Select a lambing time likely to maximise survival of new-born lambs. Birth weight is the most important determinant of lamb survival. Manage ewe density and mob size for best lambing results. Early selection and pasture preparation in lambing paddocks ensures that lambs reach target weaning weights.

Introduction

Important principles to increase lamb survival are:

• Select a lambing time that is likely to maximise survival of new-born lambs.
• Manage ewes to produce lambs with optimum birth weights. There is a close relationship between ewe condition at lambing and lamb birth weight.
• Cold, wet and windy weather increases lamb mortality, particularly with lambs that have a low birth weight. Manage ewes to minimise the impact of weather at lambing.
• Early selection of lambing paddocks on the basis of size, availability of shelter, and pasture quality and quantity available for ewes are critical management decisions affecting the ability to wean more lambs.
• The effects of prolonged birth and the combination of hunger and mismothering account for the majority of lamb deaths.
• If ewe nutrition is poor, there is delayed production of colostrum and new-born lambs are at risk if they do not receive a drink soon after birth. In addition, mothering ability and lamb behaviour are depressed when ewe nutrition is poor.
• The longer a ewe stays at the birth site, the greater the chance of the ewe and lamb bond forming.
• Depending on the individual ewe and the breed type, it takes up to six hours for a ewe to recognise her lamb and in this time a ewe may accept any lamb as her own. It also takes lambs twice as long to recognise their mothers and if a lamb is abandoned within six hours of birth it has little chance of survival. Merino ewes do not recognise twins very well.
• Ewes about to give birth may ‘pirate’ recently born lambs only to abandon them when their own lamb is born.
• When the number of ewes lambing is at its peak, the lambing paddock is a busy and cluttered place. Best practice is to minimise any disturbance in the lambing flock.
• Predators can account for between 5–10% of losses in some situations. But predators are usually of secondary importance compared with hunger, mismothering and hypothermia.
• When predators are known to cause lamb loss, start baiting well before lambing and continue until well into lambing.

Key decisions, critical actions and benchmarks

Lamb survival rate targets

Lambing management needs to aim for lamb survival better than:

As ewe condition score at lambing increases, so does lamb survival, especially in twin bearing ewes. In the period from three days after birth to before weaning, aim to keep lamb death rates at less than 3%.

Selection of lambing paddocks

Several key features need to be considered when selecting lambing paddocks.

Pasture availability targets
The following pasture targets provide a guide to best practice:

• Where ewes are scanned and drafted into single and twin bearing, allocate ewes to lambing paddocks that have the best pasture/best shelter to least pasture/most exposed on the following basis:

• As a guide, aim for:

   

  - FOO of at least 1,200 kg green DM/ha in lambing paddocks, and preferably more with twin lambing groups.
  
  - On annual clover-based pastures, FOO of 1,500-1,800 kg green DM/ha is recommended at commencement of lambing.
  
  - Prioritise the available pasture resources to ensure paddocks have adequate quantity for ewes at lambing.

• If pasture is likely to be limited during lambing, save pasture in early pregnancy or consider adopting strategies to increase pasture production.
• If pasture availability targets cannot be met on a regular basis use tool 10.2 to review your current lambing time.

Lambing paddock shelter

The factors contributing to the risk of hypothermia in lambs include combinations of temperature, rainfall and wind speed. Of these, only wind speed can be controlled by using naturally sheltered lambing paddocks. As a guide, sheltered paddocks can reduce lamb mortality rates by about 10%.

Ideally, lambing paddocks that are sheltered from the prevailing winds and provide shelter over the entire paddock are best for lambing. Satisfactory shelter can be provided by trees, shrubs and tussocks. It is important that shelter belts are designed properly otherwise they may act as wind tunnels when grazing livestock remove the foliage from the lower branches (see procedure 5.3 in Protect Your Farm’s Natural Assets).

When selecting lambing paddocks, consider the sheep grazing behaviour and paddock characteristics and avoid those where ewes are likely to lamb in exposed areas. Preferred paddocks are north and east facing, have good sunlight in the morning, are well drained and provide good access to water.

Paddocks with low worm risk

In high rainfall regions, gastrointestinal parasites are a major cause of production loss in ewes and poor growth in lambs. Ideally, graze ewes on paddocks with low worm contamination during lambing. Worm management is discussed in procedure 11.2 in Healthy and Contented Sheep.

Paddock and mob size

The most important consideration is to stock lambing paddocks to match pasture availability with breeding ewe demand (see tool 7.6 in Grow More Pasture for a range of pasture assessment tools). As a general guide, keep stock densities under
18 ewes/ha in twin lambing paddocks. A smaller mob size will also improve lamb survival, most probably due to lower incidence of mismothering.

These are only guides and many other factors must be considered, including the cost of subdivision and management issues with extra mobs.

