They get calls from well-meaning passers-by saying a gate must have come open because their merino ewes and lambs are on the lucerne paddocks.
But grazing lucerne has been a conscious decision for the couple, who have changed their approach to farming at Bog Roy Station, a 2800ha property on the shores of Lake Benmore.
Speaking at Beef and Lamb New Zealand's Innovation at Invermay field day, Mr Anderson said the ''old system wasn't working too good'' and the couple felt lucerne could be the catalyst to make a change.
Earlier this year, the couple won the Massey University discovery award in the Canterbury Ballance farm environment awards.
The judges commented there had been a ''quantum shift'' from a business under pressure to a sustainable state, an innovative strategy to become profitable and noted they had seized the initiative in using experts for top quality advice while at times being ahead of the latest developments.
The couple have become involved with lucerne specialists like Prof Derrick Moot, and Marlborough farmers Doug and Fraser Avery, who recently featured on Country Calendar.
They now have about 155ha in lucerne or lucerne mix and are considering adding another 250ha.
They were now running just over 3900 ewes and about 140 cows and, with the additional lucerne, he expected they would increase the ewe flock to about 4000 and run a ''couple of hundred cattle'', while increasing weaning weights and lambing percentage.
Another benefit had been a lighter stocking rate on their hill country, where they had now built a feedbank.
For those contemplating lucerne, the first question they needed to ask was if they needed lucerne at all, AgResearch senior scientist Dr David Stevens said.
If you had very little water and wanted to maximise use of it, then planting lucerne was a ''no brainer''.
At Landcorp-owned Freestone, in the Te Anau basin, farm manager Chris Johns had become concerned about the ''quite high wastage'' from the number of lambs scanned to the number weaned. Lamb survival was an issue, he told the field day.
They ''definitely'' needed to change, so they sought advice and tools, did more planning, used incremental feed increases for ewes and took regular measurements.
Genetics equalled potential while management equalled realising the potential, he said.
Their scanning percentage has increased, there has been a marked increase in twin and triplet lamb survival and the number of twin and triplet ewes weaning a lamb or lambs was up.
Weaning weights had also increased.