The sheep sector is currently enjoying a period of renewed optimism, which is being underpinned by improved farmgate prices for lambs and cull ewes. This, in turn, is feeding in to a strong start to breeding sales, with both ram and specialist ewe lamb and ewe hogget sales recording a significant increase in average sale prices.
Given the sums of money potentially changing hands, safeguarding your investment is a focus that is likely to carry more weight this year. The area where there is likely to be a greater financial risk is via purchased sheep bringing disease into the flock.
There are two main components of a good quarantine protocol – administering health treatments to reduce known disease risks and monitoring animals quarantined
As such, a good quarantine programme is important, not only to protect your investment, but also to reduce the risk of bringing disease on to the farm.
There are two main components of a good quarantine protocol – administering health treatments to reduce known disease risks and monitoring animals quarantined for a sufficient period so that if animals’ exhibit disease symptoms, action can be taken before the risk is spread to the entire flock.
If possible, the prior treatment of sheep should also be explored, where possible, with the vendor, as this will help develop a targeted programme.
Segregation of animals
In general, the longer newly purchased animals can be kept away from animals currently on the farm, the better. Some farmers can successfully implement a programme whereby replacement ewe hoggets or ewe lambs are retained as a group, but for other animals such as rams, this is not an option. As a rule of thumb, breeding animals should be quarantined for a minimum period of 21 days and preferably 28 days before joining the rest of the flock.
Many farmers like to join a new ram, for example, with some companion animals to help them settle on arrival to the farm
Sheep should also be transferred directly to a shed or sheltered yard on arrival to the farm, so that health treatments that guard against anthelmintic resistance in particular can be administered. They should remain in these confines for 24 to 48 hours.
Many farmers like to join a new ram, for example, with some companion animals to help them settle on arrival to the farm. Once this happens, then these animals should also remain in the quarantine group until you are satisfied there is no disease risk.
Anthelmintic resistance is becoming a growing concern on sheep farms, irrespective of the size of the flock. It is well documented that there are resistance issues on many farms with benzimidazoles or white drenches, but an increasing number of farmers are now worryingly identifying resistance to avermectin and levamisole-based products.
The latest advice to combat the risk of bringing resistant worms on to the farm is to treat sheep with a new-generation wormer and a moxidectin-based product on arrival to the farm. Startect is not available to farmers in Ireland currently, while reports suggest there has been some recent supply issues with Zolvix, which should hopefully be sorted now.
Sheep should be treated on arrival and kept off pasture for 24 to 48 hours
Zolvix is a prescription-only medicine and as many veterinarians do not stock it as standard, it is important to order it well in advance of when it will be required.
Where there is no chance of implementing this option, or there are supply issues with the new generation wormers, then the next best option for most farms is treating purchased sheep with a moxidectin-based product and a levamisole-based wormer.
Sheep should be treated on arrival and kept off pasture for 24 to 48 hours, so that worm eggs present in the gut will not pass on to pasture.
Following treatment, sheep should be turned out to pasture that is referred to as ‘dirty’ – ground that has been previously grazed by sheep.
With regard to liver fluke, there is a risk of bringing fluke parasites in sheep carrying a fluke burden on to farms which do not suffer a challenge. And while it is not at the same risk level as anthelmintic resistance, there is also a danger of introducing liver fluke parasites that have developed resistance to flukicides.
The greatest threat in this regard is resistance to trichlabendazoles, with this issue identified in some areas with a particularly high risk profile and where products with this active ingredient were used continuously.
Where there is a perceived risk, the current advice is to use a product containing trichlabendazole and another product with an active ingredient, such as closantel, to safeguard against liver fluke resistance to trichlabendazole.
The risk of external parasites is often not evident during the summer months, with lower activity of sheep scab, lice etc. Plunge dipping is the optimum method for controlling external parasites.
Remember, for complete control, sheep should be immersed for 60 seconds, with their head plunged under the solution at least once.
Pour-on products can be used in certain circumstances
The options outside of dipping are more limited, due to the fact that there is no one product that controls all of the main external parasite threats in one treatment.
Plus, given the increase in anthelmintic resistance and the identification of sheep scab resistance to moxidectin, it is no longer advised to use avermectins for routine treatment to control sheep scab.
Pour-on products can be used in certain circumstances to reduce the risk of naïve animals falling foul of tick-borne disease in endemic areas.
The critical disease to guard against is the introduction of contagious ovine digital dermatitis, which is commonly known as CODD. If this ailment gets established in a flock, it is difficult to treat and eradicate it completly. It can be identified by an infection at the coronary band and in advanced cases, the hoof horn will be lifting away from the band.
Footrot is also a significant risk
It is important to check sheep closely for this ailment on arrival and this is one of the big reasons behind the advice to keep animals segregated for at least 21 days. Treatment options are limited and require veterinary approval.
Footrot is also a significant risk, and again, sheep should be examined for signs of the disease. Sheep should be footbathed as a precautionary measure and a treatment plan should be put in place for any lame sheep, with affected sheep isolated from the rest of the flock until you are sure all problems have been addressed.
Footbathing will not cure footrot and antibiotic treatment may also be necessary. There is only one option for vaccination for footrot, with the Footvax vaccine offering preventative and also treatment properties.
The use of vaccines will be influenced by the risk profile on the farm and prior history. Clostridial disease vaccination is the obvious option for any purchased sheep.
In addition,s vaccination against abortion-causing agents such as chlamydia abortion (enzootic abortion) and toxoplasmosis should be strongly considered.
Vaccines for these ailments are also prescription-only medicines and need to be ordered in advance of when they will be required, as they need to be administered three to four weeks before the start of breeding.
Sheep farmers need to be mindful of a range of other diseases, such as ovine pulmonary adenocarcinoma (OPA) or Jaagsiekte, caseous lymphadenitis (CLA), Johnes disease and maedi-visna.
These diseases are hard to distinguish and strengthen the argument for implementing as long a quarantine period as possible and purchasing, where possible, from known sources.