Feeding ewes
Lamb growth rates are governed to a major degree by the ewe's milk production. Maximum growth rates are achieved while on the ewe, so attention to feeding the ewe enough high-quality spring pasture after lambing is critical to your farm profit.
After lambing, the ewe's demand for energy rises to reach a peak about 3-5 weeks into lactation. If the ewe is feed-restricted during this time, her potential milk yield will not be achieved which in turn will have a direct affect on the growth of her lamb(s).
A 65kg ewe that lambed 3 weeks ago with twins at foot will require about 3kg DM/day (with a single lamb, 2.6kg DM/day) to maintain body condition and lactation. Therefore, the pasture must grow at 30kg DM/ha/day to maintain pasture covers 3 weeks after lambing, assuming 10 stock units to the hectare. Clearly, this will not be possible in some areas if lambing in late July/early August.
Ewes can be set stocked on sward heights of 3cm (1300kg DM/ha) without penalising lamb growth rates, but at these low sward heights, ewes will lose up to 10kg by weaning time (60-70 days). Thus, sward heights of 4-6cm (1500-1800kg DM/ha) are more appropriate to prevent this liveweight loss, ensure good milk production, and sustainable production between years. Sward heights of 6cm (1800kg DM/ha) will just about maximise ewe intakes, as ewes will physically be unable to harvest the extra dry matter made available.
Therefore, if feed is tight post-lambing, this will adversely affect ewe body condition and survival rates, and growth rates of the lambs at foot. Remember, the most efficient time to put weight back on ewes is in late lactation (prior to weaning).
For more hints and helpful guidelines, contact your vet at either branch of Totally Vets.
