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Almond kernels and 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 

Almond, bitter almond, sweet almond (tree) [English], bian tao, amandier, amandier commun  (tree), amande, amande douce, amande amère (fruit)[French], mandel, mandelbaum, bittermandelbaum [German], amendo, amendoeira, amêndoa amarga, amêndoa doce[Portuguese], almendro; almendra [Spanish]

Synonyms 

Amygdalus communis L., Amygdalus dulcis Mill. (basionym), Prunus amygdalus Batsch, Prunus communis (L.) Arcang., Prunus dulcis var. amara (DC.) Buchheim

Related feed(s) 
Description 

Almond trees are cultivated for their valuable edible nuts that are highly priced by gastronomes, by bakery, pastry and candy industries all over the world. Almond kernels are consumed raw worldwide, cooked or dry-roasted, sliced, ground or whole, blanched (without the skin) or unblanched (with the skin). It is extensively used in bakery and confectionery products, and in food preparation in general. It has been increasingly used as an ingredient in manufactured food products due to its physico-chemical, nutritional, and sensorial features: it is mixed with water to make almond "milk" a succedane of cow milk for people with lactose intolerance or other milk allergies.

Almond kernels and byproducts are the fruit of the almond tree and the byproducts that are yielded during the processing of almond kernels. An overview of  the way Californian farmers and manufacturers cultivate and process almonds is provided in the following video:

The fruit of the almond tree is a drupe where the pericarp + mesocarp form the fibrous green-gray hull, and the mature stony endocarp forms the shell, light brown in colour. Inside the shell is the seed also named kernel which is surrounded by a light-brown coloured, thin tegument called testa or skin.

The various processing (see picture above) of almonds yields several byproducts that can be used in animal feeding:

  • Culled and discarded almonds are almonds that do not meet commercial quality standards,
  • almond hulls are the botanical mesocarp+pericarp that split open when the fruit is mature, they represent about 52.0% of the total fresh weight of the almond fruit (Prgomet et al., 2017)
  • almond shells are the botanical stony lignified endocarps that are removed to reach the kernels, they represent 33% of the total fresh weight of the almond fruit (Prgomet et al., 2017)
  • almond testa/skin is the tegument of the kernel that is removed when the kernel is blanched for some preparations, it accounts for 4.0–8.0% of the total shelled almond fresh weight (Prgomet et al., 2017)
  • almond oilcake/meal is resulting from the extraction of oil which is used in cosmetics and pharmaceuticals.

Once hulled and shelled, the almonds can be blanched and used raw or be cooked in dishes or be roasted without removing the testa and salted/sweetened to make snacks. The almond kernels can also be ground to be used as a powder in pastries and bakery products. They can be candied or used to make "turron" and other delicacies. The kernels can also be extracted for oil which has dual purpose as culinary oil and cosmetics. In the recent years, the demand for almond "milk" has been increasingly growing, resulting in huge amounts of byproducts, particularly the shells.

The total amount of almond byproducts has been estimated to 70.0–85.0% of the whole almond fruits. Their use is animal feeding is a good way to prevent waste and losses. Almond hulls are the main animal feed among these byproducts.The shells can be used to make mulch, or animal bedding.

Distribution 

The cultivated almond is thought to have originated in the arid mountainous regions of Central Asia. Several wild species are also found growing in these mountainous areas from Tian Shan mountain in western China through Kurdistan, Turkestan, Afghanistan and into Iran and Iraq (Grasselly 1976b; Kester et al., 1996). 

Almond trees are among the first fruits crops to have been domesticated during Antiquity with the date palm, olive, grape, fig, and pomegranate. They do not seem to have changed a lot since then (Janick, 2012).

The distribution of almonds, both in cultivation and in the associated semi wild state, has been divided into three areas: Asia, Mediterranean Basin, and California (OECD, 2006).

The principal almond-producing area of the world is the central valley of California with 77 % of the world production.

In 2019, worldwide almond production was 1.368 million tons. California was the first producer with 1.060 million tons (77%), followed by Australia at 103 700 tons (8%), Spain at 78 089 tons (6%), Turkey at 20 000 tons (1,5% ), Italy at 18 000 tons (1.3%) and the other producers represented 88 596 tons (6.4%) (INC, 2020). Almond byproducts are available in the place where almonds are processed.

