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Potato (Solanum tuberosum) by-products

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
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Common names 

Potato pulp, potato peels

Description 

Potato by-products are numerous and very variable depending on the processing method that yielded them.

Potato by-products (Bradshaw et al., 2002, Charmley et al., 2006, Nelson, 2010) are the following:

  • Potato peels: Potato peel removed from the raw potato by heating the potatoes with high-pressure steam. It is a sticky product with the consistency of peanut butter, 
  • Screen solids: small potatoes and pieces, white waste or hopper box,
  • Cooked product (fries, hash browns, crowns, batter, crumbles): These products can be high in fat and may contain high levels of seasoning,
  • Potato slurry: material from water recovery systems (oxidation ditch, belt solids, filter cake) that varies from mostly microbial cells and solubles (oxidation ditch) to fine potato particles from clarifers after drum or belt-type vacuum filtration (filter cake or gray starch: Sludge from settling tanks, comprised of free starch and small potato pieces),
  • Dried potato meal: Combination of by-products generated by potato processing. The waste is dried and sold as a high value energy feed,
  • Potato pulp from starch extraction.

They 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).

Distribution 

World potato production was about 374 million tonnes in 2013 and 239 million tonnes were used for food. 

Processes 

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 [3]. It consists of approximately 12% to 15% dry matter and, of that, 6% to 75% is starch. Potato slurry is an unstable product : the starch content changes rapidly during storage due to fermentation process which tranforms it into simple sugars available for bacteria, acids are produced and the pH decreases to 3.5 while carbon dioxide is released, accounting for digestible energy losses. Bacteria are half  aerobic and half facultative anaerobic groups. Under certain circumstances of storage, some 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).

Potato peel

Potato peel waste results from the potato peeling process in which steam and heat are used to remove the outer peel from potatoes. Steam increases moisture and gelatinizes starch contained in the peel. Steam has a sanitation effect as it has anti microbial effect or bacteriostatic effect (Bradshaw et al., 2002).

Nutritional aspects
Potential constraints 

Green potato death

The major potato glycoalkaloids, i.e. a-solanine and a-chaconine, have been incriminated as causing ‘green potato death’ in ruminants (Bradshaw et al., 2002, Nelson, 2010). Symptoms include trembling, staggering, convulsions, weakness, diarrhea, and sudden death (Bradshaw et al., 2002, Nelson, 2010). 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 (Nelson, 2010).

Cysticercosis

At least since the end of the 80ies, feeding potato by products has also been suspected to be involved in the cysticercosis problem, or beef measles (Bradshaw et al., 2002, Nelson, 2010). Cysticercosis is caused by encysted eggs of the human tapeworm Taenia saginata. Some potato processors and feedlots pasteurize potato coproducts to ensure 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 

Nutritive value

The chemical composition and nutritive value of potato by-products is highly variable and depends on the type of by-products (Charmley et al., 2006, Nelson, 2010). Generally, potato by-products are fed as a mixture of various types, the proportions of which vary according to production practices employed in supplier potato processing plants (Charmley et al., 2006). Some farms can store separate types of potato by-products and improve nutrient balance through on-farm blending. (Charmley et al., 2006). All potato by-products, except cooked by-products, ensiled rapidly. More specifically, filter cake, steam peels or screen solids can be fed to ruminants in that form (Nelson et al., 2000). A lot of research studies in ruminants reports compositional data on ensiled by-product (Nelson, 2010).

Most potato by-products are characterized by low and very variable DM content, the exception being dried potato meal (DM content > 85.0%) which is sold as a high value feedstuff (Charmley et al., 2006). All potato by-products are mainly composed of starch, with relatively low contents of protein, minerals and fiber (Charmley et al., 2006). Thus, they are used as energy concentrates. 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 (NRC, 2000, 2001, INRA-AFZ, 2004, Charmley et al., 2006, Nelson, 2010). However, these values can decrease substantially during storage, due to fermentation losses (Hashizume et al., 1974a, Charmley et al., 2006). The ME for cooked by-products is higher and can reach ME value above 14 MJ/kg DM, above that of corn (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). Apparent digestibility of potato by-products has been found to be approximately 78.0 %  (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 corn 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). Starch from cooked potatoes is expected to be degraded in the rumen at a higher rate than that of barley (Eriksson and Murphy, 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 (Nelson et al., 2000, Charmley et al., 2006). French fries by-products can have a fat content over 20% DM, which can be a problem because ruminants rumen biota 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 French fries 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 above all used as a high quality feed for beef feedlots. The feeding value of potato by-products in this context has been reviewed by Charmley et al. (2006), Nelson (2010) and Bradshaw et al. (2002).

