Effect of live yeast vs. sodium sesquicarbonate supplementation on milk yield and milk components in dairy cows

Abstract Text:

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