A comparison of liveweight gain of lambs weaned early onto a herb-clover mixed sward and weaned conventionally onto a ryegrass-clover pasture.

Objective: The aim of the present study was to identify the impact of early weaning of lambs at approximately seven weeks of age onto a herb-clover mix on the liveweight gain of lambs and their dams.

Methods: In 2015, twin-born lambs that weighed a minimum of 16 kg (n=134) were randomly allocated to one of three treatments:(i) Early-weaned (58 days after the midpoint of lambing) onto an unrestricted allowance (>1200 kg DM/ha) of herb-clover mix (HerbEW); (ii) Lambs + dams unweaned onto an unrestricted allowance of herb-clover mix until conventional weaning (95 days after the midpoint of lambing) (HerbCW); (iii) Lambs + dams unweaned onto an unrestricted allowance of grass-clover pasture until conventional weaning (GrassCW). In 2016, twin-born lambs that weighed a minimum of 16 kg (n=170) were randomly allocated to one of four treatments: i, ii, iii (similar to 2015) and (iv) Lambs + dams unweaned onto a restricted allowance (<1200 kg DM/ha) of grass-clover pasture until conventional weaning (93 days after the midpoint of lambing) (Restricted-GrassCW).

Results: In 2015, liveweight gain from L58 to L95 of HerbCW and GrassCW lambs did not differ (p>0.05), but were greater than HerbEW lambs. In 2016, HerbCW lambs had greater (p<0.05) liveweight gains from L51 to L93 than GrassCW followed by HerbEW and Restricted-GrassCW lambs.

Conclusion: These results indicate that when grass-clover pasture supply can be maintained at unrestricted intake level there may be no benefit of weaning lambs early. However, at restricted pasture conditions lambs can achieve greater liveweight gains when weaned early onto a herb-clover mix.