Biosecurity in the Sheep Flock
Historically, disease management did not occur until one or more of the animals in a group became ill. They were treated, while the remainder of the group were watched for clinical signs. The outcome was either recover, partial or complete, or death. Whichever happened, there was an economic loss to the producer. In recent years there has been a change in attitude from fighting disease in the individual animal to preventative health management of the whole population. This change stems from an increased awareness of the interaction between nutrition, health management, housing and the environment in the disease syndrome. Individual animals will still get sick and need to be treated, but the economic loss from a chronic disease will be greater and the cure harder to implement.
An integral part of this health management is the biosecurity of the flock. A biosecure flock is one in which the chance of disease entering, either through other sheep of some indirect vector, is minimal.
How biosecure is you flock? Before you say "very", answer these questions:
- How near is the next sheep flock? Some distance away, a neighbouring
farm, through the fence? The nearer your sheep are to another
flock, the greater the chance of airborne spread of agents, especially
the respiratory viruses like maedi-visna.
- When you buy replacement animals, do you quarantine them for
28 days away from your flock? Vaccinate them, deworm them, look
for external parasites and signs of clinical disease? Do you know
the health status of the flock of origin? Do you buy all your
replacements from one breeder, or do you buy at a sale of the
- Visitors are always a problem. You like to show your sheep off
but do you have a standard procedure that all visitors come to
the house first, put on your boots and coveralls, and step through
a footbath at the entrance to the sheep yard or barn from outside
the biosecurity barrier?
- How about shipping? Do you have special boots and coveralls
to wear when shipping lambs to market? If you use a trucker, are
there other sheep on the truck when yours are loaded? Is the truck
clean of manure when it comes to your operation? Does the truck
come into the yard to load or do you load the lambs at the lane
- Do you bury your dead stock as soon as possible, or are they
left at the back fence for the scavengers to eat? Dead sheep encourage
coyotes; turkey vultures will cover considerable distances in
search of carrion.
- What about the manure pile? Is it away from the sheep? Does
the runoff cross the yard? There have been cases where stomach
worms have been spread in the runoff from the manure pile. Do
you spread your own manure? If you use a contractor, can the equipment
reach the pile without crossing the sheep yard? Manure on the
equipment could be carrying the bacteria of Johne's disease.
- Cats are good rodent controllers, but do you have a neutered population? Active females will encourage males to visit from other farms. The kittens can be the vectors of toxoplasmosis until they are seven or eight months old. Do you cover your grain bins to stop animals defecating in the grain?
The list can go on. These are factors to be considered in assessing the effectiveness of a flock's biosecurity. All have a reason behind them to stop some route of disease entry into the flock.
Once it is biosecure, your flock will develop immunity to the soup of bacteria and viruses present within it. With it will come improved performance as management and nutrition are more effective. Biosecurity controls do not have to be onerous, using a common sense approach can prevent the accidental introduction of disease. To the buyer of your animals, the fact that you are using biosecurity sends a signal of a conscientious producer who values the flock. With good biosecurity too, there is peace of mind that the flock is well protected and will respond to good management.
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