Cow 'currency' getting an update

Production worth (PW) is an economic index calculated for all New Zealand dairy cows as an estimate of their lifetime production ability. It helps farmers identify the top performers in their herd, to decide which cows to keep or cull, and to help figure a value for buying or selling.

Four traits figure in the PW calculation: milk volume, milk fat, protein and liveweight. A fifth trait will be added in February -- somatic cell. 

Somatic cells are produced by a cow’s immune system to fight an inflammation in the mammary gland (mastitis). Some cows are more prone to it than others and it can curb their ability to produce milk, even when the infection is cured. 

The update will make PW more relevant for today’s farmers, says Malcolm Ellis, dairy farmer and LIC’s general manager NZ markets. 

“Somatic cell can hit a cow’s health, production and reproduction. On our farm PW is a tool to lead culling decisions, to identify and retain the most valuable cows in the herd; but like many other farms we also review somatic cell data to help inform those decisions. 

“We want to make that secondary consideration seamless, with all that information in PW.” 

It will be the first update of PW since it was introduced in 1996 by the forerunner to LIC.  Somatic cell was added into BW in 2005.