Processes 

Almond harvest

Traditional almond harvest was done by knocking the dehiscing almond fruits with poles. The fruits then fell on nets situated on the floor. This was a labour intensive operation, and, where possible, trunk shakers have replaced traditional harvest method. Modern shakers are self propelled. They shake the trunk above ground. Some shakers (as it is the case in Italy) have their own receptacle (umbrella inversed), other are simple shakers,  (i.e. Californian harvesters)  they let the fruits fall on the ground and an other self-propelled machine (a picker-upper) takes the almonds from the soil. For picker-upper to perform adequately it is necessary to have smooth soils (Pascuzzi et al., 2017).

Almond hulling and shelling

The almonds are then carried to the farm/manufactory where they can undergo a short drying and be stored prior to hulling and shelling. The almonds are first screened to remove impurities (stones, leaves, twigs) and are conveyed to the hulling and the shelling machines. Those machines are series of rotating cylinders placed at variable distances that can be adapted to the size of the almonds. After a first course through he rollers, the almonds are screened, and the hulls are removed by aspiration. Once hulled, the almonds undergo a similar operation to crack and remove the shells. Almond kernels and shells are separated through counter-air flow (US EPA, 1995). 

The hulls are used in cattle feeding ans the shells may go to mulch, compost or animal bedding. They can also be used for energy production (Gonzalez et al., 2006).

Almond parching

Almonds can be further peeled (parched) for confectionary and bakery purposes. They are parched via hot water blanching, a process which generates blanched water and almond skins (4-8 % FW). These skins are rich in fibre and phenols that are responsible to a significant extent for the high radical scavenging activity capacity (Prgomet et al., 2017). Almond skins have the potential for valorization in functional foods, nutraceuticals, and/or food additives but do not seem to be used in animal feeding (Chen et al., 2019).

 

Nutritional aspects
Nutritional attributes 

Almond kernels

Almond kernels are energy sources because of their high lipid content. The oil is primarily unsaturated, composes mostly oleic and linoleic fatty acids (García-López et al. 1996). The kernel also contains considerable proteins, minerals, and some vitamins (Kester et al. 1991; Kester and Gradziel, 1996).

Almond hulls

Almond hulls are fibrous and variable energy sources with crude fibre between 10 and 17% DM and sugar from 18 to 30% depending on variety, cultivation and harvest conditions. They also have low protein content (2-5% DM) (Aguilar et al., 1984)

Almond oilcake/meal

The detoxified cake can be fed to all domestic animals, but it is usually sold to bakeries at a higher price.

Potential constraints 

The kernels and the oilcake contain the glucoside amygdalin, which can yield prussic acid. Kernels and cakes must therefore be cooked thoroughly before being used as feed.

Almond hulls

Shell and mold contamination

Almond hulls should be carefully screened so that no or as little as possible shell remain in the hulls: the shells lower the digestibility of the hulls and decrease the overall value of the product which must be counterbalanced by high quality feeds and result in higher feed costs (Asmus, 2015). Moreover, almond hulls are sensitive to moisture, and subsequent heating and molding during storage (Asmus, 2015; Miller, 1949). 

Quality loss

There are many factors of quality loss. Some occur during cultivation or storage, other during the processing of almonds. Almond hulls are thus a very variable product. Rain is particularly detrimental to almond hulls quality as the sugars contained in the hulls are flushed by the rain (Asmus, 2015).

Ruminants 

Almond hulls

Almond hulls can be used as a source of energy for ruminants. 

Degradability

The in vitro DM and OM degradability and gas production of dried almonds hulls measured with sheep rumen liquor were respectively 60.5%, 62.7% and 69.7 mL/200 g DM. Those values were higher than those observed on green almond hulls and on green and dry leaves of almond tree . Dried almond hulls had also the highest metabolizable energy value (10.1 MJ/kg DM) (Elahi et al., 2017).

Cattle
Steers

DM digestibility of almond hulls was about 60-61% (59.6% to 62.1%) and the digestible energy (DE) was about 10 MJ/ kg  (9.99 to 10.54MJ/kg) in steers (Aguilar et al., 1984).

In Iran, almond hulls fed to steers had higher in situ total potentially degradable fraction (a+b) than alfalfa. The "a" value was also higher than for alfalfa which could be in favour of higher intake. The degradation rate was however lower in almond hulls than in alfalfa. Overall results showed that almond hulls could be used to feed steers and more broadly ruminants (Jafari et al., 2015).

