Red clover (Trifolium pratense)

Datasheet

Description

Click on the "Nutritional aspects" tab for recommendations for ruminants, pigs, poultry, rabbits, horses, fish and crustaceans

Common names

Red clover, peavine clover, purple clover, cow grass [English]; trèfle violet, trèfle rouge, trèfle des prés [French]; trébol violeta, trébol común, trébol rojo [Spanish]; trevo dos prados, trevo violeta, trevo vermelho [Portuguese]; rode klaver [Dutch]; Wiesen-Klee, Rot-Klee [German]; trifoglio dei prati, trifoglio rosso, trifoglio violetto [Italian]; koniczyna czerwona, koniczyna łąkowa [Polish]; cỏ ba lá hoa đỏ [Vietnamese]; برسيم أحمر , برسيم المروج , النفل الأحمر ,نفل المروج [Arabic]; 红车轴草 [Chinese]; ムラサキツメクサ [Japanese]; 붉은토끼풀 [Korean]; Клевер красный, Клевер луговой [Russian]

Species

Trifolium pratense L. [Fabaceae]

Synonyms

Trifolium expansum Waldst. & Kit., Trifolium fontanum Bobrov, Trifolium nivale Sieber ex W. D. J. Koch, nom. inval., Trifolium pratense var. frigidum Gaudin, Trifolium pratense var. nivale W. D. J. Koch, nom. illeg., Trifolium pratense var. spontaneum Willk., Trifolium sativum (Schreb.) Crome ex Boenn., Trifolium sativum subsp. praecox Bobrov

Related feed(s)

Description

The red clover (Trifolium pratense L.) is a short-lived perennial (2-4 years) legume forage, mainly from temperate areas. It has an erect habit and may lodge when the plant becomes stemmy. It forms a 1 m deep taproot in the first year and then produces secondary adventitious roots that explore the upper soil layer (30 cm deep). Basal buds form a crown above the soil and may root at the nodes. Each bud produces 4-6 upright, hollow and pubescent stems, up to a height of 60-80 cm. The leaves borne on the basal crown are long and petiolate, while the leaves borne on stems are often nearly sessile. The leaves are trifoliate or palmate-trifoliate, pubescent and alternate. Leaflets are oval or elliptic, 1-3 cm long x 0.5-1.5 cm broad (FAO, 2013; Ecoport, 2013; Hannaway et al., 2004). They are typically variegated with a white V-like mark (Hannaway et al., 2004). The inflorescences are terminally or axillary borne on the stems, and are globose clusters of many tubular flowers, 10-15 cm long, and pink, purple or magenta-coloured. The inflorescence develops into an oblong-ovoid pod containing 2 seeds (FAO, 2013; Ecoport, 2013). There are many varieties and cultivars of red clovers. The two main types of cultivars are the early-flowering cultivars, called medium or double-cut, which produce at least two cuttings per season, and the late-flowering cultivars, called mammoth or single-cut, which produce one cutting per season (Duke, 1983).

Red clover is an important forage in temperate climates. It is also grown in subtropical regions at high altitudes. A highly productive forage, red clover is relished by livestock and is used for pasture, cut-and-carry systems, hay and silage. Red clover has a good N-fixing ability and is also a valuable break crop in arable and organic farming. Red clover is a major source of honey (FAO, 2013; Ecoport, 2013; Hannaway et al., 2004). Red clover has several medicinal uses: it has a high estrogen content and is used in symptomatic treatment of the menopause, though its efficacy is not proven (Geller et al., 2009).

