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Sulla (Hedysarum coronarium)


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Common names 

Sulla, cock's-head, French honeysuckle, honeyplant, Italian sainfoin, soola-clover, Spanish sainfoin, sulla sweet vetch, sulla clover [English]; sainfoin d'Espagne, seille, sulla du nord [French]; sanfeno-da-Espanh, sula [Portuguese]; esparceta roja, pipirigallo, zulla, astorki [Spanish]; Spanische Esparsette, Französischer Süßklee, Italienischer Süßklee, Hahnenkopf [German]; lupinella selvatica, lupinellone, erba lupina, guadarulio [Italian]; فويلة إكليلية [Arabic]; Копеечник венечный [Russian]


Sulla coronaria (L.) B. H. Choi & H. Ohashi

Feed categories 

Sulla (Hedysarum coronarium L. and other Hedysarum species), is a biennial or short-lived perennial herbaceous legume used for forage in the Mediterranean basin.

Morphological description

Sulla is mostly upright, 30-150 cm high with thick, succulent stems that become slightly woody after flowering. It has a deep, branching tap-root (up to 2 m deep), with many secondary roots. The leaves consist of 7-15 pairs of oval leaflets with a single terminal leaflet. They are glabrous above and hairy below. The flower heads are racemes of 10-35 florets, light pink to bright red and crimson, each 3-6 mm long. Sulla produces brown segmented pods with a rough, thorny surface. The pods are non-shattering, but will split into segments (de Koning et al., 2010Foster, 2010). 


In the Mediterranean area, Hedysarum coronarium is the main sulla species used for livestock feeding, and its use is reported in feeding trials, notably in Italy. However, the related species Hedysarum flexuosumHedysarum carnosum and Onobrychis humilis (Loefl.) G. López (formerly Hedysarum humile Loefl.), that are indigenous to North Africa, are also used (Boussaid et al., 2004Amroun et al., 2006). The composition of these forages is more influenced by the vegetative stage at harvest than by the botanical species (Kadi, 2012). It should be noted that the sulla species is not always reported precisely in research papers.

Sulla is a highly palatable, nutritious and productive forage for ruminant production (de Koning et al., 2010Foster, 2010). It is cultivated throughout the Mediterranean basin, where it is extensively grown as a 2-year forage crop for grazing and/or hay or silage production. The species plays a key role in cereal-based systems of semi-arid regions, particularly in organic and low-input agriculture, and is commonly used to enhance the productivity and sustainability of farming systems (e.g. as a nitrogen supply and to maintain soil organic matter) (Ruisi et al., 2011). One of the main values of sulla is its water requirement coupled to its ability to provide large amounts of palatable forage in steppe areas (Crocker et al., 2003Lloyd et al., 2003). Since the 2000s, there has been a growing interest in sulla in traditional and non-traditional areas (particularly in New Zealand and Australia), due to its excellent adaptability to marginal and drought-prone environments, versatility as a good quality, high-protein forage crop, and its moderate levels of condensed tannins beneficial to ruminant production (Ruisi et al., 2011). Sulla is often compared to alfalfa for its quality and productivity, but unlike this legume its higher tannin content makes sulla suitable only to ruminants (including deer and alpacas) and other herbivore species that can tolerate tannins. It is not used in poultry or pig production, or in aquaculture.


Sulla originated in the western Mediterranean region and North Africa. It was domesticated only recently, in the 18th century in southern Italy and Sicilia, and is still popular there (Ruisi et al., 2011). In the late 1990s, 300 000 ha were grown in Italy, of which about 80 000 ha were in Sicily (Leto et al., 2002), and it was the second forage after alfalfa (FAO, 2013). Wild and domesticated sulla are also found in Spain, Portugal, Tunisia, Algeria and Morocco, though populations have declined in North Africa due to drought and agricultural pressure (Ben Jeddi, 2005). It has been introduced into other countries, notably New Zealand and Australia. One limitation to the introduction of sulla outside its native area is that it requires a specific root-nodule bacteria (Rhizobium sullae) for optimum nodulation and maximum nitrogen fixation. In countries where the soil does not contain this rhizobium, it is necessary to inoculate the seeds. This factor and the lack of commercial seed supply have in the past reduced the acceptance of sulla in New Zealand (de Koning et al., 2010; Ramirez-Restrepo et al., 2005).

