Research shows skin thickness could be next trigger to help lamb survival
A study showing lambs with thicker skins have a better chance of survival could be worth millions of dollars for the New Zealand sheep industry.
The Massey University study done in conjunction with Manawatu romney breeder Ross Humphrey has also shown the skin thickness is hereditary.
"I just wanted to know if I could breed sheep with thicker skins so they would have a better chance of surviving when they were born," Humphrey said.
In 2009 he took the idea to Professor Hugh Blair at Massey University, who had been working alongside the Trigg Romneys group Humphrey is part of.
A literature review showed the subject had not been tackled elsewhere in the world and for the past eight years Humphrey has been working with an animal breeding and genetics team at the university – recording, measuring, testing and finally proving.
"This is worth millions of dollars to New Zealand in increased lamb survivability and it is important for our reputation for animal welfare."
"It is early days but lamb deaths is an industry issue… social licence to operate is so important. It's not just sheep either – we're going through the bobby calf thing, de-budding, docking – they're all things we need to have on our watch list now and researchers have to be looking at them all. But if we can help in this direction it will be fantastic. The urban sector is becoming more removed from farming animals and it's nice to get a positive story out there."
The Massey team included Iranian PhD student Masoud Soltanighombavani, his supervisor Rao Dukkipati and Professor Blair.
The first step was to figure out how to measure the skins. They finally validating a medical scanner used by Chris Spark from scanning firm Ward and Rosa. The skins of 7000 eight-month-old lambs were measured over eight years, which showed a range of 1mm-3mm.
"I remember Hugh saying "wow" when we found that massive variation. No-one really had any idea. If the range had been one to 1.5mm then it would have been hard to make genetic gain but there was a big difference."
The next test was whether or not the extra thickness could make a difference with survival. The animals were split into two groups with thin skins (average of 2.1mm) and thick skins (3.2mm) and put in a chamber that simulated wind and rain on a farm. Skin surface temperature was measured with an infrared camera temperature and kept within a normal range while heat production was measured with a calorie counter.
"Those lambs with the thinner skin lost more heat and had to product more heat to compensate," Soltanighombavani said.
The next question was whether a ewe and ram with thick skins would breed a lamb with a thick skin.
Testing estimated skin thickness hereditability at 0.26 – a moderate hereditability trait (similar to other traits such as weaning weight at 0.32 and number of lambs born at 0.30). The genetic correlation between skin thickness and lamb survival is 0.27 while lamb survivability as a heritable trait is 0.05.
"Sheep are being pushed into harder and harder country. Now we know we can make genetic gain and breed thicker-skinned sheep and they will survive greater," Humphrey said.
Dukkipati says there is a focus on increased lambing rates.
"The more triplets that are born, the more likely their skin will be thinner, so a thicker skin would be a huge benefit."
The lambs were measured at eight months when moved to Humphrey's Kiwitea farm because of the logistics of measuring them on Taihape hill country - Ross and Wendy Humphries' Brookfield Romney flock is run in partnership with Mike and Vicki Cottrell at Omatane, Taihape. Massey also tested and confirmed skin thickness didn't change between birth and eight months.
With seven years of data and six years of taking the skin thickness into consideration within his breeding programme, Humphrey is gradually increasing the average skin thickness. The thickest measured this year was 4.7mm.
Humphrey said the impact of the research was huge for animal welfare and the basic economics of sheep farming.
"Give us a few years and here we are charging down the path of breeding thicker and thicker skins, if we can have a 5 per cent greater survivability across New Zealand that's millions of lambs. People are wanting farmers to be doing this sort of thing. No-one likes dead lambs. It is colossal for animal welfare. Every part of this story is good news. We're lucky to have Massey involved and we're lucky every result along the way has been positive."
Blair said he was stoked with the outcome but wouldn't have predicted it.
"If you'd asked me what I would have expected from Masoud's experiments I would not have picked it was so obvious. I actually looked at him across the table and said "Are you sure that's right?" But it does fit. If you have thicker skin, you lose less heat and have to generate less heat. What we don't know is the next step – do they grow more or do they eat less?
"This is not over. This is the first step in hopefully a significant direction. We're certainly hoping this preliminary information might kick on to something else."
Blair said they're now looking for a way to give farmers a tool to improve lamb survival.
"Having a guy turn up and run an ultrasound over all their lambs is not that tool. That's a research tool we've used to take the first steps. Somewhere down the pathway, if this all continues to go right, we'll need find that usable tool. We're a couple of steps away from that."
He says the study has only tested a small number of lambs in the cold compared with the thousands of lambs on Ross Humphrey's farm and in the wider Trigg Romneys group.
"When we're getting down to what this thicker skin actually means, we have to be there watching them and manipulating them so we see what changes in their physiology or in their metabolism… seeing if we can identify something a farmer can measure quickly, easily and cheaply. If you have to carry an ultrasound machine around with you, it's just not going to work," he said.
"We haven't got to the end yet but there's no doubt, we're off to a brilliant start."