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Sweet potato (Ipomoea batatas) forage

Datasheet

Description
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Common names 

Sweet potato [English] ; patate douce [French] ; boniato, batata, chaco, papa dulce, camote [Spain] ; batata-doce, batata-da-terra, batata-da-ilha, jatica, jetica [Portuguese] ; patats [Afrikaans] ; Süßkartoffel, Batate, Weiße Kartoffel, Knollenwinde [German] ; ubi jalar, ketela rambat [Indonesian] ; patata dolce, patata americana [Italian] ; kamote [Tagalog] ; khoai lang [Vietnamese] ; 番薯 [Chinese] ; શક્કરીયાં [Gujarati] ; शकरकन्द [Hindi] ; サツマイモ [Japanese] ; 고구마 [Korean] ; रताळे [Marathi] ; सखरखण्ड [Nepali] ; Бата́т, сла́дкий карто́фель [Russian] ; வற்றாளை [Tamil]; มันเทศ [Thai]

Product names: sweet potato vines, sweet potato foliage, sweet potato leaves, sweet potato leaf meal, sweet potato vine meal

Synonyms 

Convolvulus batatas L., Ipomoea apiculata M. Martens & Galeotti

Description 

Sweet potato (Ipomoea batatas (L.) Lam.) is a plant grown for its tuberous roots in tropical, subtropical and warm-temperate regions. Sweet potato tubers are a staple food or an alternative food in many countries and part of the production is used for animal feeding.

Morphology

Sweet potato is a perennial plant mainly grown as an annual. The roots are adventitious, mostly located within the top 25 cm of the soil. Some of the roots produce elongated starchy tubers that vary largely in shape, colour and texture depending on the variety. The flesh of the tubers can be white, yellow, orange and purple whereas their skin can be red, purple, brown or white. The stems are creeping slender vines, up to 4 m long. The leaves are green or purplish, cordate, palmately veined, borne on long petioles. Sweey potato flowers are white or pale violet, axillary, sympetalous, solitary or in cymes. The fruits are round, 1-4 seeded pods containing flattened seeds (Ecocrop, 2010; Duke, 1983).

Utilisation

Sweet potato is cultivated for food in more than 100 countries, sometimes as a staple food but usually as an alternative food. Because of its fast growing period, low input and work requirements, sweet potato is often planted in Africa as a security crop or famine prevention crop (Scott et al., 1993). While the tubers are the main agricultural product derived from the sweet potato crop, the vegetative parts are a very valuable feed for livestock. Sweet potato vines and foliage can be fed to cattle, sheep, goats, pigs and rabbits. Sweet potato forage can be an emergency supply of cattle feed in periods of water stress (drought or dry seasons) (Scott, 1992). It may be fed fresh, dried or ensiled, and makes a very palatable silage with a pleasant fruity smell (Lebot, 2009). Dried vines and foliage compare favourably with alfalfa hay for cattle (Duke, 1983). Sweet potato forage can alo be dried, ground and mixed with sugarcane by-products. Other sweet potato products are suitable for livestock: see the datasheets on Sweet potato tubers and Sweet potato by-products (Duke, 1983).

Distribution 

Sweet potato is thought to be have originated between the Yucatán Peninsula of Mexico and the mouth of the Orinoco River, in Venezuela. Sweet potatoes as old as 8000 years have been found in Peru. The plant later spread to the Caribbean and Polynesia. It is now widely cultivated between 40°N and 32°S, up to 2000 m (and up to 2800 m in equatorial regions) (Ecocrop, 2010; Paneque Ramirez, 1992). The main sweet potato producers are China, Indonesia, Vietnam, India, Philippines and Japan in Asia, Brazil and the USA in the Americas and Nigeria, Uganda, Tanzania, Rwanda, Burundi, Madagascar, Angola and Mozambique in Africa. The area under cultivation was 8.5 million ha in 2009. It is one of seven food crops with an annual production of more than 100 million t (FAO, 2010).

