Calf Talk

January, 2006

Volume 12, No. 1

SRP Vaccine Is Effective Against Salmonella

By: Russ Schnepper, D.V.M.

THIS ARTICLE REFLECTS MY OPINION AND IS NOT BACKED BY DATA, BUT EXPERIENCE WITH THE PRODUCT. The ½ dose usage in young calves is off label. SRP is Siderophore Receptors and Porins protein derived from an extract of Salmonella newport. The vaccine was first developed in the poultry business and proved very effective. A siderophore is an iron binding site on the cell wall of Salmonella bacteria. Salmonella require the ability to extract iron from the animal host to fuel the bacteria’s metabolic processes. The SRP vaccine targets this specific site and neutralizes their ability to absorb iron. Without iron the Salmonella’s metabolism shuts down and the bacteria die. SRP vaccine is being used as treatment and has proven effective at shutting down a salmonella outbreak within a very few days. How can a vaccine do this? I do not know, however it works much too rapidly to be a mere antibody response. There is some other scenario at work here. I do not know what it is, but we do know it has proven effective in several Salmonella outbreaks in four to sixteen week old Holstein calves.

In a couple cases, SRP was helpful, but did not totally stop the death loss. It is my opinion the partial effectiveness was due to other simultaneous problems with the calves. As you all know, we never have just one problem at a time with young calves. How should we use SRP? I think 1 ml (½ dose) should be given subcutaneously at two and four weeks, if the problem is developing early. If Salmonella is striking after five weeks, I would give the SRP at four and six weeks. Give the full two ml dose to cows and repeat in two to four weeks.

The vaccine appears to drastically reduce the shedding of Salmonella. A sick calf can shed several million viable Salmonella per day. So reducing this shedding helps to stop the spread of the disease. I have seen the Salmonella problem, in the calves, stop once the cows had been vaccinated with SRP and the calf facilities had been cleaned. Without SRP, shedding continues months after the animal recovers.

Are we replacing the Endovac bovi with the SRP? Currently, calf raisers have been adding the SRP, due to an existing, or feared, problem. I believe the SRP vaccine is specific for Salmonella. There are many species of Salmonella and SRP technology should work on all of them, as they have the same metabolic need for iron. The need to use Endovac bovi depends on why you are using it. Endovac bovi causes the calf to produce antibodies against Gram Negative Endotoxins which are produced by the bacteria and make the calf sick. Endovac is helpful against E. coli, Salmonella, Pasteurella, and Moraxella bovis (causes pink eye).

Salmonella newport causes more respiratory problems than scours and usually strikes calves after a month of age. Sensitivity tests on the bacteria have shown most of them sensitive to Excenel. But I am aware of these calves not responding to huge doses of five ml per 100 pounds twice a day. SRP has proven to be our best tool to fight the Salmonella, especially S. newport. Someday we will learn why it works.

Contact information for ordering information and questions about our products:

Schnepper International, Inc.

3210 County B, Platteville, WI 53818

608-348-6141, Fax: 608-348-6146