Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy and Food Science

First Advisor

Maristela Rovai


dairy cows, immunity, mastitis, methionine


Mastitis is a significant problem in the dairy industry, posing numerous challenges for dairy farmers worldwide. Mastitis refers to the inflammation of the mammary gland, primarily caused by bacterial infections. This condition affects the health and well-being of dairy cows and has severe economic implications for farmers and overall dairy production. The prevalence of mastitis substantially threatens milk quality, productivity, and profitability, making it a top concern in the dairy industry. Preventing mastitis in cows is crucial for maintaining the herd's health and ensuring highquality milk production. Nutritional strategies have recently gained greater attention due to a direct impact on immune function and a large effect on mastitis prevention. This study evaluated the effects of rumen-protected methionine (RPM) during a subclinical mastitis challenge to enhance the immune system in dairy cows. Thirty-two multiparous Holstein cows were enrolled in a randomized complete block design and assigned to either a basal diet (CON; n=16) or a basal diet supplemented with rumen-protected methionine (SM; n=16, Smartamine M 0.09% DM). The dietary treatment was administered to cows at -21 days relative to a SMC, and data were collected from 0 to 3 d relative to SMC. At 0 d relative to SMC, the mammary gland's rear right quarter was infused with 500,000 cfu of Streptococcus uberis (O140J). RPM did not prevent subclinical mastitis or showed lower SCC during SMC. However, it helped to maintain milk production, improved milk components and showed improvements in oxidative stress status. In addition, RPM supplementation during subclinical mastitis challenge might attenuate inflammation and enhance blood and milk immune cells protein synthesis through the mTOR pathway.


South Dakota State University



Rights Statement

In Copyright