Climatic Effects on Occurrence of Clinical Mastitis

D. Morse, M. A. DeLorenzo, C. J. Wilcox, R. J. Collier, R. P. Natzke, D. R. Bray

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Clinical mastitis records for 6.5 yr from a large north Florida dairy and corresponding daily weather data were analyzed. Monthly incidence of clinical mastitis was expressed as percent of cow-days in milk and graphed against monthly average daily maximum temperature humidity index values and monthly total rainfall. No trends were evident with rainfall. In 3 of 6 yr, monthly incidence of clinical mastitis increased more than 50% above annual incidence, and this followed high monthly temperature-humidity values. Least squares was used to estimate regression coefficients of temperature-humidity index categories based on 999,969 Holstein records. A temperature humidity index category represented the number of days used to calculate average daily maximum temperature-humidity index value. Sources of variation in observed occurrence of clinical mastitis were cow, parity, month, year, interaction of parity by month, and continuous effects of temperature-humidity index categories 2, 6, 15, 30, 60, each to third order and 60 by parity interaction. In all temperature-humidity index categories as the temperature-humidity index value increased, occurrence of clinical mastitis increased. When values rose from 55 to 80, twice as many for 2 d cows showed signs of clinical mastitis.

Original languageEnglish (US)
Pages (from-to)848-853
Number of pages6
JournalJournal of dairy science
Issue number3
StatePublished - 1988
Externally publishedYes

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics


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