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Barrel medic (Medicago truncatula)

Datasheet

Description
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Common names 

Barrel medic, barrel medick, barrelclover, barrel clover, caltrop medic, cylindrical bur medic, strong-spined medick [English]; luzerne tronquée [French]; medica troncata [Italian]; trébol barril [Spanish]; luzerna-cortada [Portuguese]; Gestutzter Schneckenklee [German]; tornlusern [Swedish]; فصة برميلية [Arabic]; یونجه سربریده [Farsi]; Люцерна усечённая [Russian]

Synonyms 

Medicago tribuloides Desr., Medicago tribuloides var. breviaculeata Moris, Medicago truncatula f. tricycla Nègre (basionym), Medicago truncatula var. breviaculeata (Moris) Urb., Medicago truncatula var. longiaculeata Urb., Medicago truncatula var. tribuloides (Desr.) Burnat, Medicago truncatula var. tricycla (Nègre) Heyn

Feed categories 
Description 

The barrel medic (Medicago truncatula Gaertn.) is a small annual weedy legume species and a close relative of alfalfa (Medicago sativa). Medicago truncatula serves as an important forage legume in regions of Australia and the Mediterranean area (Küster, 2013).

Morphology

Medicago truncatula is a semi prostrate annual with ascending stems to 15-50 cm high. It branches from the base and produces a large number of runners. Its vegetative parts variably covered with hairs. The leaves are alternate, trifoliolate, with sharp serrations on the upper half. Like for other medics, the central leaflet has a longer stalk than those of the other two leaflets. Barrel medic flowers are creamy to yellow and form clusters of 6–12. The mature seed pods are barrel-shaped, spiny with 2–8 coils, light yellow to dark grey. The seeds are kidney-shaped, light yellow to brownish, carried in a cylindrical coil (SALTdeck, 2006; Lonchamp, 2000; Küster, 2013). Medicago truncatula hybridizes with Medicago littoralis (Küster, 2013) and it closely resembles Medicago rigidula (Lonchamp, 2000).

Uses

Medicago truncatula is widely used to feed livestock as fresh forage and hay in Mediterranean countries and in Australia. Several hundred ecotypes have been collected and characterized, and there are commercially available cultivars, including some with spineless pods (Küster, 2013). Medicago truncatula is a long-established model for the study of legume biology and the decoding of its genome sequence in 2011 provided significant opportunities to expand alfalfa’s genomic toolbox (Young et al., 2011).

Distribution 

Medicago truncatula is of omni-Mediterranean origin. It is one of the most common weedy Medicago species of Old World rural habitats, and it is widely used and cultivated in all Mediterranean countries in North Africa and Southern Europe as well as in Australia, South Africa, and North America and (Ates et al., 2013; Küster, 2013).

Barrel medic can grow in places where annual rainfall is higher than 2750 mm and does well on sandy loams to clayey, neutral to alkaline soils (pH>6.5) in Australia (Nair et al., 2006). It has been referred to as a good legume forage in calcareous soils of the dry Causses in Southern France (Nair et al., 2006).

Forage management 

Medicaco trunculata is particularly adapted to the hot Mediterranean climate conditions. It has a short vegetation period centered on late winter/early spring. It is a winter-growing autogamous annual species with a short generation time of 3–6 months. The annual germination occurs in late autumn, the growth being mainly in winter and early spring, with flowering, maturing, pods production and senescence in late spring. Plants are completely dead in summer. Hardseededness is very important (until 80-9%) to avoid rapid germination if any rainy period in summer or in early autumn. Pods allow annual self-reseeding, with very large amounts of hard seeds produced (300-3000 kg pods/ha) (Michalk et al., 1976 ; Denney et al., 1979 ; Brownlee et al., 1985; Küster, 2013). In Australia, Medicago truncatula flowers September to December (SALTdeck, 2006).

In Australia and in the Middle East, annual medics are used in ley-farming systems, in alternance with annual crops such as cereals (2-year rotations, with one year of self-reseeding medics grazed by sheep, and one year of sown cereals such as wheat) (Michalk et al., 1976 ; Ates et al., 2013). Various commercially available Medicago truncatula varieties are commonly grown in rotation with cereal crops on a variety of soils in areas of Australia receiving up to 400 mm annual average rainfall (Küster, 2013).

The annual productivity of Medicago truncatula is good for forage (4-7 t DM/ha/year) and for pods (0.5 to 3 t DM/ ha/year), despite its short growing period. The seeds produced in late spring enable the reseeding of the pasture at the next autumn, and also enable to feed small ruminants grazing during the summer (Brownlee et al., 1985 ; Doyle et al., 1989).

Environmental impact 

N-fixing legume

Medicago truncatula develops root nodules in symbiosis with the nitrogen-fixing soil bacterium Sinorhizobium meliloti (Rhizobiaceae). It is able to grow in nitrogen-depleted soils, which is key to its use in sustainable agricultural systems (Küster, 2013).

Nutritional aspects
Nutritional attributes 

Green forage

Barrel medic is recognised as a good quality forage when fed green, particularly in the context of the dry Mediterranean areas. Its energy value may be considered as similar to that of a fresh alfalfa, with high a protein concentration, often close or greater than 20% DM) (Denney et al., 1979; Brand et al., 1991a; Shrestha et al., 1998, Selmi et al., 2010; Gasmi-Boubaker et al., 2012). There are large variations in the crude protein content according to the vegetative stage or the season ranging for instance beween 15.4% DM in summer to 30.8% DM in winter (Brand et al., 1991a; Brand et al., 1991b). In Tunisia, the average crude protein content of Medicago truncatula harvested at mid-bloom was estimated at 19.6% of DM and the NDF content at 41.0% (Gasmi-Boubaker et al., 2012).

