Amino acid digestibility in rice co-products fed to growing pigs

The global production of paddy rice exceeds 700 million tons per year. The primary objective of rice production is to produce polished white rice for human consumption, but in this process, several co-products that may be fed to livestock are also generated. The objective of this experiment was to determine the coefficient of ileal apparent digestibility (CIAD) and the coefficient of ileal standardized digestibility (CISD) of crude protein (CP) and amino acids (AA) in 2 sources of full fat rice bran (FFRB), 1 source of defatted rice bran (DFRB), and in broken rice when fed to growing pigs. Seven finishing pigs with an average initial body weight of 70.1 ± 6.3 kg were used. Pigs were surgically fitted with a T-cannula in the distal ileum. Animals were allotted to a 7 × 7 Latin square design with 7 diets and 7 periods. Seven diets were prepared, but 1 diet was unrelated to this experiment; therefore only 6 diets were used in this experiment. One diet was based on bakery meal, and 1 diet was based on broken rice. Three additional diets were formulated by mixing bakery meal and each of the 2 sources of FFRB (FFRB-1 and FFRB-2) or DFRB. The last diet was an N-free that was used to estimate the basal ileal endogenous losses of CP and AA. The CIAD of CP and AA in bakery meal and broken rice was calculated using the direct procedure, but the CIAD of CP and AA in both sources of FFRB and in DFRB was calculated using the difference procedure. The CIAD and CISD of CP and AA in broken rice were greater (P < 0.05) than the CIAD and CISD of CP and AA in all other ingredients. The CIAD of the average of indispensable AA was greater (P < 0.05) for broken rice and less (P < 0.05) for DFRB, than for the 2 sources of FFRB. The CISD for the average of indispensable AA in broken rice (0.949) was greater than in FFRB-1 (0.862), FFRB-2 (0.850), and DFRB (0.817), but there were no differences between the 2 sources of FFRB, and the average CISD of indispensable AA in DFRB was less (P < 0.05) than in the other ingredients. The concentrations of CISD CP and indispensable AA in DFRB were greater (P < 0.05) than in all other ingredients. In conclusion, the CIAD and CISD of CP and AA in broken rice was greater than in FFRB and DFRB, but the greater concentration of CP and AA in FFRB and DFRB result in greater concentrations of CISD CP and AA in FFRB and DFRB than in broken rice.