What triggers lameness?
US DAIRY herds which manage heifers as a separate group reduce the rate of lameness to 16% compared with 33% for mature cow groups.
When a heifer is lame during her first lactation, she has a greater risk of becoming lame in subsequent lactations, said researcher Nigel Cook of the vet school at Wisconsin-Madison University.
“Work at Bristol University has shown that hormones seem to trigger enzymes which eat away at the connection between the pedal bone and the claw horn capsule at first calving. Moving heifers into cubicles at calving and changing their diet seems to exacerbate this damage.”
Further trigger factors resulting in claw horn lesions, such as laminitis, include sub-acute ruminal acidosis (SARA), said Dr Cook. His studies have revealed many lesions occur in early autumn following a period of heat stress in summer because it takes two months for the sole to grow.
Low-ranking cows in particular do not get the same access to feed as boss cows. “A boss cow can eat the same whether she has 1m of feed access or 0.5m, but in subordinates we see a dramatic reduction in intakes once they only have 0.5m.”
To prevent SARA, Dr Cook suggested the rumen”s capacity to buffer should be increased using sources of bicarbonate. Producers can also help cows regulate their own ruminal pH by providing continuous, predictable access to feed.
Laying rubber in walkways will also help to prevent rough concrete from shaving off too much of the sole which can lead to toe ulcers. However, Dr Cook cautioned against using rubber for cows standing at the feed fence.
“When cubicle design is an issue, cows will prefer to lie on the rubber and may also spend more time standing on it than lying in cubicles.”
The biggest benefit could be seen in the collecting yard as 45% of a herd spends more than three hours a day standing to be milked.
“In herds milked three times a day, the fastest cows are in and out within an hour, but others spend six hours a day waiting to be milked and walking back to cubicles. I think these are the lame cows in a herd.”