Protect your farm and your family from Salmonella
Over the past few years, there has been an increasing number of salmonella infections among dairy herds in North Canterbury mostly occurring before and during calving. Infection strikes without warning, spreads quickly and places you, your farm workers and family at risk.
What can you do to prevent infection?
Whole herd vaccination is the best option. Salvexin+B is the only licensed vaccine that provides protection against the 3 most common strains of Salmonella (Typhimurium, Brandenburg, Bovismorbificans).
Two vaccinations are required, a sensitizer followed by a booster injection 4 weeks later. And if animals have been previously vaccinated, an annual booster is needed to provide ongoing protection. Vaccines come in a Vaxipak with a draw-off set (rubber tubing) which can be attached to a standard vaccinator gun.
What is the best timing for vaccination?
“A pre-winter vaccination program prior to dry-off will provide protection against an outbreak. It is not advisable to delay vaccination until the first signs of disease occur.”
Selecting an appropriate timing for vaccination requires careful planning. Ideally, vaccinating in the transition towards dry-off makes practical sense as many cows are managed with reduced handling on grazing blocks over the dry period. Vaccinating early ensures animals are covered during the stressful period of calving and can build antibodies and give protection to calves via colostrum.
Notes: Lepto vaccination boosters are commonly given at dry-off and cannot be given at the same time as salmonella vaccinations. These should be given at least 1 week apart. After vaccinating for Salmonella, animals may be slightly off-colour for up to a week as the vaccine stimulates an immune reaction to produce antibodies to provide ongoing protection. Vaccinating in the lead-up towards dry-off will have the least impact on milk production.
Preventative Vaccination Schedule
Calves
If dams have been vaccinated pre-calving, calves will be protected against Salmonella infection if there has been sufficient colostrum intake.
For unvaccinated dams, calves can be vaccinated from an early age. There is no minimum age requirement, although vaccinating from 4 weeks of age is preferable. However, if you are buying in calves, earlier protection from 4 days old is advisable.
What should you look out for?
On the 1st day, the cow is ‘just-not-right’ and usually has a high temperature. Sick animals usually separate themselves from the herd, are dull, have reduced appetite and a sudden drop in milk production. By the 2nd day, a profuse smelly, watery scour will appear and may contain blood, mucous or pieces of tissue from the lining of intestines.
Infection can occur following severe weather, onset of calving, sudden changes in diet, overcrowding or high stocking rates. Survivors can fail to come into milk. And in severe cases, there can be significant stock losses and lost milk production.
Infected pregnant cows may abort. Aborted calves rapidly decompose and foetal membranes are often retained. Farmers may report more stillbirths or more dead/rotten calves than usual so the incidence of infection is likely under-reported.
Carrier animals are the main source of infection and these can exist in the herd without showing any clinical signs. Infection remains hidden in lymph nodes and can flare-up during periods of stress, shedding large numbers of bacteria and catching you off-guard.
What to do if you suspect an infection?
Veterinary attention is essential and earlier treatment results in better chances of survival. Death may occur within 48 hours in untreated animals as they become quickly dehydrated and lose weight rapidly.
There is a risk of spread into the calf sheds, so separate potentially infected animals to prevent further spread to other animals. Clinically affected animals excrete large numbers of bacteria in their faeces and can also shed bacteria in urine and milk.
In the event of an outbreak, vaccination may reduce stock losses, so act promptly.
Don’t forget to protect yourself
Salmonella is highly contagious and humans can become infected through contact with sick animals. “Contracting salmonella around calving is not an ideal period to have time off-work.”
Avoid eating, drinking, smoking near cattle.
Don’t drink untreated milk.
Wear PPE and gloves when handling cattle.
Maintain good standards of hygiene with regular hand washing.
Discard milk from scouring cows
Remove aborted material
Maintain good biosecurity
How much does vaccination cost?
Vaccinating against Salmonella is cost effective and is even cheaper than vaccinating for Leptospirosis. Salvexin+B 250mL $154.85 (excl. GST). 125 doses $1.24 per dose. (Dose 2mL) 500mL $278.43 (excl. GST). 250 doses $1.11 per dose.
