**4.2.1 Whole milk**

Mean total bacterial counts ranged from 10.12 log cfu/ml of milk collected from Jimma to 8.30 log cfu/ml of milk sampled from Debre Zeit and Adama with the average value being 9.10 log cfu/ml. These values exceed the acceptable value of 105 cfu/ml for milk in most European counties (Council Directives 92/46/EEC, 1992; IFCN, 2006). Mean counts of *Enterobacteriaceae* were greater than 5 log cfu/ml and coliform counts greater than 4 log cfu/ml of milk sampled from all study sites.

In Ethiopia, milking animals are kept with the rest of the stock in a shade or enclosure during the night. Milking is done in the shade, grazing field in front of the homestead, or under a tree. However, as these areas are not generally kept clean enough, milking cows usually become soiled with dung and urine. Moreover, cleaning of the udder and hind quarters of the cow is not a common practice. This coupled with the unhygienic cleaning and handling of milk containers result in microbial contamination of milk (Tola, 2002; Gonfa *et al.*, 2001).

According to an earlier report, milk samples collected form smallholder producers in East Wollayta (Southern Ethiopia) had average total microbial count of 7.60 log cfu/ml (Tola, 2002). A total bacterial count ranging from 6.0 to 8.8 log cfu/ml in which 15% of the samples had a count equal or above 7.7 log cfu/ml in raw milk samples in Southern Ethiopia was also reported (Beyene, 1994). In another report, milk sampled from most of the dairy cooperatives operating in the country had total bacterial count of 108 cfu/ml (Francesconi, 2006). These values are much higher than the acceptable limits in different countries (104 to 105 cfu/ml) (IFCN, 2006). This implies that the sanitary conditions in which milk has been produced and handled are substandard subjecting the product to microbial contamination and multiplication. It is indicated that total bacterial count is a good indicator for monitoring the sanitary conditions practiced during production, collection, and handling of raw milk (Chambers, 2002). A good instance worth mentioning is a reduced total bacterial count observed in milk sampled from farmers who received training on hygienic milk production and handling, and who used recommended milk containers as compared to that produced by the traditional milk producers (control) (Tola, 2002; Nebiyu, 2008; Sintayehu *et al*., 2008). A similar result was also reported for large-scale producers and research centers where there is a better access to dairy facilities as compared to small-scale producers (Yilma and Faye, 2006).

According to a report from Southern Ethiopia, raw cow's milk sampled from smallholder producers contained coliform counts of about 4.46 log cfu/ml (Tola, 2002). Similar counts were also observed in raw milk sampled from smallholder producers in the central highlands of Ethiopia (Yilma and Faye, 2006; Yilma *et al.*, 2007a). Higher counts of different species of *Enterobacteriaceae* were reported with *Escherichia coli* being the most abundantly isolated species (Yilma *et al.*, 2007a), which is a good indicator of recent fecal contamination (Bintsis *et al.*, 2008).

In a study focused on the identification of major bacterial species found in milk as it comes from the udder, it is reported that *Micrococci* represent the largest proportion followed by *Streptococci* and rods (O'Connor, 1994). In a separate study, *Staphylococci* and *Micrococci* are reported to be the most common udder-specific bacteria of environmental origin in milk samples taken directly from the udder (Godefaye and Molla, 2000).


Microbial Properties of Ethiopian Marketed Milk and Milk Products and Associated Critical Points of Contamination: An Epidemiological Perspective 309

308 Epidemiology Insights

Mean total bacterial counts ranged from 10.12 log cfu/ml of milk collected from Jimma to 8.30 log cfu/ml of milk sampled from Debre Zeit and Adama with the average value being 9.10 log cfu/ml. These values exceed the acceptable value of 105 cfu/ml for milk in most European counties (Council Directives 92/46/EEC, 1992; IFCN, 2006). Mean counts of *Enterobacteriaceae* were greater than 5 log cfu/ml and coliform counts greater than 4 log

