04 September 2015

Lamb mortality – not lamb weaning – rates are the real indicator of a successful lambing, according to NSW DPI Livestock Research Officer Dr Gordon Refshauge, who said ewe management is a vital factor in delivering healthy lambs.

Gordon will show producers at the MLA-supported Mandurama Pasture Update on 15 September how performing a lamb autopsy can identify the most likely cause of death.

“You can’t manage what you don’t measure,” he said.

“Many producers assume lamb mortality is due to foxes or cold weather, but mostly that isn’t the case.”

Gordon said research showed brain injury was a leading contributor to lamb mortality, as it reduced the lamb’s drive to suckle, interfered with bonding and impacted its ability to keep warm.

Brain injuries in lambs can be minimised when pregnant ewes are managed better and selected to rear lambs.

“The best way to improve lamb survival in the short term is better ewe management, by ensuring they have adequate nutrition which provides for a good birth weight of lambs, and also excellent early vigour, good mothering behaviour and milk let-down. Over a longer term, improvements come from selecting for the ewe's rearing ability,” Gordon said.

While Gordon’s ‘tool kit’ includes judicious ram choice, shelter during lambing and predator control, he said the top three factors which can impact lamb survival are:

Nutrition: Adequate ewe nutrition translates to better foetal growth, survival and lactation. The risk of dystocia increases for both light and heavy lambs, so aim to lamb ewes in condition score 3 and avoid weight loss in the last 50 days before lambing. Twin lambing paddocks should offer about 1,500kg DM/ha of high quality (75% digestible) feed at the start of lambing and remain above 1,000kg DM/ha. Start at 1,000kg DM/ha for single bearing ewes for the lambing period. Feeding 400g/head/day of lupins for twin bearing ewes for two weeks before and two weeks after lambing improves colostrum, milk yield, lamb survival and weaning weight, even when ewes are in lush pastures. Assessing reproductive performance: Learn how to identify ewes that have successfully lambed and reared or have failed to lamb or rear. Give ewes in self-replacing flocks a second chance, but cull after their second failure to rear. A quarter of the ewes rear 8% of the lambs and are responsible for 60% of the losses so identify the dry ewes so you can find them in future. Pregnancy scanning: Scanning 40 days after rams are removed identifies ewes that need the most care and supports feed and stock flow budgeting. From around day 100 after joining (last 50 days before lambing), preferentially manage the ewes carrying twins giving them the best feed. At lambing allocate twin bearing ewes to shelter paddocks with good pasture (at least 1,500 kg DM/ha). Don’t lamb in mobs greater than 400 for singles and 200 for twins, and reduce this by 50 for maiden ewes. Don’t lamb at rates of more than 10 ewes/hectare. Use tools like MLA’s feed budget  or CSIRO’s Pastures from Space to plan ahead.

More information:

Mandurama Pasture Update
Date: Tuesday 15 September 2015
Time: 12pm - 5:30pm
Venue: 1576 Burnt Yards Rd, Mandurama NSW 2792
Cost: $20 - Includes lunch and afternoon snack
RSVP: Friday 11 September - essential for catering purposes to Phil Cranney (Central Tablelands LLS) (02) 6363 7888 E: phil.cranney@lls.nsw.gov.au