On a purely economic basis, electronic identification tags in sheep and cattle can cost more than they return, research has shown.
AbacusBio consultant Simon Glennie assessed the costs and returns of electronic identification (EID) in various classes of stock and the management gains that resulted.
He found there were gains when used with trading cattle but costs when used in ewes and breeding cows.
The trial at Traquair Station near Outram took no account of the wider issue of securing market access through animal tracking being promoted through the National Animal Identification and Traceability (Nait) project.
Tagging 3000 ewes cost $1.90 a stock unit.
Using information from the tags to cull poor-performing ewes was calculated at $1.83 a stock unit.
Mr Glennie said at a field day last week the tags provided more accurate information on ewes which easily lost weight or condition or repeatedly only reared single lambs.
Cheaper tags could be used but there were concerns about their efficiency.
The trial tagged 200 cows at a cost of 85c a stock unit.
The return on the investment from the information gained was 59c, again by accurately gathering performance information.
Mr Glennie said he modelled the purchase of 1000 trading steers, bought in lots of 50 from 20 vendors.
Each was tagged and he calculated that by using the production information to identify the 10% of vendors who supplied the poorest-performing steers, he could increase income by $11.40 a steer.
The trial was also extended to Friesian bulls bought for finishing by Traquair.
The top 20% had an average weight of 583kg and were worth $1064, while the bottom 20% averaged 540kg and were worth $983.
But at the time of purchase, the bottom 20% were 30kg lighter than the top 20%.
One of the station owners, James Reid, said at the field day Traquair introduced EID tags to get greater information about the lamb finishing operation.
Some difficulties were encountered, such as having to modify the ear tag machine and changing the position in which the ear tag was placed.
The Reids planned to tag 800 calves at weaning.
Farmers voted down two remits on the Nait project at Meat and Wool New Zealand's recent annual meeting in Gore.
A remit calling for the producer board to stop spending money on the Nait concept was lost on a weighted vote by 3302 to 7301.
Another, calling for a farmer referendum was lost by 3346 to 7227, also on a weighted voting system.