Feedipedia
Animal feed resources information system
Feedipedia
Feedipedia

Rape forage

IMPORTANT INFORMATION: This datasheet is pending revision and updating; its contents are currently derived from FAO's Animal Feed Resources Information System (1991-2002) and from Bo Göhl's Tropical Feeds (1976-1982).

Datasheet

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

Rape forage, forage rape, rapeseed forage, canola forage [English]; colza fourrager, canola fourrager [French]; canola forrajera, colza forrajera, forraje de canola, forraje de colza [Spanish]

Description 

Rape forage (Brassica spp.) is a catch crop that can besown from spring to autumn and produce valuable fodder for livestock worldwide. It can be grazed, cut for cut-and-carry systems, made into hay or silage. Rape forage helps bridging the forage gap by the end of summer. Rape forage also provides several environmental services (improves the soil, decreases the risk of N leaching and soil erosion, fights against parasites)(GNIS, 2019).

Morphology

Rape forage has very variable habit depending on the variety or  the type of hybrid. Forage rape is taprooted, the stems are erect, many branched above. The basal and lower leaves are petiolated, very variable in shape, 5-40 cm long x 2-10 cm broad. The upper leaves are sessile, lanceolate, ovate or oblong, 8 cm long x 3.5 cm broad (eFloras, 2014). 

In the USA, two types of forage rape have been described: giant type that is leafy and upright and a dwarf type that is short and branched (Lemus et al., 2014). Giant type is reported to be preferred by cattle (Lemus et al., 2014).

Uses

Rape forage can be used for pasture, silage and in cut-and-carry systems. The plant can be sown in spring or after harvest of the main crop (wheat, barley, maize, etc...) at the end of summer or during autumn so that it can produce supplementary green forage for livestock during summer or just before or after winter and provides green feed to the animals in times of scarcity. Rape forage provides several environmental services: it improves the soil, decreases the risk of N leaching and soil erosion, it fights against parasites and is nest for wildlife. It is also a source of nectar for bees (GNIS, 2019).

Distribution 

Rape forage is thought to have originated from Europe and is now grown worldwide.

Oilseed rape is mostly cultivated in temperate areas but it is also grown in the tropics at high elevations (between 1500 and 2200 m) (Ecocrop, 2014). When it is grown for forage, oilseed rape can be sown during spring, summer or autumn. Oilseed rape is winter hardy and frost resistant: winter types can survive down to -15°C/-20°C for short periods (Ecocrop, 2014). However, rape forage cannot grow below 5°C (GNIS, 2019)

Rape forage does well under a wide range of soil conditions, provided that they are well-drained and that moisture and fertility levels are adequate (Snowdon, 2006; Duke, 1983). It grows where annual rainfall is between 300 and 2800 mm. It responds positively to N and P fertilizers and requires large amounts of sulphur (Herkes, 2014; Duke, 1983). Oilseed rape is sensitive to aluminium and manganese toxicity in acidic soils but it is relatively tolerant of soil salinity (up to 5-6 dS/m) (CCC, 2014).

Rape forage is a fast growing species that can yield valuable amount of forage within 60-80 days. It does not require much work nor fertilizer and it is suitable for direct drilling (GNIS, 2019).

Forage management 

Oilseed rape sown for forage production can be sown during a long period between spring and autumn. It can be sown in order to be used very quickly  (60-80 days after sowing) and then removed by grazing/cutting or it can be let for regrowth and grazed/cut once again. It has been possible to gain multiple forage harvests when 30 cm high stems are left to recover for 30 days (Johnston, 2009). Oilseed rape can also be sown, grazed and then let to regrow during winter (vernalization) for further oilseed production (Paridaen et al., 2015).

Seeds of forage rape can be drilled into stubbles just after harvest of the main crop or after grass or it can be broadcast on naked soil. Sowing density varies from 6-10 kg depending on sowing conditions and locations (direct drill or broadcast) (GNIS, 2019; Limagrain, 2019). Lower seed rate were reported in the USA (3.5-4.5 kg/ha)(Lemus et al., 2014; Johnston, 2009).

