Ewes need to pull weight

Mating starts at weaning, and the target body condition score is 3.0 – and that’s the goal, not the average, Dwayne Cowin writes.

With the potential for another year of promising lamb-schedule pricing, most farmers will be eagerly anticipating the annual weaning event, in which the present season’s lamb crop is harvested.

By the time lambs have been drafted, weighed, drenched, dipped or shorn, most farmers are glad to see the back of the last sheep leave the yards. It is therefore easy to forget the tool that provided this lucrative crop – the ewe – and easy to ignore the next phase in the annual sheep production cycle – “mating starts at weaning”.

Most farmers these days would have heard, and had forced on them to varying degrees, that “ewes need to have an ideal body condition score (BCS) of 3.0 at mating”.

While there is a raft of scientific research and evidence to confirm the benefits of achieving this ideal BCS, such as increased conception rates and lamb survivability, the trap can be thinking that this is a target for an average condition score of our ewes. Using this as a target for an average leads us down a dangerous track – as with any data there are likely to be numbers (or in this case ewes) both above and below the average.

A typical range within an average is represented below in a typical bell-shaped curve, and can be applied to a typical ewe flock.

As the graph shows, even at an average of 3.0, 50% of the flock is below the ideal body condition score. While the eternal optimist may say that means 50% are above, the reality is there is still a large opportunity to shift a reasonable percentage of the flock towards or over the goal line of 3.0.

Onfarm this could be done in two ways:

1. Increase the feed intake of the ewe flock and therefore liveweight gains in the ewes – i.e. shift the whole curve to the right
2. Target different feeding regimes for different groups of ewes along the curve – i.e. narrow up the curve and remove the outliers.

For most farmers, weaning coincides with the busiest time of year – either just before or after Christmas – and most farmers take the easiest option of finishing weaning and sending all the ewes out the back in one mob for the summer. This allows only one level of feed intake over our entire ewe flock, and if ewe body condition score increases are targeted, the whole ewe flock needs to be fed at an increased level in order to achieve these targets.

This may be achievable at minimal cost if feed is readily available and there’s surplus, but with hotter, drier summers seemingly the norm, quality feed is now more valuable and scarce over summer. Therefore the outcome for most farmers with this option is only maintaining ewe body condition (and sometimes even only minimising the level of ewe condition loss).

Setting up for a targeted ewe feeding programme over summer can achieve significant benefits for a much smaller level of extra feed inputs, rather than having to lift the average BCS of the whole ewe flock.

Table 1 shows the likely number of ewes in each BCS range (based on a 2000-head ewe flock, the bell shaped curve, and the flock being an average of 3.0 at weaning) and what a specific targeted plan would be  for each ewe group leading up to mating.

As Table 1 shows, with a bit of front-end work at or straight after weaning to draft and body condition score the ewes, a targeted feeding programme can be set up for each group of ewes to achieve a different outcome. While the thought of multiple mobs may have some farmers reading this article no further, practically, onfarm four mobs can be run in the following groups:

1. The < 2.0 BCS ewes in with the finishing or ewe lambs being ad lib fed (which will also help with worm refugia, but these ewes need to be well weaned for two or three weeks before to prevent lambs mothering back up on the ewes)
2. The 2.0 to 3.0 BCS ewes in front of the 3.0–4.0 BCS ewes in a rotation
3. The > 4.0 BCS ewes on the lane/in one paddock and stay there until they are condition scored again.

Table 2 compares the total required feed inputs for a 2000-ewe flock under three scenarios:

1. Maintaining the whole flock at BCS 3.0
2. Increasing the whole flock to BCS 3.5
3. Implementing a targeted feeding regime for each group.

As Table 2 shows, increasing the whole flock average BCS from 3.0 to 3.5 requires a 25% lift in total feed inputs compared to maintaining a ewe flock at 3.0. It also still leaves 17% of the flock (350 out of 2000) below BCS 3.0 at mating.

Successful implementation of a targeted ewe feeding regime requires only an 11% increase in total feed inputs over maintaining a ewe flock, yet leaves only 5% of the flock below BCS 3.0 at mating (despite the average flock BCS being 3.3). If 100 “non-performing” light ewes are removed before mating, this reduces the extra feed inputs to only 5% above maintaining a flock, but with the significant benefit of shifting 950 ewes into the ideal category of BCS 3.0 –4.0.

This a substantial return potential for some extra work of condition scoring in a timely manner, and implementing a few changes with our summer ewe grazing management.

With the above results in mind, the following checklist is designed to help implement a targeted ewe summer management programme:

1. Start thinking about this as early as possible. The ewe programme is a constantly revolving cycle from lambing, weaning, mating, scanning.

At set stocking, set stock lighter ewes

(ewes BCS 2.5 and below) separately, either on a higher pasture cover or at a lower stocking rate. This gives us the ability to preferentially feed this target group through spring if feed conditions allow. Also, set stock older and potential cull ewes separately.

3. Book your cull ewes in with your processor early (September onwards) for the day you wean, so you are not stuck with culls later in the summer.
4. Identify and mark your cull ewes ideally before weaning – most farmers handle their sheep at least once between set stocking and weaning. Go through the older ewes then and cull on teeth, feet, udders, constitution, and then age.
5. Removing cull ewes from your farm as soon as they are weaned frees up feed for the most productive asset – the ewes you are going to mate the following year. Don’t get caught telling yourself you need to put a bit more weight on the culls before they go.
6. Remember you generally only have 100 days between weaning and mating, and the feed supply is becoming increasingly limited in this period, so every day of under or over-feeding counts!
7. Body condition score at weaning, or the day after weaning, and draft into groups based on BCS. If the plan is to shear the ewes at weaning, have the weaning and shearing dates booked well in advance so these jobs can be completed at the same time.
8. Be aggressive in your management of your heavy condition scored ewes – surprisingly it takes quite a restricted intake to pull weight off a heavy ewe.
9. The biggest opportunity lies in the BCS 2.0–3.0 group, lifting as many of these ewes to the next group prior to mating will yield the biggest returns next year.
10. A ewe needs to gain 70/g day from weaning to mating to gain 1.0 BCS – it may not sound a lot, but many farmers struggle to achieve 100/g on lambs over summer when they are trying to finish them.
11. Condition score the ewe groups again monthly or six-weekly, depending on feed levels and rate of BCS change within the flocks. Individual ewes can go up and down between the groups. Recheck udders at the first condition scoring post weaning, and remove any further culls.
12. A percentage in the light ewes (BCS < 2.0 group) will never increase in BCS despite preferential feeding. Cull these animals before mating – you will thank yourself later.
13. Enjoy the fruits of a productive and successful mating by listening to the sheep scanner’s comment about the lift in scanning percentage from last year!

As tempting as it may be to relax and enjoy the satisfaction of ticking off the weaning task for another year once the last lamb leaves the yards, don’t forget about those ewes, and that “mating starts at weaning!”

• Dwayne Cowin is a senior consultant for PerrinAg.