Last updated 08:14 17/09/2013
A lamb that has been left undocked will not grow any faster than a lamb that has been docked.
While many farmers might argue otherwise, preliminary findings into a tail docking trial by the Alliance Group has found that leaving a lamb's tail intact has no beneficial or detrimental effect on its growth rate.
Alliance Group livestock manager Murray Behrent said he was surprised by the results.
"I really thought undocked lambs would have faster growth rates because there would be no check [at tailing time]," he said.
Alliance has just completed the first year of a three-year study into the effects of tail docking on lamb growth and the welfare effects of the practice.
Lambs were usually docked three to four weeks after birth with the aim of reducing dag formation and the risk of fly strike.
The research looked at four different tail lengths: flush (1cm); short (3 to 4cm) commonly used in New Zealand; long (7 to 10cm) commonly used in the United Kingdom; and intact.
Leaving a tail long or intact suggested it would have a positive effect on total meat yield, but the results were inconclusive across breed and sex of the lamb, Mr Behrent said.
Riverton farmer Euan Templeton, who was involved in the study along with farmers in Canterbury and Manawatu, said he was also surprised by the results.
"I've been leaving some of my lambs tails intact for a number of years and I've been confident I've been doing the right thing," he said.
The study on Mr Templeton's farm involved docking 300 sets of twins.
One twin's tail was docked short at 3 to 4cm while the tail of the other twin was either left long (7 to 10 cm) or intact, but there was no difference in lamb growth at weaning.
"I thought there was a week to 10 days' check at tailing, but this trial proved that those lambs always catch up," he said.
Last season Mr Templeton docked only his replacement ewe lambs and left his ram lambs and terminal sire ewe lambs with their tails intact.
However, he still managed to get 40 per cent of his lambs, all long tailers, away before Christmas.
Mr Templeton said he was unlikely to change his management practice because his Texel-cross lambs produced few dags.
"I like crutching them with a long tail.
"It gives me something to hang on to," he said.
Mr Behrent said there was a lack of scientific information on the productive, economic and welfare aspects of docking lamb tails.
"This situation leaves New Zealand farmers vulnerable to any concerns from international markets in regards to the actual length of tails docked," he said.
Mr Behrent said the study was important to support the image of New Zealand product in key markets.
Evaluation of the economic benefit and/or cost to the farmer of leaving the tail longer, or intact, will be part of the remaining two years of the study.
"Once complete, the research should provide suppliers with reliable information in assessing the impact of their tail docking practices."
As part of the research, a best practice booklet on tail docking will be developed and distributed to Alliance suppliers in 2015.
The tail docking study was supported by the Ministry for Primary Industries' Sustainable Farming Fund, UK supermarket Sainsbury's and Beef + Lamb New Zealand. Fairfax NZ
- The Southland Times