Vet: Switch in seasonal grazing conditions bring its own unique health issues

Eamonn Connell
Eamonn Connell

Eamon O'Connell

The change from summer to autumn brings a change in the weather and with it, a change in grass growth. This brings with it some cattle health issues that are unique to this time of year.

CCN (Vitamin B1 deficiency)

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Vitamin B1 (also known as Thiamine) is normally produced by bacteria in the rumen of healthy cattle on a well-balanced diet with plenty of fibre.

Unfortunately at this time of year, a lot of grass is very lush, with a very low fibre content. Ingestion of this type of grass, especially by young cattle, can lead to a disturbance in rumen flora, with a resulting upset in the production and/or availability of Vitamin B1.

A deficiency of Vitamin B1 reduces energy available to the brain, leading to a type of brain degeneration. Signs to watch out for include:

• An animal away from the main group, often walking with its head held abnormally high (star gazing).

• Apparent blindness, circling and bumping into walls etc.

• Hyper-excitability - very sensitive to noise and touch.

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• These initial signs will progress to seizures and the condition is ultimately fatal if not treated early.

Treatment involves injections of Vitamin B1 at regular intervals, often over three days. This should only be done in consultation with your vet as other conditions such as meningitis can have similar clinical signs. It is important to be definite about the cause before treatment begins.

As with a lot of neurological conditions, prevention is definitely better than cure. Avoid sudden changes in diet. If moving calves from rough pasture onto lush grass, some form of fibre should be made available.

With the availability of lots of hay country wide this year, this shouldn't be a problem.

Also, don't suddenly increase the volume of concentrates fed. A very slow and gradual increase gives the rumen time to adjust.

Ferns in the diet too can leave animals more exposed to developing CCN so this should be avoided if possible.

Excess sulphur in the diet should also be avoided.

Fog Fever

It's not too often that a phone call alone can make a vet almost certain of a diagnosis.

A call from a very worried dairy farmer last autumn, however, was one of these rare occasions. He was ringing to get me to call to a cow that was unable to stand when he went to get the herd in for milking.

"Listen to the noise she's making," he said, as he turned the phone in the cow's direction.

The characteristic laboured loud grunt of a cow with fog fever could be easily heard.

Fog fever is an acute pneumonia of adult cattle which occurs when cattle are moved from rough pasture or tight grazing into a paddock with an abundance of fresh lush grass. It usually occurs in autumn, 5-10 days after the change to lush grass.

This condition does not affect young stock. Rumen bacteria are very slow to adapt to the sudden dietary change, especially the amount of available protein in the lush grass. One of the amino acids in the protein, tryptophan, is converted by the rumen bacteria to a substance called 3MI, which is produced in large quantities and is very damaging to lung tissue.

Signs include:

• Great difficulty breathing, often with an open mouth and a characteristic loud grunt.

• Frothing at the mouth.

• Coughing

• The animal will be very distressed.

• Cattle don't normally have a high temperature.

• In advanced cases, there will be a build up of air under the animals' skin. It will feel like bubble wrap.

• The condition is often fatal.

There is no specific treatment for fog fever. Supportive treatment such as anti-inflammatory medication is always required to at least try to make the affected animal more comfortable.

Despite our best efforts with the cow that could be heard down the phone, she did not pull through. This shows just how aggressive a condition fog fever is and that irreversible damage can already be done before clinical signs are seen.

Prevention involves strip grazing very lush pastures at this time of year or, if possible, alternating grazing rough pasture and lush pasture.

Switch in seasonal grazing conditions bring its own unique health issues

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