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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 #41627
Title: RELATIONSHIP OF INFLAMMATORY CYTOKINES, GROWTH HORMONE, AND INSULIN-LIKE GROWTH FACTOR-I WITH REDUCED PERFORMANCE DURING INFECTIOUS DISEASE

Author
item SHUSTER DALE E - AMER. CYANAMID, N JERSEY
item Kehrli Jr, Marcus
item BAUMRUCKER CRAIG - PA STATE UNIV., PENN

Submitted to: American Society for Experimental Biology and Medicine Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/1995
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 U.S. 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 levels of hormone involved with milk production are altered during bacterial mastitis. A potential benefit of this type of research would be development of new compounds to combat lost milk production during recovery from disease. Growth hormone and insulin-like growth factor I are two hormones vitally important to milk production. Our data demonstrate that reduced milk production is not caused by reduced concentrations of growth hormone or insulin-like growth factor I. We also found that hormones of the immune system known as inflammatory cytokines are produced at a time consistent with a possible role in the inhibition of milk synthesis. The main benefit of this work is the identification of factors contributing to lost production efficiency for dairy farmers.

Technical Abstract: Production of inflammatory cytokines and concentrations of growth hormone and insulin-like growth factor-I (IGF-I) were studied during Escherichia coli mastitis to determine their potential involvement in reduced milk production. Reduced lactational performance was first apparent at 24 h after experimental infection, and maximal decrease averaged 70% among both infected and uninfected glands of challenged cows. By 6 d, all cows had nearly or completely eliminated the E. coli, and milk production had partially recovered. High levels of tumor necrosis factor and interleukin- 1 were detected in milk of infected glands, and their appearance preceded or coincided with development of the mammary inflammation, systemic reaction, and hypogalactia. Serum IGF-I concentrations changed little during the mastitic episode. In contrast, serum growth hormone hormone concentration increased from 6.1 to 9.6 ng/ml (p <.05 vs. control). .Levels of IGF-I in milk whey increased from 5.0 to 12.2 ng/ml among infected glands and from 4.4 to 8.5 ng/ml among uninfected glands. These data demonstrate that: (1) reduced lactational performance is not caused by reduced concentrations of growth hormone or IGF-I; and (2) inflammatory cytokines are produced at a time consistent with a possible role in the inhibition of milk synthesis.