Distribution

Trifolium pratense grows naturally on wet to dry meadows, in open forests, on field borders and paths. It is found between 30 and 68° latitude, from moist to wet boreal zones to subtropical moist forests. It can grow where annual rainfall ranges from 310 to 1920 mm with annual mean temperatures between 4.9°C and 20.3°C. Optimal growth occurs between 18°C and 25°C. Red clover is cold hardy provided it can make a rosette and store sufficient N in the roots before winter sets in (Ecoport, 2013; Duke, 1983). It does well under low light and can be intercropped with other species or sown with taller companions in pasture (FAO, 2013). Red clover grows on a wide variety of soils. However, it prefers well-drained loams, silt loams and even heavy soils to light, sandy or gravelly soils. Optimal soil pH should be above 6 with adequate Ca, though red clover is tolerant of high and low pH in aluminium-rich soils (Ecoport, 2013; Duke, 1983). Red clover can replace alfalfa in areas too wet or too acidic for it (Kephart et al., 2010). Red clover has some soil salt-tolerance (up 4 dS/m) (Hannaway et al., 2004). It is somewhat drought-tolerant. Some cultivars may withstand some waterlogging but not long periods of flooding (Ecoport, 2013; Duke, 1983).

Processes

Hay

During hay making, red clover is susceptible to leaf shattering and subsequent nutrient losses. It is advisable to mechanically or chemically condition red clover before hay making. Dry conditions are recommended as conditioned red clover might lose soluble carbohydrates and minerals by leaching in the event of rain (FAO, 2013). Red clover should be cut for hay when no more than 50% is in flower, when it has the optimal feeding value, with more than 14-15% protein. Harvesting red clover later impairs its feeding value but also compromises the second cut, as young shoots already elongated may be removed during the first cutting (Wheaton, 1993).

Ensiling

Red clover can be made into silage but has a low DM, low water soluble carbohydrates (WSC) content, and high buffering capacity. It is thus advisable to wilt red clover for 24-48 h before ensiling so that it reaches 25% DM, concentrates WSC and reduces water losses during fermentation. Prolonged wilting is not advisable because over-dry leaves may shatter, resulting in loss of nutrients. Short chopping may be useful (FAO, 2013). Use of additives (such as molasses, inoculants or enzymes), though not mandatory, can help obtain satisfactory silage (FAO, 2013; Dardni, 2010). Mixtures of red clover and grass make ensiling easier (FAO, 2013).

Forage management

Yield

Red clover grown in pure stands yields 4 to 18 t DM/ha in Europe. In the USA, pure stands of red clover yielded 15-19 t hay in 1998 (Satell et al., 1998). Yields are in the range of alfalfa (20 t DM/ha), but red clover does not yield as early as alfalfa (Duval, 1993). In mixed stands, a mixture of red clover with grass resulted in a yield equivalent to those from pure grass stands receiving fertilizer (FAO, 2013).

Establishment

Red clover can be sown (drilled or broadcast) with non aggressive grasses such as timothy (Phleum pratense), tall fescue (Festuca arundinacea), Italian ryegrass (Lolium multiflorum), or with vegetable crops such as chicory (Cichorium intybus). Red clover can be under-sown or direct-sown in small grain crops (maize, sorghum, wheat). In grass swards, red clover can be oversown for sward renovation. Red clover stands may be oversown with other clovers: white clover (Trifolium repens) is a frequent complement of red clover (Hall, 2007; Hannaway et al., 2004). Red clover can be sown in autumn as an annual winter forage, or in spring (Hall, 2007).

Cutting and grazing

Red clover can be primarily grown for hay or silage and should then be cut at the early-flowering stage for high yield and feed value (Hall, 2007). Two to three cuts/year are possible provided that the sward received enough fertilizers (P, K). In some cases, after a first cut, regrowth can be grazed. Rotational grazing is best suited for persistence. Light grazing is recommended for better persistence during the year of establishment. Heavy grazing is deleterious to persistence particularly during autumn as the plant cannot make sufficient carbohydrate and N reserves in its roots to withstand the winter. Trampling damages the crowns (FAO, 2013).

Environmental impact

Cover crop and soil improver

Red clover can be planted in autumn in order to provide cover to the soil during winter. An N-fixing legume, red clover can be used as green manure: it provides about 4.2 t DM/ha and 93 kg N/ha to the soil. Used as cover in orchards, red clover smothers spring weeds and improves soil tilth (Satell et al., 1998).

Estrogen contamination

Feeding red clover to ruminants may lead to the release of phytoestrogens in the environment through animal excretion. Phytoestrogens are recognized as endocrine-disrupting chemicals, responsible for growth and reproductive impairment in aquatic species when discharged into water (Harrison et al., 1995, Crisp et al., 1998 cited by Tucker et al., 2010).

