Drought in the North Island had a significant impact on the number of lambs tailed in the first half of this season.
With the right quantity of legume-based forages, early-weaned lambs can grow as fast – if not faster – than their unweaned equivalents on traditional ryegrass and clover pastures.
Early-weaned ewes can either be sold early, which frees up feed for other stock, or benefit from having more time to recover body condition before mating.
In late lactation, all lambs, but especially multiples, receive very little nutrition from the ewe. When grass growing conditions are below optimal, the ewes are competing with their lambs, compromising the performance of both.
By weaning them early onto correctly managed, high quality, legume-based forages, the lambs are given more opportunity to realise their genetic growth potential. Weaned lambs should be allowed unrestricted access to high quality, legume dominant pasture (between 1200 kgDM/ha and 2000 kgDM/ha). Or, ideally, a legume-based crop with a height of 7-10 cm.
If lambs are being weaned onto a crop, they should be given time to adjust to a change in feed. Running the ewes and lambs onto the crop for a few days before weaning, then running the lambs back onto the crop after weaning, will minimise the weaning check.
In trials run at Massey University, researchers looked at weaning lambs early, at a minimum liveweight of 16kgLW, onto either a herb-clover mix or a lucerne sward. They found heavier lambs (over 20kg) coped best with early weaning, but the quality of the forage on offer was the biggest determinant of how lambs grow post-weaning.
Early weaning is most effective in seasons when grass growth is limited (pasture covers of under 900 kgDM/ha), and lambs weaned early are offered a herb-clover mix with a minimum pasture cover of 7cm.
Farmers using lucerne, should follow Good Management Practice for lucerne grazing.
Early weaning can be a flexible stock and pasture management tool, used to benefit the whole farm system. For example, weaning a proportion of the flock early means some ewes can be used as a grazing management tool to prepare pastures for when the balance is weaned later.
Early weaning can be particularly useful in hoggets, as they typically lamb later than the mixed-age ewes but mated as two-tooths at the same time. This means that despite their age, they are required to regain body condition more quickly than the older ewes.
Maximising lamb growth rates in the late spring, early summer period has on-going benefits. They are finished faster and therefore consume less feed postweaning. It is easier to breed from heavier ewe lambs as hoggets, and there is flexibility to hold them back later when feed resources are more limited.
Heavy lambs require fewer animal health remedies and less labour inputs, so any management strategy that helps maximise lamb growth rates is worth considering.
Key management factors include:
- A minimum weaning weight of 16kgLW, provided suitable feed is available
- Having a high quality, legume-based pasture for weaned lambs
- Maintaining legume crops above 7cm to allow unrestricted grazing
- Early weaning can be a flexible management tool
- Not all management options work on every farm. Adopt and adapt management strategies to fit your system.