Effect of live yeast vs. sodium sesquicarbonate supplementation on milk yield and milk components in dairy cows
The trial objective was to determine the effect of supplemental live yeast (LY) (10x109 cfu/cow/d; Saccharomyces cerevisiae CNCM I-1077) vs. sodium sesquicarbonate (SS) (227 g /cow/d) on milk yield, milk components, and DMI. Four pens of Holstein cows (200-230 cows/pen) in a freestall barn were paired as follows: Parity 1 and Parity 2+. Each pair was balanced pre-trial for parity, DIM, milk yield, and milk components. One pen per pair received LY and one pen per pair received SS . The study was 16 wk in length with 12 wk of diet adaptation and 4 wk of data collection. Parity 1 and Parity 2+ diets were similar except Parity 2+ contained 25% BMR corn silage and forage NDF was higher (24.26 vs. 23.45%). Daily milk yield of individual cows was recorded. Individual milk components were assessed twice with a 2-wk interval between tests. Data was analyzed using JMP statistical software. Only cows remaining in study pens for the entire 16 wks were included (LY=295 cows; SS=279 cows). The statistical model for milk yield and components included treatment, DIM category, and pair as fixed effects with cow within pen as random. Pre-trial milk yield and componentswere included as covariates. Pair-wise comparisons were recalculated using JMP’s contrast analysis which utilizes Student’s t-test. The statistical model for DMI used treatment and pair within treatment as fixed effects. Daily milk yield (kg/d) was unaffected by treatment. Weekly average daily milk yields around component test days tended (P=0.10) to be higher for LY, especially in Parity 2+ cows (42.08 vs. 40.26 kg/d for LY and SS, respectively (SE=0.56)) (P=0.01). Percent milk fat and milk true protein were not affected (P>0.10) by treatment. For all cows, yield of 3.5% FCM tended to be 1.29 kg higher with LY (P=0.08) but for mature cows only, yield of 3.5% FCM was significantly higher with LY (45.66 vs. 43.56 kg/cow for LY and SS, respectively (SE=0.63)) (P=0.01). Live yeast improved (P=0.02) overall milk true protein yield by 0.04 kg/d. Mature cows responded to LY with higher DMI (28.24 vs. 26.88 kg/d for LY and SS, respectively) (P<0.01). Yield of milk and milk components was similar or higher with LY. Mature cows consuming a diet with more digestible forage NDF had a greater positive 3.5% FCM yield response to LY than first-lactation cows.
Keywords: live yeast, sodium sesquicarbonate, milk yield, milk components