Ability of milk pH to predict subclinical mastitis and intramammary infection in quarters from lactating dairy cattle

S. A. Kandeel, A. A. Megahed, M. H. Ebeid, Peter D Constable

Research output: Contribution to journalArticle

Abstract

Milk pH is increased in lactating dairy cattle with subclinical mastitis (SCM) and intramammary infection (IMI). We hypothesized that milk pH testing provides an accurate, low-cost, and practical on-farm method for diagnosing SCM and IMI. The main objective was to evaluate the clinical utility of measuring milk pH using 3 tests of increasing pH resolution: Multistix 10 SG Reagent Strips for Urinalysis (Multistix strips, Bayer HealthCare Inc., Elkhart, IN), pH Hydrion paper (Microessential Laboratory, Brooklyn, NY), and Piccolo plus pH meter (Hanna Instruments, Woonsocket, RI), for diagnosing SCM and IMI in dairy cattle. Quarter foremilk samples were collected from 115 dairy cows at dry off and 92 fresh cows within 4 to 7 d postcalving. Quarter somatic cell count (SCC) was measured using a DeLaval cell counter (DeLaval, Tumba, Sweden), with SCM defined as SCC >200,000 cells/mL and IMI defined as SCC >100,000 cells/mL and the presence of microorganisms at ≥10 cfu/mL of milk. Milk pH was measured at 37°C using the 3 test methods. The Hydrion pH paper performed poorly in diagnosing SCM and IMI. Receiver operating curve analysis provided optimal pH cutpoints for diagnosing SCM for the pH meter (dry off, ≥6.67; freshening, ≥6.52) and Multistix strips (dry off and freshening, ≥7.0). Test performance of the pH meter and Multistix strips was poor to fair based on area under the receiver operating curve, sensitivity, specificity, positive likelihood ratio, and kappa coefficient. The pH meter and Multistix strips performed poorly in diagnosing IMI at dry off and freshening. We concluded that milk pH does not provide a clinically useful method for diagnosing SCM or IMI in dairy cattle.

Original languageEnglish (US)
Pages (from-to)1417-1427
Number of pages11
JournalJournal of Dairy Science
Volume102
Issue number2
DOIs
StatePublished - Feb 1 2019

Fingerprint

Mastitis
mastitis
dairy cattle
Milk
milk
Infection
infection
somatic cell count
Cell Count
Reagent Strips
testing
Urinalysis
urinalysis
cells
Sweden
health services
dairy cows

Keywords

  • bromothymol blue
  • cow-side test
  • intramammary infection
  • milk pH
  • subclinical mastitis

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

Cite this

Ability of milk pH to predict subclinical mastitis and intramammary infection in quarters from lactating dairy cattle. / Kandeel, S. A.; Megahed, A. A.; Ebeid, M. H.; Constable, Peter D.

In: Journal of Dairy Science, Vol. 102, No. 2, 01.02.2019, p. 1417-1427.

Research output: Contribution to journalArticle

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