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Lifetime Ewe Management in the pastoral zone

Posted by Bestprac on Nov 06 2010

Deb Maxwell, Sheep CRC
The Lifetime Ewe Management program aims to optimise production of both meat and wool from ewes and their progeny...

with a key focus on reproduction and increased survival of lambs and weaners. It is based on the AWI-funded Lifetime Wool Research Program.

With the current market and ever-changing community perceptions, it is no longer acceptable, financially or ethically, to have low weaning rates. In general, the factors affecting reproduction are universal across Australia and are not unique to the pastoral zone, but individual factors may be more or less important in a region or on a particular property.

The pastoral zone has particular challenges, especially from predators and poor nutrition; however, these issues can be managed even in the harshest environments.

Regardless of location, the priority is to have ewes at optimum condition or weight at joining. Adult ewes should be condition score 3—it is their condition that is most important for adults, rather than their weight. It is more difficult to put condition on still-growing maiden ewes so base weight is important for maidens—aim for a minimum of 38 kg.

While these benchmarks are generally quite achievable with non-Merinos or crossbreds, Merinos may take more effort, such as by providing preferential nutrition to the lighter ewe hoggets well in advance of mating. Failure to get maidens to weight and in lamb has a serious negative impact on profitability.

Key points for the breeding year are:

Wean at about 14 weeks after the start of lambing: this is a good time to ‘wet and dry’ the ewes to monitor individual reproductive performance. Fat ewes are fat because they did not have a lamb, rather than them not getting into lamb because they were fat. Adult ewes that were dry or lambed and lost can be culled; however, maidens should be given a second chance.

Post-weaning: provide ewes with good nutrition to allow them to recover live weight and body condition lost over lactation for the next joining.

Pre-joining: check your rams and carry out any management actions at least 7 weeks prior to joining so as not to affect sperm production at joining. Feed rams as needed so that they are least score 3 by joining.

Joining: ewes should be at score 3 and it is important to maintain their condition over the joining period. It is a myth that a rising plane of nutrition achieves high conception rates. Rather it is the actual condition of the sheep that determines ovulation and conception levels. There will still be lower ovulation and conception rates for poor sheep on a rising plane of nutrition compared to fatter sheep on a declining plane.

Join for 2 cycles (35 days) so that lambing, marking, weaning and later activities are more manageable. Under harsh conditions or with maiden Merinos, a 3-cycle joining can be considered.

It is advisable to align joining with the pasture cycle. The time of joining is best chosen so that lambing coincides with the maximum feed availability, as lactation has the biggest nutritional requirement (about twice that of a dry ewe) and feed is the most expensive requirement for reproduction.

Producers contemplating more frequent joining (e.g. 3 times in 2 years) should at least experience one annual cycle to establish a benchmark and determine the viability of an accelerated program for their district. Continuous (or overly long) joining presents a host of problems with management and marketing and is not advisable.

Autumn is the most common joining time, but in some areas where winter and spring are generally dry, ‘out-of-season’ joining in spring is preferable. The drawbacks are fewer twins due to naturally lower ovulation rates, higher rates of early embryonic deaths from hot weather early in pregnancy and restricted development of the placenta reducing nutrition to the foetus, also from prolonged exposure to heat.

Regardless of where sheep are run in Australia and even when seasonal conditions are quite poor pregnancy rates of well over 90% in adult Merinos are achievable.

Mid-Pregnancy: if ewes are lambing onto high quality green feed, they can be allowed to drop to a condition score of 2.5, by mid-pregnancy, if there is good pasture in the last third of pregnancy to regain any lost condition by lambing. But where mid-to-late-pregnancy usually coincides with lesser feed, their condition should not be allowed to drop from score 3, as it is too expensive to supplementary feed them back up for lambing.

Pregnancy scanning is strongly recommended provided it is to determine twins and singles, not just wet or dry. This pays off by allowing the twin-bearing ewes to receive preferential nutrition and lambing paddocks. All properties should at least scan in the year when a concerted effort is being made to improve reproduction; this will assist in identifying at what stage(s) losses are occurring.

Lambing: before lambing ensure ewes are shorn or crutched and provided with appropriate treatments including vaccinations, and worm and fly treatments that will protect them through to early lactation.

Lambing paddocks should provide shelter and seclusion, as well as good water and protection from predators; also, smaller mob sizes and smaller lambing paddocks result in higher lamb survival. In districts and seasons where worms are a problem, prepare low-worm lambing paddocks.

Predators should be controlled all year round with a particular focus for the few months before lambing. Coordinated district campaigns and integrated programs using a variety of control methods are most successful. Combined use of shooting, baiting, trapping and guard animals (guardian dogs or alpacas) is highly successful against foxes and pigs. Additional fencing is usually required when dingos/wild dogs are a problem.

Lamb marking: this event in the pastoral zone presents a serious risk of mismothering with subsequent lamb deaths. While marking is ideally done no later than 2 weeks after lambing finishes, this may need to be delayed in areas with poorer feed so that lambs are 15 kg (in case they are weaned through mismothering). To further lower the risk of mismothering, mark at portable yards in the lambing paddock in mob sizes of less than 600, and while lambs are being marked ensure that the ewes are watered and kept close to the yards to reclaim their lambs.

Weaning: the risk of deaths again comes to a peak at weaning, with lighter lambs having the highest risk of death. Ensure that ewes continue to have both a high quality and quantity of feed from marking to weaning to achieve high weaning weights. This will provide the best start for good weaner growth and survival.

If you expect that your sheep will need supplementary feeding sometime during their life (especially for the weaners themselves in their first year), provide a small amount of the supplement to ewes and lambs for about a week, prior to weaning. Provided the ewes have already eaten that supplement, they will ‘teach’ the lambs to eat it, making its introduction later in life much faster.

Finally, to gain the benefits of more replacement sheep from which to select, increased wool returns and more surplus sale sheep, weaners will require special management. They are more susceptible to various health issues so need effective parasite and disease management and growth rates of at least 0.5 kg growth/month are essential for survival and production (especially in Merinos).

More Information: Email Sheep CRC

Last changed: Feb 07 2012



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