WHAT IS BVD?
Bovine Viral Diarrhoea is a virus that can be the underlying cause of many cattle health problems. The most common complaints are that it interferes with reproduction in both cows and heifers, as it can cause infertility as well as abortion and calf deformities. It also reduces calf immunity to other diseases such as scour and pneumonia, and can sometimes result in Mucosal Disease. These complaints all result in the increased use of drugs.
We use simplified terms to explain the different levels of exposure to the disease:-
White coloured animals mean animals that have not been exposed to
the disease.
Green coloured animals are the animals that are antibody positive,
have been exposed the disease, and are effectively naturally immune.
Red coloured animals are the persistently infected animals that are
virus positive and the main carriers of the disease, commonly referred to
as "Pl's".
Infection immediately before or during the breeding season will reduce conception rates and cause the early death of embryos. Infection at any stage of pregnancy can result in abortion, but if the infection is during the first third of pregnancy, when calves are developing in the womb and they survive until birth, these remain persistently infected with the virus. These are known as "Pl's" or as we call them at OLA "red" animals. These "red" animals are the major cause of the spread of BVD. Some may die at birth or not long after, but they often appear normal, so they can shed virus on to healthy calves, reducing their immunity levels. Animals that have been in contact with a "red" animal usually turn from "white" to lagreen".
HOW DO I KNOW IF I HAVE BVD IN MY HERD?
You may know that BVD is present in your herd if you have had aborted or
dead calves tested at the lab with BVD positive results, or an older animal
has become ill and tests have revealed the same. If you are unsure about
your BVD status, you should have a screen test done by your vet.
NEVER ASSUME THAT YOU DO NOT HAVE BVD IN YOUR HERD IF YOU HAVE NOT TESTED!
A screen test is a simple procedure, which involves your vet taking random blood samples from 10 yearling animals (preferably aged between 9 and 18 months). If you have a small herd (less than 20 breeding cows) you can have a "Whole Herd Test" done in the first instance.
Your vet will inform you of the result of your screen test. If it is negative, you should vaccinate your breeding stock (cows, bulling heifers, bulls) and/or your farm boundary should be at least 3 meters from your neighbours, unless they are of the same status.
A screen test must be carried out annually on each new batch of yearlings to make sure that BVD has not entered the herd.
PREVENTION IS BETTER THAN CURE
If your screen test result is positive, this means that your herd is presently infected or been exposed to BVD, and a whole herd test must be carried out. All animals on the farm over 9 months of age must be sampled to identify any "red" animals.
At present, Orkney Islands Council pays the lab fees for Whole Herd Tests (including small herds), which is a saving of 75% of the usual cost.
When you receive the results of your whole herd test from your vet, you will probably find that almost all the animals are "green". They do not require vaccination, as they have been exposed to BVD and are naturally immune. You may have a few "white" animals, and these must be vaccinated to prevent infection.
If any "red" animals are found, these must be strictly quarantined from the rest of the herd. Older animals are best sent to the over thirty month slaughter scheme, but younger animals may be fattened and sent direct to an abattoir.
Red animals must not be sent to Orkney Auction Mart where they can spread the disease.
Approximately one year after your whole herd test, you must have all your next batch of yearlings tested. It is possible that a red animal could be detected here, as they would have been calves at foot or still in their mothers womb when you had your initial whole herd test.
When you have carried out a whole herd test the first year, and then had all your next batch of yearlings tested the next year, this should have eradicated BVD from your herd. You should only need to perform a screen test every year after that to monitor the situation, to make sure that re-infection has not occurred.
LEVEL 1 VISIT
The Level 1 phase of membership should be the starting block for members,
but we started with the BVD eradication programme that is part of the Level
2 phase.
Level 1 entails a visit from your vet, and together you should discuss your farm and stock in general. From this you will create a "Herd Health Plan" which is an annual record of your stock's health. The Level 1 visit also acts as our inspection for farms eligible for disease accreditation. Quarantine facilities, boundary fencing, and vaccination records will be checked.
You are eligible for BVD accreditation when you have completed your herd health plan with your vet, and you have had two consecutive annual clear screen tests.
BIO-SECURITY
This was a relatively new term to everyone until the Foot and Mouth epidemic,
and now everyone understands its importance.
When you become a member of OLA, you receive a list of rules for the BVD eradication scheme which give instructions on keeping your stock safe from infection. They were made to eradicate and prevent the disease, and if you follow them correctly, you will benefit.
PURCHASING STOCK
An OLA member recently bought a cow and calf from an ordinary breeding cow
sale. As he did not know their status, he kept them separate from the rest
of his herd. And it was a good job he did! After having the two of them
tested it was discovered that the calf was "red". Had he taken these animals
home and put them in with his existing herd without having them tested first,
is a prime example of how easily BVD is spread.
OLA sales began so that buyers could purchase animals from farms that have been tested and are of a known status, and buying from accredited herds gives you an even bigger guarantee.
