March 11 2010

Mid Canterbury sheep farmer Mark Greenslade has become a part-time crime scene investigator in an effort to cut down on lamb losses.

Reproductive wastage – the loss of lambs between scanning and tailing – is a fact of life on New Zealand sheep farms, and not all losses can be prevented. But there are some things that can be done to minimise losses and the first step is understanding what's causing them.

Mark Greenslade and five other farmers have been taking part in a trial to help understand what stops young lambs making it as far as tailing. The trial was supported by the Sustainable Farming Fund and facilitated by veterinarian Chris MacFarlane, who showed the participants how to take random samples of dead lambs and carry out autopsies to help identify causes of death.

Mark, his parents and wife Penny run 1700 mixed age breeding ewes and 400 hoggets at Montalto, along with a mix of deer, bull beef and grazers.

Over the past five years they've averaged 165% at tailing – not a bad result, but there's always room for improvement.

Marks says scans taken at 50 days' gestation and then at 80 days during the trial, which started in 2006, identified the twin and triplet bearers and showed that there was little reproductive loss by that stage. On his own property the total loss between scanning and tailing was a relatively light 11%, a very good result considering it was the year of the big snow that saw much of Mid Canterbury freeze for weeks.

Other farms in the discussion group had bigger losses – up to 25% – from a wide variety of causes such as listeria from bad hay.

On Mark's farm, dystocia was identified as the biggest cause of lamb losses. Singles and twins were affected about the same, but triplets were more likely to succumb.

He says the trial was interesting and gave him a greater understanding of what kills lambs before tailing, but for him the focus is on protecting ewes as well as their lambs. Last year he had ewe losses of around 5–6%, and with them their unborn lambs.

"Every year you'll lose lambs. My biggest concern is making sure there's enough pasture cover to support the ewes and lambs on the ground, and enough to stop the ewes wandering off and leaving their lambs while they're searching for feed."

One source of lamb losses that Mark hasn't had to worry about for a number of years is the twin scourges of toxoplasmosis and campylobacteriosis. All hoggets and two-tooths on the property are routinely vaccinated with ToxoVax® and CampyVax®4.

"I just can't remember abortion losses being a problem since we started vaccinating," Mark says.

By managing the risk of losses from these diseases he has been able to focus on other issues such as condition score, feet, conformation, nutrition and shelter – all factors that can help improve on an already good result.