Selecting the optimum breeding date for your flock

There have been significant changes to the lambing date profile on Irish farms over the last 10 to 15 years. The number of farmers practising a traditional early lambing system has seen a major reduction, with as many farmers now likely to be lambing flocks in April as in January.

Teagasc research and modelling has shown that the optimum system of production for a high percentage of farmers is a grass-based production system and targeting the lambing date to the normal onset of grass growth. However, earlier or later lambing suits a percentage of farmers for a multitude of reasons.

For example, some farmers have pushed lambing dates into February with the aim of capturing higher prices before seasonal downward pressure kicks in and to try and lower costs of lambing in January.

Others are lambing at this time to combine favourably with other enterprises on the farm and balance grass demand.

Religious festivals

The sharp fall in prices in recent weeks where more than €2/kg has been wiped from the value of lambs in five weeks has got more farmers, who normally try and target sale dates for a percentage of progeny to religious festivals, assessing their options.

Table 1 details the date of religious festivals from 2023 to 2030. As can be seen, Easter and Ramadan have fallen in close succession in recent years.

This has helped to raise prices to peak spring levels, while a void in supply thereafter in 2024 has helped to sustain prices at a higher level.

Demand for the festival was largely satisfied with hoggets in 2023, but a lower carryover of hoggets in 2024 left very little differentiation between prices paid for hoggets and ewe lambs.

The experience of the last few years has also taught us that there is a danger in predicting market performance. Sheep markets are now much more exposed to global market dynamics.

Reduced numbers

That said, it is fair to predict given the reduction in the national ewe flock that the number of sheep available for slaughter in the first half of 2025 will record a further decline on 2024 levels.

Since 2019, Easter and the start/end of Ramadan have been separated by just two weeks. This will extend to approximately three weeks in 2025.

The later date for Easter could provide more opportunities for early lamb producers to capitalise on festival demand. Easter school holidays are also a factor in some households with family help lessening the workload, but the late date is probably unfeasible for a lot of enterprises to target in 2025.

The Eid al-Adha festival has typically underpinned price, or delayed the seasonal decline in prices, for a few weeks rather than actually bringing about any increase in price.

Like Ramadan, this festival moves forward by about 10 days each year due to differences between the Gregorian and Christian calendars.

The level of throughput recorded ahead of the festival in 2024 was limited by tight supplies, but still recorded an increase of over 15,000 head from the previous weeks.

Grass growth

The challenging weather this spring is also bringing a greater focus on matching the lambing date to grass supplies.

The experience of one year cannot dictate or influence major changes. The experience of a few years needs to be taken into account.

For example, is the farm continually in a position of being tight on grass post-lambing despite taking the necessary steps in closing up paddocks or, alternatively, is demand slow to rise meaning grass supplies often get ahead of stock and are hard to manage?

Frank Campion, Teagasc, has significant experience in tackling such questions through his role managing the Teagasc BETTER farm sheep programme.

Frank comments that having grass growth figures to hand makes planning much easier but, in their absence, decisions can still be made taking previous experience to hand and forecasting demand for grass in early lactation.

He says the target for most lowland flocks is to let ewes and their lambs to grass within 24 to 48 hours after lambing, weather permitting.

Figures 1, 2 and 3 show grass growth and ewe demand for three different scenarios – lambing at the correct time to match grass supplies, lambing too early and running into a grass deficit and lambing too late, and developing a grass surplus.

Grass growth should match demand from about one month post-lambing

The grass supply curve and lambing dates used for Figure 1 are the ideal lambing time taken for one of the flocks participating in the BETTER farm programme. Grass growth should match demand from about one month post-lambing.

Where the lambing date is too early for the farm, as demonstrated in Figure 2, then the shortfall will need to be made up with supplementary feed via concentrates and/or forage supplementation.

In such a scenario, it takes the farm a significant period of time to recover with feeding required at the most critical time period in early lactation, which will undoubtedly increase costs and dent lamb performance.

In Figure 3, the lambing date is too late in comparison to the grass growth curve meaning surpluses build up in early spring. This has knock-on consequences in reducing grass quality, making management more difficult and potentially reducing sward quality.

Implementing decisions to change the lambing date requires careful planning in terms of ensuring ewes and rams are in prime condition at the time of joining and putting in place an autumn-winter grazing planner to ensure paddocks are closed up in adequate time to have sufficient grass available next spring.

In summary, swards will typically require a rest period of approximately 120 days prior to turnout.

This means that for an early March lambing flock, rams are turned out in mid-October and the first paddocks are closed from there onwards, with 20% of the farm closed by late October, 40% by mid-November, 60% by late November and 80% by mid-December.

Stocking rate needs to be factored into account with such a breeding programme and grass supply curve typical of a farm stocked at approximately 10 ewes per hectare and growing 1t grass dry matter for each ewe and her lambs.

The other area that came under significant pressure in spring 2024 was facilities, straw supplies and labour.

As already mentioned, one abnormal year cannot dictate major changes, but questions also need to be asked following this spring if the lambing date is conducive to having to keep ewes and lambs indoors, if required.

The other aspect that needs to be borne in mind, particularly for earlier lambing flocks that retain ewes indoors for a significant period of time, are straw supplies and prices.

There are suggestions that straw availability will be improved following last week’s proposal by the Minister for Agriculture to suspend the Straw Incorporation Measure (SIM) and that supplies may be increased, but this was still to be finalised at time of going to print.