PS8-21. Substantial Variability in Corn Silage Nutrient Composition Across Brazil: Importance of Routine Laboratory Analysis.

Abstract Corn silage is the primary forage used in Brazilian feedlot and dairy systems; however, its nutritional composition varies substantially across regions, which may impair diet formulation accuracy and animal performance. This study characterized the variability in nutrient composition of corn silage samples using a large-scale commercial dataset from the ESALQLAB. A total of approximately 35,000 samples were evaluated for dry matter (DM), ash-free neutral detergent fiber (aNDFom), 48-h NDF digestibility (NDFD48), and starch. Samples were analyzed by near-infrared spectroscopy (NIRS) using Dairy One calibration equations. Results demonstrated substantial variability among samples. Dry matter (DM; n = 34,799) averaged 331.2 g/kg, with Q1 and Q3 of 294.0 and 363.0 g/kg, respectively (SD = 55.5 g/kg). Starch concentration (n = 36,385) averaged 271.1 g/kg (Q1 = 223.0; Q3 = 324.0; SD = 78.7 g/kg), ranging from 167.0 (P10) to 368.0 g/kg (P90), indicating marked variation associated with differences in kernel processing efficiency, grain-to-stover ratio, and harvest maturity stage. Neutral detergent fiber digestibility (NDFD48; n = 35,652) averaged 602.3 g/kgNDF (Q1 = 570.0; Q3 = 630.0; SD = 45.1 g/kgNDF). The aNDFom concentration (n = 33,442) averaged 458.9 g/kg, with Q1 and Q3 of 417.0 and 500.0 g/kg (SD = 62.6 g/kg). Overall, the wide variation in corn silage composition observed across Brazil highlights the substantial risk of misformulation when relying on tabular values, particularly under high-concentrate feeding systems. These results emphasize the importance of routine laboratory analysis to support precision feeding strategies, reduce uncertainty in diet formulation, and improve nutrient utilization efficiency in ruminant systems.