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Animal health impact of wet August will linger into the winter months

The risk of parasite infections is on the rise after moist and humid conditions in some parts of the country


Early doors: Some stock had to be temporarily housed and while they are back out again in most areas, rainy weather forecasts for the days ahead may see them return indoors sooner than we would like

Early doors: Some stock had to be temporarily housed and while they are back out again in most areas, rainy weather forecasts for the days ahead may see them return indoors sooner than we would like

Early doors: Some stock had to be temporarily housed and while they are back out again in most areas, rainy weather forecasts for the days ahead may see them return indoors sooner than we would like

The weather last week was idyllic, but many farmers, especially in the west of the country, are still feeling the effects of a very dull and wet month of August. Parts of Galway recorded their wettest August in decades. Sunshine levels have been below normal despite balmy temperatures. There are a number of animal health issues these weather conditions can lead to over the coming weeks and months.

Silage quality

Some silage that was made in the past few weeks may not be as high in quality as we think. Sugar levels may be lower due to decreased sunshine, which can lead to poorer fermentation of silage. Water content may be higher too, which leads to reduced nutrients. Slow wilting can lead to excessive protein and sugar loss.

If there is any doubt as to the quality of silage, it is vital that a silage analysis is carried out before it is fed. Dry matter, energy, protein, mineral and vitamin content can all be accurately measured. Depending on what group of animals are being fed, the diet can then be manipulated to meet requirements.

Poor quality silage can cause conditions such as listeriosis or poor weight gain in cattle. Similarly in dairy stock, milk fever, ketosis, metritis and many other production diseases can all be attributed to feeding of poor quality silage over the winter months.

Straw quality

This year's harvest has been particularly trying. Straw quality in some places is questionable at best. Straw that is dark in colour and/or damp should not be fed to any cattle. Similarly, mouldy straw should not be used for bedding.

Grass quality

I have heard a number of reports lately of grass "flowing through cows". The fibre content of grass, especially on dairy farms with tight grazing rotations, is quite low. Cows appear scoured and rumen fill is poor. This leads to a reduction in milk production, weight loss and we have even seen a few cases of abomasal ulcers in cows over the past few weeks. Similarly, some batches of young calves appear to be scoured for the same reason. The addition of some source of fibre to the diet can correct this issue quite quickly.

Rumen fluke and liver fluke

Both flukes have the same intermediate host - the mud snail. The mud snail thrives in mild and wet conditions. With live stock grazing water-logged pasture in late August, the risk of developing fluke is quite high. It is very important to confirm if a group of animals are suffering from rumen and/or liver fluke before treatment is carried out. This is done by analysing faecal samples, usually after housing, and also using the feedback provided by factory reports.

Lungworm and ostertagia

The wet and humid conditions have led to a dramatic increase in parasite infestation in grass, especially compared to this time last year (see panel below).

Early housing

Some cattle, especially heavier stock, have had to be housed temporarily. Cattle are back out again in most areas, but with weather forecasts predicting rain again for the days ahead, they may be back in sooner than we would like.

Pneumonia is the most common health issue associated with housing cattle, especially weanlings. This is exacerbated when housing occurs hurriedly and in very wet and humid weather. Pneumonia vaccinations should be completed prior to housing, so now is the time to get started. Cows too can suffer from a prolonged period indoors, as it can lead to an increase in the incidences of lameness and mastitis.

Consider the health implications on your herd as we head towards the housing period. Make plans where possible to ensure a smooth transition from pasture to housing. Diet, dosing and vaccines should all be discussed with your vet to ensure your herd remains healthy into the winter months.

Eamon O'Connell is a vet with the Summerhill Veterinary Clinic, Nenagh, Co Tipperary

Lungworm vaccines to play a greater role as dairy herds expand

"I used that really expensive dose you gave me only six weeks ago and they're coughing as bad as ever again". This is a scenario we are encountering in a number of dairy herds over the past few weeks.

Usually, in June or July, a farmer will complain that a significant portion of cows in the herd are coughing, particularly when coming in from the paddock for milking. Milk production is down, but cows are not in any way sick.

Our first course of action is to investigate using a combination of bulk milk antibody testing, BALs (lungwashes) and a detailed herd history. Lungworm is the most common diagnosis. A zero-milk withdrawal pour-on or injectable product is used, resulting in a subsidence in coughing and an increase in the volume of milk in the tank. However, a combination of factors has led to the 'perfect storm' for treated cows becoming re-infested with lungworm.

* Humidity and rainfall: The warm, wet weather over the past number of weeks has made for ideal conditions for lungworm larvae to survive on pasture. Heavy rain has helped to disperse the larvae from infected faeces throughout paddocks. Conditions which are ideal for growing grass are unfortunately ideal for lungworm as well.

* Tight grazing rotations: Many extensive dairy farms are getting cows back into paddocks as early as 17/18 days after the last grazing. A single cow can shed millions of fresh lungworm larvae on to pasture. Paddocks can be literally heaving with infective larvae by the end of August.

* Immunity: In the last number of years, a trend has developed whereby dairy replacement stock are reared on a separate block of land to the milking cows. They are wormed very regularly and by the time they enter the milking herd, they have little or no immunity to lungworm.

* A dry year followed by a wet year: Last year won't be forgotten in a hurry as grass literally burnt to a crisp on many dairy farms.

A very dry year meant very little lungworm. This means that cows did not get exposed to lungworm last year, resulting in a gap in immunity.

* Product duration of action: Products that can be used in milking cows provide protection against re-infestation with lungworm from 14 days up to a maximum of 28 days.

The length of time from ingestion of infective larvae to development of clinical signs (coughing) can be as little as 14 days. This combined with the factors listed means cows can be coughing as bad as ever 4-5 weeks after being treated for lungworm.

This can be a very bitter pill to swallow, mainly due to the fact that any zero milk withdrawal wormer is quite expensive and once should be more than enough to have to use it in most farmers' minds.

Anecdotally, questions have been asked about the efficacy of pour-on products over injectables but, in reality, if used according to manufacturers' specifications (accurate dosing to weight and ensuring cows are dry on application and remain dry for a minimum of two hours after) a pour- on product is perfectly effective. Plans should be put in place to address this phenomenon in order to prevent it becoming a regular and very expensive occurrence.

An in-depth review of worming protocols for replacement heifers in their first and second grazing season should be undertaken, the aim of which should be to have first calving heifers entering the herd with a strong immunity to lungworm.

There is also a vaccine available that gives cows immunity to lungworm. This will definitely play a greater role in the next few years as dairy herds continue to expand.

It is never too early to sit down with your vet to devise a strategy to control lungworm infestation in your herd.

Indo Farming