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Keeping Count – Recalibration of EID Readers Necessary

Yearly re-calibration of hand-held readers and scanners is just one measure taken as a result of an Advance Party project aimed at improving deer counting accuracy at Landcorp’s Stuart Farm, near Te Anau. Manager Mark Bolger says a reliable count of the number of deer on hand is a bottom line requirement.

“We have to get stock reconciliation right because it has a big bearing on our feed budgets, reproductive and financial performance.”

But getting an accurate tally was proving to be easier said than done. In theory the scanning of EID deer tags should make the counting process straightforward and fail-proof. But Mark started questioning the accuracy of the electronic technology for counting, suspecting that mob sizes were being under-recorded in some situations.  In 2015 he embarked on a project as part of being in the deer industry Southland Advance Party to compare the accuracy of EID with manual counting. His objectives were to find out the most reliable counting method and secondly the reasons for any EID-related counting discrepancies.

Over the year a number of different manual and EID-based counting strategies were tried and compared when deer were brought into the sheds. During 2016 pregnancy scanning counts were taken five different ways; two electronically and three manually. This included two people counting pen by pen within the shed, and another counting as they exited the shed in a single file plus electronic recording as the deer moved over the scales. The comparison exercises showed a 2% discrepancy between the electronic and manual count systems. Mark says two people manually counting the deer immediately prior to leaving the deer shed proved to be the most accurate method, giving a consistent result that could be rechecked with the two counts taken within  the deer shed. The findings surprised Mark.

“I was surprised at the variance and that the EID way was less reliable. I thought it would have been the other way around.”

Further investigation of the causes for the less than accurate performance of electronic counting revealed that lost and unread tags were contributors. Sixty of the 4,800 hinds at scanning had lost tags.

“Some tags were damaged and didn’t read, and some others possibly weren’t read because of the animal’s head positioning when scanned.”

Another discovery was that the reading distance of the two hand-held wands and two panel readers reduced as the season progressed, making recalibration necessary.

Mark admits this was painstaking and time consuming, but reckons it was a worthwhile project that has assured him of reliable reproduction figures and conservatively uncovered another $50,000-plus of breeding hinds.

“The 2% discrepancy doesn’t sound a lot but for us it’s another 96 breeding hinds which at $500-600 each adds up.”


At a glance:

Stuart Farm, Landcorp

Effective area                                     2,721ha

Stock on hand (July 2016)

Deer (60% Red, 40% Red/wapiti)

R1yr hinds                                          1,760

R2yr Hinds                                         620

MA Hinds                                           3,550

R1yr Stags                                          1,764

Breeding stags                                  360

Weaning weight (ave)                       65.7kg

Weaning date  2015                           17 April

Mated MA ewes and hoggets                      6,550

R1 & R2 steers/heifers                      767

In-calf MA cows and heifers             411