Sweet potatoes are cultivated wherever there is enough water to support their growth: optimal annual rainfalls for growth range between 750-2000 mm. When rainfall level is below 850 mm irrigation may be necessary but it should be stopped before harvest in order to prevent the tubers from rotting. Sweet potato is a warm-season annual, requiring 20-25°C average temperatures and full sunlight for optimal development. It needs a frost-free period of 110-170 days and growth may be hampered below 20°C average day temperatures. Sweet potato thrives in well-drained loamy soils with high humus content that provides warm and moist environment to the roots. Optimal soil pH is between 5 and 7 (Ecocrop, 2010; Ecoport, 2010; Paneque Ramirez, 1992). Sweet potato is mildly drought-tolerant and can survive dry spells during the summer. However, low humidity impairs crop quality even if the plant resume growth after a water stress (Ecoport, 2010; Paneque Ramirez, 1992).

Processes 

Huge amounts of sweet potato foliage are produced during tuber harvesting and the vines decay in 2 or 3 days. When animals cannot consume the forage in such a short time, it may be interesting to dry or ensile it using low-cost methods (Renaudeau, 2010, personal communication).

Silage

Sweet potato leaves and vines can be preserved by ensiling (Nguyen Thi Tinh et al., 2006; Lebot, 2009). After harvest, green and healthy material is chopped to 0.2-0.5 cm length and carefully prewilted during 1-4 h in the sun so that moisture content is reduced by 40-45%. The prewilted material is then thoroughly mixed with 10% rice bran, corn meal or cassava or sweet potato root meal and 0.5% salt. After mixture, the material is put in impermeable plastic bags, heavily pressed to remove the air from the mixture and the bags are carefully tight and dated (Nguyen Thi Tinh et al., 2006).

Sweet potato vines can be fermented with chicken manure: it results in higher crude protein, DM and ash contents than the other silages. Ensiling provides a good sanitary that does not contain aflatoxins, Salmonella, and Escherichia coli (Lebot, 2009).

Forage management 

For optimal leaf and stem production, it is advisable to cut at intervals of 20 days with a defoliation of 50% of the total stems, since greater defoliation could reduce root production. Vines and leaves can be harvested three or four times per growing season (Lebot, 2009).

Environmental impact 

Sweet potato is remarkably adapted to scarce conditions since it thrives even with very low inputs and minimal horticultural practices. It grows very quickly, has some tolerance of drought and provides high amounts of nutrients during the scarcer periods (Scott, 1992).

Nutritional aspects
Nutritional attributes 

Sweet potato forage is mainly a source of protein and contains about 15-30% DM of crude protein but the forage quality depends on the proportion of leaves and stems, the latter containing much less protein than the leaves. Lysine is the main limiting amino acid (Le Van An, 2004). Unlike legume forages, it does not contain notable quantities of antinutritional factors.

Potential constraints 

The vines contain trypsin inhibitors but at relatively harmless levels.

Ruminants 

The vines are separated from the roots after harvest and provide a nutritive and relished green feed for ruminants (Nguyen Thi Tinh et al., 2006). It is a suitable protein supplement for animals receiving low quality forage.

Digestibility and degradability

Dry matter digestibility was found to be 70% (Ffoulkes et al., 1978a) and dry matter degradability was in the 40-50% range (Etela et al., 2008a). Protein degradability of fresh sweet potato forage was found to be quite high (about 70%), but the undegradable dietary protein was lower than that of protein supplements of similar degradability (cottonseed meal and Gliricidia sepium) so that less digestible true protein is available to the animal for metabolism after digestion and absorption (Kabi et al., 2005).

Dairy cows

A cow of 400-500 kg can consume 50-70 kg daily (Göhl, 1982). Sweet potato forage can be fed to dairy cows as a supplement to forages such as Guinea grass (Megathyrsus maximus) or sorghum silage (Etela et al., 2009; Etela et al., 2008b; Ashiono et al., 2006). Such supplementation results in lower DM intake, but higher ME utilization for milk production (Etela et al., 2009; Etela et al., 2008b). While it has no negative effect on milk quality, it can only sustain low levels of milk production and does not compare favourably with dried brewers' grains or cassava forage as a supplement for milk production, though it could help saving production costs for smallholders (Etela et al., 2009; Etela et al., 2008b; Lopez et al., 1998).

Sweet potato vines can efficiently supplement sorghum silage in dairy cows diet and they have great potential for improving milk yield at up to 70% inclusion (Ashiono et al., 2006; Göhl, 1982).

