UC Davis

Fibrolytic enzymes have been shown to enhance nutrient availability by increasing fiber digestibility of dairy cow rations. The objective of this study was to determine if a TMR supplemented with an exogenous fibrolytic enzyme product (EFE; RumaThrive; Wilbur-Ellis, Portland, OR) increased milk production or improved reproduction on a commercial dairy. A total of 2,990 Holstein cows were randomly assigned to 1 of 4 study groups: 1) primiparous control (PC: 2 pens) fed only a TMR; 2) primiparous EFE supplement (PT: 2 pens) fed a TMR with added EFE; 3) multiparous control (MC: 3 pens) fed only a TMR; 4) multiparous EFE (MT: 3 pens) fed a TMR with added EFE. The enzyme product had a declared minimum of 44,750 units/g of xylanase. Supplementation of EFE began 2 wk prior to parturition (pre-calving period) and continued 180 d into their lactation. Cows on PT and MT received EFE at a rate of 2 g/cow/d during the pre-calving period and 4 g/cow/d during the lactation period. Data were collected during the first 180 d of lactation, analyzed as a completely randomized design with repeated measures for milk production using the Mixed procedure of SAS (Statistical Analysis System, v.9.4) and Cox proportional hazard regression model with RStudio (v1.4.1106, RStudio: Integrated Development for R, Boston, MA) for time to conception. Primiparous and multiparous pens were analyzed separately. There was no difference in mean days of exposure to EFE between control and EFE primiparous or multiparous pens. The PC had higher milk fat yield, percentage fat, FCM and ECM compared to PT. The MT also had lower milk fat yield, FCM and higher milk protein percentage compared to MC. The PT had a 18% higher risk of conception when compared to PC pens (P ≤ 0.02). Results of this study indicate that feeding EFE to primiparous dairy cows decreased time to conception.