Concentration of available energy and digestibility of amino acids in extruded and pelleted defatted rice bran fed to growing pigs

The objective of this study was to evaluate the digestible energy (DE), metabolizable energy (ME) content, and apparent total tract digestibility (ATTD) of gross energy (GE) in extruded defatted rice bran and pelleted defatted rice bran, and to determine apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of crude protein (CP) and amino acid (AA) in two types of defatted rice bran (DFRB) fed to growing pigs. Extruded DFRB is the rice bran co-product remaining after oil is removed by steam pressing and extracting whereas pelleted DFRB is produced by pelleting and extracting. In experiment (Exp) 1, 30 barrows [Duroc x (Large White x Landrace)] with an initial body weight (BW) of 37.6 +/- 4.4 kg were allotted to one of five diets (n = 5) including a corn-soybean meal basal diet and four DFRB test diets containing 292 g/kg of two types of DFRB replacing corn or soybean meal in one basal diet. Pigs were placed in metabolism crates for 7 days of adaptation followed by a 5-day total collection period of feces and urine to detect DE, ME and ATTD of GE in DFRB. Experiment 2 was conducted to evaluate CP and AA digestibility of DFRB. Six growing pigs (24.7 +/- 5.2 kg BW) were allocated to 1 of 3 treatments. Diets included one N-free diet and two test diets which contained 600 g/kg extruded DFRB or pelleted DFRB as the only source of CP and AA. On a dry matter (DM) basis, extruded DFRB contained less fibrous compounds than pelleted DFRB. Except for cysteine, the concentration of AA was less in extruded DFRB than in pelleted DFRB. On an as-fed basis, ME contents in extruded DFRB were greater (P < 0.05) than pelleted DFRB. Pelleted DFRB had greater (P < 0.05) AID of Trp and Gly than extruded DFRB, but for other AA, AID was not different. The SID of all AA was not different between the two sources of DFRB. In conclusion, compared with pelleted DFRB, extruded DFRB may be better for pigs considering its greater DE value.