Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/1998
Publication Date: N/A
Technical Abstract: Ten Saint Croix wethers were used in two 5 x 5 Latin square digestion trials to determine the effects of grain sorghum (Pioneer 8699) planting density and subsequent processing method on apparent dry matter and N digestibility (DMD and NDIG, respectively), starch digestibility (SD), and retention of P (PR) (as a percentage of intake) by ruminants. Diets contained either high-density (HD) or normal-density (ND) grain sorghum (3 or 76 cm rows, respectively) processed by dry-rolling (DR), steam-flaking (SF) (.36kg/L), or high-moisture ensiling (HM) to give the following treatments: 1) HM/HD; 2) HM/ND; 3) SF/HD; 4) SF/ND; and 5) DR/ND. Grains processed by high-moisture ensiling were harvested at 30% moisture and rolled before ensiling. Diets fed in Trials 1 and 2 contained 40 and 10% roughage, respectively, and were formulated to meet all nutrient requirements. At the beginning of each period, lambs were adjusted to their respective diets for 16 d. Feces, urine, and feed refusals were the collected, weighed, and composited over the following 5 d. Digestibility and retention data were analyzed by analysis of variance as a 5 x 5 Latin square design. The effects of processing method on digestibility and retention tended to be greater than the effects of planting density. Grain processing and planting density did not significantly affect DMD in either trial. Lambs fed DR sorghum had lower ( P < .5) starch digestibility than lambs fed SF or HM sorghum. Lambs fed SF sorghum had lower N digestion than lambs fed DR of HM sorghum. Planting density did not significantly affect dry matter, starch, or N digestion; however, lambs fed sorghum planted in 38 cm rows tended to have greater P retention than lambs fed sorghum planted in 78 cm rows.