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Feedipedia

Potato (Solanum tuberosum) by-products

Datasheet

Description
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Common names 
  • Abraded peel [English]; pelures d'abrasion [French]
  • Potato slurry/potato puree/potato filter cake [English]; boues de pommes de terre, purée de pomme de terre, gâteau de filtration de pomme de terre [French]
  • Screen solids [English]; screenings [French]
  • Potato pulp from starch extraction [English]; pulpe de pomme de terre issue de l'extraction d'amidon [French]
  • Steam peel, potato feed [English]; pelure vapeur [French]
  • Culled fries, culled crisps, hash browns, crowns, batter, crumbles, nubbins [English]; frites de retrait, chips de retrait [French]
  • Dried potato meal/ potato flakes [English]; flocons de pomme de terre; mash/purée déshydraté.e de pomme de terre [French]
  • Potato puree feed [English]; purée pelure [French]
Description 

The processing of potato (Solanum tuberosum L.) for food and for the manufacture of starch, alcohol, glucose and dextrin has been steadily increasing and yields large amounts of an extremely diverse range of by-products. These by-products can be a threat to the environment, but they are also very valuable for animal feeding (El Boushy et al., 2000). Potato by-products are numerous and very variable depending on the processing method that yielded them.

Potato by-products (Nelson, 2010; Charmley et al., 2006; Crawshaw, 2004; Bradshaw et al., 2002) can be classified into raw by-products, cooked by-products and mixtures of both classes:

Raw by-products
  • Abraded peel: the peel removed from raw potatoes intended for crisp processing.
  • Potato slurry / potato puree / potato filter cake: material from water recovery systems (oxidation ditch, belt solids, filter cake) containing variable amounts of microbial cells, solubles and of potato particles after filtration (filter cake or gray starch: sludge from settling tanks, comprised of free starch and small potato pieces).
  • Screen solids: small potatoes and slices, white waste, nubbins, hopper box.
  • Potato pulp from starch extraction.
  • Potato protein concentrate (see Potato protein concentrate datasheet)(Crawshaw, 2004; Bradshaw et al., 2002).
Cooked by-products
  • Steam peel also called potato feed: the potato peel removed by heating the potatoes with high-pressure steam. It is a sticky, slurry-like product.
  • Culled fries, culled crisps, hash browns, crowns, batter, crumbles, nubbins: these products can be high in fat and may contain high levels of seasoning salts.
  • Dried potato meal / potato flakes: Combination of by-products generated by potato processing. The waste is dried and sold as a high value energy feed (Crawshaw, 2004; Bradshaw et al., 2002).
Mixture of raw and cooked by-products
  • Potato puree feed is a blend of potato filter cake and steam peel that mix pretty well. It is a porridge-like slurry and it provides a high grade feed with qualities of both components of the mix. As it is also half cooked and half raw, it can be used in both ruminants and pigs (Crawshaw, 2004)

Utilization

Potato by-products are primarily used for animal feeding but they have a wide range of uses. They can be used as source of nutritionnally or pharmaceutically important compounds. In bakery, the high level of fibre in potato peels can be useful. Potato peels are used in muffin preparation where they replace wheat and prevent muffin oxidation (Hung et al., 2004).

As a feed, potato by-products may have very different nutritive value either being starchy or fibrous. The latter case is found for potato pulp, whose protein and fibre content depends on the proportion of potato solubles added back into the material. Therefore, it is necessary to have such materials analysed chemically before feeding livestock or to purchase them on the basis of a guaranteed analysis (Blair, 2008). Potato waste may have high N content and can be used as fertilizer. It was reported to be as effective as ammonium nitrate fertilizer for maize growth under optimal application level (Hung et al., 2004).

Distribution 

World potato production was about 374 million t in 2013: 239 million t were used for food in fresh or processed form. China was the main potato producer in the world with 100 million t produced in 2017 (FAO, 2019). World frozen potato (french fries) market was reported to reach 117 million t in 2017 with 42 million t in China (37%), 38 million t in India (31%), 16 million t in the USA and 5.8 million t in Pakistan (5%) (PotatoBusiness, 2019). In Europe, approximately 5.3 million t of potatoes were processed into frozen potatoes. The main producers were from North Western Europe: Netherlands (1.6 million t), Belgium (1.3 million t), Germany (0.83 million t), and the UK (0.42 million t) (CBS, 2016). The overall market of processed potato in Europe (EU-28) dealt with 9.644 million t of products (being mainly frozen fries, crisps, potato starch, and dried potato products (flakes, granules) (De Cicco et al., 2019).

Processes 

Raw products

Resulting from the peeling

The amount of peels resulting from the peeling of potatoes depends on many factors including the size of potatoes, their maturity and the methods of peeling: it was reported to vary from 2 to 50% (El Boushy et al., 2000).

Abraded peels

Abraded peels are raw potato peels of potato obtained through abrasion (scrapping) in the processing of crisps. They contain less starch than steam peels. Once abraded, the potatoes are washed and the abraded peels are transported with water. The byproduct has thus a low DM content. It can be later pressed or contrifuged (Crawshaw, 2004).

Resulting from screenings
Potato slurry/ potato filter cake

Filter cake is a raw by-product that consists of fine particles of potato pumped from settling or clarifier tanks to remove part of the water. It has a low DM content (12% to 15%) and 6% to 75% of that is starch. Due to its starch content, potato slurry is an unstable product under aerobic conditions. The starch can rapidly ferment during storage: it yields simple sugars suitable for bacteria developement, acidification occurs and CO2 is released, accounting for digestible energy losses. Bacteria are half aerobic and half facultative anaerobic groups. If storage is not adequately done, some of these bacteria and molds can produce toxins or pathogenic bacteria may develop and become an issue for the health of the animals fed on potato slurry (Bradshaw et al., 2002).

