Scientist warns of tough year ahead for sheep producers

Significant challenges face sheep producers this year as they strive to achieve optimal lamb performance and prevent condition loss in ewes, a leading scientist warns.

Flock performance is likley to be hampered as a consequence of the bad weather in the first three months of the year and the resultant limited feed supply, according to EBLEX.

Dr Liz Genever, the organisation’s senior livestock scientist, said the major driver for lamb growth rates up to around eight weeks is milk yield, which may be an issue this year due to low feed supply affecting ewes.

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To maintain condition, a 70kg dry ewe requires around 11 megajoules (MJ) of metabolisable energy (ME) per day, and during lactation, these requirements increase dramatically, with a 70kg ewe rearing a single or twins three weeks into lactation normally requiring around 32 MJ and 36 MJ of ME per day.

It has been a challenge for ewes to meet these requirements, she said, resulting in many cases in a loss of body condition. However, if the ewe had a below target body condition score before lambing, there is a greater chance of a reduction in milk yield and an increased risk of mastitis, an infection affecting udders.

The target for growth rates depends on the system, in particular whether or not creep feed is being used, Dr Genever said. EBLEX StockTake data suggests that average growth rates in 2012 were 250g/day, with the lambs on the best performing farm growing at around 400g/day.

Within any group of lambs, performance will vary, and it is likely that this year there will be more “poor doers” than previously, she said, and where lambs are not meeting targets, it is highly unlikely that their feed conversion efficiency is good enough to make creep feeding cost-effective. Reducing stress through grouping them with other lambs their own size, ensuring good quality forage is available and good health planning are all likely to help improve performance, she added.

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It is important to maintain a focus on worms this year and producers should monitor parasite warnings, such as the nematodirus warning which is currently in force for mid to late April, she said.

Dr Genever also advises making decisions early to ensure good quality feed is available for ewes into the autumn and weaning lambs sooner, at 10 to 12 weeks or earlier for ewe lambs to prevent further condition loss.

Early weaning is likely to be particularly beneficial this spring, she said, as ewes will be in poor condition, so will need more time to recover and it takes six to eight weeks on unrestricted grazing for ewes to gain one BCS (body condition score). If ewes are above target BCS at weaning, it is unlikely that there will be significant benefit for growth rates of keeping the lambs on them longer. Instead, it is probably best to wean the lambs then manage the fat ewes as a group, she said.