Last updated 22:08, Tuesday, 17 June 2008

At last the winter housing period has come to an end and we are now noticing lots of cows in poorer condition.

Condition: While most cows, like these ones, thrive, others struggle to make the grade

Is this due to poorer silage as a result of last year’s wet summer. Or is there an underlying disease problem?

I sampled 10 dairy farms during the winter and nine out of 10 farms showed high levels of exposure to liver fluke.

Cows do not build up an immunity to liver fluke. Due to the high amount of rain last year, there was a lot of fluke on the pasture. All cows should be treated for fluke at least once a year.

On the hill ground we are also noticing trace element deficiencies – copper, cobalt, selenium and iodine – which will have an impact on body condition, fertility and strength of the calves.

Once again, last year’s wet weather will have leached the elements out of the ground. It may be worth taking a few samples to check for this.

A common reason for individual thin cows is Johne’s disease. We are seeing more and more cases of this disease.

Johne’s disease is caused by mycobacterium, which causes thickening of the gut. This thick gut makes it difficult for the cow to absorb the nutrients properly so she looses weight, develops a scour and gets thinner and thinner. All the cake in the world will not fatten these cows.

This problem can affect any breed of cattle from as early as two years old.

Currently, there is no effective treatment for this disease. Control can be achieved by early identification of the animals that are carrying the disease and removing them from the herd when they are still in good condition. (This does not mean you sell them on at the auction and let someone else worry about them.)

Once you have identified that you have a problem with Johne’s on your farm, it doesn’t have to be the end of the world. Appropriate testing and husbandry measures can control and eradicate the disease. If you do nothing and bury your head in the sand, this disease will spread slowly through the herd and have a huge economic impact. The one thin cow may just be the tip of the iceberg.

As a practice, we regard this disease as very important and are putting control plans in place on many of our farms.

On some, we are aiming for eradication, but on others we are implementing Johne’s reduction plans. On farms where we have implemented this in the past few years, we are already seeing reduced financial losses from cutting the numbers of cows which go thin and eventually die.

It is these thin, profuse scouring cows that are the highest contaminants of the environment and highest risk to young calves – often the future replacement stock on the farm.

To control the disease you must first identify how many cows are infected. Dairy farms can do a bulk milk tank antibody test which will tell us how much disease is on the farm, but will not identify the cows which are harbouring it.

Beef farms can test any older, thin cows to establish the presence of the disease.

To control the disease, all stock older than two years should be tested. Positive cows should be isolated and removed from the herd.

Colostrum from infected cows will spread the disease, so avoid pooling colostrum and feeding it to calves unless you know the cows are negative.

We see a range of other causes of thin cows, often relating to infections and traumatic damage at or around calving.

Feet problems can especially lead to chronic pain, which in turn reduces feed intakes and results in thin cows. Prompt treatment of lameness will prevent this occurring.