A midlife crisis and the desire for a new challenge were the catalysts for Nathan and Rosie Hughes’ switch to smaller herd dairy farming three years ago.
In pasture-based systems only four lameness conditions account for almost 90% of the lameness: white-line separation (WL), sole injury (SI), footrot (FR) and axial wall crack between the toes (AWC).
Chesterton told the Smaller Milking and Supply Herds (SMASH) conference in Hamilton recently that each condition has a different set of risk factors.
“So it is important to know what lameness conditions your cows have if you want to identify the risk factors on your farm,” he says.
“To know what is happening, you will need at least the following records for each lame cow: date treated, cow ID, lesion causing the pain (WL, SI, FR or AWC).
“Most farmers only record the cows receiving antibiotic because of milk withholding. You must start to record.”
Chesterton also stresses there are risk factors for lameness, not causes.
“In the past we used the word ‘cause’ of lameness; so we might say, for example, ‘lameness is caused by wet weather’. It is true that every time it rains for extended periods, lameness prevalence in a district will increase; but not every cow gets lame.
“So it is more accurate to say ‘wet weather increases the risk of lameness’.”
Each lameness condition has a different set of risk factors. Risk factors for white-line injury are separation of sole and wall of the hoof, long walking distances, thin soles, damaging walking surfaces, yard size too small for the herd, backing gate/top gate moves too fast, people/dogs causing pressure herding on the track and/or yard and feet slipping or twisting on concrete.
Risk factors for sole injury (bruising, penetrations) are long walking distances, thin soles, poor walking surface on tracks, sharp gravel, gravel on concrete surface, and people/dogs causing pressure herding on track.
Risk factors for footrot are injury and then infection of inter-digital skin by the bacteria Fusobacterium necrophorum in faeces of cows; also excessive crowning of tracks resulting in cows walking in side drains, and track surface breakdown.
Risk factors for axial cracks are stone injury of the coronet between claws; or genetic -- the same risk factors as for footrot when stones about 1cm diameter lodge between the claws.
Chesterton says a look at the list of risk factors will show immediately why long periods of rainfall may increase the likelihood of each problem occurring.
“Rain can damage track surfaces, exposing base materials which then can be carried onto concrete on muddy feet,” he says.
“Cows are likely to walk slower on rain soaked surfaces of tracks. People are more likely to get impatient at slow cow flow. Early studies identified the two important success factors that would reduce lameness : maintenance of the track and patient handling of the herd.”
Chesterton also spoke about some basic rules of treatment for lameness.
It’s important to remove all under-run wall or sole.
Lift the foot off the ground with a block on the healthy claw and do not give antibiotic injections unless there is swelling above the hooves.
The second important risk factor for lameness is the management of the herd.
On many farms the tracks are well designed and maintained, but a farmer may have too many lame cows with white-line injuries.
On the track and/or milking yard you can see the cows are under pressure from the way they are managed.
“Very often the pressure put on the cows is not done because the farmer is angry, but because his/her impression is that the herd is not flowing very well and needs a push,” he says.
“So they use the gate behind the herd to encourage the rear cows to walk forward.
“The problem is that from the pit it is difficult to recognise the signs of pressure. Many farmers come out of the pit to encourage the cows to move into the milking bails.
“This can be done well, but if a milker doesn’t recognise the signs of pressure or understand cow behaviour it is easy to overdo the ‘encouragement’.”