Monitoring major mastitis pathogens at the population level based on examination of bulk tank milk samples

Abstract

The objective was to determine the proportions and bacterial counts of major mastitis pathogens in samples of bulk tank milk (BTM), as well as to clarify the relationship between these bacteria counts and bulk tank somatic cell count (BTSCC). The purpose was to judge the importance of the counts of mammary pathogens for BTSCC at the population level. Samples of BTM were collected from 268 randomly selected anonymous dairy herds (with approximately 29 000 dairy cows). Staphylococcus aureus, other coagulase-positive staphylococci, Streptococcus agalactiae and Streptococcus dysgalactiae were grouped as contagious pathogens, and Streptococcus uberis, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Enterococcus faecium as environmental pathogens. Based on assessment of the dominant pathogen in each herd, environmental pathogens were found to dominate. Counts of specific mammary pathogens in BTM samples did not exceed a geometric mean of 1000 cfu/ml. Significant differences were documented in BTSCC between BTM samples containing Str. agalactiae, Staph. aureus, and Str. dysgalactiae and BTM samples that were pathogen-free. Geometric means of BTSCC associated with these pathogens were noticeably higher than the overall BTSCC (Str. agalactiae 243 628; Staph. aureus 205 610; Str. dysgalactiae 203 978; overall 173 000 cells/ml). It follows that the somatic cell count (SCC) associated with these pathogens contributed substantially to the overall BTSCC. Environmental pathogens predominated in samples of BTM with SCC <300x103/ml and contagious mastitis pathogens predominated in BTM samples with SCC >300x103/ml. No correlation was detected between bacterial counts of specific pathogens and BTSCC. This study revealed that the assessment of bacterial counts of mammary pathogens in samples of BTM in relation to BTSCC is applicable for the monitoring of changes in the occurrence of major mastitis pathogens in dairy herds at a national level.

Investigation of udder health and milk quality parameters of dairy farms in Northern Cyprus. Part I: SCC and bacteriologic examination

“…High levels of BTMSCC during all seasons was thought to be associated with infection prevalence rather than a seasonal influence. Bulk tank milk cultures are among the most important methods that reveal milk quality and udder health (12,14,25,27,31). In this study, bacterial isolation was achieved in 88.4% of tank milk samples, while no isolation could be done in 11.6% of the samples.…”

Extraction of Mastitis Pathogen DNA from Sample Collecting Cards: Practical Consequences

“…In commercial dairies, total bacterial counts (BC) of shipped milk usually range from 10 3 to 10 5 cfu/mL. Although BTM cultures Journal of Veterinary Science & Animal Husbandry have been recommended for identification of herds at risk for contagious mastitis [1,15,16], enumeration of specific mammary pathogens is not systematically performed; when available BC can be as low as 10 3 cfu/mL [2]. An European study found that high BTMSCC herds (467-909x10 3 cells/mL) harboured S. aureus and mastitis streptococci at enumerable levels of 3x10 2 and 1.5x10 3 cfu/mL respectively [17].…”

Effect of Streptococcus uberis infections on cell population of bovine mammary gland

“…Therefore, it is very important to study the processes leading to this disease. The significance of bovine mammary gland pathogens as a factor increasing the bacterial count in herd bulk milk has been analysed before (Hayes et al, 2001;Jayarao et al, 2004;Zadoks et al, 2004;Rysanek et al, 2009a;Rysanek et al, 2009b). A significant correlation was found between the number of mastitis streptococci (Streptococcus uberis, Streptococcus agalactiae, Streptococcus dysgalactiae) and the somatic cell count which is the most widely accepted standard for measuring udder health and milk quality (Fenlon et al, 1995;Bagnicka et al, 2011;Borne et al, 2011).…”