Nutritional aspects

Nutritional attributes

Red clover is a nutritious forage, rich in protein (15-27% DM), minerals and soluble carbohydrates. Crude protein decreases with maturity, from 22% to 16% DM between the vegetative stage and the end of bloom for a French red clover, while NDF increases from 40% to 51%. Later cuts may contain more protein than the first and second ones (INRA, 2007).

Potential constraints

Bloat

Like many other forage legumes such as alfalfa or other clover species, red clover may cause bloat in livestock. This risk depends on intake and there are several ways to reduce it. It may be preferable to avoid pure stands of red clover and prefer mixed stands of red clover with grasses or legume species that are not prone to produce bloat, such as chickpea and sainfoin. Hungry livestock should be prevented from entering pure stands of red clover, for instance by feeding dry forages to them beforehand. Another method consists in preventing consumption peaks by keeping livestock in the stand at night. Risk of bloat decreases with plant age: livestock entering a full-bloom red clover stand have less risk of bloat than animals grazing a younger stand (Dalto et al., 2009; Kopp, 2003).

Urolithiasis

Red clover, as other clovers and forage legumes, may cause an increase in urinary calculi (clover stones) in sheep (Nagy, 2009; Hall, 2007). This may be due to the presence of benzocoumarins (a class of phytoestrogens) (Hall, 2007).

Reproductive disorders

Red clover contains several isoflavones, including daidzein, genistein, formononetin and biochanin A (Steinshamn, 2010; Saviranta et al., 2008; Cox et al., 1974). Cultivars with high isoflavone levels may have estrogen-like effects on animals. These compounds may disrupt reproductive cycles or impair fertility in sheep (McDonald et al., 1994). Reproductive disorders were also observed in sows fed red clover (Ballarini et al., 1977). In ewes, isoflavones were more concentrated in certain tissues (kidneys) than in muscles, making it unlikely that such compounds can be found in meat (Urpi-Sarda et al., 2008). Cattle appear to be less sensitive to these compounds (Dewhurst et al., 2009). Feeding red clover to dairy cows might increase concentrations of formononetin, daidzein and equol (an isoflavandiol metabolized from daidzein) in milk (Andersen et al., 2009; Mustonen et al., 2009; Steinshamn et al., 2008a). However, the intake of red clover had no influence on the equol content of meat (Moorby et al., 2004). As noted in Environmental impact, the excretion of isoflavones raises environmental concerns (Tucker et al., 2010).

Anthelmintic effect

In finishing lamb systems, red clover, like other legume forages, can contribute to the control of nematode parasites. Lambs grazing red clover had lower faecal egg counts and improved live-weight gains compared to lambs grazing ryegrass. However, red clover pasture increased re-infection of grazing lambs with Trichostrongylus species compared to ryegrass following anthelmintic treatment (Marley et al., 2005).

Ruminants

Red clover is a common forage for ruminants in temperate countries where it is used for grazing, hay and silage.

Palatability

As other legumes, red clover leaves are highly prehensible, especially during the spring heading period (Dewhurst et al., 2009). A mixture of red clover and ryegrass is very palatable to cows and helps to mitigate the risk of bloat (Van Dorland et al., 2006; Charles, 1976). Red clover silage is highly palatable, more than grass silage but less than white clover silage (Steinshamn, 2010; Brink et al., 1988; Thomas et al., 1985; Steen et al., 1982).

Digestibility and degradability

The decrease of digestibility of red clover during maturing is lower for red clover than for grasses (Thomas et al., 1985). Red clover has a greater cell wall content than white clover and, therefore, a lower in sacco degradability and in vivo digestibility (Dewhurst et al., 2009). Compared to grasses, red clover has a higher rate of particle size reduction (Bowman et al., 1996) and a higher rate of degradation, linked both to its lower cell wall content and higher soluble carbohydrate content (Steinshamn, 2010; Moharrery et al., 2009). The differences in cell wall structure and degradation rate may explain the higher intake with red clover compared to grasses, as red clover has a lower rumen fill.