The NDF concentration may be low in young plants after 2 to 3 months of growth or in leaves (35-41% DM), with moderate ADF concentration (25-29% DM) (Shrestha et al., 1998; Selmi et al., 2010). Mineral composition (P, Ca, K, Na, MG and Fe) is typical of that of good quality cultivated legumes species (Pisum sativum or Vicia sativa) (Gasmi-Boubaker et al., 2012; Benyoussef et al., 2016).

Hay

The barrel medic hay is of similar nutritive value as a good quality alfalfa hay, because of its high leaf proportion and thanks to the fineness of the stems (Denney et al., 1979).

Pods

Pods are characterised by a low energy value due to very high fibre concentration, high lignification and very low fibre (ADF) digestibility (Denney et al., 1979; Kotzé et al., 1995). However, seed pods may represent a primary protein source during the summer dry period because of their high CP concentration (14-22% DM : Denney et al., 1979; Kotzé et al., 1995; Valizadeh et al., 1993).

Potential constraints 

When compared to other Mediterranean legume species in Tunisia, Medicago truncatula was found to have low concentrations of anti-nutritional components such as phenols (6.2% DM), tannins (3.6% DM) and condensed tannins (1% DM) (Benyoussef et al., 2016).

Ruminants 

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).

Rabbits 

No information seems available in the international literature (April 2020) on the use of Medicago tuncatula in rabbit feeding. As shown in the previous sections, this annual lucerne is used to feed ruminants in various countries and has a good nutritional quality. For these reasons, Medicago tuncatula must be considered as a good potential fodder for rabbits with utilisation constraints similar to that of alfalfa. An important point that needs to be monitored is the actual composition and particularly the protein content of the batch of barrel medic that would be used to feed rabbits. However direct experiments would be welcome.

Nutritional tables

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 17.6   11 21 3  
Crude protein % DM 18.5 5.5 10.2 29 39  
Crude fibre % DM 19.3 8.8 10 34.6 25  
Neutral detergent fibre % DM 41.7 13.8 21.5 69.1 15  
Acid detergent fibre % DM 27.8 9.9 16.6 54.5 13  
Lignin % DM 3.4   3.2 3.7 2  
Ether extract % DM 3.1       1  
Ash % DM 21.5 9.5 11.7 47.6 27  
Gross energy MJ/kg DM 16.8         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 20.7   16.1 27 4  
Phosphorus g/kg DM 3.2   1.8 4.6 3  
Potassium g/kg DM 15.2       1  
Sodium g/kg DM 2.2   1.6 2.8 2  
Magnesium g/kg DM 3.7       1  
Iron mg/kg DM 300       1  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins (eq. tannic acid) g/kg DM 40       1  
Tanins, condensed (eq. catechin) g/kg DM 10       1  
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 72.2 11.3 36.4 77.6 24 *
Energy digestibility, ruminants % 69         *
ME ruminants MJ/kg DM 9.2         *
Nitrogen digestibility, ruminants % 73.6         *
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 7.3         *
MEn rabbit MJ/kg DM 6.4         *
Energy digestibility, rabbit % 43.7         *
Nitrogen digestibility, rabbit % 100         *

The asterisk * indicates that the average value was obtained by an equation.

References

Alane et al., 2020; Alford et al., 2003; Benyoussef et al., 2016; Brand et al., 1991; Franklin-McEvoy et al., 2007; Gasmi-Boubaker et al., 2012; Shrestha et al., 1998; Vargas et al., 1965

Last updated on 22/10/2020 15:54:25

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 94.9   94.6 95.6 4  
Crude protein % DM 16.9 2.4 14.2 20.2 6  
Crude fibre % DM 33.5       1  
Neutral detergent fibre % DM 69.1 3.1 66.2 73.7 5  
Acid detergent fibre % DM 50.3 6.7 45.3 60.7 5  
Lignin % DM 12.3 1.9 10.8 15.6 5  
Ether extract % DM 4.9       1  
Ash % DM 7.4 7 3.8 21.7 6  
Gross energy MJ/kg DM 19.4         *
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 34 6.1 24.3 39.6 5  
Energy digestibility, ruminants % 30.9         *
DE ruminants MJ/kg DM 6         *
ME ruminants MJ/kg DM 4.7         *
Nitrogen digestibility, ruminants % 63.9 3.5 60 68.5 5  
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 6.5         *
MEn rabbit MJ/kg DM 6         *
Energy digestibility, rabbit % 33.8         *
Nitrogen digestibility, rabbit % 61.4         *

The asterisk * indicates that the average value was obtained by an equation.

References

Denney et al., 1979; Kotzé et al., 1995; Valizadeh et al., 1993

Last updated on 22/10/2020 16:10:44

References
References 
Datasheet citation 

Heuzé V., Tran G., Delagarde R., Lebas F., 2020. Barrel medic (Medicago truncatula). Feedipedia, a programme by INRAE, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/274 Last updated on October 26, 2020, 15:25