Eight steps to Johne's calf assessment

The AHI technical working group has designed a worksheet for specially trained vets to use when assessing the risk of Johne’s spread on dairy farms. It is called the Johne’s Veterinary Risk Assessment and Management Practices (VRAMP) and it allows a farmer and vet to make a thorough, systematic assessment of management practices that have been shown to impact on the spread of infection.

This article provides information on how a vet will assess the management of heifers less than six months old, which is one of four key focus areas during assessment.

It is planned that over 1,800 farmers will have signed up to be part of the Johne’s on-farm assessments by the end of the year. The following is a summary of some of the questions they will be asked. The lower your farm can score, the better the result. This is not an audit and the scoring is used primarily to outline potential options for managing the disease on your farm. Assess and score your own calf management using the scoring system outlined below.

Q 1: Are calves fed colostrum from own mother or from known low-risk colostrum cows or artificial colostrum (recommended only in emergency situations)?

Feeding “own mother to only one calf” helps prevent further spread of Johne’s. ‘Clean colostrum’ refers to colostrum which has not been contaminated by faeces; the cleaner cows are at calving the less likely it is to be contaminated.

Score 1 - If all calves receive fresh clean colostrum only from their own test-negative mother, or are fed colostrum from known low-risk cows. If all calves born to a test-positive mother are removed from breeding programme permanently.

Score 4 - If all calves receive clean colostrum from only their own mother (no selection but no exposure of calves to cows other than their own mother) or are fed from a single low-risk ‘donor’ cow (selected because test negative and older [>8 years of age].

Score 7 - If colostrum from another cow(s) (pooled or frozen), with no selection based on JD status, is fed to 1%-10% of calves.

Score 10 - If colostrum from another cow(s) (pooled or frozen), no selection, is fed to more than 10% of calves.

Q 2: Are at least 3 litres of colostrum (first milking) consumed within the first 2 hours?

Feeding calves at least 3 litres of clean colostrum within the first two hours is recommended.

Score 1 - If every calf (bulls and heifers) gets at least 3 litres of clean colostrum (use 2 to 3 litres for Jersey calves) in the first two hours.

Score 4 - If more than 50% of all calves get at least 3 litres in the first 2 hours.

Score 7 - If < 50 % of all calves get at least 3 litres in the first 2 hours.

Score 10 - If no calves get at least 3 litres.

Q 3: Are calves fed on low-risk whole milk, pasteurised low-risk milk or milk replacer?

Low-risk whole milk comes from cows selected on their perceived JD infection risk. In the absence of testing, some farmers may select to feed milk only from younger cows or cows known not to have JD infected relatives, which should be lower risk for milk transfer of JD. Milk replacer is unlikely to contain JD, but can become a risk if it is mixed with manure-contaminated water or fed in manure contaminated-buckets or bottles.

Score 1 - If calves have been fed milk replacer or pasteurised milk all the time for at least the past two years (no exceptions).

Score 4 - If calves are always fed whole milk selected from JD test negative or first calved heifers.

Score 7 - If calves are fed whole milk from individual cows (e.g. no selection) JD test status unknown (e.g. over quota milk).

Score 10 - If calves are fed whole milk from the whole herd e.g. from the bulk tank

Q 4: How often is non-saleable whole milk (high-risk) fed?

Non-saleable milk is milk that is not suitable for sale for milk processing e.g. Mastitis milk, high SCC, transition milk or antibiotic milk.

Score 1 - If non-saleable milk is never fed.

Score 4 - If non-saleable milk is fed once or twice per year (“rarely”).

Score 7 - If non-saleable milk is fed once or twice per month.

Score 10 - If non-saleable milk is fed weekly.

Q5: Are calves housed in individual pens or in groups for the first week?

There is evidence that in highly stocked pens other potentially clean calves can become infected if calves that have been infected are housed with them.

Score 1 - Calves are housed in single pens and away from the main cubicle/housing/calving area.

Score 4 - Calves are housed in single pens in the main cow cubicle or housing / calving area.

Score 7 - Calves are housed in groups >9.

Score 10 - Calves are housed in groups >10.

Q 6: Is there exposure to cow manure in calf housing or grazing area?

Young, milk-fed calves can ingest Johne’s from cow manure if it contaminates bedding, alleyways, grazing areas, roadways, feed and water.

Score 1 - Calf housing, pasture and feeding is entirely separate from any manure (or slurry) from adult animals or movement areas (including using different equipment and wearing different clothing and boots).

Score 4 - Calves are housed or at pasture near adult animals but there is no possibility of contamination by manure (or slurry) from adult animals.

Score 7 - Calves are housed or at pasture near cows (or followers) and are exposed via cow traffic areas (roadways) or via people movement (i.e. there is no attempt to maintain a barrier).

Score 10 - Calves are housed or grazed near cows (or where slurry was spread), share feeding areas or water; direct contamination or contact is likely (i.e. there is no barrier and contact risk is high).

Q7: Is there exposure to cow manure by water or feeding utensils?

Calves can be directly exposed to Johne’s if feeding hygiene is not excellent. Using contaminated water for mixing milk replacer or for calf drinking can increase exposure.

Score 1 - If mixing utensils and feed/water buckets are visibly clean and all are washed daily with detergent or disinfectant.

Score 4 - If trace amounts of manure are visible or mixing utensils/buckets are washed less frequently than daily but at least weekly.

Score 7 - Regardless of cleaning practices, manure is clearly visible.

Score 10 - Regardless of cleaning practices, manure contamination is extensive.

Q8: Are calves fed forages that have received slurry from adult animals within the last year?

Slurry may be a potential source of Johne’s. The evidence for the degree of risk is not clear. It is frequently of concern to farmers or managers and calves are the most vulnerable group.

Score 1 - Grass/silage/other forages fed to calves not spread with slurry/ farm yard manure from adult animals in the previous 12 months.

Score 4 - Hay fed to calves spread with slurry/ farm yard manure from adult animals in the previous 12 months.

Score 7 - Silage/other conserved forages fed to calves spread with slurry/ farm yard manure from adult animals in the previous 12 months.

Score 10 - Grass fed to calves spread with slurry/ farm yard manure from adult animals in the previous 12 months.

Your farm score

Q1 –

Q2 –

Q3 –

Q4 –

Q5 –

Q6 –

Q7 –

Q8 –

Total = /80

Footnote: A high score should alert you to the potential for Johne’s spread on your farm and the need to improve management.