Monday, April 21, 2014

Using UV Equipment to Reduce
Bacteria in Milk and Colostrum

Bottom Line: 
1. UV equipment is effective in reducing the concentration of certain kinds of bacteria in milk. Rates of reduction in bacteria in milk seem to depend on which bacteria are being cultured and counted. Using commercial units on farms significant decreases in most bacteria counts were observed. This study did not use mycoplasma, salmonella and MAP (Johnes organism) pathogens.

2. UV equipment is effective in reducing the concentration of certain kinds of bacteria in milk, less effective in colostrum. Using laboratory-scale equipment significant decreases in bacteria counts were observed including salmonella. MAP (Johnes organism) was included and UV was not effective in reducing these counts. Colostrum exposed to UV light had, in my opinion, too little decrease in bacteria and too great decrease in antibodies (IgG) to be a viable option at this time. 

More Detail:
The first study [Gelsinger, et al. "Efficacy of on-farm use of ultraviolet light for inactivation of bacteria in milk for calves." Journal of Dairy Science, May 2014, 97:2990-2997] included samples from 9 farms using UV technology for 15 days (544 samples). Each farm used the UV unit that had been on the farm in everyday use.

It is interesting to note the variation among samples of naturally-occuring bacteria. The highest raw milk standard plate count (SPC) was 296,000,000cfu/ml and the lowest was 200cfu/ml. With an average of raw milk SPC of 3.057,005 these samples should be tell us that there is a lot of opportunity to improve our milk handling procedures.

The second study [Periera, R.V. et al., "Evaluation of the effects  of ultraviolet light on bacterial contaminants inculated into whole milk and colostrum and on colostrum immunoglobulin G." Journal of Dairy Science, May 2014, 97:2866-2875] used sterile homogenized milk 3.25% fat and inoculated these samples with selected bacteria. Thus, in contrast to the Pennsylvania work, this work at Cornell  had only the selected contaminants present in known concentrations. Without going into great detail on the pathogens, the researchers chose common bacteria including Strep ag, Staph aureus and Salmonella. All of these had large reductions with UV treatment. This was not true for the Johnes-causing organism.

The high dry matter content of colostrum seemed to be a major issue in the efficacy of using UV treatment for bacteria. And, there was, in my opinion, an unacceptable large drop in IgG in treated colostrum.

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