Growing and fattening cattle

Heifers

Heifers fed on Napier grass (Pennisetum purpureum) and supplemented with sweet potato forage have lower DM intake than heifers fed on grass alone. Growth performance (500 g daily weight gain) is similar on grass and grass + sweet potato and lower than on grass+alfalfa (Kariuki et al., 1998)

Bulls

In Zebu bulls, supplementation with sweet potato forage of a diet based on sugarcane stalks increased voluntary intake and live weight gain, which was explained by the protein in the sweet potato forage acting as a by-pass nutrient and by the physical nature of this forage improving the rumen function (Ffoulkes et al., 1978a). Addition of N urea in association with sweet potato forage supplementation resulted in further live weight gains. This was was possibly due to the improvement in the rumen ecosystem which may encourage microbial growth and create a demand for fermentable N (Meyreles et al., 1979).

Calves

Sweet potato vines were found to be a high quality feed for calves due to their high yield, palatability and crude protein content. When offered ad libitum to calves fed Napier grass, they did not significantly affect the average daily gains of calves, and up to half of the milk can be saved when sweet potato vines are fed as a milk replacer (Orodho et al., 1996). Calves fed on Napier grass and sweet potato forage alone did better than those fed on Napier alone, but less that those fed on Napier grass supplemented with mixtures of sweet potato vines and other legume forages such as alfalfa, desmodium, Leucaena leucocephala and Sesbania sesban (Lanyasunya et al., 2006).

Sheep

The carrying capacity of sweet potato plots pruned for sheep feeding was comprised between 100 and 165 heads/ha and an interval of 6 weeks may be adopted to optimize yield and quality of the forage (Olorunnisomo, 2007a). Mixing sweet potato forage and roots resulted in better nutrient utilization and lower cost per kg of live weight gain was reduced. A 50:50 sun-dried mix maximized economic returns from cultivating sweet potato for sheep feeding (Olorunnisomo, 2007b). Sheep seem to prefer cassava leaves to sweet potato leaves (Haryanto et al., 1982).

Lambs grazing sweet potato leaves recorded daily weight gains around 50-60 g (Rondon et al., 1989).

Goats

Though fairly relished by goats, sweet potato vines have low CP intake, poor N retention and poor CP and DM digestibility (Katongole et al., 2009a). It compared unfavourably with cassava leaf meal or Sesbania grandiflora as it resulted in lower DM intake and lower live weight gain (Vo Lam et al., 2004). However, better results in DM intake and animal performance have been yielded when goats could get accustomed to sweet potato vines (Kebede et al., 2011). Poor animal performances (less than 15 g daily weight gain) are also recorded when sweet potato vines are used to supplement a diet of Napier grass (Pennisetum purpureum), maize bran and Leuceana leucocephala leaves (Katongole et al., 2009a). Higher animal performances (44 to 82 g daily weight gain) are obtained when sweet potato vines supplement a cottonseed cake and maize bran mixture at 1:4 ratio (Katongole et al., 2009b) or a low quality grass (Ischaemum aristatum var. indicum) (Aregheore et al., 2004), respectively. Hence, sweet potato vines provide sufficient crude protein and metabolizable energy to sustain goat meat and milk production in tropical conditions, even during scarce periods where standard feeds are lacking (Katongole et al., 2009b; Katongole et al., 2008; Nambi et al., 2001). Feeding goats with sweet potato vines provides cheap nitrogen and increases feed efficiency (Aregheore et al., 2004). Sweet potato vines could profitably replace 50% concentrate feed (78.4% wheat bran, 20.6% noug seed cake) in male goats diet (Kebede et al., 2011).

Goats seem to prefer cassava leaves to sweet potato leaves (Haryanto et al., 1982).

Pigs 

Sweet potato vines are one of the most promising protein sources coming from tropical forages for pigs (Bui Huy Nhu Phuc, 2000). Thanks to its high crude protein content, high CP digestibility (above 65%) sweet potato foliage in fresh, dried or ensiled form can be used as a valuable protein and amino acids source in low fibre pigs diets in tropical areas (Le Van An et al., 2004; Rodriguez et al., 2003; Barrios et al., 2002).

