Beef + Lamb NZ: Wean early in case of drought

There are predictions of a dry summer this year, bringing the threat of drought.

The very real prospect of a summer drought has prompted B+LNZ to suggest options for farmers to cope with the threat of feed shortages.

Predictions of a dry summer may make early weaning an attractive option for sheep farmers this year provided they have high-quality legume-based forages available for their weaned lambs.

Chris Brandolino, principal scientist — forecasting for NIWA said indications were for low, to below normal rainfall over the North Island, including the lower west coast.

"Between now and the end of January we are predicting low, to below normal rainfall. It is very unlikely to be a wet summer," Brandolino said.

NIWA's three-month seasonal climate outlook covered November through to the end of January.

Temperatures in the central North Island have a 45 per cent chance of being above average and a 40 per cent chance of being near average during that time.

Early weaning can be a flexible stock and pasture management tool which can be used to benefit the whole farm system

The central North Island includes Taranaki, Manawatu, Wellington and Whanganui.
The temperatures in every New Zealand region have been forecast with the same probability as the central North Island.

Meanwhile, rainfall has a 40 per cent chance of being below normal and a 35 per cent chance of being near normal.

What that basically boils down to is that rainfall is expected to be below normal in most New Zealand regions.

Armed with that information and with the right management, early weaning can be a valuable tool that benefits both ewes and lambs by reducing competition for feed, especially in seasons where grass-growth is limited.

Early-weaned ewes can either be sold early, which frees up feed for other stock classes, or be given more time to recover body condition before mating next year.

Trials run at Massey University found lambs over 20kgLW coped best with early weaning (minimum weaning weight was 16kg LW), but it was the quality of the forages on offer that was the greatest determinant of how well lambs grew post-weaning.

Professor Paul Kenyon, who led the early-weaning trials, says early-weaned lambs should be given unrestricted access to legume-based forages such as a herb clover mix at a minimum cover of seven centimetres in height or ryegrass white clover mix masses between 1400kg DM/ha (5cm) and 2000kg DM/ha (10cm) — ideally with a high percentage of clover.

If lambs are weaned on to the crop, they should be given time to adjust to a change in feed. Running the ewe and lambs onto the crop a few days before weaning, then running the lambs back onto the crop after weaning will help minimise the weaning check.

Flexible tool

In late lactation all lambs, but especially multiples, are receiving very little nutrition form the ewe, so when grass-growth is limited the ewes are competing with their lambs for feed, compromising the performance of both.

Paul says early weaning can be a flexible stock and pasture management tool which can be used to benefit the whole farm system.

For example, by weaning a proportion of the flock early means some ewes can be used as a grazing management to prepare pastures for when the balance is weaned later.

Early weaning can be particularly useful in hoggets as it will give them more time to recover body condition between lambing and mating again as a two-tooth.

Partitioning high quality feed into lambs in the last spring early summer period will benefit the whole farm system.

It means more lambs can be sold prime before the height of summer — making more feed available for capital stock — and ewe lambs can be grown out to heavier weights early.

This means there is flexibility to hold them back later when feed resources are more limited.