In the USA, it was possible to use almond hulls as a roughage in fattening steers diet at 7.5 and 15% inclusion in order to replace alfalfa and oat hay. No significant difference could be found in weight gain, intake or feed efficiency. Meat quality parameters remained unaffected by the use of almond hulls as a roughage source (Beckett et al., 1992). Earlier, in 1984, in a digestibility trial it had been possible to include up 40% almond hulls in a diet containing alfalfa hay, oat hay, barley, and urea and to maintain steers to maintenance + 10% (Aguilar et al., 1984). However, this could not be confirmed in 1991 when 8 month old Hereford steers, recorded  less intake and 42% lower weight gain when they were fed on 40% almond hulls. The feed efficiency was also significantly hampered but the carcass quality remained unchanged. It was suggested to limit almond hulls inclusion to 30% for growing steers (Porte et al., 1991).

Dairy cows

Almond hulls were worth 60% of the energy provided by maize grain and 4.2% of the protein provided by soybean (Grasser et al., 1995). Based on their nutritive value, almond hulls were reported to enter the least-cost calculated rations for high producing cows in California at levels varying from 0.4 kg/day in Northern California to 1 kg in Central California and up to 2.45 kg in southern California out of (Grasser et al., 1995). 

In 1984, it had been possible to feed lactating dairy cows on 25% almond hulls (dietary DM) without affecting weight gain and milk production performance (Aguilar et al., 1984).

When compared to other coproducts, almond hulls were reported to be less palatable the sugarbeet pulp and less productive than citrus pulp (Williams et al., 2018). In a recent experiment, almond hulls and ensiled citrus pulp have been assessed on dairy cows for milk production and enteric methane emissions. Almonds hulls (4 kg representing 25% of the dietary DM) or citrus pulp (3 kg representing 18% dietary DM) replaced alfalfa in the cows diet. Almond hulls yielded lower milk (24.6 kg) than the control (27.4) or the ensiled citrus pulp (26.2 kg). Dietary treatment did not affect milk composition parameters like fat, protein, and lactose or fat yields or fatty acid profile (Williams et al., 2018). Formerly, the use of almond hulls or sugarbeet pulp in lactating dairy cows in Japan, resulted in similar milk yield and milk quality (Ueyama, 1979).

An early report from 1949 in California demonstrated that almond hulls should not be used as a sole feed for dairy cows because it resulted in poor condition and performance. It was advised to replace half of the alfalfa hay in dairy cows diet (Miller, 1949).

Recent concern about methane emissions have raised awareness about the potentiel effect of some coproducts on the reduction of emissions. Almond hulls have been assessed for their possible effect on methane enteric emissions of cows but did not prove to be beneficial (Williams et al., 2018).

Sheep

Almond hulls were shown to have higher degradation parameters (a, b and c) and higher in situ degradability "effective degradability of DM" than alfalfa in sheep. The a parameter, is favourable to good intake. All theses values advocate for almond hulls to be a potential fair value source of energy for sheep, though their lignin content could be a constraint (Yalchi et al., 2010).

Former digestibility trial had reported that the OM digestibility of coarse almond hulls was 63.3% and the digestible energy was 12.04 MJ/kg. It has also been shown that N supplementation of the diet could increase the intake and that digestibility was reduce by the grinding of almonds hulls which was thus not recommended . It was concluded that almond hulls, mostly deprived of protein could be used as an energy source in sheep and also in cattle (Alibes et al., 1983). 

Raw and ground almond hulls

Raw and ground almond hulls are relished by sheep (Miller, 1949).

In the USA, it was possible to prepare finishing diets containing increasing (0, 5%, 10%) levels of almond hulls as a replacer of alfalfa for Hampshire x Suffolk lambs. The almond hulls diet neither had effect on daily gain feed intake and feed efficiency, nor had it effect on carcass yield or quality at slaughter (Phillips et al., 2015).

In former trials, in Italy, almond hulls could be included at up to 15% or even 30% dietary level (Vicenti et al., 1993; Vonghia et al., 1989). Farm fattening sheep could be fed during 56 days on isonitrogenous, isoenergetic diets supplemented with either 15% almond hulls or 10% safflower cake or 15% almond hulls+10% safflower cake.  All the diets yielded similar weight gain, feed intake and feed conversion efficiency. However, the dressing percentage was higher in for animals fed on safflower cake than those fed on almond hulls. It was concluded that it was possible to feed lambs of both almond hulls and safflower either in combination or alone (Vicenti et al., 1993). It was possible to offer up to 30% almond hulls to finishing lambs provided they could receive enough protein through the diet (Vonghia et al., 1989).

