Publication Date


Advisor(s) - Committee Chair

Eric Conte, Getahun Agga, Moon-Soo Kim

Degree Program

Department of Chemistry

Degree Type

Master of Science


Bovine mastitis is caused by a wide range of pathogens which results in a substantial economic loss for the dairy cattle livestock industry. β-defensins are a part of the innate immune system and act as the first line of defense against mastitis in bovine. β-defensins (~6- 10kDa) are antimicrobial peptides that contain about 28 to 67 amino acids, the presence of six cysteine residues results in their three disulfide bonds and a β-sheet structure. A few β- defensins have been identified in cows based on the site of occurrence and time of expression in tissue, but not in milk. A solid phase extraction (SPE) and liquid chromatography mass spectrometry (LCMS) method is developed for the identification of β-defensin in bovine milk of healthy and mastitic cows. The LCMS responses for infected bovine milk were compared with the response obtained from a healthy sample. The concentrations for BNBD4 (Bovine neurophil β-defensin 4) were 31.2 ±1.0 ppm, 44.8 ± 2.2 ppm, and 97.2 ±7.4 ppm for healthy, subclinical and clinical mastitis cow milk respectively, and for LAP (Lingual antimicrobial peptide) were 45.2 ±1.3 ppm, 63.6 ±2.5 ppm, and 138.9 ±11.4 ppm for healthy, subclinical and clinical mastitis cow milk, respectively. These differences between the healthy and subclinical and between the subclinical and clinical mastitis milk were significant (p < 0.05). Other antimicrobial β-defensin peptides are expected in milk from mastitic cows and will be explored. Significant β-defensin increase was observed in clinical mastitis milk compared to subclinical mastitis milk and healthy milk which was significant (P= 0.005 BNBD4, P= 0.006 LAP). Healthy milk had the lowest concentration of β-defensin observed.


Agriculture | Animal Sciences | Biochemistry | Biochemistry, Biophysics, and Structural Biology | Chemistry | Dairy Science | Life Sciences | Physical Sciences and Mathematics