HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Interpretive Summary Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Whist, A. C. Articles by Sølverød, L. Search for Related Content PubMed PubMed Citation Articles by Whist, A. C. Articles by Sølverød, L.

Streptococcus dysgalactiae Isolates at Calving and Lactation Performance Within the Same Lactation

A. C. Whist^*,,1, O. Østerås^*, and L. Sølverød^,

^* Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
Department of Norwegian Cattle Health Services, TINE Norwegian Dairies, Ås, Norway
TINE Norwegian Dairies Mastitis Laboratory, Molde, Norway

¹ Corresponding author: anne.c.whist{at}veths.no

The objective of the study was to investigate the association between early lactation Streptococcus dysgalactiae isolates and milk yield, somatic cell count (SCC), clinical mastitis, and culling in the same lactation. The 178 commercial dairy herds were randomly placed into 3 penicillin- or penicillin-dihydrostreptomycin-based dry-cow treatments and 3 different postmilking teat disinfection groups—negative control, iodine, or external teat sealant. All cows were sampled in early lactation, and Strep. dysgalactiae-positive and culture-negative cows were followed throughout the remainder of the lactation. Mixed models, including repeated measurements, with test-day observation as dependent variable, were used to compare milk yield, SCC, and available milk quality variables throughout the remaining lactation. Survival analyses, using a positive frailty model to account for any herd random effects, were used to estimate the hazard ratio for clinical mastitis and culling. Streptococcus dysgalactiae-positive cows had a significantly higher SCC throughout the lactation compared to culture-negative cows. For primiparous or multiparous cows, respectively, the differences in the geometric mean SCC between Strep. dysgalactiae-positive and culture-negative cows was 197,000 or 280,000 cells/mL at the beginning of the lactation, 24,000 or 46,000 cells/mL in mid lactation, and 39,000 or 111,000 cells/mL at the end of the lactation. Streptococcus dysgalactiae-positive primiparous or multiparous cows produced 334 or 246 kg less milk, respectively, during a 305-d lactation compared with culture-negative cows. Compared with culture-negative cows, the hazard ratios for clinical mastitis in Strep. dysgalactiae-positive cows were 2.3 (1.9 to 2.9) and 1.6 (1.3 to 2.0) for culling. For cows with both Strep. dysgalactiae and Staphylococcus aureus isolates, the hazard ratio for culling significantly increased to 2.5 (1.9 to 3.2).

Key Words: Streptococcus dysgalactiae • cow • clinical mastitis • culling

This article has been cited by other articles:

				O. Reksen, L. Solverod, and O. Osteras Relationships Between Milk Culture Results and Composite Milk Somatic Cell Counts in Norwegian Dairy Cattle J Dairy Sci, August 1, 2008; 91(8): 3102 - 3113. [Abstract] [Full Text] [PDF]