Screen solids from process water/potato waste

These are raw small potatoes and slices, white waste, nubbins, hopper box that are removed by screening or settling. They are mostly fed to ruminants (Crawshaw, 2004; El Boushy et al., 2000).

Potato starch

This by-product is recovered in process water after the uncooked potato have been cut, sliced chipped and have released the starchy content of damaged cells. This starch is recovered from cold water. It remains uncooked and makes a valuable source of slow-release energy for ruminants though it goes only seldom to feed markets (Crawshaw, 2004).

Potato pulp from starch extraction

For starch extraction, potatoes are rasped and washed in cold water so that the starch exsudates. Potato pulp remains after extraction of starch and of protein water solubles. Per 100 kg potatoes, starch extraction yields 3-3.5 kg dried potato pulp, 16-20 kg starch, and 3.2-5.8 kg protein water solids (Boucqué et al., 1988; Treadway, 1987; Howerton et al., 1948).

Cooked products

The production of french fries or crisps involves steam-peeling, cooking/blanching or deep-frying. Steam peels, lye caustic peels, culled fries, culled crisps, hash browns, crowns, batter, crumbles, nubbins are by-products that have undergone heat treatment and may have been added oil, seasoning salts etc. Heat treatments gelatinize starch that becomes readily digestible and deep-frying in oil increases energy amount (Crawshaw, 2004).

Resulting from the peeling
Potato feed/steam peel

Potato feed or steam potato results from the peeling process occurring during the production of chips (french fries) or potato dehydration. In this process steam at 200°C and pressure are used for a few seconds to remove the outer peel from potatoes. Steam increases moisture and gelatinizes starch contained in the peel. Peel is removed by a scrubber. Steam has a sanitation effect as it has anti-microbial effect or bacteriostatic effect (Bradshaw et al., 2002; van Lunen et al., 1989). The product has a porridge-like aspect and it is recommended to store it in special tanks or in bunker silo where it forms a firm gel. It can be used a sealing substance for moist feeds prone to decay during ensiling. It has been used to seal silos of brewer's grains, sugar beet pulp, grass and maize silage. A layer of 30-40 cm potato feed has been advised for adequate sealing of silos (Decruyenaere et al., 2005). However, the potato feed layer requires to be sheeted in order to prevent birds, cats and vermin contamination and comply with safety rules of storage (Crawshaw, 2004).

Lye caustic peel

In the lye peeling process, potatoes are washed with a hot (76-99°C) sodium hydroxide (5-20% NaOH) solution and then mechanically peeled yielding about 14% solids (El Boushy et al., 2000; Hinman et al., 1978). Peels resulting from lye peeling are alkaline and require neutralization before use as animal feed. Thanks to the chemical treatment, lye caustic peels have a low microbiological load and do not spoil during storage provided pH remains high (Hinman et al., 1978).

Resulting from screenings/trimming
Prime potato puree

Prime potato puree (PPP) is recovered after potatoes are sliced, chipped or diced and after ungelatinized potato starch has been extracted. The remaining starchy material is washed with hot water which gelatinizes the starch and increases its digestibility and passage rate. This starchy material may contain some peels removed by steam peeling which bring fibre and protein and makes PPP very different from potato starch. Because processes are very variable, PPP composition is also very variable and should be assessed prior to formulating rations (Crawshaw, 2004).

The PPP has high moisture content and may be centrifuged to reduce water content. Because reducing moisture in the PPP decreases its pumpability in pig liquid feeding, it is thus important that PPP moisture content remains between 17-23% for pig feeding while it can be drier in ruminants feeding (Crawshaw, 2004).

Culled fries, culled crisps, hash browns, crowns, batter, crumbles, nubbins

These are partially or fully-cooked by-products separated from final products because they do not comply with the size or colour standards of food-grade products. However, they have the same nutritive value as fries or crisp. They are highly energetic feeds containing not only high level of gelatinized starch but also of oil (up to 20%). Those products are considered to have higher energy level than any animal feed but oils and fats. The oil used for deep-frying affects the levels of saturated/unsaturated fatty acids with consequences on rumen microflora/microfauna and on methane emissions. Products cooked in rapeseed oil or sunflower oil may have defaunating effects, reduce methane emissions and thus limit the energy losses in ruminants (Crawshaw, 2004). Those by-products are also seasoned and may contain 0.5-1.75% sodium, the upper limit being an issue in pigs diet (Crawshaw, 2004). Potato hash is a mixture of potato skins, starch, fats and yellow maize obtained after the production of snacks. In South Africa, potato industry yields 50 t/day of potato hash that can be used in animal feeding (Nkosi et al., 2011).

Potato mash/ dried potato meal/ potato flakes/potato granules

Those products are obtained after the cooking of potatoes in the processing of chips or of dehydrated puree, potato flour and in the process of artificial chips like "Pringles" reconstituted from potato puree. Those potato by-products have high energy level, high amount (75%) of highly digestible starch (gelatinized) but also good quality protein, little fibre and some minerals (Crawshaw, 2004). They can be used in pigs diets and in ruminants diets provided the ration has enough fibre to prevent acidosis and enough rapidly available N to improve protein synthesis in the rumen (Crawshaw, 2004)..