When oilseed rape is sown after a cereal, the straw should be removed before sowing. The seeds should be plugged to a depth of 2-4 cm depending on soil texture and moisture (GNIS, 2019). When oilseed rape is sown at the end of spring weeding is not necessary because the plant develops readily and smoother weeds (GNIS, 2019).

Oilseed rape establishes readily and can be ready to harvest for forage between roughly 60-80 days for first cut (GNIS, 2019; Johnston, 2009). In Zacatecas, a semi-arid area of Mexico, it has been reported that livestock could graze rape forage sown during autumn after only 30-42 days and that the better time for making silage was 63 days after sowing (Sanchez-Gutierrez et al., 2018). The plants are reported to be ready when they develop a reddish tinge (Lemus et al., 2014).

Yields 

Forage rape yields high amount of green matter, average yields in Europe were reported to range between 25-36 tonnes green matter/ha that can provide 4-5 tonnes dry matter /ha (GNIS, 2019; Limagrain, 2019). In semi-arid zone of Mexixo, it still produces 2.5-3 tonnes DM/ha (Sanchez-Gutierrez et al., 2018). In the high rainfall zones of Australia it was possible to grow biennal dual-purpose  (forage and seeds) type of rapeseed and have 1000–2000 sheep-grazing days in winter (2.5-4 tonnes DM/ha) with little impact on seed yields (3.5–5.0 t/ha)(Paridaen et al., 2015).

Management

Green feed

Rape forage can be grazed by all classes of livestock. However, strip-grazing is recommended for cattle while it is not necessary for sheep or goats

Strip-grazing

It is possible to have rape forage strip-grazed by livestock. This can be achieve with the use of an electric fence set on a large front and moved everyday so that animals are allowed to access long narrow strips which will reduce wastage. Animals should be introduced to the crop slowly (8 to 15 days are necessary), they should preferably enter the stand in the afternoon and they should have access to water and to a dry run back to keep them clean. It is recommended that dairy cows do not consume rape forage at least one hour before milking to avoid "cabbage" taint in the milk (GNIS, 2019).

Cut-and-carry

Green rape forage can be brought to the stall and fed to livestock

Silage

It is possible to make silage from rape forage provided it is cut at optimal DM (13-14%) and sugar (25%) contents. Prewilting is recommended prior to ensiling. The forage should then be chopped to 3-4 cm pieces. It can be mixed with dried beet pulp to prevent leaching and it is possible to add beet molasses to fasten fermentation process. Unlike maize or grass silage, the pile of rape forage should not be too compacted. It is important that no soil particles are brought to the pile as it may contaminate the silage (GNIS, 2019).

Environmental impact 

Cover crop, soil improver

Rape forage is a valuable cover crop during end of summer, autumn and winter. It prevents soil erosion and N leaching (GNIS, 2019). It can be used as green manure in order to improve soil structure  (GNIS, 2019).

Water saving

In dairy semi-arid areas of Mexico, rape forage can be an alternative to traditional feeds for dairy cows (oats, barley, wheat and Lolium perenne) as it requires 40% less water than these latter (Sanchez-Gutierrez et al., 2018

Nutritional aspects
Potential constraints 

Bloat

Rape forage is readily degraded in the rumen. It is then necessary to balance the ration with fibre alongside the crops, and introduce non-hungry stock gradually (Limagrain, 2019).

Nitrate poisoning

If rape forage grew fast after rain on a soil with high N fertilizer of nitrate content, the leaves accumulate nitrates that can cause nitrate poisoning in livestock. Nitrate content was reported to be between 1.5-2% at first grazing in Australia. This condition can be detrimental to cows if they are not restricted (Fulkerson, 2008)

Sulphur induced haemolytic anemia and polioencephalomalacia

Rape forage contains high amounts of sulphur in the form of S-Methyl Cystéine Sulfoxide (SMCO). The levels of SMCO are worse when soil phosphate levels are low and nitrogen and sulphur levels are high. SMCO levels also increase when crops are flowering (Limagrain, 2019). The content of forage rape in sulphur is 0.5-1.3%, much higher than the recommended requirement for cattle (Johnston, 2009). 

