Effects of Arazyme Intake on Growth Performance, Ruminal Fermentation, Nutrient Digestibility, and Blood Parameters in Feedlot Cattle

The use of exogenous enzymes in feedlot cattle nutrition has been investigated as a strategy to increase nutrient utilization efficiency and productive performance. The objective of this study was to evaluate the effects of including arazyme, an exogenous metalloprotease, in the diet of feedlot beef cattle on zootechnical performance, hematological parameters, serum biochemical biomarkers, ruminal fermentation, and apparent nutrient digestibility. Twelve male Holstein cattle, with an average initial body weight of 352.5 ± 20.6 kg, were distributed in a completely randomized design with two treatments: control (no additive) and basal diet with arazyme (0.67 g/kg of dry matter consumed) for 63 days. The diet was formulated with a forage/concentrate ratio of 40:60. Although the sample size was small, the inclusion of arazyme proved effective under these conditions, with animals receiving the enzyme showing greater total weight gain, higher average daily gain, and better feed conversion, without affecting dry matter intake. No significant changes were observed in hematological parameters or in most serum biochemical biomarkers, indicating an absence of adverse effects on the metabolic or hepatic health of the animals. Higher total concentrations of volatile fatty acids in the rumen, particularly acetic, propionic, and butyric acids, as well as a higher ruminal pH on day 63, may be related to the enzyme’s action. Additionally, the apparent digestibility of crude protein and neutral detergent fiber was higher. Therefore, the inclusion of arazyme in the diet of feedlot cattle may be a promising alternative for improving digestive efficiency and intensifying ruminal fermentation, potentially resulting in improved productive performance. Future research with a larger number of replicates and different doses of the additive is necessary to understand its action.