It is considered that increasing the incorporation of potato by-products beyond 20% DM of the diet results in a decline of DM intake (Stanhope et al., 1980, Busboom et al., 2000, Radunz et al., 2003, Charmley et al., 2006). However, huge discrepancy about this inclusion rate exits (Nelson, 2010). A reason of that may be that adaptation to a potato-based diet lasts approximately 6 week, which may contributes to the reduction in DM intake in the early feeding phase (Bradshaw et al., 2002, Charmley et al., 2006).

For Charmley et al. (2006), potato by-products can replace conventional energy concentrates either partially or completely without negative effects on animal performance. A main reason of that is that 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 corn. Even though cattle can decrease their intake of diets containing high levels of potato by-products, this appears 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% for Duynisveld and Charmley (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 (Charmley et al., 2006, Nelson, 2010). 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 (Busboom et al., 2000, Radunz et al., 2003, Charmley et al., 2006, Nelson, 2010, Duynisveld and Charmley, 2016).

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 is a palatable alternative to ground corn or cracked wheat (Schneider et al., 1985, Jurjanz et al., 2004). It has 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). Dickey et al. (1971) observed that, at 22% DM of inclusion rate, intake of dairy cows was lower with dried potato by-product rather than dried potato pulp with no effect in milk production and composition. It has also been observed that addition of 7.5% of 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 also 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 (Brown et al., 1983). 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-product has been reported to be linked to the low DM content of the resulting diets (Hashizume et al., 1974b, Brown et al., 1983). Onwubuemeli et al. (1985) observed that feeding up to 20% DM of potato by-products in replacement of high moisture corn had no adverse effect on ingestion, milk production and composition but feeding up to 20% DM of potato by-product had negative effect on fiber digestibility and milk fat content.

Growing lambs

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

Nutritional tables

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 25.0       1  
Crude protein % DM 12.8       1  
Crude fibre % DM 17.6       1  
Ether extract % DM 10.8       1  
Ash % DM 22.4       1  
Gross energy MJ/kg DM 17.2         *
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, Ruminant % 46.9       1  
ME ruminants (FAO, 1982) MJ/kg DM 6.5       1  
Nitrogen digestibility, ruminants % 37.5       1  

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

References

Woodman, 1945

Last updated on 24/10/2012 00:44:49

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 91.2       1  
Crude protein % DM 17.5       1  
Crude fibre % DM 39.1       1  
Ether extract % DM 6.4       1  
Ash % DM 10.8       1  
Gross energy MJ/kg DM 19.3         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 13.9       1  
Phosphorus g/kg DM 1.4       1  

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

References

Chopra, 1970

Last updated on 24/10/2012 00:44:49

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 23.0       1  
Crude protein % DM 10.9       1  
Crude fibre % DM 27.0       1  
Ether extract % DM 4.3       1  
Ash % DM 13.5       1  
Gross energy MJ/kg DM 17.7         *
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, Ruminant % 48.2       1  
ME ruminants (FAO, 1982) MJ/kg DM 6.6       1  
Nitrogen digestibility, ruminants % 44.0       1  

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

References

Woodman, 1945

Last updated on 24/10/2012 00:44:49

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 17.8   14.3 21.2 2  
Crude protein % DM 13.1   9.9 16.3 2  
Crude fibre % DM 3.3       1  
ADF % DM 13.3       1  
Ether extract % DM 0.5       1  
Ash % DM 6.1       1  
Gross energy MJ/kg DM 17.2         *
               
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  
               
Amino acids Unit Avg SD Min Max Nb  
Isoleucine % protein 1.9       1  
Leucine % protein 3.1       1  
Lysine % protein 3.3       1  
Threonine % protein 1.7       1  
Valine % protein 2.6       1  
               
Pig nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, growing pig % 84.9         *
DE growing pig MJ/kg DM 14.6   14.3 15.1 2 *
Nitrogen digestibility, growing pig % 77.2   76.2 78.2 2  

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

References

Van Lunen et al., 1989; Woodman, 1945

Last updated on 24/10/2012 00:44:49

References
References 
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/23075 Last updated on July 11, 2019, 18:01

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