The ingestion of high sulphur forage causes feed intake depression, weight loss, weakness and haemoglobinurea and risk of heamolytic anemia in cattle (Johnston). It can also cause the outbreak of a health condition called polioencephalomalacia (PEM) which results in lethargy, ataxia and blindness. This is also called "rape blindness". (Kelly, 2013).

Poliencephalomalacia can be prevented by limiting the rape forage to 35 - 50% of total dry matter intake (Limagrain, 2019). Flowering rape forage should not be fed to cattle.

In a case of outbreak in Australia, it was possible to alleviate the problem by injecting thiamine at the dose rate of 8mg/kg intramuscularly (Kelly, 2013).

Goitre

Rape forage contains elevated levels of isothiocyanates, a compound that block the uptake of iodine from the diet. Moreover it is also low in iodine, which may increase the risk of iodine deficiency, affecting the thyroid gland and the hormones it produces (Limagrain, 2019; Johnston, 2009). The iodine deficiency then induces goitre in livestock. Goitre has the following symptoms: growth depression, thyroid enlargement, hypothermia and tendon contractions in neonates (Johnston, 2009).

To avoid the above problems, it is recommended that rape forage greenfeed or silage are not fed above 35-50 % of total dry matter on a daily basis, with the remainder of the ration being other fibrous and/or dry feeds such as straw, hay and grains (Limagrain, 2019).

Scouring

Long-term feeding of canola at greater than 60 per cent of the diet may cause scouring (Johnston, 2009). 

Pesticides residues

In case rape forage was not originally intended as for cattle feed, it is important to check grazing and feeding restrictions which may apply to crops treated or sprayed with pesticides or herbicides (Johnston, 2009).

Ruminants 

Rape forage is a valuable fodder for ruminants providing green feed during summer, autumn and early spring when grasses are not available. Rape forage helps sparing grass hay or silage. However, due to several potential constraints some precautions should be taken before introducing cattle to this forage. 

Animals should get used to eat rape forage gradually. This can be done through mixing the rape forage with other forages (Johnston, 2009). After the accustoming period, livestock should be offered sufficient dry feeds like hay or straw and free access to water (GNIS, 2019; Limagrain, 2019). Rape forage should not represent more than 35 - 50% of total dry matter intake (Limagrain, 2019).

Cattle

Degradability, digestibility

Rape forage from different varieties were all reported to have high IVDMD, ranging from 87 to 91% (Pearce et al., 1991; Lancaster et al., 1990Guillard et al., 1988, Jung et al., 1988). This high IVDMD could result in acidosis if the ration is not adequately balanced with roughage (Meslier et al., 2014).

In France, rape forage can be a valuable grazed resource for cattle. Strip-grazing of rape forage is recommended in order to prevent trampling. Dairy cows should be allowed to graze 20 m²/day to receive a quarter to a third of their daily ration. Grazing rape forage provides good complement to maize silage and it can help saving 1 kg concentrate/day (Sagot, 2012).

In Australia, it is recommended to supplement dairy cows with high fibre sources like grass or maize silage, kikuyu, or paspalum (Fulkerson, 2008).

Dairy cows should preferably graze rape forage after the afternoon milking as the nitrate content of rape is lower and the sugar content is higher. They  should never  graze rape forage less than 2 hours before milking because of the milk taint provided by rape forage (GNIS, 2019; Fulkerson, 2008).

Milk quality

Milk thiocyanate content was shown to be increased for dairy cows fed on approximately 50% rape forage (Grongnet, 1982). This higher thiocyanate content was shown to have goitrogenic activity on rats fed on milk only. This could be a theoretical issue for new-borns fed only on milk from rape forage grazing cows (Grongnet, 1982). 

