Effect of increasing levels of rice distiller’s by-product on growth performance, nutrient digestibility, blood profile and colonic microbiota of weaned piglets

Objective: This study was conducted to evaluate the effects of diets containing different wet rice distiller's by-product (RDP) levels on growth performance, nutrient digestibility, blood profiles and gut microbiome of weaned piglets. Methods: A total of 48 weaned castrated male crossbred pigs, initial body weight 7.54 ± 0.97 kg, and age about 4 wks, were used in this experiment. The piglets were randomly allocated into three iso-nitrogenous diet groups that were fed either a control diet, a diet with 15% RDP, or a diet with 30% RDP for a total of 35 days. Chromium oxide was used for apparent digestibility measurements. On d14 and d35, half of the piglets were randomly selected for hemato-biochemical and gut microbiota evaluations. Results: Increasing inclusion levels of RDP tended to linearly increase (p ≤ 0.07) average daily gain on d14 and d35, and decreased (p = 0.08) feed conversion ratio on d35. Empty stomach weight increased (p = 0.04) on d35 while digestibility of diet components decreased. Serum globulin concentration decreased on d14 (P = 0.003) and red blood cell count tended to decrease (P = 0.06) on d35, parallel to increase RDP levels. Gene amplicon profiling of 16S rRNA revealed that the colonic microbiota composition of weaned pigs changed by inclusion of RDP over the period. On d14, decreased proportions of Lachnospiraceae_ge, Ruminococcaceae_ge, Ruminococcaceae_UCG-005, and Bacteroidales_ge, and increased proportions of Prevotellaceae_ge, Prevotella_2, and Prevotella_9 were found with inclusion of RDP, whereas opposite effect was found on d35. Additionally, the proportion of Lachnospiraceae_ge, Ruminococcaceae_ge, Ruminococcaceae_UCG-005, and Bacteroidales_ge in RDP diets decreased over periods in control diet but increased largely in diet with 30% RDP. Conclusion: These results indicate that RDP modulates in a favorable way gastrointestinal microbiota composition and improves piglet performance despite a negative impact on digestibility of lipids and GE.