Beyond the ram release: managing the joining window for better conception rates
For many woolgrowers, joining starts the day the rams go out, but a targeting better scanning results starts well before the rams are released. But reproductive performance is influenced well before — and well after — that point. If you are aiming for stronger scanning results, management during the four weeks leading up to joining, and during the joining period itself, is critical.
There are three key drivers of reproductive performance: ewe condition score at joining, appropriate nutrition leading into and during joining, and sound ram management.
Measure and manage
Ewe condition score (CS) at joining is one of the most important determinants of reproductive rate (Figure 1). Making More From Sheep recommends targeting an average condition score of 3 at joining for both Merino and maternal (composite and first cross) ewes. The LifetimeWool research underpinning these recommendations shows that even a 0.5 condition score difference at joining can significantly influence ovulation rate and subsequent lamb numbers (Figure 1).
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Rather than guessing, it is important to condition score a representative sample — typically 25–50 ewes — from each mob to determine the mob average. Where possible, draft and management ewes according to their condition. Lighter ewes (CS 2–2.5) may benefit from preferential feeding to lift condition before joining, while heavier ewes can be managed to avoid unnecessary feed costs.
A rising plane of nutrition in the two to three weeks before and during joining can further bolster ovulation rate. Equally important is avoiding a sudden decline in nutrition at joining.
In Tasmania, where autumn pasture availability can vary, feed budgeting is essential to maintain consistency through this window.
Ram soundness and condition also matter
Rams should be in good working order well before joining commences. Assess rams at least eight weeks before joining to allow time to address any issues.
Aim to have rams in condition score 3.5 at joining and carry out a thorough soundness examination, including checks of feet, legs, teeth and testes, along with scrotal circumference. If your rams need to increase CS before joining, feed a high-quality feed such as lupins for 50 days prior to joining to ensure maximum testes size and sperm output.
Ensure vaccinations and general health status are up to date to reduce the risk of preventable reproductive failure.
Appropriate ram-to-ewe ratios should reflect paddock size, terrain and ewe age to ensure adequate mating activity. Join rams at 1% plus one extra ram for mature ewes (at least five rams for a mob of 400 ewes), at least 1.5% for maiden ewes and 2% for ewe lambs. Increase the ram percentage if you’re joining in large mobs as the ‘plus one extra ram’ gets more diluted the larger the mob gets. Higher ram joining rates are necessary in large paddocks with multiple watering points or when rams are joined outside the main breeding season.
The joining period: minimise disruption
Under good management and adequate nutrition, a high proportion of ewes will conceive in the first oestrus cycle (approximately 17 days). Maintaining stable nutrition during this period supports embryo survival.
Avoid unnecessary stress during joining and early pregnancy. Avoid major disruptions, such as shearing, transport or excessive handling where possible, particularly during the first few weeks after introducing the rams.
Ewe health throughout the reproductive cycle is extremely important. Any health issue, such as worm burdens, liver fluke or footrot, will slow weight gain or cause weight loss resulting in lower reproductive rates
Keep joining tight
Keeping your joining periods to five weeks (two cycles) — most ewes get pregnant in two cycles (Figure 2). Extending the joining for longer periods is not recommended as the 2-4% of extra lambs born holds up completion of important management events, such as marking and weaning. Delaying weaning for a few late lambs can result in serious worm burdens, leading to weight loss in both ewes and lambs. Late weaning also compromises ewe condition recovery in preparation for the next reproductive cycle.
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Removing rams promptly at the end of the joining period also allows more accurate interpretation of scanning results and tighter lambing management.
Joining is not a single event but a defined management window. By measuring mob condition score, managing nutrition strategically, preparing rams thoroughly and minimising stress during early pregnancy, you can position your flock for improved conception rates, tighter lambing and stronger whole-farm profitability.
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