Sheep

Rape forage is not very palatable to sheep because of the cabbage taint. Thus nor gradual introduction to rape forage, nor restricted feeding (strip-grazing) are necessary provided sheep have been fed prior to entering the stand. After a while, rape forage is eaten more readily and no concentrate is required (Sagot, 2012).

In Australia, in high rainfall zone, dual-purpose rape forage was grown during winter to feed Merino growing lambs (hoggets). The sheep readily ate rape forage and had 210 g/day growth rate. The digestibility of rape forage was high (86-88%) (Kirkegaard et al., 2008).

In the UK, finishing lambs grazing on rape forage could gain 273 g BW/day without requiring other forage and reducing their concentrate needs dramatically in comparison to lambs fed on concentrates (5 kg vs. 66 kg per kilogramme of meat) (AHDB, 2015). For better economical returns, it was recommended to feed finishing lambs and culled ewes on rape forage (AHDB, 2015).In a comparative experiment growing lambs were fed either on rape forage, either on irrigated grass pasture. During the first 6 weeks of the experiment, growth rates for both diets but after thereafter, lams fed on grass pasture had lower weight gains. At slaughter, lambs fed on rape forage were heavier but also fattier, the carcass had higher pH, the meat had significantly lighter colour but there was no significant difference in cooking loss. Overall meat quality based on objective assesssments was the same for both groups of lambs but sensorial analysis through panellists detected a stronger, less acceptable flavour from the meat of rapefed lambs (Hopkins et al., 1995).

Rabbits 

Green rape is a forage frequently grazed by wild rabbits, and many authors describe rabbit as a potential rape predator (Inglis et al., 1992; Mithen, 1992; Griffiths et al., 1994). Almost all published papers indicate that rabbits grazing pressure in rape crops is independent of the type of rape, simple or double zero, i.e. independent of the forage glucosinolates content, even if grazing increase significantly the glucosinolate content of leaves (Griffiths et al., 1994; Inglis et al., 1992; McFarlane-Smith et al., 1991).

For domestic rabbit, rape is a green forage used for rabbit familial production since a long time as are also other Brassicaceae such as cabbage, turnips, radishes, white mustard or swedes (Wilson, 1944; Nollet, 1943; Charon, 1927). When distributed ad libitum together with a mixture of grains also proposed ad libitum during 6 weeks, the spontaneous intake of rape forage represents 21% of the total intake of growing rabbits. It should be noticed that in the same conditions, cabbage intake represents 24% of the total intake, and live weight gain during the experimental period was 1000 and 1080 g for rabbits of the rape and cabbage groups respectively (Fedeli-Avanzi et al., 1976). For experimental reasons green rape forage was proposed as only feed to almost adult rabbits, a feeding regime which appear able to permit at least weight maintenance on a period of 30 days minimum, without apparent health disturbance (Richter et al., 1989; Bonadonna et al., 1957). Similarly, rations mixing dried rape pellets (2 cultivars in comparison), together with wheat straw also allowed increased liveweight, independently of the type of rape cultivar (Richter et al., 1989).

Despite the known possibility of safe use of rape forage in rabbit feeding, no experiment seems available in the international literature on the optimum conditions of introduction of this forage in balanced rabbits diets. The nutritive value was not determined, but since digestibility of dry matter or energy of 3 other Brassica fresh forages i.e. cabbage, turnips and rutabaga (swedes) are close to 100% (Voris et al., 1940), it can be supposed that it is the same for rape forage. Digestibility of proteins of these 3 forages was 90-97% and that of crude fibre 82 to 100% (Voris et al., 1940)

Thus, for rabbits, rape forage may be considered as a source of energy (about 16- 16.5 MJ/kg DM), of digestible proteins (20-25%) and of digestible fibre.

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

IMPORTANT INFORMATION: This datasheet is pending revision and updating; its contents are currently derived from FAO's Animal Feed Resources Information System (1991-2002) and from Bo Göhl's Tropical Feeds (1976-1982).

