Willow fodder blocks—An alternate forage to low quality pasture for mating ewes during drought?

Two grazing experiments were conducted in the East Coast region of the North Island of NZ with ewes grazing on willow fodder blocks or control grass-based pastures during mating. Experiment I was conducted for 86 days with three treatments; short drought pasture (5–7 cm), long drought pasture (25–30 cm) and full access to willow fodder blocks which also contained long pasture (25–30 cm). Experiment II was conducted for 35 days with two treatments; control pasture and full access to willow fodder blocks. All ewe groups were combined at the end of mating and grazed on pastures until lambing and weaning. Live weight (LW) was recorded fortnightly during experimental grazing, body condition score (BCS) was scored monthly, and reproductive data was recorded at ultra-sound pregnancy scanning, lambing, docking and weaning. In Experiment I, short drought pasture and long drought pasture contained, respectively, a metabolisable energy (ME) of 8.2 and 9.6 MJ/kg dry matter (DM) and only traces of condensed tannins (CT). Herbage in the willow fodder blocks was intermediate in ME to short drought pasture and long drought pasture, whilst trees in willow fodder blocks contained 38 g of CT/kg DM and had a ME of approximately 10 MJ/kg DM. Willow fodder block herbage was consistently of higher legume content than drought pasture of similar mass. Ewes grazing short drought pasture lost 40 g/day of LW and had a low reproductive rate, as would occur in a drought situation, whilst ewes grazing long drought pasture gained LW and had a higher reproductive rate. Ewes grazing willow fodder blocks maintained LW and their reproductive performance was intermediate to ewes mated on long drought pasture and short drought pasture. Calculated intakes of DM, ME and crude protein (CP) were low for ewes grazing short drought pasture and higher and similar for the other two groups, while intake of secondary compounds was much higher for ewes grazing willow fodder blocks. In Experiment II, ewes mated on willow fodder blocks had lower LW gain than ewes mated on control pasture, but reproductive performance was similar for both groups. Willow fodder blocks are a useful source of supplementary feed during droughts, but the grazing management that optimizes animal performance needs further research.