Ewe nutrition

Ewe nutrition is important to ensure the best reproductive performance in a flock. Optimum nutrition will provide the best conditions for ewes to conceive when joining the flock.

Energy requirements of sheep

The energy requirements of sheep will vary with:

• the feed quality they are eating
• the amount of walking they are doing to find the feed
• their current status of nutrition
• for ewes, whether they are dry, pregnant or lactating. 

Regular condition scoring of the flock is important to determine if the feeding rates are adequate for their needs.

For a medium-framed, Merino of 50kg mature weight in good condition with no fleece, the average feed requirements are presented below. Note that sheep that do not produce wool have a 2–3% lower requirement to maintain the same weight.

Nutritional requirements for a 50kg sheep

Assessing pasture availability

It is important to assess pasture availability to determine if nutritional requirements of lactating ewes can be met.  If you are not able to assess pasture on a kilograms of dry matter basis (kg DM/ha), use pasture height as a guide. 

These pasture benchmarks are for the start of lambing. To maintain adequate livestock performance the stocking rate (ewes/ha) needs to be set so that pasture growth is able to keep pace with livestock consumption.

Feed Quality for Ewes (Kg Dry Matter/Ha)

Note: NS – Not Sustainable, ewes will lose weight.

Source: PROGRAZE

Ewe nutrition and varying pasture digestibility

Dry standing feed is a valuable resource, however additional feed may be required depending on the pasture digestibility.

It takes around 240g of barley per ewe per day to maintain liveweight when grazing dry standing pasture at 50% digestibility (assuming 1500 kg of DM/ha is present). Without the dry pasture the feeding rate would need to be increased to around 560 g per day! If you are unsure about the quality of your dry feed it is recommended that you send a pasture sample away for feed quality testing.

If pasture benchmarks are not met, it may be necessary to supplement ewes during lambing. Providing adequate nutrition during the first 4 weeks of lactation is important to drive milk production. This is particularly important for twin bearing ewes and ewes that lamb down in relatively light condition (Fat Score 2.5 or less) as they have less fat reserves to draw upon.

The amount of supplement required will be a function of pasture conditions, ewe condition, stocking rate, number of lambs at foot and level of production that you are targeting. Cereal grains that are high in energy are likely to deliver the best ‘bang for buck’, but protein also becomes important where pasture is very short.

Grain supplementary feed in kg

Self feeders

Feeding ewes via a self feeder is generally preferred over trail feeding as there is less disturbance of the mob, thereby reducing the risk of mismothering. However, if you are using a self feeder it is critical that the number of feeders is matched to the size of the mob. The general rule of thumb is no more than 200 ewes per self feeder. By reducing the number of ewes per feeder you reduce the risk of shy feeders and smothering issues at the feeder. Some recent research is indicating that reducing mob size can also have a positive impact on lamb survival, especially for twinning mobs.

If you don’t have enough self feeders for all your ewes, allocate them on a priority basis. For example, if you’ve scanned, use the self feeders for your twining mobs and trail feed the singles. If you haven’t scanned, you might allocate self feeders to maiden ewes or those ewes in poorer condition.

If you are trail feeding, daily feeding in the early afternoon (where possible) is the preferred approach to reduce the risk of mismothering.

Ewe nutrition pre lambing

Ewe nutrition is crucial in meat and wool production systems. Producers should pay particular attention to ewe feed requirements such as protein and energy in the lead-up to joining.  

Nutrition of the ewe can be measured in many different ways, but one of the most effective methods is measuring body condition score (BCS). This is due to the fact that condition scoring is a quick and reliable tool for managing ewes to meet production targets, is independent of frame size and enables timely decisions to optimise reproduction rates. 

• For ewes to be joined, BCS should be at approximately condition score 3.0 to 3.5.
• Maiden ewes need to be at least 75-80% of their mature weight at joining.

For example, a maiden ewe with a mature weight of 45kg needs to be joined at a weight of approximately 34-36kg and at BCS 3-3.5.

