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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #62858
Title: BACTERIAL GROWTH, INFLAMMATORY CYTOKINE PRODUCTION, AND NEUTROPHIL RECRUITMENT DURING COLIFORM MASTITIS IN PERIPARTURIENT VERSUS MIDLACTATION COWS

Author
item SHUSTER, DALE - FORMER USDA, ARS, NADC
item LEE, EUNG - IA STATE UNIV., AMES, IA
item Kehrli Jr, Marcus

Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Mastitis is an infection of the mammary gland that affects more than half of the dairy cows on over 95% of all dairy farms. On average, the US dairy farmer will lose more than $180 per cow annually. Mastitis is also a legitimate concern to consumers because of potential antibiotic residues as a result of treating cows for mastitis. The research reported here was designed to determine whether cows are more susceptible to mastitis after calving than later during lactation. The main benefit of this work was confirming earlier findings that white blood cell function appears to be critical for combatting mastitis in cows around calving time. We also were able to gain new insight into problems with the immune system at calving time, that we did not know before, that might lead to better approaches for disease treatment. A potential benefit of this type of research would be less use of antibiotics in cows to treat mastitis.

Technical Abstract: To define causes of the high susceptibility to coliform mastitis during the periparturient period, six midlactation cows were paired with six periparturient cows. Pairs of cows were then challenged with Escherichia coli MacDonald strain 487 in one mammary gland of each cow when the periparturient cow was 6 to 10 d postpartum. One day prior to challenge, peripheral blood neutrophils were evaluated for chemotactic activity and expression of CD18 and L-selectin. Differences between chemotactic activity and adhesion molecule expression by resting neutrophils were small and not statistically significant. However, up-regulation of CD18 expression following stimulation with platelet activating factor (PAF) was significantly less among periparturient cows. Compared with midlactation cows, periparturient cows suffered more severe coliform mastitis, as indicated by significantly more rapid growth of E. coli after challenge (P<0.05), significantly higher peak bacterial concentrations (P<0.05), more severe pyrexia (P<0.05), and a trend for greater hypogalactia (P<0.10). Leukocyte recruitment was delayed and weak in one of the six periparturient cows, which apparently contributed to her extreme mastitic episode.