Pre-Exposure of Early-Weaned Lambs to a Herb-Clover Mix Does Not Improve Their Subsequent Growth.

Twin sets of lambs were randomly allocated to one of six treatments: (1) lambs born and managed on ryegrass-clover-based pasture until conventional weaning approximately at 99 days of age (Grass-GrassCW); (2) lambs born on ryegrass-clover-based pasture and early weaned onto a herb-clover mix at ~45 days of age (Grass-HerbEW); (3) lambs born on ryegrass-clover-based pasture, transferred with their dam onto a herb-clover mix at ~45 days of age until conventional weaning (Grass-HerbCW); (4) lambs born on ryegrass-clover-based pasture, transferred with their dam onto a herb-clover mix at ~15 days of age and early weaned onto a herb-clover mix at ~45 days of age (Grass-HerbD15EW); (5) lambs born and managed on herb-clover mix until conventional weaning (Herb-HerbCW); (6) lambs born on herb-clover mix and weaned early onto a herb-clover mix at ~45 days of age (Herb-HerbEW). In both years, Herb-HerbCW lambs had greater (p < 0.05) growth rates than lambs in other treatments. The liveweight gains and rumen papillae development of Herb-HerbEW, Grass-HerbD15EW and Grass-HerbEW lambs did not differ (p > 0.05). The weight of the empty digestive tract components at either early weaning or conventional weaning did not differ (p > 0.05) between treatments. Exposing early-weaned lambs to the herb mix for a prolonged period, prior to early weaning, does not improve their subsequent growth.