The objective of our project was to investigate the factors and practices that affect the Total Bacterial
Count (TBC) in milk on farms. Farmers struggle to keep their TBC levels under the EU regulated level.
Total bacterial count (TBC) is the total number of living bacteria per ml of milk. TBC must not exceed
100000cfu/ml on two-month geometric average. For farmers to receive the top price for their milk, they must not exceed 50000cfu/ml.
according to ‘Cleanline Farm Services Ltd.’, in the past 5 to 10 years it has become increasingly difficult for farmers to keep their TBC below 50 thousand. We wanted discover what farmers can do to lower the TBC in the milk on Farms
Investigation into whether teat preparation pre-milking has an effect on TBC (Total Bacterial
Count) levels of the milk
Objective: We set out to investigate whether farmers should carry out teat preparation on their cows before they are milked in order to lower the amount of bacteria in the milk of the cows.
What we did?: We carried out this investigation on four different evenings, on 57 cows overall. We sprayed the teats of 19 cows with anti-bacterial disinfectant spray pre-milking. We washed the teats of
19 cows with fairy liquid pre-milking. We carried out no teat preparation on 19 cows pre-milking. Each sample of milk was taken in a sterile test bottle. We stored each sample of milk in a fridge overnight at
5˚C.
The following morning we brought the samples of milk to centenary co-op, where we plated each sample and stored them in an incubator for 72 hours. After 72 hours , we took the agar plates out of the incubator and counted the amount of bacteria on each agar plate and calculate a TBC result for each milk sample.
Investigation into whether the temperature of the bulk tank on a farm has an effect on the TBC (Total Bacterial Count ) levels of the milk that is stored in the bulk tank
Objective: We set out to investigate whether the temperature that the milk is stored at on a farm has an effect on the TBC levels of the milk. Moreover, we wanted to find out what the best temperature is to store the milk at.
What we did?: We took 21 samples of milk from the milk jar of a cow. We stored seven samples of milk at 2˚C, we stored seven samples at 4˚C, and we stored seven samples at
6˚C. We stored the 21 samples at the 3 different temperatures for 72 hours. After 72 hours, we took the samples out of the fridges and brought them to the co-op to plate the samples and store them in the incubator for 36 hours. After 36 hours, we took the samples out of the incubator and counted the colonies of bacteria on the agar plates and calculated a TBC level for each milk sample.
 Green = A cow that teats were sprayed with anti-bacterial disinfectant spray pre-milking
 Purple= A cow that teats were washed with fairy liquid premilking
 Beige= A cow that had no teat preparation carried out on it pre-milking
From this experiment, we can conclude a number of different things. Firstly, that Teat preparation pre-milking is a contributing factor to the total bacterial count (TBC) in milk. We have proved this to be true by repeating the experiment three times, to provide more accurate results with fewer errors.
We sprayed the teats of 19 cows and towel-dried their teats before milking, which goes against the common practice of many farmers to spray the teats of their cows after milking. We can conclude from the TBC results of the cows that were sprayed with antibacterial disinfectant teat spray, that farmer should spray the teats of their cows with antibacterial disinfectant spray premilking in order to lower the TBC in the milk of their cows. The cows that were sprayed pre-milking had very low TBC results in comparison to the cows that had no teat preparation carried out on them pre-milking, this is clear from looking at our graphs.
We washed the teats of 19 cows with the fairy liquid and warm water and then towel-dried the teats of the cows, This method proved to be the second best method of teat preparation, as the
TBC results of the cows that were washed with fairy liquid and warm water were overall lower than the cows that had no teat preparation carried out on them pre-milking, but were higher than the cows that teats were sprayed with antibacterial disinfectant spray pre-milking.
The TBC results of the cows that had no teat-preparation carried out on them were significantly higher than the TBC results of the cows that had teat preparation carried out on them pre-milking, this is clear from looking at our graphs.
From our results, we can conclude that farmers should set the temperature to 2°C in order to reach low TBC results in their milk. We recommend that farmer should keep their bulk tanks between 1°C and 3°C.
This is one of our agar plates.
We diluted a sample of milk and put the dilution on the agar plate. The agar plate was stored in an incubator for 36 hours at 37 ˚C. After 36 hours, we took the agar plate out of the incubator and counted the colonies of bacteria on the agar plate. We then calculated the
Total Bacterial count level for that milk sample based on the amount of dilution and the colonies of bacteria on the agar plate.
Conclusion
From our investigations, we can conclude that farmers should carry out teat preparation on their cows pre-milking. The best method of teat preparation is to spray the teats with an anti-bacterial spray and towel-dry the teats. Moreover, the temperature of the bulk tank on a farm has an effect on the TBC levels of the milk. The best temperature to store the milk at is 2˚C.