The Alliance Group will continue its research project on the economic and animal welfare impacts of docking lambs' tails, despite inconclusive results from the first year.
It is the usual practice on New Zealand farms to remove lambs' tails, to prevent the build up of dags and increasing the risk of fly-strike.
Alliance began the three-year project because little objective research had been done on the pros and cons of docking. It includes a farmer survey and field trials assessing four tail lengths.
Alliance livestock manager Murray Behrent said preliminary results showed varying the tail lengths made little difference.
"The objective was to see if the long tails had a detrimental effect on growth rates and quality of the animals and also ... dags.
"The first year up was inconclusive and showed us that tailing or not tailing, the effect on the growth rates and the yields of the lambs were not too dissimilar."
Any link between tail length, dags and fly strike also remained unclear, largely due to last year's drought.
Results for the next two years would give a clearer idea of the effect of docking on dags, Mr Behrent said.