The requirements for protein and energy increase 2.5 – 3 fold during late pregnancy and early lactation, and ewes often cannot eat enough pasture to meet these needs. As a result of this, ewes will start to mobilise fat and muscle and this highlights the importance of having ewes in the optimum body condition score at joining.

Studies conducted by Lifetime Wool have shown that an increase of around 20% extra lambs have been reared for each rise in condition score at joining.  

The relationship between ewe condition score at joining and proportion of dry, single, and twin ewes is shown in the graph below.

• Joining ewes below BCS 1.5 is deemed to be unproductive as it is unlikely this animal will conceive.
• Ewes with a BCS of 4-5 are deemed too fat, and are likely to have problems at both conception and at lambing.  

One of the best methods to ensure that a higher proportion of ewes conceive is to monitor the condition score of the ewe from weaning.  During this post-weaning/pre-joining period draft off the ewes in a lower condition (below BCS 2) and allocate these animals the best feed.

Early weaning is effective as feeding a dry ewe and a weaned lamb requires less energy than feeding an ewe and lamb unit.  Producers should consider their options before early weaning lambs and can chat with their ag advisor for more information.

Lambing ewes

Winter lambing flocks are under a lot more pressure during winter as feed requirements increase dramatically leading up to lambing, especially in twin-bearing ewes. Providing the right nutrition can substantially increase ewe and lamb survival rates.

With winter lambing ewes we recommend keeping feeding rates up once the autumn break occurs to help pastures get ahead of the stock. You are better off feeding ewes in late pregnancy as once lambing starts the risk of miss-mothering increases, especially if you are trail feeding.

Ewes carrying multiple lambs have higher energy requirements and are more susceptible to pregnancy toxaemia. Managing multiple-bearing ewes separately reduces the risk of losses. Producers should also be on the lookout for hypocalcaemia, also known as ‘milk fever’, or low blood calcium, in ewes in late pregnancy and early lactation.  

Providing a loose lick containing lime can supply essential dietary calcium while ewes in the early stages of sickness can be treated with an injection of calcium solution. Pre-lambing is also a good time to administer an annual clostridial vaccination such as a ‘5-in-1’ treatment that provides immunity to both the ewe and lambs.

A pre-lambing drench is usually warranted, and carrying out a worm egg count will help confirm if drenching is required. As heavily pregnant ewes are more susceptible to internal parasites, lambing paddocks with a low level of larval contamination should be selected for lambing. Producers that find abortions, stillbirths, lamb mortality, ewe mortality, or lameness in their ewe flock are encouraged to contact their LLS vet.

Weight gain in sheep

Following improved seasonal conditions, producers should be checking ewe conditions to see whether they need to limit weight gain.

Favourable weather can see stock putting on valuable condition. While a favourable autumn is a good result, it does present challenges to livestock producers.

It is important sheep producers are constantly checking ewe condition. Ewes grazing highly digestible green pasture could be putting on 0.8 – 1.0kg a week. If ewes are already in good condition (e.g. 3 score), there is a risk that they could be a 4 score in 6 to 8 weeks if action is not taken. You really want to avoid Merino ewes exceeding Fat Score 3.5 at lambing (Fat Score 4.0 for cross-bred ewes).

Early action is key, and the only option is to limit weight gain by managing pasture height.

To maintain ewe condition, this involves grazing those high-quality pastures down and limiting ewes to around 500 – 600kg Dry Matter/ha (1.5 - 2cm high).  For slight weight gain, these targets might be increased to 800 – 900kg (2.5 – 3.0cm). Therefore, your pasture target will depend on fat score. The higher the fat score, the more important it is to act early and to a greater extent

Whatever nutritional ‘hand brake’ you chose to apply, at some point it needs to be released. For twin-bearing ewes the pressure needs to be eased 4 weeks prior to lambing. At this point the minimum pasture target increases to around 800 – 900kg/ha. For single ewes, the pressure could be maintained until 10 days out from lambing.