Sulla grows from sea level to the frost line in the uplands in the Mediterranean area. Sulla has been observed in areas with more than 300 mm rainfall (Ben Jeddi, 2005) and has a high drought tolerance. For that reason, it is used for forage in semi-arid and arid regions (Foster, 2010). It prefers well drained, fertile, medium-to fine-textured soils. It usually does not grow well on coarse-textured soils, where inconsistent nodulation has been reported. Sulla prefers slightly acid to alkaline soils (5.5-8.5 in CaCl2), sandy loams, loams to clays. Better growth is achieved on the more alkaline soils (de Koning et al., 2010). It has moderate to high fertility requirements. It has low to moderate tolerance to waterlogging and no tolerance to salt. Sulla is not seriously affected by pests and diseases but under wet conditions it can be susceptible to root rot and is occasionally affected by powdery mildew and Rhizoctonia. Sulla has good tolerance to aphids, redlegged earth mite and alfalfa flea (FAO, 2013; Foster, 2010).


With its high dry matter yields and ease for cutting, sulla is suitable as green forage crop or for hay or silage. It is not recommended to cut sulla in the first year as a first year cut will weaken the stand and DM yield is often much higher in the second year. Sulla should be cut at early flowering as the stems can become woody after flowering and quality will be much lower despite higher yields (Foster, 2010de Koning et al., 2010). 


Sulla makes good silage. Including large amounts of sulla in silage (e.g. 75% and above) increases the level of lactic acid, resulting in lower pH and higher quality silage. Sulla has a high water soluble carbohydrate content which enhances silage quality. The condensed tannins of sulla slow down protein degradation during ensiling (Foster, 2010de Koning et al., 2010). However, fresh sulla has a low DM content (15-18%) that can hinder the ensiling process, and wilting may be necessary (Ben Jeddi, 2005). A good fermentation was achieved when sulla was ensiled at a DM content of at least 35% at the early bud stage, and fermentation was also acceptable when ensiled at 25% DM at the early flowering stage (Cavallarin et al., 2007).


Hay should be cut before peak flowering, preferably around 10% flowering (de Koning et al., 2010). However, cutting at the right stage is not always possible, resulting in lignified stems and lower quality hay (Leto et al., 2002). Like other legumes, sulla tends to shed leaves during hay making but leaf retention is better than for alfalfa. Sulla retains most leaf if conditioned and raked carefully. It is recommended to cut sulla 20-30 cm from ground level so that the cut plant can dry off the ground supported by the cut stems (Foster, 2010de Koning et al., 2010). 

Forage management 

Yield and productivity

Sulla is considered a productive forage. Under semi-arid conditions in southern Italy and Sardinia, sulla pastures grazed by dairy sheep reached 6-7 t DM/ha. Yields of 6.6 and 9.6 t DM/ha have been reported in Italy in non-irrigated and irrigated stands, respectively (FAO, 2013). In New Zealand, yields can reach 12-18 t DM/ha in stands grazed by sheep or cattle (FAO, 2013). Second-year yields are often (not always) higher than first-year yields. In Australia, under ideal conditions of moisture and temperatures, sulla can produce up to 10 t DM/ha in the first year and over 20 t DM/ha in the second year (de Koning et al., 2010). In Tunisia, yield of irrigated sulla was 6.3 t DM/ha in the first year and 16.4 t/ha in the second year, though usual yields vary between 3-6 t/DM ha (1st year) and 4-8 t DM/ha (2nd year) (Ben Jeddi, 2005). When grown under poor conditions (e.g. coarse-textured soils, low fertility), the productivity and persistence of sulla are low and generally inferior to alfalfa (Foster, 2010).