Effective nitrogen degradability was reported to be about 65-70% for fresh forage or silage, but only 60% for that stored in wrapped round bales (Aufrère et al., 2002; Marichal et al., 2010). However, there are differences between cultivars: in a study of 133 samples (16 to 21% DM protein), the nitrogen degradation rate varied from 0.088 to 0.146 and by-pass protein ranged from 29 to 41% (Broderick et al., 2004). During ensilage, red clover undergoes extensive protein degradation: the resulting high levels of quickly degradable nitrogen require carbohydrate-rich feeds in order to add energy to avoid inefficient nitrogen utilization and a large loss of N in the urine (Vanhatalo et al., 2009). However, supplementation of red clover with a high-protein ryegrass could increase nitrogen losses, which does not help to mitigate methane emissions (Van Dorland et al., 2007).

Dairy cows

Pasture

A pasture combining red clover, white clover, tall fescue, phalaris and cocksfoot was reported to be a good choice for Jersey cows and was of better nutritive value than one based on ryegrass and white clover (Thom et al., 2001). Milk from cows grazing or fed fresh forage, especially from species-rich grasslands or forage legumes, had a considerably higher ratio of unsaturated to saturated fatty acids, and a higher content of nutritionally beneficial trans-fatty acids (e.g. CLA, vaccenic acid) than milk from cows fed silage or hay (Kalac et al., 2010).

Silage

In a review of forage legumes (Steinshamn, 2010), it was noted that, at similar DM intake, dairy cows fed red clover silage produced a little less milk than those fed white clover silage. Cows on red clover silage diets had a milk fat content lower on average by 2.0 g/kg milk than cows fed grass silages, and milk protein content also tended to be lower. The milk protein decrease may be linked to the polyphenol oxidase enzyme, which produces phenols that bind to amino acids. Even if red clover causes a higher supply of amino acids to the intestine, sulphur-containing amino acids are less available than the other amino acids, and this imbalanced amino acid supply might explain the relative decrease in protein content compared to other sources (Vanhatalo et al., 2009).

Red and white clover grown in mixtures with grasses gave similar results for silage intake, milk yield and milk composition, but milk fat content of C18:3n-3 and C18:2n-6 was higher, and n-6:n-3 fatty acids ratio was lower on red clover diets (Steinshamn et al., 2008b). Partial replacement (40%) of grass silage with red clover silage increased yields of milk, protein and lactose, due to increased flows of microbial and dietary N entering the small intestine (Vanhatalo et al., 2006). Replacement of alfalfa with red clover increased feed and N efficiency, the digestibility of DM and cell wall components, and consequently the net energy for lactation. Nitrogen from red clover was better utilized when milk protein production was higher (Broderick et al., 2001; Broderick et al., 2000). Mixtures of red clover and maize silage (25:75 or 40:60) led to a significant increase in DM intake compared to grass silage (perennial ryegrass), and to a higher milk yield without altering milk composition. The N partition was more favourable to milk than to urine, due to an increased microbial protein synthesis permitted by the increased dietary starch provided by maize (Dewhurst et al., 2010).

The lower milk fat content resulting from legume-based diets (compared to grass-based diets), may be due to an increased supply of long-chain fatty acids to the mammary gland which inhibits the de novo fatty acid synthesis (Vanhatalo et al., 2007; Wiking et al., 2010). A second explanation might be the decrease in the molar proportion of rumen butyric acid, which is one of the main acids for the de novo synthesis (Vanhatalo et al., 2009). Red clover silage leads to reduced rumen biohydrogenation of 18:3 fatty acids, because the enzyme polyphenol oxidase, which is abundant in red clover, reduces lipolysis, a prerequisite of rumen microbial hydrogenation of unsaturated fatty acids (Lee et al., 2009b; Lourenço et al., 2008). Feeding red clover silage, especially at a young stage, increases α-linolenic acid (18:3n-3) in milk, which is beneficial to human consumption (Dewhurst et al., 2006; Van Dorland et al., 2008; Vanhatalo et al., 2007). In some studies, milk oxidative stability was lower for cows fed red clover diets, which was due to the increase in C18:3n-3 in milk (Havemose et al., 2006; Kalac, 2011). A solution to this problem is to supplement cows with Vitamin E (Al-Mabruk et al., 2004), even though clover silages are known to be among the most important sources of Vitamin E in organic farming (Beeckman et al., 2010). Replacing ryegrass silage with red clover silage did not modify the flavor of milk even when it decreased fat and protein concentration, and increased PUFA (polyunsaturated fatty acids) (Moorby et al., 2009). Substituting high quality ryegrass silage with red clover silage during the dry period had no influence on the performance of dairy cows in early lactation (Moorby et al., 2008).

