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Effects of yeast product supplementation on production, feeding behavior, and metabolism in transition dairy cows
The objective of this study was to assess the effects of supplementing a yeast product derived from Saccharomyces cerevisiae on production, feeding behavior, and metabolism in transition cows. Forty multiparous Holstein cows were blocked by expected calving date and randomly assigned within block to 1 of 4 treatments (n = 10) from 21 d before expected calving to 42 d postpartum. Rations were top-dressed with yeast culture plus enzymatically hydrolyzed yeast (Celmanax®, Vi-COR®, Mason City, IA) at the rate of 0, 30, 60, or 90 g/d throughout the experiment. Dry matter and water intake, feeding behavior, and milk production were monitored. Plasma collected on -21, -7, 1, 4, 7, 14, 21, and 35 d relative to calving were analyzed for glucose, β-hydroxybutyrate, nonesterified fatty acids (NEFA), and haptoglobin. Data were analyzed using mixed models with repeated measures over time. Pre- or postpartum DMI and water intake did not differ (P > 0.10) among treatments. There were quadratic dose effects (P < 0.05) for prepartum feeding behavior, reflecting decreased meal size, meal length, and intermeal interval, and increased meal frequency for cows received 30 and 60 g/d of yeast products. Postpartum feeding behavior was unaffected (P > 0.10) by treatments. Milk yields were not affected (P > 0.10; 45.3, 42.6, 47.8, and 46.7 kg/d for 0, 30, 60, and 90 g/d, respectively) by treatments. Tendencies toward increased (0.05 < P ≤ 0.10) percentages of milk fat, protein, and lactose were detected for cows receiving yeast. A treatment × wk interaction (P < 0.01) was observed for somatic cell linear score (SCS), reflecting a quadratic dose effect on SCS in wk 1 (P = 0.03; 2.34, 2.85, 1.47, and 4.05 ± 0.57 units for 0, 30, 60, and 90 g/d, respectively). Yeast product increased (P < 0.01) plasma β-hydroxybutyrate and tended to decrease (quadratic P = 0.06) glucose, but did not affect NEFA or haptoglobin. Yeast product supplementation during the transition period did not affect milk production, but may modulate feeding behavior, mammary gland health, and metabolism.
Keywords: production and metabolism, transition cow, yeast