Mixtures of by-products

Potato puree feed (PPF)

Potato puree feed is a combination of potato feed (steam peel) and prime potato puree. The mixture is easy to prepare, contains 15-16 % DM and the two components do not separate in the silo. As a mixture, PPF combines advantages and restrictions of both components: it contains cooked and partially cooked materials, it has the starch content of PPP and protein and fibre content of potato feed. It is thus recommended for both ruminants and pigs (Crawshaw, 2004).

Environmental impact 

Disposal

The potato peels and cut-offs may represent a severe disposal problem to the potato industry, especially since they contain high level of moist organic matter prone to rapid microbial spoilage. Their use as feed or as a source of bioactive compounds for the pharmaceutical or for the food industry is a way of alleviating this issue (Schieber et al., 2001).

Nutritional aspects
Nutritional attributes 

The wide diversity of potato by-products makes it difficult to provide consistent data about their composition. Generally, potato by-products are actually mixtures of various by-products, the proportions of which vary according to production practices employed in potato processing plants. Some farms can store separate types of potato by-products and improve nutrient balance through on-farm blending (Charmley et al., 2006). Most potato by-products are characterized by low and very variable DM content, the exception being dried potato pulp which is sold as a high value feedstuff (Charmley et al., 2006). Many potato by-products are rich in starch, depending on the amount of tuber left in the by-product, and are valuable as energy feeds. They often have relatively low contents of protein, minerals and fibre, but the latter may be important if peels are included in the by-product. Likewise, fat content is typically low, but by-products such as culled french fries can contain a large amount of oil.

All potato by-products, except cooked by-products, ensile rapidly: particularly, filter cake, steam peels and screen solids can be fed to ruminants in that form. Many studies in ruminants report data on ensiled by-products (Nelson, 2010).

Potential constraints 

Green potato death

The main potato glycoalkaloids, α-solanine and α-chaconine, have been incriminated as causing "green potato death" in ruminants. Symptoms include trembling, staggering, convulsions, weakness, diarrhea, and sudden death. The potato by-product with the greatest risk of increased glycoalkaloids content is the potato peel due to greening, sun burning, or injury or wounding (Bradshaw et al., 2002, Nelson, 2010).

Cysticercosis

Since the end of the 1980s, feeding potato by products has been suspected to be involved in the cysticercosis problem, or beef measles. Cysticercosis is caused by encysted eggs of the human tapeworm Taenia saginata. Some potato processors and feedlots pasteurize potato by-products to secure hygiene and destroy Taenia saginata eggs, especially in the Pacific Northwest States of USA (Bradshaw et al., 2002, Nelson, 2010). Ensiling at 35°C or lagooning at 7°C for 30 days appears similarly effective to pasteurization (Nelson, 2010). The highest risks of cysticercosis seems to be with the potato slurry or with animals fed potato by-products during long periods (Bradshaw et al., 2002).

Ruminants 

Energy and protein value

Raw potato by-products

The metabolizable energy (ME) value of potato by-products that has not been processed with exogenous fat sources is high, similar or slightly higher than that of barley, with reported values between 11 and 14 MJ/kg DM (Nelson, 2010; Charmley et al., 2006; Sauvant et al., 2004; NRC, 2001; NRC, 2000). However, these values can decrease substantially during storage, due to fermentation losses (Hashizume et al., 1974a, Charmley et al., 2006). Apparent digestibility of potato by-products has been found to be approximately 78% (Charmley et al., 2006). Starch from uncooked potato is more slowly degraded in the rumen than that of barley or wheat likely because starch granules are larger in potatoes than in barley or wheat and contained higher proportion of amylopectin (Monteils et al., 2002). This relatively slow rate of rumen metabolism should result in a more balanced rumen pH and better utilization of nutrients by rumen microorganisms and a better utilization of starch by the animal (Charmley et al., 2006). Indeed, it has been shown that substitution of maize grain by potato peels in graded diets ranging from 0 to 40% potato peels reduced the amount of organic matter (OM) digested in the rumen but did not affect apparent OM digestibility (Radunz et al., 2003).

Cooked potato by-products

The ME for cooked by-products is higher and can reach ME value above 14 MJ/kg DM, above that of maize grain, which is a direct result of the utilization of fats and oils during the processing of the products (Bradshaw et al., 2002, Charmley et al., 2006). Starch from cooked potatoes is expected to be degraded in the rumen at a higher rate than that of barley (Eriksson et al., 2004).

Even though the lipid content of potatoes is low, some cooked potato by-products, such as french fries, can have high lipid contents as a result of adding fat during processing (Charmley et al., 2006; Nelson et al., 2000). French fries by-products can have a fat content over 20% DM, which can be a problem because the rumen microbiota cannot tolerate concentrations of fat in the diet higher than 3-5% DM (Charmley et al., 2006). This has been confirmed by the observation in sheep that increasing the proportion of ffries in the diet from 15 to 60% DM reduced the extent of organic matter digestion (Rooke et al., 1997). For that reason, it is recommended to mix cooked potato by-products with other low fat by-products (Charmley et al., 2006).

