Minimizing the Level of Bacillus cereus Spores in Farm Tank Milk

Abstract

In a year-long survey on 24 Dutch farms, Bacillus cereus spore concentrations were measured in farm tank milk (FTM), feces, bedding material, mixed grass and corn silage, and soil from the pasture. The aim of this study was to determine, in practice, factors affecting the concentration of B. cereus spores in FTM throughout the year. In addition, the results of the survey were used in combination with a previously published modeling study to determine requirements for a strategy to control B. cereus spore concentrations in FTM below the MSL of 3 log10 spores/L. The B. cereus spore concentration in FTM was 1.2 +/- 0.05 log10 spores/L and in none of samples was the concentration above the MSL. The spore concentration in soil (4.9 +/- 0.04 log10 spores/g) was more than 100-fold higher than the concentration in feces (2.2 +/- 0.05 log10 spores/g), bedding material (2.8 +/- 0.07 log10 spores/g), and mixed silage (2.4 +/- 0.07 log10 spores/g). The spore concentration in FTM increased between July and September compared with the rest of the year (0.5 +/- 0.02 log10 spores/L difference). In this period, comparable increases of the concentrations in feces (0.4 +/- 0.03 log10 spores/g), bedding material (0.5 +/- 0.05 log10 spores/g), and mixed silage (0.4 +/- 0.05 log10 spores/g) were found. The increased B. cereus spore concentration in FTM was not related to the grazing of cows. Significant correlations were found between the spore concentrations in FTM and feces (r = 0.51) and in feces and mixed silage (r = 0.43) when the cows grazed. The increased concentrations during summer could be explained by an increased growth of B. cereus due to the higher temperatures. We concluded that year-round B. cereus spores were predominantly transmitted from feeds, via feces, to FTM. Farmers should take measures that minimize the transmission of spores via this route by ensuring low initial contamination levels in the feeds (<3 log10 spores/g) and by preventing growth of B. cereus in the farm environment. In addition, because of the extremely high B. cereus spore concentrations in soil, the contamination of teats with soil needs to be prevented.

Prevalence and risk factors for Bacillus cereus in raw milk in Inner Mongolia, Northern China

“…This result is in general agreement with those reported by others, which have shown that the presence of B. cereus and B. cereus spores in farm tank milk was significantly higher in summer months than in the rest of the year (Vissers et al . ). Previous studies have also found that the highest concentrations are generally observed during summer and early autumn (Giffel et al ).…”

Prevalence, virulence factor genes and antibiotic resistance of Bacillus cereus sensu lato isolated from dairy farms and traditional dairy products

“…To ensure consumer safety and increase patronage of the Ghanaian traditional dairy products, attempts have been made to characterize the dominant microorganisms and to select starter cultures for the production of quality and safe products [24, 25]. The incidence of Bacillus cereus on dairy farms and in milk products has been reported elsewhere, particularly in Scandinavia, the Netherlands, Australia and Brazil [26–29]. However, there is currently no reported study on the prevalence of Bacillus cereus in dairy farms and milk products in Ghana, and their associated virulence and antibiotic resistance profile.…”

Microbiological quality of raw milk produced in Estonia

“…2008). The increased aerobic spore concentration in farm tank milk during the spring and summer months has been associated with the contamination of teats with soil during grazing (Vissers et al. 2007).…”

“…Their spores survive pasteurization, germinate, outgrow, and they have been linked to spoilage of raw and pasteurized milk and dairy products such as fermented and ultra heat treated (UHT) milk (McGuiggan et al 2002;Coorevits et al 2008). The increased aerobic spore concentration in farm tank milk during the spring and summer months has been associated with the contamination of teats with soil during grazing (Vissers et al 2007). During the housing period, the teats can be contaminated by faeces, feed and bedding material: hay and dust have been considered important sources of contamination in winter (Magnusson et al 2007;Christiansson et al 1999).…”