In the establishment year, sulla should be lightly grazed to ensure good root development and plant numbers for the second year. Sulla does not tolerate heavy grazing as the relatively high soft crowns and succulent stems are preferentially grazed and easily damaged. Rotational grazing is to be preferred with 38-85 days of rest between grazing (regrowth of 30-40cm high), depending on moisture, day-length and soil temperature. After grazing, at least 10 cm of stubble should remain to avoid  delay in regrowth. Grazing during wet soil conditions should be avoided as this can result in damage from hooves, particularly from cattle (Foster, 2010de Koning et al., 2010).

Environmental impact 

Soil improver and erosion control

Sulla can be a pioneer species in poor, compact and degraded soils and, as an N-fixing legume, improve soil fertility for the next crop (Ben Jeddi, 2005). Notably, sulla was introduced in the 1950s for erosion control in New Zealand (Krishna et al., 1990). 

Methane emissions

In New Zealand, dairy cows grazing sulla produced less methane per unit DM intake (19.5 vs. 24.6 g CH4/kg DM) and per unit milk solids (243.3 vs. 327.8 g CH4/kg of milk solids) than cows fed perennial ryegrass, due to the higher nutritive value of sulla and to the presence of condensed tannins (Woodward et al., 2002).

Other environmental benefits

Sulla is valued for honey production, roadside beautification and landscape architecture (Foster, 2010; Ruisi et al., 2011).

Nutritional aspects
Nutritional attributes 

Fresh sulla is a forage legume with a high protein content (15-27% DM), and a composition close to that of alfalfa or red clover (Trifolium pratense). Its nutritive value decreases rapidly as the plant matures (Ben Jeddi, 2005). The hay has a lower quality than the fresh material due to the loss of leaves during and after harvest. One important characteristic of sulla is the presence of condensed tannins, which have positive and negative effects on nutrition (see Potential constraints below).

Potential constraints 

Sulla is reported to be safe to livestock. In particular, it does not cause bloat in ruminants (FAO, 2013).


The leaves, stems and flowers of sulla are rich in condensed tannins and levels of 0.8-5% (Italy, Amato et al., 2005) and 3-12% DM (Australia, Foster, 2010) have been reported. Tannin levels depend on the environment, growth stage and genotype (Amato et al., 2005). In New Zealand, a sulla pasture contained more condensed tannins in spring than in autumn (8.4 vs. 5.1% DM) (Hoskins et al., 1999).

Condensed tannins have detrimental effects in monogastrics and their effects in ruminants are debated. On the one hand, it has been suggested that levels lower than 6% DM, such as those found in sulla, have a positive effect in ruminants as they bind protein and improve protein utilization and thus performance (Bonanno et al., 2011). Sulla tannins may help to lower methane emissions in ruminants (Woodward et al., 2002). They also have beneficial effects on animal health by reducing parasite numbers (Waghorn, 2008). On the other hand, in warm and hot climates, the condensed tannins of sainfoin, sulla and Lotus species tend to be detrimental to ruminant performance, as they reduce protein availability in forage diets that are already deficient in protein (Waghorn, 2008). When sulla was grazed at flowering by dairy sheep, the condensed tannins had negative effects on DM and protein digestibility, though this was partially counterbalanced by a better metabolic utilisation of the nutrients (Molle et al., 2009).


Sulla is a high quality forage for ruminants. In Australia, it is considered as ideal for finishing prime lambs or beef cattle due to enhanced growth rates. Sulla has the capacity to increase milk production in dairy cows (de Koning et al., 2010). However, most feeding experiments reported concerned sheep production. 

Digestibility and nutritive values

Sulla is quite digestible, with OM digestibility values as high as 75%. The nutritive value decreases with maturity: in a trial in Tunisia, OM digestibility decreased from 74% at budding to 56% at flowering (Ben Jeddi, 2005). High levels of rumen protein degradability have been reported (> 70%) (Dentinho et al., 2011).


Sulla is very palatable to livestock, who will selectively graze it when sown in a mixed sward. Quality peaks just before flowering, but the foliage becomes less palatable once flowering starts as stems become more fibrous (de Koning et al., 2010). The stems are succulent and well accepted by livestock: in a trial, 85% of sulla stems were eaten by young lambs (Douglas et al., 1999).