Growing steers

Potato by-products are used as a high quality feed in beef feedlots and their value in this context has been extensively reviewed (Nelson, 2010; Charmley et al., 2006; Bradshaw et al., 2002). It is considered that increasing the inclusion of potato by-products beyond 20% DM of the diet results in a decline of DM intake (Charmley et al., 2006; Radunz et al., 2003; Busboom et al., 2000; Stanhope et al., 1980). However, there are huge discrepancies about this inclusion rate (Nelson, 2010). A reason for this may be that adaptation to a potato-based diet requieres approximately 6 weeks, which may contribute to the reduction in DM intake in the early feeding phase (Bradshaw et al., 2002, Charmley et al., 2006).

Potato by-products could replace conventional energy concentrates either partially or completely without negative effects on animal performance (Charmley et al., 2006). The high energy value of most potato by-products and their slow rate of digestion in the rumen confer several nutritional advantages to these by-products over either barley or maize. Even though cattle decreased their overall intake when they were offered diets containing high levels of potato by-products, this appeared to be offset by higher digestible energy content. Maximal body weight gains could be observed at inclusion level largely higher than 20%, for instance 80% (Duynisveld et al., 2016).

It has been believed that inclusion of potato by-product in the finishing diet of beef cattle had deleterious effects on carcass and meat quality (Nelson, 2010; Charmley et al., 2006). However most published studies did not confirm any effect of the inclusion of potato by-products in the diet of beef on either carcass characteristics, meat composition, meat water retention capacity, technological properties or deleterious taste of meat (Duynisveld et al., 2016; Nelson, 2010; Charmley et al., 2006; Radunz et al., 2003; Busboom et al., 2000).

Dairy cows

Potato by-products have also been used in dairy cows, in dry form (potato meal or dried pulp) or in wet form. When fed in a dry form, potato by-products are a palatable alternative to ground maize or cracked wheat (Schneider et al., 1985, Jurjanz et al., 2004). It has a very limited effect on intake and milk production with inclusion rate beyond 30%. It can even have a clear positive effect of milk fat content (Jurjanz et al., 2004). Its greatest benefit would appear to be in diets with high degradable nitrogen in the rumen (Schneider et al., 1985). Inclusion of 22% (DM basis) dried potato by-product (mixture of various by-products containing 7% protein, 5% ether extract, 5% crude fibre, 16% ash and 59% carbohydrates) resulted in lower intake of dairy cows than dried potato pulp with no effect in milk production and composition (Dickey et al., 1971). In another experiment, the addition of 7.5% dried potato by-product in chopped form, in an unwilted grass-legume silage, improved the feeding value of the silage for dairy cows (Schneider et al., 1985).

Because of large expenditures for drying, wet by-products have been fed to dairy cows (Brown et al., 1983; Onwubuemeli et al., 1985). When wet potato by-products were used to replace an appropriate amount of the regular commercial dairy concentrate on a DM, intake decreased when the incorporation rate increased between 12 to 24% DM . Milk production increased with incorporation rate of 12% DM but decreased when the incorporation rate reached 24% (Brown et al., 1983). The negative effect of wet potato by-products has been reported to be linked to the low DM content of the resulting diets (Hashizume et al., 1974b, Brown et al., 1983). Feeding up to 20% DM of potato by-products in replacement of high moisture maize had no adverse effect on ingestion, milk production and composition but feeding up to 20% DM of potato by-products had negative effect on fibre digestibility and milk fat content (Onwubuemeli et al., 1985).

Growing lambs

Potato by-products can be used as a source of energy instead of maize grain in growing lamb diets without any adverse effect at an inclusion rate up to 14% DM (Omer et al., 2010). However, adverse effects on digestibilities have been observed when inclusion rate reached 25% DM (Tawila et al., 2008).

Pigs 

Potato by-products resulting from cooking processes can be used as inexpensive and energy-dense material for pigs diets. Cooked potato by-products have a higher apparent protein digestibility than raw potato by-products (> 70% vs. < 50%) (Whittemore, 1977). However, some of these products (frozen french fries, crisps hash browns) have been seasoned and contain high levels of salt (0.5-1.75%), so they should be included carefully in pig diets (Crawshaw, 2004). Wet potato by-products may raise contamination concerns, though a French survey regarding the hygienic quality of potato mash-peel (a mixture of potato puree and peels) showed there was no concern with aflatoxin contamination or bacterial contamination in farm storage conditions (Radutza et al., 1998).

Potato by-products are used as source of energy and can partially and satisfactorily replace cereals in pigs diet. Inclusion rates (DM basis) were provided in a Belgian review (Decruyenaere et al., 2005):

  • starter pigs: 10%
  • growing pigs: 25%
  • sows: 30%

These values are global guidelines and should be modulated according to the specific composition of the by-product. A general rule should be to include potato by-products in pigs diet according to the results of the analysis of the batch.

Cooked potato by-products

Potato steam peel/liquid potato feed

Growing pigs from 40-15 kg to 93 kg BW could be fed safely on potato steam peel to replace up to 35% of the DM of their diet . Steam peel had satisfactory digestibility coefficients for dry matter, organic matter and energy at 76-82%. It was reported that feed intake was slower at all levels of potato steam in the diet and feed intake was reduced over 30% inclusion. Considering growth performance and feed conversion ratio, all levels decreased average daily gain and feed efficiency (Nicholson et al., 1988). It was agreed that potato steam peel could be satifactorily fed to pigs in commercial farms at levels not higher than 25% (DM basis)(Nicholson et al., 1988; Edwards et al., 1986). A later study reported that 30% inclusion of potato steam peel add with methionine did not have any deleterious effect on performance (van Lunen et al., 1989). Attention should be paid to the loss of DE (-23%) in liquid potato feed after a 7-week storage as the carbohydrates are converted in organic acids (Edwards et al., 1986).

