Sheep deficient in vitamin E preferentially select for a feed with a higher concentration of vitamin E.

Given the capacity of ruminants to modify diet selection based on metabolic needs, we hypothesised that, when given a choice, lambs experiencing a vitamin E deficiency would consume more of a vitamin E-enriched feed than lambs not deficient in vitamin E. Fifty-six Dohne Merino lambs were divided into two groups and fed either a vitamin E-deficient diet over 40 days to induce low plasma vitamin E or a vitamin E-enriched diet to induce high plasma vitamin E. The lambs were then offered a choice of vitamin E-enriched and vitamin E-deficient pellets. For half of the animals, the enriched diet was paired with strawberry flavour and the deficient diet was paired with orange flavour, while the reverse pairings were offered to the others. Lamb preference for the diets was measured daily for the following 15 days. There was a three-way interaction between the high and low vitamin E treatment groups×vitamin E content and type of flavour in the feed×time (days). The lambs preferred pellets flavoured with strawberry but this preference changed to orange flavour in vitamin E-deficient lambs if the orange flavour was paired with high vitamin E. Lambs without a deficiency continued to prefer strawberry-flavoured pellets, regardless of the vitamin E concentrations in the pellets. It is possible that self-learning contributed to the low vitamin E group of lambs changing preference to orange flavour in order to consume more vitamin E, presumably to remediate the deficiency.

The effect of grazing saltbush with a barley supplement on the carcass and eating quality of sheepmeat.

The carcass and eating quality of sheep grazing a saltbush dominant saline pasture system or on a 'control' dry pasture, stubble plot both supplemented with barley for 14 weeks was investigated (Experiment 1, 50 (2×25) 6 month merino lamb wethers and Experiment 2, 50 (2×25) 18 month old merino hogget wethers). Treatment had no significant effect on eating quality attributes (P>0.05). Saltbush grazed sheep in both experiments had a significantly (P<0.01) lower carcass fat and significantly higher lean (P<0.01) content than the control grazed sheep. This is a positive finding as fat denudation is a significant cost to processors. The long term consumption of saltbush and barley prior to slaughter did increase muscle fluid content (P<0.05) but did not result in a decreased carcass weight loss at slaughter due to confounding changes in body composition. Grazing saltbush resulted in increased urine weight (P<0.001) and decreased urine concentration (P<0.05) at slaughter indicating an improved hydration status at slaughter. However both experiments demonstrated sub-optimal liveweight gains indicating that saltbush with a barley supplement can still be effectively used as a maintenance ration without compromising carcass and eating quality.