled sorghum improves broiler efficiency and whole sorghum improves gut development

The effects of particle size and type of milling of dietary sorghum for broilers were examined. Sorghum treatments were: whole (WS), hammer-milled with a 3 mm screen (HM3), roller-milled with 0.15 mm roller spacing (RM0.15) and hammer-milled with a 1 mm screen (HMI ). Diets HM3 and RM0.15 were milled to the same particle size. All diets were pelleted. Birds fed RM0.15 were more efficient than those fed the other treatments at 21 and 35 days of age (d), but there was no effect on cumulative feed intake and bodyweight at 35 d. At 35 d, there was no particle size effect of hammer milled sorghum on performance; birds fed WS were least efficient. Nitrogen-corrected apparent metabolisable energy (AMEn) was increased by whole sorghum relative to that of processed sorghum. Relative gizzard weight was proportional to pre-pellet particle size at 21 d and was decreased by HM 1 relative to the other treatments at 35 d. Relative proventriculus weight was increased by HM 1 at 21 d and 35 d. Neither particle size nor processing type affected relative weights of intestinal segments. Digesta pH decreased in the gizzard and increased in the duodenum for WS relative to HM 1. At 21 d, the surface area of duodenal digesta particles was smaller for WS and HM1 than for HM3 and RM0.15. At 35 d, the specific surface area of duodenal digesta particles was highest for WS. Feed conversion and gut development were improved by roller-milled sorghum. Whole sorghum improved gut development and AMEn at the expense of performance.