ABSTRACT
This study was to evaluate 1 current and 2 newly developed Saccharomyces cerevisiae fermentation products (SCFP, Diamond V Original XPC and 2 test products) on the production efficiency of mid-lactation dairy cows. Eighty mid-lactation (164.5 ± 67.5 d in milk: DIM) Holstein cows (56 multiparous and 24 primiparous) were blocked by parity, DIM, and milk production, and randomly assigned to 1 of 4 treatments. Treatments consisted of: 1) Control (CON): corn silage and haylage based ration; 2) XPC: CON ration with Original XPC added at 14 g/d; 3) Product 1 (P1): CON ration with Product 1 added at 5 g/d; and 4) Product 2 (P2): CON ration with Product 2 added at 19 g/d. Treatments were blended with dried distillers grains and then mixed into a total mixed ration at 454 g/d. The first 14 d of the study (d-14 to 0) was for training cows to use the Calan door feeding system and cows were fed the CON ration during this period followed by an 8 wk continuous experimental period. Dry matter intakes were similar (P > 0.10) when cows were fed all treatments (25.7, 26.1, 25.1, and 26.2 kg/d for CON, XPC, P1, and P2, respectively). Milk production (33.3, 34.4, 35.5, and 36.8 kg/d) was improved (P < 0.05) for cows fed P2 compared to cows fed CON, with cows fed other treatments being intermediate and similar (P > 0.10). Feed efficiency (milk yield/dry matter intake) was improved (P < 0.05) for cows fed P1 and P2, compared to cows fed CON and XPC (1.30, 1.34, 1.49 and 1.41 kg/kg). Milk fat content was reduced (P < 0.05) for cows fed P2 (4.17, 3.93, 4.08, and 3.85%) compared to cows fed CON, with cows fed other treatments being intermediate (P > 0.10). Milk protein and lactose percentages were similar (P > 0.10) among treatments. Cows fed P2 had reduced (P < 0.05) molar proportion of ruminal acetate (63.8, 64.0, 63.1, and 62.3%) and greater (P < 0.05) propionate (18.9, 19.3, 19.7, and 20.6%) than cows fed other treatments. Supplementing a dairy ration with SCFP, such as P2, can improve milk production and feed efficiency of mid-lactation cows.