Boiled potato peels

Boiling potato peels is a current processing method in smallholder farms. It is for instance a common practice in Vietnam (Ncobela et al., 2017). Boiling peels is easy at smallholder scale since it only requires pots, fire, water and time. One limitation is that it is not possible to boil large amounts of peels (and thus not possible to feed many pigs at a same time). Another limitation is that the boiled potato peels readily spoils after cooking and should be fed quickly. Boiling may have deleterious effect on folate content and on thiamine content but it improved digestibility and dietary nitrogen utilization by pigs of all ages (Ncobela et al., 2017, Stea et al., 2007). This could be explained by starch gelatinization and by inactivation by heat of proteolytic enzyme inhibitors (Whittemore, 1977; Whittemore et al., 1975).

Potato slices

Potato slices are passed through a hot air rotating drier at 175° F for about 2 hours. They were reported to be a valuable substitute for barley and maize grain in growing pig diets. It was recommended to include cooked-dried potato slices at 20% in grower diets and 40% in finisher diets. Beware that inadequate cooking could reduce their nutritive value (Thaler et al., 2010).

Potato flakes

Potato flakes are cooked products with low protein, low fibre but a high starch level. They have good digestibility in pigs and their metabolizable energy was reported to be equal to or higher than that of maize. Best performance could be observed when potato flakes were limited to 30 to 40% of the diet, but satisfactory performance could be obtained when potato flakes replaced up to 50 to 60% of the cereals in the diets of starting, growing, and finishing pigs (Thaler et al., 2010).

Potato crisps and French fries

These products contain gelatinized starch and oil. They are very high in energy but do not bring any other valuable nutrient (Thaler et al., 2010)

Raw potato by-products

Potato pulp/potato pulp and solubles

Raw (uncooked) potato pulp should not be fed to pigs but potato pulp pressed dried into meal form, or dried into pellets, or wet and mixed with solubles could be fed to growing pigs (35 kg BW). The pigs had lower feed intake on potato pulp meal than on potato pulp pellets. Most nutrients of these potato by-products had high digestibilities (80-90%): crude fibre and NFE digestibilities were about 90% but protein digestibility in potato pulp that was not added solubles was negative. Pelleting was reported to significantly increase digestibility of energy, organic matter and dry matter. Energy digestibility increased as the pigs got older (Boeve et al., 1973).

Fermented potato pulp included at 5% in lactating sows diet had positive effect on their milk yield. At the same inclusion level in growing and fattening pigs diet, fermented potato pulp improved weight gain and feed conversion ratio. Fermented potato pulp had also health benefits: it reduced the gastric pH and the number of coliform bacteria in the gut. It could have positive effect on pancreatic secretion and villosities (Scholten et al., 1999).

Ensiled pressed potato pulp was reported to be suitable for pigs as a source of energy, though its negative protein digestibility and the overestimation of its feeding value should be taken into account. There was no suggestion for maximum inclusion of ensiled pressed potato pulp in growing pigs diet (Jongbloed et al., 1992).

Potato hash, ensiled

In South Africa, potato hash (containing potato skins, starch, fats and yellow maize ) could be ensiled with or without lactic ferment in 210 L drums with other ingredients at 80% (fresh basis). Inoculation was reported to improve potato hash silage quality (reduced pH, butyric acid and ammonia-N and imroved lactic acid and propionic acid content). After 3 months, the silage was fed to growing pigs (20 kg BW) during 8 weeks. It resulted in poor growth performance in pigs (120 g/day vs. 400 g/day on average in commercial pigs) (Nkosi et al., 2011). These results confirmed prior observations (Thomas et al., 2010). The very low protein content and high fibre content of the diet could be responsible for these poor performance (Nkosi et al., 2011; Thomas et al., 2010).

Miscellaneous

In Japan, growing-fattening pigs fed up to 30% potato by-products (of unknown process and composition) were reported to have similar growth rate to pigs fed a conventional diet. At the higher level of potato by-products (30%), backfat thickness, intramuscular fat content and meat tenderness were higher than in other diets (Kimura et al., 2009).

Poultry 

Potato by-products can be used in poultry feeding provided that feed formulation is adapted to their highly variable chemical composition. Uncooked potato starch is not as well digested by chickens as other starches: starch digestibility was 40% in young chicks and 70% in cockerels, vs 99% for wheat starch at both ages (Yutste et al., 1991).

Raw potato by-products

Potato peels and waste meal

These products with moderate protein content can be used as substitutes for cereals. Potato peels were used in grower broilers at 15% without impairing growth performance or feed conversion. Growth was reduced in in starter broilers, but enzyme supplementation restored performance (Abdel-Hafeez et al., 2018).

Cooked potato by-products

Potato chips

Rejected potato chips with high fat content (31%) had a good nutritive value and their inclusion in starter chickens at up to 7.5% improved growth performance and feed intake with unchanged feed efficiency. The fat and salt content have to be considered in feed formulation (Rahnema et al., 2004).

Cooked potato flakes

Cooked potato flakes were successfully included up to 20% in broiler diets without adverse effects on growth and feed efficiency. At a higher inclusion rate (40%), growth and feed intake were affected, and there were problems of wet litter (Whittemore et al., 1974).

Mixed potato by-products

Potato waste meal (potatoes + peelings + discarded fried products) was successfully used at 15% in broiler diets, with no effect of age. However performance decreased at a higher inclusion rate (20%)(Hulan et al., 1982a; Hulan et al., 1982b).

