Available energy and amino acid digestibility of defatted rice bran fed to growing pigs1

This study was conducted to determine and compare available energy and apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA in 9 samples of defatted rice bran (DFRB) fed to growing pigs and to generate prediction equations for DE and ME based on chemical analysis. In Exp. 1, 60 crossbred growing pigs (Duroc × Landrace × Yorkshire; 40.7 ± 3.5 kg BW) were fed 1 of 10 diets in a completely randomized design to determine the available energy of DFRB. The diets included a corn-soybean meal-basal diet and 9 experimental diets formulated by replacing the corn and soybean meal with 29.16% DFRB. In Exp. 2, 6 growing pigs (initial BW = 28.5 ± 2.8 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in a 6 × 6 Latin square design with 6 diets and 6 periods. The diets included an N-free diet based on cornstarch and sucrose and 5 experimental diets containing 60% DFRB as the sole source of AA. Chromic oxide (0.3%) was used as an indigestible marker. Among the 9 samples, the concentrations of ether extract (EE), crude fiber (CF), NDF, ADF, starch, Ca, and P averaged 1.33 (0.50% to 4.14%), 14.54 (9.78% to 23.85%), 28.62 (20.19% to 38.85%), 14.22 (9.32% to 23.99%), 38.80% (30.62% to 47.55%), 0.16% (0.09% to 0.24%), and 1.96% (1.11% to 2.28%), respectively. The average DE and ME were 2,643 and 2,476 kcal/kg DM, respectively, and ranged from 2,039 to 3,157 kcal/kg DM and 1,931 to 2,978 kcal/kg DM, respectively. In Exp. 2, there were significant differences in the AID and SID of CP and most AA except for His, Tyr, and Met (P < 0.05). The AID and SID of CP averaged 67.75% and 76.37%, respectively. The digestibility of Met was the greatest, averaging 86.15% and 90.08% for AID and SID, respectively. The AID and SID of Lys ranged from 51.88% to 71.43% (mean = 63.27%) and from 61.93% to 79.98% (mean = 72.97%), respectively. These results indicated that there is significant variability in chemical composition, energy content, and the SID and AID of CP and most AA among the selected DFRB. The DE and ME of DFRB are primarily related to their NDF and starch concentrations.