People often tell us they have a closed herd, but they seem to forget that their bull was not bred on the premises! When buying a bull, you should ask if it has been tested. If it has been tested, has it been vaccinated? We have been actively encouraging bull breeders to test and vaccinate their bulls before they attend sales. All bought-in animals should be quarantined for three weeks after they are purchased, so that any virus they are carrying (not just BVD) will disappear. If they have not been tested, you must also test them before mixing them with your own herd.
If you need advice or further information, please contact Karen Tait. She is in the OLA office which is in Orkney Auction Mart every Monday (01856 878293), Mobile 07900 231 954 or Home 01856 721 448 (not after 5pm).
ORKNEY LIVESTOCK ASSOCIATION RULES FOR MEMBERS PARTICIPATING IN BVD ERADICATION SCHEME
- A herd is defined as cattle that are under a unified management system, not necessarily on the same premises, but intermingle periodically throughout the year. A member who keeps groups of cattle separate can join as one membership, but has to screen test the groups individually.
- When a member's herd screen tests positive, they have to carry out the whole herd test and make every effort to eradicate the disease.
- Farm boundaries must prevent cattle from straying off or on to the farm,
and must prevent nose-to-nose contact over fences or walls. Double fencing
with a space of at least 3 metres between their cattle and neighbouring
cattle of a poorer or unknown status is required for BVD and IBR programmes.
Where this is impractical, members should vaccinate all BREEDING
cattle in uninfected herds. On infected holdings that carry out the whole
herd test, members should vaccinate all the ''WHITE" BREEDING cattle
in the herd. Members should avoid vaccinating young animals under 15 months
of age as this would jeopardise the result of the screen test - hence
the accredited status.
WHITE coloured animals mean animals that have not been exposed to the disease.
GREEN coloured animals are the animals that are antibody positive, have been exposed the disease, and are effectively naturally vaccinated.
RED coloured animals are the persistently infected animals that are virus positive and the main carriers of the disease, commonly referred to as "Pl's". - Purchased cattle that are of an inferior health status either from within or out-with the scheme MUST be quarantined in suitable facilities until the appropriate test results of that particular animal are received.
- Suitable quarantine facilities are in the form of pens or paddocks that do not allow contact with other livestock. These must be available for cattle coming in to the herd.
- Equipment, livestock trailers and handling facilities that are shared between health scheme cattle and other livestock or cattle of a poorer or unknown status, must be cleaned and disinfected before used by health scheme cattle.
- Blood samples can only be collected by a veterinary surgeon, someone designated by a veterinary surgeon, or in the case of milk samples, by a tnilk recorder. Where the herd uses more than one bulk tank, representative samples must be taken from each tank.
- Pl's (red animals) must be culled or strictly quarantined in a facility where there can be no danger to any other animals either on that farm, or any other farm. They should be slaughtered as quickly and as practically as possible. They should not be moved off the holding other than directly to slaughter facilities. Veterinary advice should be sought regarding the best option to take.
- SHOWS AND SALES
Only animals of a known health status should be shown. Unless the animal is GREEN, it should be vaccinated before it attends the show and quarantined for 3 weeks after the event. This vaccination and quarantine policy will also apply to live cattle sales where there is a possibility of the cattle returning home. Particular attention must be paid to pregnant animals, as it is paramount that the foetus is protected. - Avoid introduction of infection on clothing or footwear, (e.g. AI technicians, vets, neighbours, hoof trimmers, lorry man etc) or equipment (e.g. vehicles, crushes, dosing equipment etc). Dedicated clothing, footwear and equipment for a particular farm is the safest option. A less secure but acceptable alternative is thorough cleaning and disinfecting of clothing, footwear and equipment before use on the fartn at risk. (Waterproof overalls are more hygienic than boiler suits). Vehicles should be cleansed and disinfected before they are used for health scheme cattle, unless they are moving direct to a slaughter house. Particular effort should be made to clean and disinfect equipment likely to be contaminated by blood (e.g. hoof knives, instruments for castrating, disbudding and de-homing). Injection equipment should never be shared among farms or species. Veterinary and surgical equipment must not be shared between farms unless it is sterilised before use.
- Limit farm access to those people deemed essential.
- Use piped mains water rather than natural water sources whenever possible.
- Prevent access of verinin and wild life to feed, bedding stores and the cattle whenever possible.
- Purchased feed and bedding constitute a risk of introducing infection, so it is important to use reputable suppliers.
- Embryos and semen should be from donors of certified disease free status.
- Sheep can harbour some of the diseases that affect cattle. Contact between sheep and cattle should be avoided as much as possible.
- When joining the scheme you have to produce an annual veterinary health
plan with your vet. This will monitor and evaluate your cattle health
status, as well as act as our inspection to make sure members adhere to
our rules.
Any breach of the rules will lead to the member losing their accredited status, and OIC would have the right to recover the laboratory testing costs from the member to whom the breach of the rules applies.
If challenged the decision would be arbitrated by Hi Health's Independent vet.