Rabbits 

Potato by-products can be used safely in rabbit feeding, generally replacing cereals in balanced diets (Omer et al., 2011; Schlolaut, 1995). The only limit is the respect of the nutritional balance of the diet. For example, potato flakes were introduced with good results at 10% and even 20% in weaning diets used 19 d to weaning at 29 d (Skodova, 1989). Potato by-products were introduced in growing rabbit diets to fully replace yellow maize (26% of the diet) without alteration of growth performance or diet digestibility (Omer et al., 2011)

The nutritive value of potato by-products for growing rabbits can be improved through fermentation with fungi, and the final product may represent up to 30% of the diet (Xu et al., 2009; Shao et al., 2002). Unfortunately, the type of potato waste and the conditions of fermentation were not described in the publications.

Non-green potato peels can be used to feed rabbits, if possible after steaming or boiling but not necessarily, in conditions similar to that of whole tubers, but taking in account the actual composition of the product (Benoit et al., 1948; Charon, 1927). In Egypt, sun-dried potato peels were introduced in growing rabbit diets at 0, 5, 10, 15 and 25%. With the 3 first levels, growth performances were similar even a little bit better with 5 or 10 % potato peels, but rabbit weight was reduced by 6% or 18% with the inclusion of 15 or 20% potato peels (Kairalla et al., 2016). Unfortunately, the solanine or chaconine content of the product was not determined in this study.

Potato pulp, the by-product of industrial production of potato starch can be used in rabbit feeding without specific restriction other than the diet nutritional balance (Volek et al., 2004; Schlolaut, 1995). It is a feed material with a low protein content, relatively high digestible fibre, and about 15% of pectin (Turquois et al., 1999). The digestible energy content was estimated at 12.2 MJ/ kg DM (Sauvant et al., 2004)

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

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 86.9 1.6 83.6 93.1 100  
Crude protein % DM 5.4 1 1.6 7.9 99  
Crude fibre % DM 18.6 2 14.2 22.7 83  
Neutral detergent fibre % DM 28.4 3.9 23.3 35.4 8 *
Acid detergent fibre % DM 20.9 3.2 16 25.2 8 *
Lignin % DM 5.9 3.2 0.6 10 11 *
Ether extract % DM 0.4 0.3 0.2 1.3 9  
Ash % DM 3.5 1.5 2.2 12.1 76  
Insoluble ash % DM 0.09       1  
Starch (polarimetry) % DM 44.3 7.4 25.5 58.6 56  
Starch (enzymatic) % DM 33.9 4.6 25.3 36.3 5 *
Total sugars % DM 1.8 2.3 0.3 7.3 8  
Gross energy MJ/kg DM 17.6         *
               
Amino acids Unit Avg SD Min Max Nb  
Alanine g/16g N 2       1 *
Arginine g/16g N 1.8       1 *
Aspartic acid g/16g N 19.5       1 *
Cystine g/16g N 1.3         *
Glutamic acid g/16g N 19.8       1 *
Glycine g/16g N 1.1       1 *
Histidine g/16g N 1       1 *
Isoleucine g/16g N 0.5       1 *
Leucine g/16g N 4.3       1  
Lysine g/16g N 1.2       1 *
Methionine g/16g N 0.5       1 *
Methionine+cystine g/16g N 1.8         *
Phenylalanine g/16g N 0.9       1 *
Phenylalanine+tyrosine g/16g N 3.2       1 *
Proline g/16g N 0.6       1 *
Serine g/16g N 1.6       1 *
Threonine g/16g N 1.3       1 *
Tryptophan g/16g N 0.3         *
Tyrosine g/16g N 2.3       1 *
Valine g/16g N 2.7         *
               
Fatty acids Unit Avg SD Min Max Nb  
Myristic acid C14:0 % fatty acids 0.3   0.3 0.3 4  
Palmitic acid C16:0 % fatty acids 18 1.1 15.6 20.3 27  
Palmitoleic acid C16:1 % fatty acids 1.2 0.8 0.3 4 27  
Stearic acid C18:0 % fatty acids 5.3 0.6 3.9 6.6 27  
Oleic acid C18:1 % fatty acids 1.9 0.8 0.9 4.8 27  
Linoleic acid C18:2 % fatty acids 55.5 3.7 49.2 60.7 27  
Linolenic acid C18:3 % fatty acids 17.4 2.5 13.4 24 27  
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 4 0.8 3 5.3 6  
Phosphorus g/kg DM 1.4 0.9 0.6 3.5 8  
Potassium g/kg DM 8.6       1  
Sodium g/kg DM 1.5       1  
Chlorine g/kg DM 0.6          
Magnesium g/kg DM 1.6          
Sulfur g/kg DM 1.2          
Manganese mg/kg DM 50          
Zinc mg/kg DM 46          
Copper mg/kg DM 8          
Iron mg/kg DM 791          
               
Pig nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, growing pig % 72.7         *
DE growing pig MJ/kg DM 12.8         *
MEn growing pig MJ/kg DM 12.4         *
NE growing pig MJ/kg DM 8.9         *
Nitrogen digestibility, growing pig % 57.2         *
               
