Effects of fixed and changing dietary forage NDF levels on ingestive behavior and blood biomarkers of Nellore bulls in the feedlot

Lay Summary This evaluated the effects of fiber level and fiber management on feeding behavior and metabolic stress in finishing Nellore bulls. Animals received diets containing either 7% or 12% forage neutral detergent fiber (fNDF), dry matter basis (DM) offered either continuously or with a change in fiber level halfway through the feeding period, allowing the evaluation of both fixed and variable fiber strategies throughout the feeding period. Higher dietary fiber promoted longer rumination and chewing times and reduced inactivity. Bulls receiving higher-fiber diets also exhibited lower blood concentrations of lactate dehydrogenase (LDH), suggesting differences in metabolic responses associated with dietary fiber level. Overall, the results indicate that both fiber concentration and its strategic use over time can modulate behavior and support metabolic health in feedlot cattle.