Livestock Improvement is working on a genetic means of reducing the incidence of cow lameness.
It involves identifying artificial breeding bulls whose daughters will be more resistant to lameness, says LIC breeding manager Allan McPherson.
Based on a “mobility breeding value” (MBV), it is a “small but significant step in selective breeding for dairy cows”, he says.
"The heritability of lameness is relatively low – less than 5%. In other words, over 95% of the observed differences between animals are controlled by non-genetic factors.”
But the potential economic impact of lameness is high enough to make the genetic variation between animals useful, McPherson says.
"Since 2003 we've been routinely collecting lameness data from LIC's sire proving scheme herds to develop a mobility breeding value which could be used to identify bulls whose daughters are more resistant to lameness.”
Almost 50% of herds surveyed had some problem with lameness. Although the average incidence reported was relatively low at 4%, there was a lot of variation between individual herds.
Fifteen per cent of surveyed herds had lameness of 10% or greater; in the herd with the greatest problem one cow in three suffered lameness.
McPherson says MBV is a “New Zealand first, at this stage restricted to bulls in the 2000 Sire Proving Scheme, including some older proven bulls.
"Although the analysis was performed on a limited dataset and the estimated heritability was low (2.3%), some interesting differences still emerged in the Holstein-Friesian breed.
"A strain difference was clearly apparent, with animals of greater
Holstein strain ancestry tending to show higher levels of susceptibility
to lameness, while those with more traditional NZ bloodlines exhibited greater resistance.”
McPherson says the new breeding value was just one of a number of tools farmers who had a high rate of lameness in their herds should utilise.
The list of bulls the MBV applies to will grow along with the data set on incidences of lameness.
