Impact of a Saccharomyces cerevisiae Fermentation Product Supplemented from 20 Days Before Dry-Off Through 60 Days of Lactation on the Metabolic Adaptation of Dairy Cows to the Peripartum Phase.

Sixty Holstein cows were enrolled at -76 days from calving (DFC) and classified based on the daily SCC during the previous week from an automated milking system. The separation thresholds for low (L, n = 46) and high (H, n = 14) classifications were 100 K/mL for primiparous and 200 K/mL for multiparous cows. Cows were then assigned to two homogeneous groups to receive diets supplemented with 19 g/d of a Saccharomyces cerevisiae fermentation product (TRT; NutriTek, Diamond V, Cedar Rapids, IA, USA) or without supplementation (CTR) until 60 DFC. Cows were dried off at -56 DFC and monitored for disease incidence, milk yield and composition, plasma metabolic profile, and whole blood count from -76 to 60 DFC. Data were analyzed utilizing ANOVA and mixed models for repeated measures. During the dry period, TRT cows had greater plasma thiol and albumin compared to CTR. TRT-L cows had greater plasma protein and globulin than CTR-L. TRT-H cows had heightened hematocrit; reduced plasma globulin and haptoglobin; and higher albumin, albumin to globulin ratio, and thiol than CTR-H. TRT-H cows had greater concentrations of leukocytes and lymphocytes and lower plasma protein and ceruloplasmin at -54 DFC; lower reactive oxygen species to ferric ion-reducing antioxidant power ratios at -44 DFC; and greater concentrations of lymphocytes and plasma gamma glutamyl transferase at -7 DFC than CTR-H. After calving, TRT cows had a lower incidence of mastitis and higher butterfat, as well as greater plasma haptoglobin and aspartate amino transferase (AST) and reduced Mg compared to CTR. TRT cows had lower SCC between 1 and 7 DFC and a greater ECM between 41 and 60 DFC compared to CTR. TRT-H cows had lower SCC between 1 and 7 DFC and greater hemoglobin and plasma AST than CTR-H. Ameliorated immune system functions due to Saccharomyces cerevisiae fermentation product administration lowered the SCC in TRT-H cows and prevented the onset of new intramammary infections across both L and H SCC groups, supporting the improved productive performance of dairy cows.