Key management factors
- Have a high quality, legume-based forage for weaned lambs.
- Minimum weaning weight of 16kg.
- Maintain pasture covers between 1200kgDM/ha and 2000kgDM/ha. If grazing legume-based crops, don’t graze below 7cm.
- 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.
Using the right forage
Speaking at B+LNZ’s Farming for Profit field days in Canterbury, Professor Paul Kenyon and Dr Rene Corner-Thomas from Massey University say trials have shown that with the right 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.
Paul says in late lactation all lambs, but especially multiples, receive little nutrition from the ewe. When growing conditions are tight, ewes compete with their lambs, compromising the performance of both.
By weaning them onto correctly managed, high quality, legume-based forages, the lambs are given more opportunity to realise their genetic growth potential. Paul says the weaned lambs should be allowed unrestricted access to high quality herbage of at least 1400kgDM/ha.
Lambs being weaned onto a crop should be given time to adjust to the change in feed. Ideally, 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.
When feeding a crop such as lucerne, ensure it is not grazed below 7cm.
In the Massey University trials, researchers were weaning to a minimum weight of 16kgLW, which is what Paul recommends. He says heavier lambs cope best with early weaning, but the quality of the forage on offer is biggest determinant of how lambs will grow post-weaning.
He says 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 for hoggets, as they typically lamb later than the mixed-age ewes – but are 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.
Early weaning is not a new concept and studies carried out in the 1960s and 1980s focused on weaning at 8-9 weeks.
Trials at Massey will now look at the impact of weaning lambs at 14kg – compared to 16kg – and whether early weaning is as beneficial, given abundant feed resources.
“For the ewe there are clear advantages of weaning early and few disadvantages for lambs; they can grow just as fast, if not faster.”
Maximising lamb growth rates in the late spring, early summer period has on-going benefits. They are finished faster and therefore consume less feed post-weaning. It is easier to breed from heavier ewe lambs as hoggets and there is flexibility to hold them back later if feed resources are limited. Heavy lambs require fewer animal health remedies and less labour inputs.
Any management tool that helps maximise lamb growth rates is worth considering.