Parasite control

Sulla has been shown to increase resistance to parasites (such as nematodes) in sheep and deer, an effect attributed to the presence of condensed tannins. It is considered as one of the best forages for sustainable long-term parasite control (Ramirez-Restrepo et al., 2005). Sulla tannins were effective in the inhibition of larval migration of deer lungworms and gastrointestinal nematodes (Molan et al., 2001).

Dairy cattle

Several experiments in New Zealand have shown sulla to be valuable for dairy cows. Sulla silage was found to be a suitable supplement for grazing dairy cows during summer. Dairy performance was similar with sulla and maize silages, with the sulla silage (6 kg DM/day) resulting in a higher DM degradation rate than the maize silage (Chaves et al., 2006). However, in another comparison, sulla silage resulted in less milk solids than Lotus corniculatus silage, perhaps due to its lower protein and lower condensed tannins (Woodward et al., 2006). Cows grazing sulla had a higher DM intake (13.1 vs. 10.7 kg DM/day) and milk solids production (1.07 vs. 0.81 kg/day) than cows grazing perennial ryegrass pasture (Woodward et al., 2002).

Beef cattle

While sulla has been reported as ideal for finishing beef cattle (de Koning et al., 2010), there is no trial in the literature (as of 2013) reporting use of sulla for beef production.


There have been numerous trials in Italy, North Africa, Australia and New Zealand looking at the value of sulla in sheep for meat, milk and wool production. Grazing on sulla forage has been shown to have a positive impact on the productivity of meat and dairy sheep (Burke et al., 2002Bonanno et al., 2007aMolle et al., 2009). In grazing trials, better lamb performance was achieved from sulla than from grass/white clover, a result attributed to a very high readily fermentable to structural carbohydrate ratio (Terrill et al., 1992a). In Australia, ewes grazing a sulla-based pasture for 8 weeks had better growth rate, final weight and wool growth (longer wool) than ewes grazing a control pasture of grass and subclover (de Koning et al., 2010). In New Zealand, better performance of lambs grazing sulla compared with alfalfa was attributed to the protective effects of condensed tannins on nematode infection and protein protection in the rumen (Niezen et al., 1995). In a comparison of Lotus corniculatus and sulla grazed as sole diets for 4 months by young lambs, the condensed tannins in sulla were detrimental to carcass yield, but sulla produced more DM and was better utilized than Lotus, being able to sustain high levels of animal production per hectare (Douglas et al., 1999). In Italy, a comparison of sulla-oat hay and sulla-oat silage fed to lactating ewes did not show differences in DM intake, milk yield, milk protein, milk fat, cheese yield and cheese microbiological characteristics, and it was concluded that sulla silage was a good alternative to sulla hay (Leto et al., 2002). A diet of sulla minimized scouring and the formation of dags (locks of wool matted with dung that tend to attract flies) (de Koning et al., 2010). 

The condensed tannins of sulla may have beneficial effects on product quality. Meat from lambs fed fresh sulla had a lower proportion of saturated fatty acids, higher n-3 fatty acids and conjugated linoleic acid, and lower n-6 fatty acids than animals fed concentrates (Priolo et al., 2005). Milk from dairy ewes grazing sulla at flowering had a lower content of conjugated linoleic acid, but was richer in n-3 fatty acid and had a lower n-6:n-3 ratio, than milk from ewes supplemented with PEG (which neutralizes the effect of condensed tannins) (Cabiddu et al., 2009).


In Italy, with goats grazing a sulla monoculture, a high stocking rate (70 head/ha) reduced sulla height and availability during the first 35 days. Intake and milk yield was higher at lower stocking rates (30 and 50 heads/ha). However, while overstocking led to a lower total milk yield per goat, it also produced the highest daily and total milk yield per ha (Bonanno et al., 2007b).


