Johne's control at farm level

With calving in full swing on Irish dairy farms, Jack Kennedy spoke with two vets on the AHI Johne's Technical Working Group about some things farmers need to be aware of at this important time.

Jack Kennedy

7 March 2014

If you have Johne's on your farm then group feeding can spread the bacteria to other calves.

Eamon Guinevan*The simple rule I use when explaining about feeding colostrum to a newborn calf is to think of the phrase ‘own or known’. Feed milk to the calf from her ‘own’ mother or from a cow of ‘known’ Johne’s status.

Eamon Guinevan*

The simple rule I use when explaining about feeding colostrum to a newborn calf is to think of the phrase ‘own or known’. Feed milk to the calf from her ‘own’ mother or from a cow of ‘known’ Johne’s status.

On the majority of farms, feeding milk to the calf from its own mother is possible. However, if a cow has poor colostrum or it’s not possible to milk the cow, then you need to write down from what cow you get the colostrum. If you find out later it is a Johne’s infected cow, then at least you know what calf is at high risk. Milk is one part of it, but remember is only takes a teaspoon of muck from an adult cow to spread the bacteria, so removing the calves from the calving area as soon as possible after birth is essential to reduce the risk.

The more I look at Johne’s, the less I worry, because I feel we are in a much better position compared to countries like Holland, Denmark and the US. They might have 30% of farms infected, and on each farm up to 30% of cows could be infected. In Ireland, I estimate that maybe 20%-25% of farms have some Johne’s infection, but only 3% of cows on those farms are infected, so the risk is much less.

This means 75% of farms are not affected at all and on the other farms, a small bit of management, such as removing the calf and proper colostrum management, can help reduce the impact of this disease. We could jump 10 years ahead of those other countries in terms of Johne’s control at farm level.

If you are switching onto milk replacer for young calves, then you need to make sure it is high-quality replacer and that the protein source is not vegetable proteins such as soya.

I estimate by the end of this year we will have 500 Carbery-supplying farms on the pilot AHI program to take either a blood sample or two milk samples. In terms of price, the milk samples will be slightly cheaper, but the window to take the samples is tight because you need to wait three months after the TB test, and for split calving herds you might have only some cows calved.

In practice, many will opt for the blood sample on the day of the TB test or on another day that suits the farmer.

*Eamon Guinevan is working in a large animal vet practice in Timoleague in West Cork and is a partner in Riverview Veterinary Clinic in Bandon, Co Cork.

Ciaran Mellett*

At this time of the year, when calving areas are very busy, the best solution to minimise the spread of Johne’s is to remove the calf, especially heifer calves, from the cow and calving pen as quickly as possible.

If this is not possible, then it might be possible to create a ‘safe haven’ within the calving pens where no cow can go. This can be as simple as a couple of large square bales at one end of the shed where newborn calves are housed before taken to the calf shed.

If taking milk from a freshly calved cow, then make sure the teats are clean.

The scoring system as partly outlined above is by no way an audit and will have no influence or ranking on any herd nationally.

If you have a problem with Johne’s, then half the progress in controlling the disease can be obtained by management and the other half by testing.

Any farmer that signs up for the on-farm assessment must, within the rules of engagement, commit to at least two years of milk or blood testing. This can be an individual cow milk test, twice per year, or an individual blood test. Neither test must be taken within three months of the annual TB test.

Milk samples can be taken at a ‘normal’ milk recording. If DIY milk recording, an extra person must be present to ensure it’s completed properly. Bulk milk testing is inaccurate and was rejected by the technical working group as having no merit.

The indicative costs for milk testing, we are told, are €2.75 per cow, twice a year, so €5.50 per cow. Plus 0.75 cent/cow, also twice a year, for the extra person to attend when taking Johne’s milk samples, so in total that’s €1.50 per cow. Therefore, in total it is €7/cow per year. The blood test can be taken at the TB test and the indicative cost we have been given is €5.50 to €6 per sample, which includes the sampling and laboratory analysis by the local vet.”

*Ciaran Mellett is a large animal vet in County Meath and he is also on the AHI led Johne’s Technical working Group.

Eight steps to Johne's calf assessment - read more here.