Table 10.2 Suggested mob sizes

Predator control

The main predators of new-born lambs are foxes and in some regions, pigs. In some circumstances predators can kill more than 10% of lambs.

If foxes are a problem, baiting, using products such as Foxoff® in conjunction with Feralmone™ (see signposts) in the three months before lambing and during lambing, is recommended (see tool 5.11 in Protect Your Farm’s Natural Assets). Pig predation is best managed by selecting lambing paddocks where pigs can be controlled.

Investigating neonatal lamb deaths

Investigate excessive new-born lamb losses and discuss with your animal health or livestock adviser. Tool 10.8 contains a check list to diagnose common causes of lamb losses so you can improve management to reduce deaths in future years.

Supervision during lambing

Best practice is to minimise the disturbance of the lambing flock. If supervision is warranted, the best time to enter the maternity paddock is in the afternoon. Develop a routine so ewes will become accustomed to human presence and will not leave their lambs.

Stock husbandry

After lambing there are two major risk periods for lamb losses.

Lamb marking and mulesing

Losses associated with marking are normally less than 1%. Time marking and mulesing for about two weeks after the last possible lambing date. Hygiene is most important for equipment.

Conduct mulesing in accordance with industry guidelines using an accredited operator (see signposts). If mulesing is conducted when flystrike is possible, treat lambs with a product to prevent flystrike on healing wounds.

Carry out marking and mulesing in clean yards close to the paddock being grazed and ensure the operation is completed early in the day so ewes and lambs can successfully mother up.

For guidelines on additional health treatments, refer to procedure 11.5 in Healthy and Contented Sheep.

Nutritional management of lambs until weaning

To achieve target weaning weights ewes and lambs need to graze high-quality pasture. Pasture quality (especially legume content) and quantity are the best indicators of potential lamb growth rates.

If pasture availability falls below the critical limit of 1,000 kg green DM/ha after the start of lambing, supplementary feeding may be necessary. Mismothering losses due to feeding are likely to be lower if paddocks and mob sizes are smaller.

When available feed resources are low, consider identifying ewes that have lost their lambs or failed to lamb, at marking and remove them to save pasture for lactating ewes. Dry ewes can be managed separately or sold.

Imprint feeding lambs before weaning

Train lambs to feed supplements by ‘imprint’ feeding before weaning. Feed lambs at least 4-5 times while with their mothers using the supplement most commonly used on the farm at a low rate. The idea is to introduce the lambs to feed so they can recognise the supplement after they are weaned.

This is an important management strategy that reduces the period taken to train sheep to eat a supplement once they are weaned.

Signposts

Read Planning for Profit – A practical guide to assist woolgrowers recover from drought. Order your free copy from AWI by: Calling: 1800 070 099 Downloading the document from: www.wool.com.au/Publications/Managing_drought/page__7134.aspx National Mulesing Accreditation Manual – details the preparation and planning, mulesing equipment, chemical and animal health product use and mulesing procedures that meet the welfare standards in the Code of Practice for the Welfare of Animals: the Sheep. To receive a copy of the manual from AWI, or to register for the National Mulesing Accreditation Program (NMAP), call 1800 221 076. Problems of mismothering and misidentification especially of multiple births – a summary of observations of maternal behaviour in a range of sheep breeds, including the causes, consequences and management options to minimise mismothering. G Alexander (1984). Wool Technology and Sheep Breeding: Vol 32: No. 3, Paper 7, pp. 121-124. Download this paper from: http://sheepjournal.une.edu.au/sheepjournal/vol32/iss3/paper7 View FeralMone™– a spray-based lure designed to increase visitation of wild dogs or foxes to bait or trap sites and to assist in bait uptake. Feralmone™ is available from rural merchandisers and agencies responsible for fox and wild dog control programmes (all state agencies except Department of Primary Industries Victoria). Livestock Library – a database of livestock research and extension information for all sectors of the livestock production industries and the general public. Visit: www.livestocklibrary.com.au Attend Lifetime Ewe Management – the workshop focuses on the health issues associated with the Merino ewe and develops sheep producers' skills in sheep assessment and feed budgeting. Contact the Rural Industries Skill Training (RIST) centre on: Telephone: (03) 5573 0943 Email: ristvic@rist.com.au Website: www.rist.com.au PROfarm is the training program developed by NSW DPI to meet the needs of farmers, primary industries, agribusiness and the community. NSW DPI PROfarm short courses are available by contacting: 1800 025 520 in northern NSW 1800 628 422 in southern NSW www.profarm.com.au The PROfarm course most relevant to this procedure is Wean More Lambs: a workshop for sheep producers who want to improve the reproduction rate of their flock. The MLA EDGEnetwork® program is coordinated nationally and has a range of courses for sheep producers. Contact can be made via: Phone: 1800 993 343 Email: edgenetwork@mla.com.au Website: www.mla.com.au/edgenetwork

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