In New Zealand, young red and hybrid deer (75:25 deer:elk) grazing sulla had higher final live weights and carcass weights than deer grazing chicory (Cichorium intybus) or perennial ryegrass/white clover pastures (Hoskins et al., 1999).


In Southern Italy, sulla is a traditional forage used in rabbit feeding. For example, sulla hay was included at 30% in the control diet used to study other types of forages (Leto et al., 1981). In small farms, sulla is cultivated as a single forage or mixed with oats, ryegrass and, sometimes, vetch, and the hay is used to feed rabbits (Bovera et al., 2008). In Algeria, sulla green forage and sulla hay (mainly Hedysarum flexuosum) are used as fodder by smallholder rabbit farmers (Kadi, 2012).

Sulla (Hedysarum coronarum and Hedysarum flexuosum) can be considered as a safe forage for rabbit feeding. It is a source of protein and mainly of fibre, with a potential use comparable to that of alfalfa or berseem. Sulla used as sole feed can support maintenance and enable good growth rates, particularly if the young plant or leaves are used (Proto et al., 1967Kadi et al., 2012). In balanced diets, sulla hay has been used up to 30-35% of the diet, mainly as source of fibre, and has, in some trials, completely replaced alfalfa hay (Alicata et al., 1988Cucchiara, 1989Kadi et al., 2011). In a study where sulla hay and a non-pelleted concentrate were both offered ad libitum to growing rabbits, the spontaneous intake of sulla hay was 53% of the total DM intake, and growth rate was identical to that of control rabbits fed a pelleted commercial diet (Berchiche et al., 1996).

Horses and donkeys 

Sulla is generally considered as highly palatable for horses (de Koning et al., 2010). However, a comparison of grazing preferences in New Zealand showed that sulla, alfalfa and sainfoin were much less palatable than grasses (brome, ryegrass, cocksfoot) and white clover (Trifolium repens) (Hunt et al., 1989).

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 12.3 2.5 9.1 15.6 11  
Crude protein % DM 20.2 3.1 15.2 27.3 28  
Crude fibre % DM 24.3 4.1 19.2 30.5 10  
NDF % DM 36.8 5.8 26.0 48.9 16  
ADF % DM 28.8 5.4 21.1 38.1 12  
Lignin % DM 8.5 2.0 6.3 12.6 10  
Ether extract % DM 2.5 0.4 1.7 3.1 11  
Ash % DM 11.4 1.7 9.1 14.3 18  
Starch (polarimetry) % DM 2.4       1  
Total sugars % DM 14.8       1  
Water-soluble carbohydrates % DM 8.3 5.5 2.7 17.6 6  
Gross energy MJ/kg DM 18.1         *
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 16.3 6.1 11.2 23.0 3  
Phosphorus g/kg DM 2.6 1.4 1.0 3.4 3  
Potassium g/kg DM 6.7       1  
Sodium g/kg DM 3.5       1  
Magnesium g/kg DM 2.8       1  
Iron mg/kg DM 200       1  
Fatty acids Unit Avg SD Min Max Nb  
Palmitic acid C16:0 % fatty acids 14.7 3.1 11.8 20.5 6  
Stearic acid C18:0 % fatty acids 2.9 0.4 2.5 3.6 6  
Oleic acid C18:1 % fatty acids 4.3 1.1 3.2 5.9 6  
Linoleic acid C18:2 % fatty acids 10.1 1.6 8.7 12.6 6  
Linolenic acid C18:3 % fatty acids 64.2 4.3 56.9 69.4 6  
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins, condensed (eq. catechin) g/kg DM 53.3 35.7 16.7 120.5 11  
In vitro digestibility and solubility Unit Avg SD Min Max Nb  
OM digestibility, cellulase % 72.6 9.7 54.0 81.9 6  
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 71.0 5.8 61.1 74.6 7 *
Energy digestibility, ruminants % 67.9         *
DE ruminants MJ/kg DM 12.3         *
ME ruminants MJ/kg DM 9.7         *
Nitrogen digestibility, ruminants % 68.5 5.5 56.4 72.0 7  
a (N) % 44.0       1  
b (N) % 43.0       1  
c (N) h-1 0.140       1  
Nitrogen degradability (effective, k=4%) % 77         *
Nitrogen degradability (effective, k=6%) % 74         *

