PSI-12 - Effects of increasing rumen propionate on dry matter intake, feeding behavior, glucose clearance, and insulin response in cattle on a finishing ration

The objective of this experiment was to determine if increasing propionate alters dry matter intake (DMI), feeding behavior, glucose clearance rate, blood metabolites, insulin concentrations, and rumen fluid lactate in steers fed a finishing diet. Ruminally cannulated Holstein steers (n = 6) were fed a finishing diet ad libitum. Steers were randomly assigned to one of three treatments in a 3×6 Latin rectangle design. Treatments of no Ca propionate (CON), 100 g/d (LOW), or 300 g/d (HIGH) were ruminally dosed daily. Individual DMI was measured using an Insentec feeding system. Weekly blood samples and body weight were collected on d 0, 7, and 14 and analyzed for glucose, lactate, NEFA, and insulin. A glucose tolerance test was conducted on d 14 of each period. Data were analyzed using a mixed model with period, treatment, time, and their interaction included, with time within period as a repeated measure, and steer as a random effect. Dry matter intake, meal size, and number of meals per day were decreased (P < 0.049) in HIGH steers. Weekly plasma glucose tended (P = 0.07) to be greater on d 7 than d 0. Plasma insulin was lower (P = 0.019) in both LOW and HIGH than CON steers. Rumen fluid lactate was decreased (P = 0.034) in HIGH steers. There was an effect of time (P < 0.0001) on rumen fluid lactate and pH, with an increase from 0 h to 6 h. There was no treatment effect (P ≥ 0.11) on weekly plasma glucose, NEFA, or lactate, rumen fluid pH, or glucose peak concentration, plateau, and rate. These data indicate that increased propionate may decrease DMI and alter feeding behavior but might not be related to glucose metabolism.