Robust Romneys

News from RomneyNZ and Lincoln Universtiy

Robust Romneys

In two years of the Merial RomneyNZ Saleable Meat Yield Trial, Romney sheep have demonstrated a combination of high lamb production and low losses.

“It’s not surprising that there seems to be resurgence in demand for Romney genetics” said Mr John Bates, CEO of RomneyNZ.

With this years lambing figures in from the Trial, from the 638 ewes that lambed, 1149 lambs were born of which 121 died at and around birth. That’s a survival percentage of 161% from a total drop of 180%.

“These were mixed age commercial ewes running in Oxford in North Canterbury, with a relatively mild lambing period, although there were two days of snow mid-lambing” said Mr Bates.

The flock was intensively lambed by Amy Horrell and Anna Smyth, postgraduate students at Lincoln University on the property of Hugh and Diane Taylor. Hugh is currently Vice-Chairman of RomneyNZ. All lambs were weighed and identified to ewe and ram at birth, mothering ability was recorded and all dead lambs were autopsied based on nationally-accepted protocols to ascertain a cause of death.

Average lamb birth weight was 5.5 kg across all lambs born, but the level of dystocia (birthing difficulties) was less than 1% of total lambs born, confirming the results of the 2006 Trial.

Associate Professor, Jon Hickford, of Lincoln University, who is involved in analysing survival data from the trials, suggests this is because within the Romney breed the feto-maternal proportion, or size of the lamb relative to size of the ewe’s pelvis is appropriate and probably reflects many years of breeding Romney sheep for ease of lambing.

“This may explain some of the difference in dystocia rates between these trials and other trials involving multiple breeds” said Dr Hickford.

Three percent of lambs born died of starvation-exposure, with total lamb losses of 10.5%, somewhat below the national average.
“The 161% lamb survival would appear to be ideal for Romneys in this environment” said Mr Bates.

“We saw high death rates in triplets with 23.8% of them dying and of the two ewes that had quads, six of the lambs died. Having multiple births greater than twinning doesn’t seem to offer any advantage based on the results of this trial. Seventy percent of ewes had twins, with 15% having singles and 13% having triplets.

Surprisingly, each twin-bearing ewe had an average 10.4 kg of live lamb at the end of lambing versus 9.6 kg of live lamb from triplet bearing ewes. What is more, given that the average birth weight of triplet lambs was lower, we would expect this to also affect subsequent growth rate,” said Mr Bates.

The trial is continuing and survival to weaning will be assessed along with growth rate calculations and a variety of other measurements. Ultimately, the ram lambs will be slaughtered and ViaScan used to assess carcass traits and saleable meat yield. Meat quality traits will also be assessed this year on the ram lambs and wool traits will be assessed on the ewes in future, given the renewed enthusiasm from Romney farmers for their wool.

DNA from the lambs born in the Merial RomneyNZ Saleable Meat Yield Trial will be analysed at Lincoln University to ascertain whether there are gene-markers for carcass and wool traits. Last year’s results are indicating a potential for the myostatin gene to be used to select high meat yielding carcasses in Romneys and this year’s result will be used to further validate this finding.

The trial continues next year at Hugh Taylor’s and is being replicated at John Jackson’s property near Pahiatua. Leading Romney sires from across New Zealand are mated to the ewes used in the trials.

ENDS

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