In small-scale pig farms, sweet potato foliage could replace up to half the protein normally provided through conventional feedstuffs such as soybean meal or fishmeal (Preston, 2006). Sweet potato foliage can be fed to pigs without any negative effects on health (Renaudeau, personal communication). In Vietnam, sweet potato foliage is much appreciated by the poorest pig farmers because it can be fed year-round and its use results in lower production costs and higher net income (Ngo Huu Toan et al., 2007). In Cuba, sweet potato crop, including roots as energy source and vines as a protein source, can compete with maize in pig feed in Cuban pig production (Dominguez, 1992).

Fresh sweet potato vines

Growing and fattening pigs

Fresh sweet potato vines can be profitably included in growing and finishing pigs diets as they enhance basal diet palatability, overall DM intake, nutrient digestibility and animal performances (Chiv Phiny et al., 2010; Chhay Ty et al., 2007; Nedunzhiyan et al., 2000). They are generally offered ad libitum (Chiv Phiny et al., 2010; Chhay Ty et al., 2007). Fresh sweet potato foliage palatability is rather high and compares favourably with other tropical foliages such as mulberry leaves (Régnier et al., 2010 (unpublished); Chiv Phiny et al., 2010). The average daily fresh sweet potato foliage intake is about 3 kg/d (500 g DM/d) for a 50 kg pig, and 750 g/d for fresh chopped vines (Régnier et al., 2010 (unpublished); Nedunzhiyan et al., 2000).

Fresh sweet potato vines can be used as the sole protein supplement, combined with other foliage such as mulberry leaves or cassava leaves or associated to a protein-rich (20-23%) supplement (Chiv Phiny et al., 2010; Chhay Ty et al., 2007; Gonzalez et al., 2003). However, they appear to have a lower nutritive value than cassava leaves, stylo (Stylosanthes guianensis) and duckweed (Du Thanh Hang et al., 2009)

Sweet potato fresh foliage offered to weaned piglets can substitute 10 % of the cereal concentrate with satisfactory animal performance (weight gain, feed conversion, mortality and herd culling) (Göhl, 1982). However, because of its bulkiness, fresh sweet potato foliage cannot be included in large amounts in the diets of young pigs (Renaudeau, personal communication).

Fresh foliage replacing 25 and 50 % of soybean meal in a sweet potatoes and soybean meal diet resulted in a decreased of dry matter intake that was probably due to its bulkiness, but the feed conversion ratio was conserved at the 25% replacement level (Göhl, 1982).

Gilts and sows

Sweet potato leaves inclusion can be as high as 50% in the diets of gilts or pregnant sows, and up to 20% for lactating sows. They can also replace up to 50% soybean meal during pregnancy and lactation (Hoang Nghia Duyet et al., 2010; Hoang Nghia Duyet, 2003).

Preserved sweet potato foliage

Sweet potato foliage in fresh, dried or silage is a valuable ingredient for pig diets. Though dried and ensiled sweet potato foliage have slightly lower lysine digestibility, the three products have similar palatability and overall nutritive values (Le Van An et al., 2004).

Many types of silages can be done with sweet potato foliage: sweet potato silage can be prepared with leaves alone or in mixtures: leaves and lysine, sweet potato leaves and cassava leaves, sweet potato leaves and sweet potato roots (Nguyen Thi Hoa Ly et al., 2010; Le Van An et al., 2005). Ensiled cassava leaves and sweet potato vine can replace more than 70% of the protein from fish meal (or 35% of total diet CP), reducing feed costs without deleterious effects on growing pig performances or carcass quality. (Nguyen Thi Hoa Ly et al., 2010). 30% inclusion rate for ensiled sweet potato foliage should not significantly affect growth performance in growing pigs (Le Van An et al., 2005). Higher inclusion rates (40 and 60% DM) would reduce growth by 16 and 30%, respectively (Hoang Huong Giang et al., 2004).

In post-weaning diets, sweet potato inclusion (meal or silage) should not exceed 10% and to 30-40 % inclusion is advisable in growing-finishing diets (Mora et al., 1992 cited by Le Van An et al., 2005).

