Dosing and vaccination at housing
Published 21/10/2015 | 02:30
'How do I know if my cattle need dosing?' is a common question in farmers' minds as the housing period rapidly approaches. The transition indoors is an excellent opportunity to control parasites, with an effective dosing strategy now potentially keeping cattle free of fluke and worms until they are turned out to pasture next spring.
The table below details the common parasites in cattle and the clinical signs associated with heavy infestations. Worryingly, cattle with light or moderate burdens can be difficult to identify other than a vague sense of poor thrive. But these under-performers are serious deadweights on profits by failing to convert expensive winter fodder into liveweight gains.
Before deciding on the best dosing strategy, the parasite status of the herd must be identified. The easiest way to do this is to take faecal samples. Group cattle into three groups: calves, second season grazers and cows. Take 10-15 individual fresh samples from each group. These samples can be pooled in the lab to keep costs down. (A bulk milk sample in the dairy herd can be a helpful addition to faecal samples). The results will detail exactly what parasites are present on the farm and at what level.
What's the best dose to use?
The answer is different for every farm. There are numerous dosing products on the market at the moment, many of which are combinations. Here are the key things to consider when choosing.
Is it active against parasites that were found in the samples? Only certain doses treat rumen fluke. Similarly, only certain wormers treat Type II ostertagia.
Some products have lengthy meat withdrawals so particular care needs to be taken when choosing a dose for cattle on the final push for the factory. Similarly, with quotas abolished, the dry period this year on dairy farms may be quite short so particular attention should be paid to milk withdrawals.
If the product used only kills the mature stages of liver fluke, it is best to delay treatment until 6-8 weeks after housing to allow all the immature fluke to mature into adults.
If animals are showing clinical signs of fluke, they can be dosed at housing and again six weeks later.
This is particularly important for dairy herds as there are only a limited number of fluke doses that can be used in dairy cows.
Continuous use of the same wormer can lead to parasites becoming resistant, which effectively means that the wormer will have a decreased effect. Your vet can devise a plan to determine if resistance to a particular product is an issue on your farm.
Ease of dosing
Pour-ons can be easier than injectables or oral dosing
This is the last thing that should dictate what dose is used. Spending a little extra on the correct product will save a lot in the long run.
Many combination products are effective against lice. If cattle are housed for a long period, a second treatment for lice may have to be considered.
Consult your vet for advice on the best product to use, since they will have an in-depth knowledge of your farm and can interpret sample results.
When cattle are housed for the winter, they are at a high risk of developing viral or bacterial pneumonia. IBR, PI3, RSV and Pasteurella are the most common agents involved. Young stock are more at risk.
Every effort must be made to minimise stress as it is biggest factor in the development and spread of pneumonia.
A number of vaccines are on the market at present to give protection against an outbreak.
IBR vaccines are available in two forms - live and dead.
The live vaccine can be administered intra muscularly (full protection in 10 days) or intra nasally (full protection in three days).
This vaccine can be given in the face of an outbreak. Pedigree breeders may need to use the dead vaccine if there is a possibility they are sending stock to an AI station.
Vaccines that provide immunity against PI3, RSV or pasteurella should also be considered.
It is important to talk to your vet about which vaccine to use as some provide immunity in 10 days, but this may be offset by the fact that protection against pasteurella may not be provided.
Nasal swabs and blood samples can be taken from animals to determine what agents are involved.
Vaccines may seem expensive but studies have shown that the benefit outweighs the cost 6:1.
This means that an outbreak of pneumonia costing €3,000 could be prevented by spending €500 on the correct vaccines.
Eamon O'Connell and Aidan Doyle are vets in Summerhill Vet Clinic in Nenagh, Co Tipperary. www.summerhillvets.ie