There is no doubt that taking steps to prevent disease occurring will significantly reduce the risk of a disease outbreak. It will also reduce the costs directly associated to the disease and any longer term impact on performance the disease may have. For these reasons, it is worth sitting down and looking at the risk factors to your flock and putting a plan in place to combat these. This article touches on a number of topical areas which may come to the fore in the coming months.

Your own health

Farmers can often put their own health at lower importance to the flock or herd. Remember, you are the most valuable asset to the farm and as such should take the time to at least carry out a yearly health check with your doctor.

Abortion

Any incidence of abortion should be treated as a possible outbreak. Causes of abortion can be non-infectious and infectious. Non-infectious causes are often triggered by mis-handling ewes in late pregnancy, injuries or factors such as inadequate feeding (twin lamb disease) or stress-related factors, but these are generally rare.

An isolated case associated with any of these factors generally passes off OK. Nevertheless, it is important to treat every case with caution and carry out further investigation, especially if there are multiple cases or there are signs of infectious disease with foetuses, for example. Alarm bells should rise if the incidence exceeds 2%.

Toxoplasmosis and enzootic abortion remain the two main causes of abortion but less common causes such as listeriosis, for example, can also end up being the root of the problem. It is important to treat every case as a potential outbreak. Isolate and mark all problem sheep until the cause of abortion is known and adopt high levels of hygiene. The success of an accurate laboratory diagnosis will be influenced by the quality of materials collected and getting them submitted as soon as possible.

If lameness gets established it can be difficult to address when sheep are housed and can be particularly troublesome at lambing.

Lameness control

Segregating and treating lame sheep has been repeatedly highlighted by veterinary specialists as the fastest way to get on top of lameness in a flock. This is particularly important for flocks that will be housing sheep in the coming weeks as failing to take action and housing healthy sheep with infected sheep can quickly lead to disease spread or an outbreak of lameness.

The starting point in putting a treatment plan in place is accurate identification of the disease causing lameness, followed by treatment with an appropriate product. It is worth contacting your vet if you are unsure of the ailment causing lameness as in the case of CODD, for example, you could be spending time and money to no effect as products suitable for treatment need to be prescribed by your vet.

Antibiotics may need to be administered to get on top of footrot, which is the most common cause of lameness. The vaccine Footvax possesses treatment and preventative properties (stimulates immunity) for footrot and is capable of playing an important role in a flock lameness programme. Chronically lame sheep that do not respond to treatment and repeat offenders should be put on the culling list.

There is no product available outside of dipping that gives complete control over all external parasites

Feeding space

As ewes enter late pregnancy and increase in size, it is important to ensure that all animals can eat comfortably together. The general recommendation of 400mm to 450mm head space per ewe for restricted feeding may need to be increased where ewes carrying multiple lambs are penned together, or alternatively extra troughs should be used to ensure all animals can eat unrestricted.

Ewes should also be monitored to ensure that shy eaters are not deterred from eating. Feed trough management is important and silage/hay feeders should be cleaned regularly if not fully eaten, while water troughs should also be checked frequently and cleaned out on a regular basis.

Body condition score and late pregnancy feeding

The importance of getting late pregnancy feeding programmes correct was highlighted by Teagasc’s Frank Campion at the 2017 Teagasc lowland sheep conference. Frank said that for every 0.5 unit drop in body condition score in the last month of pregnancy, lamb survivability will reduce by 5%. He added that lamb survival will also drop 5% for every 0.5 of a BCS unit ewes are below BCS 3.0 at lambing.

This also has negative implications on lamb vigour and colostrum production. He advised farmers to consider the protein and energy content of the diet with the recommendation to focus on high value energy ingredients and soya bean as the best source of protein, with an overall protein content of the concentrate preferred by Frank at 20% and no lower than 18%.

Dipping is the complete option for treating all external parasites and should be the first port of call if possible.

Sheep scab and lice

External parasite issues caused by lice or sheep scab generally present themselves in the winter period. An issue can be easily identified with wool stained from ewes scratching. Like lameness, the first port of call is establishing what is causing ewes to be aggravated. In most cases, scab or lice will be the issue.

If sheep are being dipped to control external parasites with the practice carried out correctly (sheep immersed in dip solution mixed at the recommended concentration), then differentiating between sheep scab and lice is not as great an issue.

Where an alternative route of treatment is being used, however, then it is critical to identify the cause of the problem as there is no product available outside of dipping that gives complete control over all external parasites. While difficult to carry out, it is possible to visually identify the parasite causing the problem.

Sheep scab mites are brown in colour, round and are tiny – barely visible to the naked eye. They feed on flesh and are generally found on the skin where scabby lesions and wool loss are characteristic of scab. In contrast, lice are easier seen by the naked eye and move through the wool. Lice are long, shaped similar to a wasp with a yellow or pale brown colour. If in doubt, your vet will be able to diagnose by examining using magnification or taking a sample for examination under a microscope.

Once the problem has been identified, then the appropriate treatment can be selected. Sheep scab can generally be controlled by select injectable products but be careful as some products require treatment seven to 14 days later to target eggs that have hatched following treatment. Products suitable for treating lice, on the other hand, are generally pour-ons. All sheep in the group must be treated on the same day to prevent reinfection.

Where orf is an issue on the farm, vaccinating lambs will help to cut down on issues with early lambs born indoors that will be consuming meal.

Orf

It is important to note that where orf has not previously been a problem on the farm, vaccination should not take place. This is as the vaccine is live and exposing it to a naive flock will just serve to introduce orf into the flock. Scabivax Forte is the vaccine available for preventing orf. Scabs resulting from the vaccination are capable of spreading the disease for up to seven weeks and therefore should not come in contact with unvaccinated sheep, lambing pens, etc, where the disease can subsequently be spread. It should also not be administered to ewes less than seven weeks pre-lambing.

Addressing soil fertility deficits can bring about a massive improvement in grassland performance while at the same time reducing costs.

Soil health

Ongoing analysis of soil sample results by Teagasc shows the alarming rate at which soil pH, phosphorus and potassium levels have fallen over the last decade, with only 10% of soils at desired levels. Fertiliser applied to soils at below the desired pH of 6.2 for grass growth will not achieve optimal uptake of nutrients.

Where recent soil analysis is not available, the focus should be to start the season by identifying the fertility status so that remedial action can be taken during 2017. The cost of a sample for pH, P and K generally varies from €12 to €25 (depends if taking yourself or getting samples taken), which is a low cost considering the wealth of information gained and the cost of incorrectly applying fertiliser.

Samples must be taken before organic or chemical fertilisers are applied and at least three months after organic or chemical fertilisers containing P and K compounds were applied. Recommendations are to take samples in similar soils with one sample sufficient for 5ha. Samples should be selected in a W shape avoiding areas where soils differ or practices such as supplementation have taken place.