Poultry 

Dried foliage

Dried sweet potato vines can be used in poultry rations as a source of protein and carotenoids, particularly beta-caroten and xanthophylls, and have been included in diets to enhance the yellow pigmentation of broiler skins and egg yolks. Early-harvested vines were as efficient as alfalfa meal at colouring yolks. Late-harvested vines were less efficient at colouring broiler skin (Woolfe, 1992). An optimum level of 10% has been suggested, as higher levels resulted in decrease of dry matter intake and body weight gain (Berhan Tamir et al., 2010) and levels of 20-30% reduced the feed conversion efficiency (Kagya-Agyemang et al., 2008). However, dried vines included at up to 16% in broiler diets have been shown to be as efficient as alfalfa meal for growth rate, food intake or food efficiency (Farrell et al., 2000) and 15% could be economically feasible if birds are sold if birds are sold on eviscerated carcass weight basis rather than live weight (Wude Tsega et al., 2009).

Fresh foliage

Fresh sweet potato leaves given to chickens gave the smallest animals, the highest mortality and the lowest economic results when compared to fresh leaves ofcentro (Centrosema molle) and leucaena (Leucaena leucocephala) (Dingayan et al., 1950).

Rabbits 

Sweet potato vines are palatable to rabbits and have been found to be more palatable that Leucaena leucocephala and other legume trees (Raharjo et al., 1985). In rabbits fed a concentrate diet, fresh sweet potato vines resulted in a slightly lower intake and daily gain (21.1 g/day) than water spinach (Ipomoea aquatica). The best performances were obtained when adding Guinea grass (Megathyrsus maximus) to sweet potato vines, water spinash or a mixture of both forages, though the digestibility of the diets was lower (Doan Thi Gang et al., 2006). Groundnut haulms and soybean forage were more cost effective than sweet potato forage for feeding rabbits (Iyeghe-Erakpotobo, 2007).

Fish 

Sweet potato leaves have been used to feed Tilapia in Ugandan fish ponds (Mwanga et al., 1988). In Vietnam, sweet potato crop residues and other macrophytes have been tested successfully for feeding Tilapia, common carps (Cyprinus carpio), giant gouramis (Osphronemus goramy) and kissing gouramis (Helostoma temminckii) (Lam My Lan et al., 2007). Sweet potato leaves were assessed to be suitable for small scale freshwater fish feeding (carps and Tilapia) due to their relatively high protein content and reduced antinutritional factors (Dongmeza et al., 2009).

Crustaceans 

Crayfish

When farmed crayfish (Procambarus clarkii) were fed vines and root trimmings from a sweet potato cannery as a supplement, dried sweet potato foliage fed ad libitum daily resulted in the highest weights and longest lengths of mature crayfish, followed by sweet potato trimmings, rice stubble and rye hay. Sweet potato vines and trimmings could be fed directly to crayfish or after a very short compost period. Fresh sweet potato forage was more efficient than forage stored in water, which may be due to unpalatable decomposition products (Goyert et al., 1977).

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 13.0 2.9 8.5 17.6 21
Crude protein % DM 16.5 4.6 8.2 24.2 23
Crude fibre % DM 21.1 5.3 11.9 30.3 17
NDF % DM 42.7 6.7 29.8 51.6 10
ADF % DM 31.7 6.8 19.9 40.6 10
Lignin % DM 8.3 2.2 4.5 11.8 10
Ether extract % DM 4.8 2.0 2.5 10.4 14
Ash % DM 11.2 2.2 8.0 15.3 17
Gross energy MJ/kg DM 18.3 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 9.5 6.6 1.3 19.8 12
Phosphorus g/kg DM 2.9 1.6 0.8 5.7 11
Potassium g/kg DM 24.9 11.8 2.5 41.4 10
Sodium g/kg DM 0.8 0.8 0.9 2
Magnesium g/kg DM 4.0 0.9 3.1 5.7 9
Manganese mg/kg DM 141 1
Zinc mg/kg DM 70 1
Copper mg/kg DM 2 1
Iron mg/kg DM 1690 1
 
Amino acids Unit Avg SD Min Max Nb
Arginine % protein 6.0 0.7 5.2 6.8 5
Glutamic acid % protein 7.9 1.2 6.4 9.6 5
Glycine % protein 5.5 1.0 4.9 7.3 5
Histidine % protein 1.4 0.4 1.1 2.0 5
Isoleucine % protein 5.1 0.4 4.4 5.6 5
Leucine % protein 8.6 0.8 7.5 9.6 5
Lysine % protein 3.6 0.7 2.3 4.0 5
Methionine % protein 1.1 0.6 0.5 2.0 5
Phenylalanine % protein 5.1 0.4 4.5 5.6 5
Threonine % protein 5.0 0.4 4.4 5.4 5
Valine % protein 5.7 0.4 5.2 6.3 5
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins (eq. tannic acid) g/kg DM 6.2 1