Poultry nutritive values Unit Avg SD Min Max Nb  
AMEn cockerel MJ/kg DM 8.8       1 *
AMEn broiler MJ/kg DM 8.8         *
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 65.9         *
Energy digestibility, ruminants % 62.4         *
ME ruminants MJ/kg DM 9.2         *
Nitrogen digestibility, ruminants % 28.4         *
Nitrogen degradability (effective, k=6%) % 65          
Dry matter degradability (effective, k=6%) % 65         *
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 11.3         *
MEn rabbit MJ/kg DM 11.1         *
Energy digestibility, rabbit % 64.1         *
Nitrogen digestibility, rabbit % 61.2         *

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

References

AFZ, 2017; Crawford et al., 1978; Kiiskinen, 1992; Macgregor et al., 1978

Last updated on 11/11/2019 18:19:19

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 20.1   14.3 24.7 3  
Crude protein % DM 10   5.5 16.3 4  
Crude fibre % DM 11.4   3.3 19.5 2  
Neutral detergent fibre % DM 19.4       1 *
Acid detergent fibre % DM 13.2   5.5 13.3 2 *
Lignin % DM 3.7       1 *
Ether extract % DM 0.7   0.2 1.5 3  
Ash % DM 5.5   5.1 6.1 3  
Insoluble ash % DM 0.8         *
Gross energy MJ/kg DM 17.1         *
               
Amino acids Unit Avg SD Min Max Nb  
Alanine g/16g N 3.4         *
Arginine g/16g N 3.4         *
Aspartic acid g/16g N 16         *
Cystine g/16g N 1.3         *
Glutamic acid g/16g N 15.2         *
Glycine g/16g N 2.9         *
Histidine g/16g N 1.5         *
Isoleucine g/16g N 3       1 *
Leucine g/16g N 4.8       1 *
Lysine g/16g N 4.4       1 *
Methionine g/16g N 1.3         *
Methionine+cystine g/16g N 2.7       1 *
Phenylalanine g/16g N 3.5         *
Phenylalanine+tyrosine g/16g N 7.3       1 *
Proline g/16g N 2.7         *
Serine g/16g N 3.4         *
Threonine g/16g N 3.4       1 *
Tryptophan g/16g N 0.8         *
Tyrosine g/16g N 3.8         *
Valine g/16g N 4.6       1 *
               
Fatty acids Unit Avg SD Min Max Nb  
Myristic acid C14:0 % fatty acids 0.3   0.3 0.3 4  
Palmitic acid C16:0 % fatty acids 18 1.1 15.6 20.3 27  
Palmitoleic acid C16:1 % fatty acids 1.2 0.8 0.3 4 27  
Stearic acid C18:0 % fatty acids 5.3 0.6 3.9 6.6 27  
Oleic acid C18:1 % fatty acids 1.9 0.8 0.9 4.8 27  
Linoleic acid C18:2 % fatty acids 55.5 3.7 49.2 60.7 27  
Linolenic acid C18:3 % fatty acids 17.4 2.5 13.4 24 27  
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 0.8       1  
Phosphorus g/kg DM 2.6       1  
Potassium g/kg DM 27.9       1  
Sodium g/kg DM 0.3       1  
Magnesium g/kg DM 1.3       1  
Manganese mg/kg DM 34       1  
Zinc mg/kg DM 57       1  
Copper mg/kg DM 12       1  
Iron mg/kg DM 258       1  
               
Pig nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, growing pig % 85.6       1 *
DE growing pig MJ/kg DM 14.6   14.3 15.1 2 *
Nitrogen digestibility, growing pig % 66.1         *
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 76.1         *
Energy digestibility, ruminants % 72.3         *
ME ruminants MJ/kg DM 10.3         *
Nitrogen digestibility, ruminants % 60.3         *
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 12.5         *
MEn rabbit MJ/kg DM 12.1         *
Energy digestibility, rabbit % 72.9         *
Nitrogen digestibility, rabbit % 62.6         *

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

References

Aregheore, 2000; Negesse et al., 2009; Van Lunen et al., 1989; Woodman, 1945

Last updated on 11/11/2019 18:34:29

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 17 4.5 9.9 24.6 14  
Crude protein % DM 12.8 3.1 7.1 18.5 16  
Crude fibre % DM 4.7 1.6 2.7 6.8 11  
Neutral detergent fibre % DM 11 7.4 7 24.2 5 *
Acid detergent fibre % DM 5.9   4.7 8.1 3 *
Lignin % DM 1.6   0.6 1.7 3 *
Ether extract % DM 1.3 1.8 0.2 5.7 8  
Ash % DM 7.1 3.2 2.8 12.2 14  
Insoluble ash % DM 2.4         *
Starch (polarimetry) % DM 45.5 8.4 30.9 55.9 8  
Starch (enzymatic) % DM 43.5         *
Total sugars % DM 2.1          
Gross energy MJ/kg DM 16.8         *
               
Amino acids Unit Avg SD Min Max Nb  
Alanine g/16g N 3.8         *
Arginine g/16g N 3.8         *
Aspartic acid g/16g N 15.1         *
Cystine g/16g N 1.3         *
Glutamic acid g/16g N 14.1         *
Glycine g/16g N 3.4         *
Histidine g/16g N 1.7         *
Isoleucine g/16g N 3.6         *
Leucine g/16g N 6.1         *
Lysine g/16g N 5.2       1 *
Methionine g/16g N 1.5         *
Methionine+cystine g/16g N 2.9       1 *
Phenylalanine g/16g N 4.2         *
Phenylalanine+tyrosine g/16g N 8.4         *
Proline g/16g N 3.3         *
Serine g/16g N 3.9         *
Threonine g/16g N 4       1 *
Tryptophan g/16g N 1         *
Tyrosine g/16g N 4.2         *
Valine g/16g N 5.1         *
               