In Ethiopia, milking animals are kept with the rest of the stock in a shade or enclosure during the night. Milking is done in the shade, grazing field in front of the homestead, or under a tree. However, as these areas are not generally kept clean enough, milking cows usually become soiled with dung and urine. Moreover, cleaning of the udder and hind quarters of the cow is not a common practice. This coupled with the unhygienic cleaning and handling of milk containers result in microbial contamination of milk (Tola, 2002; Gonfa

According to an earlier report, milk samples collected form smallholder producers in East Wollayta (Southern Ethiopia) had average total microbial count of 7.60 log cfu/ml (Tola, 2002). A total bacterial count ranging from 6.0 to 8.8 log cfu/ml in which 15% of the samples had a count equal or above 7.7 log cfu/ml in raw milk samples in Southern Ethiopia was also reported (Beyene, 1994). In another report, milk sampled from most of the dairy cooperatives operating in the country had total bacterial count of 108 cfu/ml (Francesconi, 2006). These values are much higher than the acceptable limits in different countries (104 to 105 cfu/ml) (IFCN, 2006). This implies that the sanitary conditions in which milk has been produced and handled are substandard subjecting the product to microbial contamination and multiplication. It is indicated that total bacterial count is a good indicator for monitoring the sanitary conditions practiced during production, collection, and handling of raw milk (Chambers, 2002). A good instance worth mentioning is a reduced total bacterial count observed in milk sampled from farmers who received training on hygienic milk production and handling, and who used recommended milk containers as compared to that produced by the traditional milk producers (control) (Tola, 2002; Nebiyu, 2008; Sintayehu *et al*., 2008). A similar result was also reported for large-scale producers and research centers where there is a better access to dairy facilities as compared to small-scale producers (Yilma

According to a report from Southern Ethiopia, raw cow's milk sampled from smallholder producers contained coliform counts of about 4.46 log cfu/ml (Tola, 2002). Similar counts were also observed in raw milk sampled from smallholder producers in the central highlands of Ethiopia (Yilma and Faye, 2006; Yilma *et al.*, 2007a). Higher counts of different species of *Enterobacteriaceae* were reported with *Escherichia coli* being the most abundantly isolated species (Yilma *et al.*, 2007a), which is a good indicator of recent fecal contamination

In a study focused on the identification of major bacterial species found in milk as it comes from the udder, it is reported that *Micrococci* represent the largest proportion followed by *Streptococci* and rods (O'Connor, 1994). In a separate study, *Staphylococci* and *Micrococci* are reported to be the most common udder-specific bacteria of environmental origin in milk

samples taken directly from the udder (Godefaye and Molla, 2000).

**4.2.1 Whole milk** 

*et al.*, 2001).

and Faye, 2006).

(Bintsis *et al.*, 2008).

cfu/ml of milk sampled from all study sites.

\*Ergo refers to fermented whole milk for smallholder farmers, while it refers to fermented skim milk for cooperatives

Table 4. Microbial count (log10) per ml/g of milk and milk products categorized by sample source (producer type)

Total aerobic plate counts were 1.1 x 105, 4 x 106 and 1.9 x 108 cfu/ml respectively for milk samples taken from milking bucket, storage container and processing plant on arrival (Godefaye and Molla, 2000). In the same study, mean coliform counts were reported to range from 1.3 x 104 cfu/ml (storage container) to 7.1 x 106 cfu/ml (on arrival at the processing plant). The hygienic quality of the milk from a collection center was poor with a mean total bacterial count of 1.3 x 107 cfu/ml. In another study, 4 x 107 and 1 x 109 cfu/ml total microbial counts were reported as lowest and highest values, respectively for raw milk samples at a processing plant in Addis Ababa. Of the total counts in raw milk, psychrophilic, thermoduric and thermophilic organisms made up 98.1, 1.4 and 0.5%, respectively.