Beef Cattle

Pasture

Steers grazing mixtures of red clover and tall fescue had greater average daily gains and larger ribeye areas than those grazing tall fescue only. However, there was no difference in muscle fatty acids concentration (Dierking et al., 2010). Moreover, a pasture rich in red clover increased the PUFA:SFA ratio in muscle from cattle compared to cattle from pastures rich in white clover or perennial ryegrass (Scollan et al., 2006).

Hay

Red clover hay associated with tall fescue for winter grazing, and Caucasian bluestem (Bothriochloa caucasica) for summer forage was found to be a very valuable supplement for stocker steers in the Southern USA (Allen et al., 2000).

Silage

Wilted red clover silage was fed to fattening bulls, even though it has a lower feeding value than maize silage, resulting in longer fattening periods, but it saved about 120-130 kg concentrate/head. Red clover silage, treated with formic acid at 3 L/t and supplemented with 0.5 kg/d of soybean meal, achieved the same level of performance as a maize silage-based diet (Weiss et al., 1993). The fatty acid profile of meat from cattle offered clover silage was better than that from cattle offered grass silage, because of an increase in the content of C18:3n-3, total n-3 fatty acids and total PUFA (Lee et al., 2009a).

Sheep

Pasture

Pure red clover swards had a lower nutritive value than white clover swards for growing sheep (John et al., 1981), but better than that of perennial ryegrass (Lolium perenne). It gave live-weight gains in lambs that were 70% greater than those obtained with ryegrass (Kemp et al., 2010). Red clover mixed with chicory, plantain (Plantago lanceolata) and white clover improved production of multiple-bearing ewes and their offspring compared to a ryegrass-dominant sward: animals were heavier, had higher body condition scores and produced more milk. Their lambs were heavier at birth and gained more weight during their first two months, which demonstrated that a herb sward mixture can improve the performance of multiple-bearing ewes as well as lamb performance compared to a ryegrass-dominant sward (Hutton et al., 2011).

Silage

Due to its high palatability, red clover silage fed to finishing lambs resulted in greater energy intake, faster growth rate, better condition score and a reduction in time to slaughter than lambs offered alfalfa or ryegrass (Speijers et al., 2004). Red clover silage replaced ryegrass silage in a way beneficial to fattening lambs (Speijers et al., 2005b). Red clover fed to ewes before lambing resulted in increased DM and live-weight gain for ewes and higher growth rates during the first 12 weeks for the lambs, compared to perennial ryegrass silage. However, red clover did not improve litter size (Speijers et al., 2005a).

Goats

Red clover, either alone or mixed with grasses in pure swards, can be used as a potential crop with a high protein content for dairy goats (Kravale et al., 2001). It can be used in zero-grazing (Masson et al., 1980). With alfalfa and ryegrass, red clover is considered one of the forages with the highest voluntary intake and milk yielding capacity for goats in temperate climates (Morand-Fehr et al., 1980), and a valuable source of protein for goats in cold arid zones such as Ladakh (Inda) (Mondal, 2009).

Pigs

Red clover can be used in pig feeding, particularly in alternative rearing systems. It can be grazed or fed as dehydrated meal or silage (Kephart et al., 2010). Red clover is considered a source of energy and protein in pig diets (Reverter et al., 1999; Lindberg et al., 1998). Mature red clover should not be fed as pigs do not relish it at this stage. Red clover should reach 15-20 cm high before being grazed. One ha of red clover can feed 30 to 50 growing pigs, 15-25 pregnant sows or 10-18 sows with litter (Duval, 1993).

