Effects of Exogenous Amylase in Transition Dairy Cows Fed Low-Starch Diets: 2. Total Tract Digestibility and Blood Urea Nitrogen

The objective of this trial was to determine the effect of exogenous amylase during the transition period on total tract digestibility, rumen pH and blood urea nitrogen in lactating dairy cows. The effect of exogenous dietary amylase supplementation on lactation diets with low starch concentration (19.5% of dry matter) and dry period diets with moderate starch concentration was evaluated (15.5% of dry matter). A total of 30 multiparus Holstein cows were randomly assigned to two groups with amylase (n=15) or control (n=15). Three cows from each group were randomly selected and ruminally cannulated for digestibility trials. The research was conducted starting at 21 d prepartum until 84 d postpartum. Digestibility of dry matter, organic matter, neutral detergent fiber, starch, and crude protein remained unaffected by treatment in postpartum. Average pre- and postpartum rumen pH concentrations were 6.25 and 6.15, respectively, and did not differ between treatments. Blood urea nitrogen (BUN) concentrations were lower in cows fed amylase supplemented diet compared to those fed diet without amylase in both pre- and postpartum periods (P<0.001). In conclusion, the dietary supplementation of amylase did may not affect the digestibility of nutrients, however, it may decrease the BUN concentration in pre- and postpartum period for cows fed amylase. Therefore, it may offer potential for improving nitrogen efficiency in dairy cows.