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

References

Bui Phan Thu Hang et al., 2011; CIRAD, 1991; Devendra et al., 1970; Dominguez, 1992; Dongmeza et al., 2009; Hassoun, 2009; Holm, 1971; Le Thi Men, 2006; Luh et al., 1979; Nguyen Nhut Xuan Dung et al., 2002; Pozy et al., 1996; Teguia et al., 1993; Thim Sokha et al., 2008

Last updated on 24/10/2012 00:45:13

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 88.5 3.3 84.0 92.6 10
Crude protein % DM 13.2 6.0 7.6 21.7 11
Crude fibre % DM 19.9 4.7 12.2 23.7 7
NDF % DM 40.1 6.3 28.4 50.2 10
ADF % DM 32.2 4.9 25.6 40.1 9
Lignin % DM 11.3 7.3 6.8 29.4 9
Ether extract % DM 2.8 1.3 1.0 5.4 9
Ash % DM 11.8 3.2 5.6 16.6 11
Starch (polarimetry) % DM 1.8 1.2 2.3 2
Total sugars % DM 7.9 6.7 9.0 2
Gross energy MJ/kg DM 17.5 0.9 16.8 18.9 4 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 12.4 2.3 8.0 13.9 6
Phosphorus g/kg DM 3.1 0.8 2.7 4.6 6
Potassium g/kg DM 14.2 12.0 8.2 35.6 5
Sodium g/kg DM 3.7 0.1 3.6 3.7 3
Magnesium g/kg DM 7.0 1.5 4.5 8.3 5
Manganese mg/kg DM 131 29 107 164 3
Zinc mg/kg DM 45 40 21 91 3
Copper mg/kg DM 11 10 5 22 3
 
Amino acids Unit Avg SD Min Max Nb
Alanine % protein 5.6 1
Arginine % protein 6.0 1
Aspartic acid % protein 9.4 1
Glutamic acid % protein 10.0 1
Glycine % protein 4.4 1
Histidine % protein 2.0 1
Isoleucine % protein 4.2 1
Leucine % protein 8.2 1
Lysine % protein 4.8 1
Methionine % protein 1.4 1
Phenylalanine % protein 5.7 1
Proline % protein 4.3 1
Serine % protein 4.1 1
Threonine % protein 4.4 1
Tyrosine % protein 4.1 1
Valine % protein 5.4 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 66.0 1
Energy digestibility, ruminants % 61.8 *
DE ruminants MJ/kg DM 10.8 *
ME ruminants MJ/kg DM 8.8 *
Nitrogen digestibility, ruminants % 33.0 1
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 42.5 38.5 46.4 2
DE growing pig MJ/kg DM 7.4 6.6 7.4 2 *
MEn growing pig MJ/kg DM 6.8 6.5 6.9 2 *
NE growing pig MJ/kg DM 4.1 *

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

References

AFZ, 2011; Bui Huy Nhu Phuc et al., 2001; CIRAD, 1991; Dixon, 1986; Du Thanh Hang et al., 2009; Richard et al., 1989; URZ, 2009

Last updated on 24/10/2012 00:45:27

Amino acids Unit Avg SD Min Max Nb
Alanine % protein 6.5 1
Arginine % protein 6.7 1
Aspartic acid % protein 9.1 1
Glutamic acid % protein 11.3 1
Glycine % protein 5.4 1
Histidine % protein 1.6 1
Isoleucine % protein 4.9 1
Leucine % protein 9.8 1
Lysine % protein 6.2 1
Methionine % protein 1.9 1
Phenylalanine % protein 6.2 1
Proline % protein 5.3 1
Serine % protein 4.3 1
Threonine % protein 5.3 1
Tyrosine % protein 4.4 1
Valine % protein 6.2 1

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

References

Walter et al., 1978

Last updated on 24/10/2012 00:45:35

References
References 
Datasheet citation 

Heuzé V., Tran G., Hassoun P., 2015. Sweet potato (Ipomoea batatas) forage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/551 Last updated on May 11, 2015, 15:36

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