Dehydrated red clover

The inclusion of 10 to 20% dehydrated red clover meal in barley-based diets for growing pigs reduced the digestibility of energy and nutrients (OM, protein, NFE) (Andersson et al., 1997). In fattening pigs fed a cereal-soybean meal diet, the inclusion of 15% red clover meal decreased the ME value of the diet but had no adverse effects on nitrogen balance or nutrient digestibility (Tywonczuk et al., 1997). In a comparison with other forage legumes meals (white clover and alfalfa) and perennial rygrass, red clover meal had the highest energy digestibility (67%) for growing pigs. Red clover had higher NDF digestibility than perennial ryegrass (Lindberg et al., 1998; Andersson et al., 1997). Red clover feeding had a limited impact on amino acid digestibility compared to other forage legumes (Reverter et al., 1999). Feeding forage meals to pigs, including red clover, resulted in higher N intake, faecal N excretion and urinary energy losses (Lindberg et al., 1998).

Pasture

In growing pigs and sows grazing a mixed pasture of ryegrass and red clover, digestibility decreased, but more so in growing pigs because they digest high fibre diets less readily than sows. Red clover pasture had a positive effect on protein digestibility (Vestergaard et al., 1995). Pigs foraging red clover had lower feed:gain ratios (Juska et al., 2012).

Silage

Pigs fed on red clover silage had lower intramuscular fat and higher PUFA, omega 3 and omega 6, than pigs fed a conventional diet. The meat, after cooking, had a higher n-3 content and a lower n-6:n-3 ratio (Johansson et al., 2002). Loins (longissimus dorsi muscle) from pigs fed on red clover silage had a lower gustatory quality, both 4 days after slaughter and after 1 year of freezer storage, than loins from conventionally fed pigs (Jonsall et al., 2000; Johansson et al., 1999).

Rabbits

Red clover is a traditional legume forage for rabbit feeding. It is a source of fibre while providing a significant amount of protein in the diet (Carabaño et al., 1992).

Fresh red clover

Fresh red clover is very palatable for young rabbits. In a comparison of 14 fresh forages, red clover was in the top 5 together with sunflower leaves, beans green vine, carrot tops and cauliflower leaves (Harris et al., 1983). The free choice distribution of a mixture of forages based mainly on red clover, lettuce and cabbage with a complete pelleted diet led to saving about 37% of pellets, without affecting growth rate (Pote et al., 1980). In the same experiment, it was found that pellets could be restricted to 50% of the pellet intake of rabbits fed only pellets when free choice greens were fed, without reducing performance.

When growing rabbits have a three-way choice between rolled cereal grains, alfalfa pellets and red clover + grass hay, the spontaneous fed intake of forages (alfalfa and hay) was too low to provide enough fibre to maintain the digestive health of the rabbits (Gidenne et al., 2010), resulting in a high enteritis mortality (Sanchez et al., 1981). However, this mortality was a consequence of the regulation of feed intake in rabbits given free choice (Gidenne, 2006) and was not linked to red clover itself.

Red clover hay

Red clover hay introduced at up to 30% in balanced diets in place of alfalfa meal (0, 33, 66 or 100% replacement) did not alter growth, digestibility and mortality (Grandi et al., 1988), indicating that red clover hay could be used safely in complete diets for rabbit feeding.

Fish

Red clover has been used in aquaculture as a growth promoter. It is considered an alternative source of estrogens and may be fed to various species to promote growth, and increase protein and fat content. Red clover included at small doses varying between 25 and 200 mg/kg diet was shown to promote fish growth, enhance protein and fat content in three fish species: 75 mg/kg in African catfish (Clarias gariepinus); 100 mg/kg in common carp (Cyprinus carpio); and in blue tilapia (Oreochromis aureus) (Turan et al., 2005; Turan et al., 2007; Turan, 2006). Survival was higher only in common carp (Turan et al., 2007).

Nutritional tables

Tables of chemical composition and nutritional value

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