Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

Johan Osorio


Inflammation, Rumen bacteria, Transition cow, Yeast culture


The transition period is the dynamic stage in the lactation cycle, where the most metabolic changes can occur. The use of nutritional strategies, such as yeast culture, can help cows during the transition from pregnancy to early lactation, improving health and decreasing the incidence of metabolic disorders. The first objective of this research was to evaluate the effects of a commercial yeast culture product (YC; Cellerate Culture Classic HD, Phibro Animal Health, Teaneck, NJ) on performance, blood biomarkers, and rumen fermentation and bacterial population in dairy cows during the transition period through 50 days in milk (DIM). Overall, the results showed that yeast culture products could promote positive responses on performance, such as milk yield, somatic cell count (SCC), and energy corrected milk (ECM). In the rumen, yeast culture product contributed to increased valerate, which was accompanied by improvements in rumen bacteria populations such as cellulolytic and lactic acid-utilizing bacteria. In addition, the results suggest that yeast may influence lipid metabolism in transition dairy cows, based on nonesterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) markers. The second objective was to assess the effects of yeast-based products on metabolism, inflammation, liver function, and immune function through blood biomarkers and gene expression in polymorphonuclear leukocytes (PMNL) in dairy cows during the transition period until 50 DIM. Yeast supplementation might stimulate a mild inflammatory response in transition dairy cows, based on blood biomarker and PMNL mRNA expression. In summary, we observed that yeast culture could promote improvements in performance, rumen bacteria population, and stimulate the immune system in transition dairy cows through 50 DIM.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds.
Yeast as feed.
Dietary supplements -- Physiological effect.
Rumen fermentation.



Number of Pages



South Dakota State University

Included in

Dairy Science Commons



Rights Statement

In Copyright