Standardized Ileal Digestibility of Crude Protein and Amino Acids in Corn, White Sorghum, and Red Sorghum Fed to Growing Pigs

Abstract An experiment was conducted to determine the standardized ileal digestibility of CP and AA in corn, white sorghum, and red sorghum. Twelve barrows were surgically fitted with a T-cannula at the distal ileum and were randomly allotted to a replicated 3 x 3 Latin square design with 3 diets and 3 periods for the determination of AID of CP and AA. Previously published values of basal endogenous losses were used to calculate the SID of CP and AA. Treatments consisted of diets containing corn, white sorghum, or red sorghum as the sole source of dietary protein; 8.19%, 9.46%, 10.44%, respectfully. Data were analyzed using the GLIMMIX procedure of SAS (v. 9.4, SAS Institute, Inc., Cary, NC) as a completely randomized Latin square design. An ANOVA procedure was used to determine the statistical significance of grain type. Pig was the experimental unit while fixed effects were treatment, and random effects were pig and period. Least square means were calculated for each independent variable, and means were separated using the PDIFF option. Results were considered significant at P ≤ 0.05 and a tendency for significance at P ≤ 0.10. The SID of Iso, Leu, Phe, Val, Ala, Asp, Glu, Tyr, and indispensable AA was decreased (P 0.02) in white sorghum compared to red sorghum and corn. The SID of Arg and His was greater (P 0.01) in corn compared with both sorghum sources. The SID of Met was greatest (P 0.01) in corn compared to white sorghum, with red sorghum being intermediate. The SID of Lys was greatest (P = 0.04) in corn compared to white sorghum; however, no differences were observed between red sorghum and corn or white sorghum and red sorghum. In contrast, the SID of Thr was greatest (P 0.01) in red sorghum compared to corn; however, no differences were observed between white sorghum and red sorghum or white sorghum and corn. Similarly, the SID of Trp was greatest (P 0.01) in red sorghum compared to white sorghum, while no differences were observed between white sorghum and corn or red sorghum and corn. No differences were observed in SID of CP or the remaining indispensable or dispensable AA. The SID of CP and AA in both corn and red sorghum were similar to that of previously published data (NRC, 2012), however white sorghum digestibility coefficients were lower in comparison. In conclusion, corn and red sorghum were similar in SID of most AA when fed to pigs and improved as compared to that of white sorghum.