|Lee, Haa-Yung - IA STATE UNIV., AMES, IA|
|Kehrli Jr, Marcus|
Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 1995
Publication Date: N/A
Technical Abstract: On well managed dairy farms, Streptococcus uberis represents as much as 20% of all clinical bovine mastitis. We wish to study the pathogenesis of S. uberis mastitis, and have attempted to develop a mastitis challenge model using two challenge doses of S. uberis (ATCC 27958). Each dose level experiment was conducted with 3 cows; two that were challenged with S. uberis and one unchallenged control. A single quarter of each challenged cow was infused with 26 or 446 cfu of S. uberis. Milk samples were preserved with bronopol for somatic cell count (SCC) and composition analysis. Serum and whey samples were obtained to measure tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8). The high dose challenge elicited an increase in SCC detectable within 6 h, peaked at 14 h, and returned to normal levels 48 h post-challenge. Low dose challenge did not significantly alter the SCC. Milk lactose content was reduced in milk of high dose challenged glands. Elevated whey TNF-alpha was detected at 4 h and 10 h post-challenge for low dose and high dose challenge glands, respectively. In serum, however, elevated TNF-alpha levels were detected 18 h post-challenge and remained elevated until 108 h post- challenge. In contrast to reports on E. coli mastitis, no detectable IL-8 was found in whey following challenge with S. uberis.