13 August 1999

May lambing cuts labour

Clover leys, worm egg

counting and mixed grazing

could help cut costs of

finishing May-born lambs.

James Garner reports

MAY lambing margins have been hit hard by tumbling late season lamb prices, but the system still has a positive future.

All sheep systems look financially unhealthy, SACs John Vipond told visitors to a Signet/SAC May lambing day at Sheepdrove Organic Farm, Lambourn, Berks. While conceding that a May lambing system looked no better than others, Dr Vipond said it had low fixed costs, essential for survival.

"Although gross margin analysis of April and May lambing systems may not look any better initially than others, you can cut man hours required by lambing outside.

"I know of situations where one stockman looks after 600-1000 May lambing ewes, because they are lambing outside."

Another favourable factor for May-born lambs is they can be finished off grass, said Dr Vipond. "There are 150 days of grass growth in which to finish May-born lambs, so cheap finishing is possible."

But to be profitable, May-born lambs must grow without check. This means avoiding summer grazing concerns, such as parasite challenge, he said.

"Dosing can control worm problems but lambs unchallenged by parasites grow 25% faster. This is because where lambs are challenged, protein is diverted to repair gut damage rather than for muscle development, so growth suffers."

Clean grazing systems, which avoid lambs grazing worm infected pastures, will improve lamb growth rates.

The best way of ensuring clean grazing is to alternate between cattle and sheep on a yearly basis and to use re-seeds as clean grazing areas, said Dr Vipond.

But avoiding parasite challenges means understanding where worm problems are coming from. "Worm egg counting gives an opportunity to establish this through monitoring worm egg levels in ewes and lambs.

"Worm problems may come from lambs grazing pasture in winter. But improving lamb growth and selling them earlier means overall worm burden will be reduced because lambs will be off farm before infecting pastures."

For producers with permanent pastures, strategic use of long acting wormers can offer some relief from worm infestation. "Using products such as Cydectin means dosed ewes act as hoovers and clean pastures when turned out.

"When a worm problem still exists five weeks after ewes and lambs are turned out, lambs should be wormed with a long-acting product. This means they too can act as hoovers, so pastures will be reasonably clean by weaning time."

But Dr Vipond said lambs should return to the same pasture after weaning. "Weaning to aftermaths may be over-rated, because the sward after re-growth is often poor quality and open, and so lamb growth rates can fall.

"Returning them to the same pasture may reduce weaning stress as lambs are used to the field and where things are, such as water troughs."

After weaning, pasture can grow away from lambs because there are fewer mouths to feed. This has a knock-on effect of diluting the number of worm eggs digested by lambs, helping improve growth rates, he said.

Another way of boosting growth and cutting fertiliser bills is to incorporate clover into pastures.

"This requires at least 18 months of clover growth before lambs will grow at rates as high as 300g/day. But clover finished lambs have larger carcasses with lower fat levels."

Tasting trials by the MLC also shows clover finished lamb tastes sweeter. Meat from clover fed lamb also shrinks less during cooking, leaving an extra 10% of lamb on the plate, he said.