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


Alibes et al., 1990; Bonanno et al., 2011; Cabiddu et al., 2005; Cabiddu et al., 2009; Cavallarin et al., 2007; Dentinho et al., 2011; Douglas et al., 1999; Fulkerson et al., 2007; FUSAGx/CRAW, 2009; Gasmi-Boubaker et al., 2012; Hoskins et al., 1999; Martiniello et al., 2000; Maymone et al., 1945; Niezen et al., 1995; Priolo et al., 2005; Terrill et al., 1992; Tisserand et al., 1989

Last updated on 09/12/2013 16:11:08

Includes a sample of Hedysarum flexuosum hay

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 87.2 1.5 85.5 88.5 3  
Crude protein % DM 14.3 1.7 12.5 16.6 4  
Crude fibre % DM 29.4   28.7 30.0 2  
NDF % DM 48.2 6.3 41.4 53.8 3  
ADF % DM 37.7 6.7 30.9 44.2 3  
Lignin % DM 8.6   8.2 9.0 2  
Ether extract % DM 2.0       1  
Ash % DM 10.9 2.3 9.1 14.1 4  
Starch (polarimetry) % DM 2.5       1  
Total sugars % DM 9.1       1  
Gross energy MJ/kg DM 17.9   17.0 17.9 2 *
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 5.8   1.2 10.4 2  
Phosphorus g/kg DM 1.6   0.3 2.9 2  
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 61.6 1.3 56.3 61.6 3 *
Energy digestibility, ruminants % 58.1         *
DE ruminants MJ/kg DM 10.4         *
ME ruminants MJ/kg DM 8.3         *
Nitrogen digestibility, ruminants % 57.6 2.1 55.7 59.8 3  
a (N) % 21.0       1  
b (N) % 54.0       1  
c (N) h-1 0.120       1  
Nitrogen degradability (effective, k=4%) % 62         *
Nitrogen degradability (effective, k=6%) % 57         *
Rabbit nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, rabbit % 52.6       1  
DE rabbit MJ/kg DM 7.9         *
Nitrogen digestibility, rabbit % 42.8       1  
MEn rabbit MJ/kg DM 7.6         *

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


Alibes et al., 1990; Dentinho et al., 2011; Kadi et al., 2011; Maymone et al., 1945

Last updated on 09/12/2013 15:57:57

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 35.4 1.4 34.1 36.8 3  
Crude protein % DM 14.4 1.4 12.9 15.7 3  
NDF % DM 51.9 2.6 50.0 54.8 3  
ADF % DM 42.8 3.7 40.6 47.1 3  
Lignin % DM 8.4   8.0 8.7 2  
Ether extract % DM 5.2       1  
Ash % DM 10.5   10.1 10.8 2  
Starch (polarimetry) % DM 2.3       1  
Total sugars % DM 2.8       1  
Gross energy MJ/kg DM 17.4       1  
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 11.0       1  
Phosphorus g/kg DM 3.0       1  
Secondary metabolites Unit Avg SD Min Max Nb  
Tannins, condensed (eq. catechin) g/kg DM 16.0       1  
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 59.6       1  
Energy digestibility, ruminants % 55.4         *
DE ruminants MJ/kg DM 9.6         *
ME ruminants MJ/kg DM 8.1       1  
Nitrogen digestibility, ruminants % 48.6       1  
a (N) % 58.0       1  
b (N) % 27.0       1  
c (N) h-1 0.090       1  
Nitrogen degradability (effective, k=4%) % 77         *
Nitrogen degradability (effective, k=6%) % 74         *

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


Chaves et al., 2006; Dentinho et al., 2011; Woodward et al., 2006

Last updated on 09/12/2013 16:03:39

Datasheet citation 

Heuzé V., Tran G., Lebas F., 2016. Sulla (Hedysarum coronarium). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/292 Last updated on October 27, 2016, 17:12

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)