Will Halliday, Beef + Lamb New Zealand’s Senior Advisor Animal Welfare and Biosecurity, says cold spring temperatures mean pasture growth rates in many regions are below normal for this time of year and this impacts pre-weaning lamb growth rates and ewe condition.
Anecdotally, farmers report tight feed supplies and this builds a strong case for weaning at least a proportion of the lamb crop early, so what high-quality feed is available can be partitioned into lambs while giving ewes the opportunity to recover body condition.
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.
If lambs are weaned onto 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.
He says 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.
Early weaning can also 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 late 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.