More than 20 people attended a Beef + Lamb New Zealand "growing great lambs" workshop at Wedderburn last week.
Workshop facilitator Steve Nichol, of Clarks Junction, said research shows the average daily lamb growth rate between birth and weaning was between 250g to 280g in New Zealand.
"The potential growth is another thing."
He asked people at the workshop if they body-condition scored their ewes.
From the response, he estimated fewer than half of the farmers at the workshop used the management tool.
The body condition of a ewe influences every part of its production, including the number of lambs conceived, born alive and survival rates.
"The condition of ewes is integral to driving productivity on our farms," he said.
A ewe’s condition prior to tupping was a massive contributor to the potential of its lambs.
Nutrition was a key driver to a lamb realising its genetic potential, he said.
"Ewe milk is important for setting up that lamb."
If a ewe was fed well during its second and third trimester, it produced a heavier lamb with stronger, better quality wool and more intramuscular fat, which improved taste.
A fatter ewe had more protein in its milk and produced lambs with more energy in their fat reserves, making it better prepared to withstand adverse weather and to have a better lifetime performance.
Thin ewes had more dags, a higher faecal egg count and more tooth and foot defects, Mr Nichol said.
As ewe body condition scores rose, the death rates of ewes and lambs fell.
A study showed a thin ewe flock could result in the death of 30% of its lambs.
A ewe with a body condition score of more than three needed to be maintained to realise its potential.
"If a ewe’s weight is going up and down, it will have a higher energy expenditure than maintaining her at three all year round because it costs more to get a ewe back up ... Maintaining the weight is key and the best use of feed, leaving more of it for growth and that’s where you make your money."
He urged farmers to score ewes in two flocks, three and above, and below three.
"You might end up with 50% of your ewes in your bottom line, which can be a bit confronting and some system changes will be needed."
Farmers should use their hand-to-body condition score, rather than their eye, to get a more accurate result, he said.
"It is important to put your hand on each one."
A feed budget could then be created by having a better understanding of the demands of your ewes.
"That is often underestimated because people don’t tend to weigh their mature animals and they don’t know what they need for maintenance."