Fatty acids Unit Avg SD Min Max Nb  
Myristic acid C14:0 % fatty acids 0.3   0.3 0.3 4  
Palmitic acid C16:0 % fatty acids 18 1.1 15.6 20.3 27  
Palmitoleic acid C16:1 % fatty acids 1.2 0.8 0.3 4 27  
Stearic acid C18:0 % fatty acids 5.3 0.6 3.9 6.6 27  
Oleic acid C18:1 % fatty acids 1.9 0.8 0.9 4.8 27  
Linoleic acid C18:2 % fatty acids 55.5 3.7 49.2 60.7 27  
Linolenic acid C18:3 % fatty acids 17.4 2.5 13.4 24 27  
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 1.9   1.4 2.4 2  
Phosphorus g/kg DM 2.3   2 2.6 4  
Potassium g/kg DM 35.1       1  
Sodium g/kg DM 0.3       1  
Chlorine g/kg DM 2.5       1  
Magnesium g/kg DM 1.6       1  
Sulfur g/kg DM 0.2          
Manganese mg/kg DM 28          
Zinc mg/kg DM 40          
Copper mg/kg DM 12          
Iron mg/kg DM 955          
               
Pig nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, growing pig % 89.8       1 *
DE growing pig MJ/kg DM 15.1       1 *
MEn growing pig MJ/kg DM 14.5         *
NE growing pig MJ/kg DM 10.5         *
Nitrogen digestibility, growing pig % 73.7       1 *
               
Poultry nutritive values Unit Avg SD Min Max Nb  
AMEn cockerel MJ/kg DM 10.5         *
AMEn broiler MJ/kg DM 10.4         *
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 85.5       1 *
Energy digestibility, ruminants % 81.6       1 *
ME ruminants MJ/kg DM 11.4       1 *
Nitrogen digestibility, ruminants % 69.8       1 *
Nitrogen degradability (effective, k=6%) % 65       1 *
Nitrogen degradability (effective, k=4%) % 70         *
a (N) % 6          
b (N) % 80          
c (N) h-1 0.165          
Dry matter degradability (effective, k=6%) % 64         *
Dry matter degradability (effective, k=4%) % 72         *
a (DM) % 6          
b (DM) % 90          
c (DM) h-1 0.11          
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 13.6         *
MEn rabbit MJ/kg DM 13.2         *
Energy digestibility, rabbit % 81         *
Nitrogen digestibility, rabbit % 62.9         *

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

References

AFZ, 2017; Chapoutot et al., 1990; Edwards et al., 1986; Rooke et al., 1997; Sourdioux et al., 1992; Willequet et al., 1993

Last updated on 11/11/2019 18:21:10

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 38.5   38.3 38.8 3  
Crude protein % DM 5.6   5.1 5.9 3  
Crude fibre % DM 0.5         *
Neutral detergent fibre % DM 4.5   2.5 6.4 2  
Acid detergent fibre % DM 1.3         *
Lignin % DM 0.3         *
Ether extract % DM 20.1         *
Ether extract (hydrolysis) % DM 22   19.1 26 3  
Ash % DM 1.9   1.8 2.1 3  
Starch (polarimetry) % DM 61          
Starch (enzymatic) % DM 58.4         *
Total sugars % DM 1.3          
Gross energy MJ/kg DM 21.3       1 *
               
Amino acids Unit Avg SD Min Max Nb  
Alanine g/16g N 2.1         *
Arginine g/16g N 1.9         *
Aspartic acid g/16g N 19.1         *
Cystine g/16g N 1.3         *
Glutamic acid g/16g N 19.3         *
Glycine g/16g N 1.3         *
Histidine g/16g N 1         *
Isoleucine g/16g N 0.7         *
Leucine g/16g N 0.3         *
Lysine g/16g N 1.5         *
Methionine g/16g N 0.6         *
Methionine+cystine g/16g N 1.9         *
Phenylalanine g/16g N 1.1         *
Phenylalanine+tyrosine g/16g N 3.6         *
Proline g/16g N 0.8         *
Serine g/16g N 1.8         *
Threonine g/16g N 1.5         *
Tryptophan g/16g N 0.4         *
Tyrosine g/16g N 2.5         *
Valine g/16g N 2.8         *
               
Pig nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, growing pig % 91         *
DE growing pig MJ/kg DM 19.4         *
MEn growing pig MJ/kg DM 19         *
NE growing pig MJ/kg DM 15.8         *
Nitrogen digestibility, growing pig % 84.7         *
               
Poultry nutritive values Unit Avg SD Min Max Nb  
AMEn cockerel MJ/kg DM 18.3         *
AMEn broiler MJ/kg DM 17.4         *
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 92.8       1 *
Energy digestibility, ruminants % 92.1       1 *
ME ruminants MJ/kg DM 16.7       1 *
Nitrogen digestibility, ruminants % 61.9         *
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
DE rabbit MJ/kg DM 18.4         *
MEn rabbit MJ/kg DM 18.1         *
Energy digestibility, rabbit % 86.3         *
Nitrogen digestibility, rabbit % 65         *

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

References

Rooke et al., 1997

Last updated on 11/11/2019 22:07:23

References
References 
Datasheet citation 

Heuzé V., Tran G., Boudon A., Bastianelli D., Lebas F., 2019. Potato (Solanum tuberosum) by-products. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/23075 Last updated on November 11, 2019, 22:13