Medicago truncatula is used to feed sheep, goats and more generally large livestock in Australia, South Africa and the Mediterranean Basin. The legume provides a green forage of good quality that can be grazed during winter and spring, and a dry forage easy to graze in late spring and summer. It can also be harvested as hay (Denney et al., 1979; Brand et al., 1991a; Brand et al., 1991b). It is mainly used for small ruminants production systems as these animals can harvest the pods on the soil with their lips. The pods may represent the major diet component in late summer and autumn (Kotzé et al., 1995). Most studies done on barrel medic have been carried out with sheep.
Forage
In Tunisia, in vitro OM digestibility of fresh forage was found to be high, in the 65-75% range (Gasmi-Boubaker et al., 2012). In South African pastures, in vitro OM digestibility measured in samples collected by oesophageally fistulated sheep ranged from 80% in early spring (young leaves, protein 35% DM) to 40-50% in summer (pods, protein 12-14% DM) (Brand et al., 1991a). OM digestibility of hay was 65% (Denney et al., 1979).
In South Africa, due to the large range of nutritive value across seasons, the digestible OM intake of sheep grazing barrel medic pastures varied between 500-600 g/day in summer to 900-1000 g/day in winters. An average daily gain of lambs of 260-300 g/d could be achieved, with a meat production of 60 to 90 kg/ha (Brand et al., 1991a; Brand et al., 1991b). In Australia, sheep grazing barrel medic pastures achieved DM intakes of 1240 and 1885 g DM/d during the green and dry seasons. Grazing barrel medic supported a weight gain of 375 g/d in the green season, but it caused a weight loss of 106 g/d during the dry season. Feed conversion efficiency of sheep was greater when grazing Medicago truncatula than Medicago polymorpha, which can be explained by the heavier pod size and the lower hardseededness of Medicago truncatula, which probably made the seeds more digestible (Casson, 1988). Sheep wool production during summer was greater when sheep grazed Medicago truncatula pastures than when they grazed Medicago polymorpha or Trifolium subterraneum pastures, despite similar or lower forage and pods availability, showing its good nutritive value (Doyle et al., 1989). The nutritive value of barrel medic hay for sheep was considered similar to that of a good quality alfalfa hay (Denney et al., 1979).
Pods
Barrel medic pods have a low OM digestibility of only 24% due to their high ADF concentration (61% DM) and to a very low ADF in vivo digestibility (10%) (Denney et al., 1979).
Sheep can eat 20,000 to 30,000 seeds of barrel medic per day in summer when eating pods, and can excret in their faeces more than 1000 seeds per day, with a germination rate of 10-15%. Sheep grazing thus actively participates to seed dissemination and self-reseeding of annual medic pastures (Kotzé et al., 1995). Despite the low digestibility of the pods compared to hay (24% vs 65%), voluntary intake in wethers was only 20% lower on pods than on hay (600 versus 740 g DM/d) (Denney et al., 1979). Voluntary DM intake of pods may be as low as 5 g DM/kg LW after a poor growing season. Mixing the pods with 15% molasses doubled DM intake, but treatment with NaOH or water spraying and washing strongly reduced voluntary intake, probably due to reduced palatability (Valizadeh et al., 1993).
