Late lactation recovery saves lamb performance

With ewes and lambs weaned at this stage on the farms participating in the Teagasc BETTER farm sheep programme, there is a chance to review performance.

This year has thrown numerous challenges at mid-season lambing flocks with comparatively poor weather conditions at lambing time and at grass in early lactation.

This was followed by a prolonged dry period in the run-up to weaning, which presented a different set of challenges.

These challenges have forced the flocks to be somewhat flexible in their management approach and use the data available to them, such as lamb growth rates and grass growth rates to navigate these challenges.

Contrasting performance

The comparatively wet spring did appear to impact lamb performance up to seven weeks when average daily gain was behind 2022 for most of the flocks.

However, the benign weather conditions in early summer seems to have allowed lamb performance from seven weeks to weaning (14 weeks) to recover and average above 2021 levels.

This has meant that most of the flocks in the programme have weaned lambs that are on average the same weight as last year. The reasons for this improved performance in the second half of lactation vary by farm, but grass quality and a lower parasite burden would appear to be the main reasons.

The slowdown in grass growth rates made it easier for some farms to maintain grass quality during late May and June when, usually, growth rates would jump rapidly and lower-stocked farms would struggle to keep on top of quality.

However, a consequence of this was that many of the flocks weaned one to two weeks earlier than planned as grass supplies tightened in June.

Weaning that bit earlier allowed grass demand to be reduced while ensuring once the lambs were weaned there was good-quality grass available to them.

Once lambs pass seven weeks of age they are more reliant on grass than milk to meet their nutrient requirements, so ensuring good-quality grass for the lambs is essential at this point.

The prolonged dry period also meant that the parasite burden on farms was lower than typically would be seen in the pre-weaning period.

All of the flocks are taking faecal samples for FECPAK analysis (faecal egg counts) and worm dosing based on these results.

The temptation would have been to dose lambs for worms after weaning but it would have been too early to be effective

Faecal egg counts have only begun to rise in the Teagasc BETTER farm samples in the last fortnight after being slow to rise initially after the weather broke.

This shows once again the importance of only worm dosing lambs based on faecal egg counts.

The temptation would have been to dose lambs for worms after weaning but it would have been too early to be effective.

All of the flocks are faecal sampling the lambs fortnightly and worm dosing in response to the FECPAK results of these.

Counts could rise rapidly on flocks in the coming weeks where they have remained low to date, so careful monitoring is essential.

The flocks will also be carrying out post-dosing testing to examine the efficacy of the worm drenches on their farms.

Taking a faecal sample from the lambs seven days (2-LV: Levamisole – yellow group) or 14 days (3-ML: Macrocyclic Lactone – clear group) after dosing will allow for the efficiency of the worm dose to be tested. For an anthelmintic product to be working, satisfactorily there must be >95% reduction egg counts after dosing.

Currently, most of the flocks have the lambs divided into at least two groups with lambs intended for slaughter that are greater than 36-38kg liveweight a separate group being offered ~500g/day of concentrates in troughs at grass.

Lambs in the finishing group are being weighed regularly and drafted for slaughter once ready. This is particularly important for flocks where weaning weights were behind target and twin lambs were averaging less than 30kg.

For these flocks, failure to take action now will potentially lead a large number of lambs still present on the farm later in the autumn when grass supplies are falling and grass needs to be prioritised for ewes at mating.

The use of targeted supplementation like this will help speed up the drafting rate of lambs by two to three weeks, while keeping concentrate feeding levels and costs low.

The remainder of the lambs are on good-quality grass swards grazing them down to 5.5cm to 6cm with the ewe flock cleaning out swards behind them.

Once the lighter lambs reach the 36kg to 38kg mark they will be drafted into the finishing group also.

The main issue facing some of these flocks now is to maintain grass quality as grass growth rates are exceeding demand and grazing days ahead is ahead of where it needs to be.

In addition, some swards became stressed during the dry weather and will potentially need to be topped to reset the sward and maintain quality. The target for the flocks presently is to have 15 to 17 grazing days ahead of the flock.

The ewes have also been checked and cull ewes marked and sold where possible.

Thin ewes have also been marked and will be monitored carefully between now and mating with any ewes failing to regain body condition score being culled.