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 11.5 2.3 8.2 15.2 13  
Crude protein % DM 24.2 2.4 18.7 27.6 17  
Crude fibre % DM 15.0 3.5 9.8 23.8 13  
NDF % DM 21.9 5.7 15.6 26.8 3  
ADF % DM 19.5 4.2 15.4 25.2 4  
Ether extract % DM 1.8       1  
Ash % DM 15.9 3.2 9.4 22.9 14  
Water-soluble carbohydrates % DM 11.3 7.7 3.3 19.0 4  
Gross energy MJ/kg DM 17.0         *
               
Minerals Unit Avg SD Min Max Nb  
Manganese mg/kg DM 35 4 32 39 3  
Zinc mg/kg DM 38 1 37 39 3  
Copper mg/kg DM 4 0 4 5 3  
Iron mg/kg DM 50 3 48 53 3  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, Ruminant % 82.2 5.3 72.5 89.9 13  
Energy digestibility, ruminants % 79.6         *
DE ruminants MJ/kg DM 13.6         *
ME ruminants MJ/kg DM 10.7         *
Nitrogen digestibility, ruminants % 88.5       1  
a (N) % 39.0   34.0 44.0 2  
b (N) % 58.0   53.0 63.0 2  
c (N) h-1 0.160   0.060 0.260 2  
Nitrogen degradability (effective, k=4%) % 85         *
Nitrogen degradability (effective, k=6%) % 81   71 85 2 *

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

References

Alibes et al., 1990; Emile et al., 1993; Fulkerson et al., 2008; Kaur et al., 2010; Kunelius et al., 1990

Last updated on 02/05/2013 17:25:34

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 16.9 1.9 14.3 19.6 6
Crude protein % DM 18.5 1.3 16.6 20.4 6
Crude fibre % DM 16.4 5.4 12.4 25.7 6
Ash % DM 19.9 4.6 13.8 25.6 6
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 81.4 7.0 68.8 87.5 6
Energy digestibility, ruminants % 78.8 *

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

References

Emile et al., 1993

Last updated on 24/10/2012 00:45:45

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 86.8 2.3 84.3 91.2 6
Crude protein % DM 15.9 3.3 11.0 19.6 6
Crude fibre % DM 19.0 10.3 12.1 38.8 6
Ether extract % DM 2.7 2.0 3.3 2
Ash % DM 15.8 4.8 9.5 20.6 6
Gross energy MJ/kg DM 16.9 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 27.5 12.4 14.7 42.7 5
Phosphorus g/kg DM 3.6 0.4 3.1 4.1 5
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 67.7 *
Energy digestibility, ruminants % 65.1 *
DE ruminants MJ/kg DM 11.0 *
ME ruminants MJ/kg DM 8.8 *

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

References

AFZ, 2011

Last updated on 24/10/2012 00:45:45

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 91.1 1
Crude protein % DM 5.8 1.4 4.2 6.9 3
Crude fibre % DM 48.2 3.7 44.1 51.3 3
NDF % DM 77.0 1
ADF % DM 62.3 1
Lignin % DM 10.8 1
Ether extract % DM 1.9 1
Ether extract, HCl hydrolysis % DM 1.4 1
Ash % DM 8.7 1.1 7.5 9.7 3
Gross energy MJ/kg DM 18.4 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 9.8 9.0 10.7 2
Phosphorus g/kg DM 0.9 0.7 1.0 2
Magnesium g/kg DM 2.6 1
Manganese mg/kg DM 30 1
Zinc mg/kg DM 9 7 11 2
Copper mg/kg DM 3 1
Iron mg/kg DM 61 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 40.1 1
Energy digestibility, ruminants % 36.5 *
DE ruminants MJ/kg DM 6.7 *
ME ruminants MJ/kg DM 5.4 *
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 14.4 *
DE growing pig MJ/kg DM 2.6 *

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

References

Abreu et al., 1998; AFZ, 2011; Rasool et al., 1998

Last updated on 24/10/2012 00:45:45

References
References 
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/15683 Last updated on July 8, 2019, 9:12

Image credits