In an earlier digestibility trial, a mixture of ground almond hulls (50% of the diet) and chopped alfalfa hay was readily eaten by finishing lambs. The total digestibility of nutrients was 64.6% which could compare to the digestibility of culled fruits and advocated for a good nutritive value of ground almond hulls for sheep (Miller, 1949).

Ensiled almond hulls

Feeding finishing lambs on maize-soybean based diet supplemented with ensiled almond hulls had positive effects on crude protein and fibre content. It had no effect on daily weight gain and final weight gain and it improved feed efficiency and resulted in lower feed cost in the ration (Omar et al., 2018).

Urea treated almond hulls

In Iran, urea-treated almond hulls were fed to Shall male lambs at  %, 20 or 40% dietary  (iso energetic and iso protein) DM to replace alfalfa. Feeding urea-treated almond hulls had no effect on DM intake. In vivo digestibilities were respectively 82%, 73% and 24% for DM, OM and CP. The substitution of almond hulls for alfalfa had no effect on rumen parameters or protozoa population. It had no effect on sheep blood parameters. Up to 40% urea-treated almond hulls could be included in sheep diet (Rad et al., 2016).

Goats

Alpine goats could be supplemented with almond hulls up to 35% (DM dietary level) as a replacer of alfalfa hay in isonitrogenous, isoenergetic rations mainly based on barley, cottonseed oilmeal molasses and limestone. Though the digestibility of DM, organic matter, NDF and ash were decreased at the higher level of almond hulls, the DM intake and weight gain increased. No significant difference in milk yield (av. 3.6-3.7 kg/day) or fat content (2.7-2.8%), could be found but protein content was significantly highest with 25% almond hulls and lowest with 35% (3.0 vs. 2.9%). ; Results indicate that almond hulls can be given at these levels to goats without adversely affecting milk production (Reed et al., 1988).

Pigs 

Almond hulls

Almond hulls are fibrous material but they are also a source of sugar that could be valuable for pigs under adequate conditions. Almond hulls were found to have antioxidant effect in the brain of pigs (Barreira et al., 2010).

Growing pigs fed on a basal diet of soybean meal and maize received increasing dietary levels of almond hulls (0, 5, 10, and 15%). No difference in weight gain, or final weight were reported. The level of almond hulls neither altered feed efficiency nor did it hinder carcass quality. Carcass weight and carcass length were not  affected. At the higher level of almond hulls inclusion, backfat was unexpectedly reduced in comparison to lower inclusion rates. The dressing percentage was also lower at 15% inclusion. It was concluded that growing pigs could safely receive 15% almond hulls to replace part of the energy in their basal diet, keeping in mind that the diet should be balanced for protein (Calvert et al., 1985).

Almond kernels

No information could be found on the use of culled almond kernels in pig diets (as of 2020).

Poultry 

Almond hulls

Almond hulls, with their high content of sugars and starch could be a valuable alternative source of energy for poultry and could save some costly feed like maize in chicken diets. Up to 9% could be fed to broilers.

In an attempt to partially replace corn-soybean meal in chicken basal diet, almond hulls of two almond varieties were ground and extruded (at 120°C), and included at increasing levels (3, 6 and 9%) during 19 days. It was shown that increasing levels of extruded almond hulls only slightly decreased animal weight gain, and slightly deteriorated feed efficiency (Woo, 2018). It was recommended to lower extrusion temperature and to test extruded almond hulls in hens diet because hen could make better use of fibre than broilers (Woo, 2018). 

Almond oil meal

Almond oil meal could be included from 10 to 30% in the diet of Japanese quails diet without any adverse and side effect on feed intake, feed efficiency, animal health parameters and performance or on product quality (the content of total cholesterol in the yolk was not affected) (Arjomandi et al., 2015). The values of the metabolizable energy were AME=3734, AMEn=3648, TME=3908, TMEn=3746 kcal/kg on an as fed basis. At the higher level of inclusion, the birds showed lower serum total cholesterol, and lower low density lipoprotein compared to control or 10% almond oilmeal (Arjomandi et al., 2015).

Rabbits 

Almond kernel

No information seems available in the international literature on the normal use of almond kernel in rabbit feeding. However it must be noticed that the daily intake by adult rabbit (1.57 kg) of 2.5 g of almond kernel during 2 month (about 3% of the daily feed intake) decreased significantly serum total cholesterol or triglycerides as expected, but failed to induce any health problem (Teotia et al., 1997).

Almond hulls

Almond hulls are sometimes used in Tunisia as source of fibre in commercial rabbitfeeds (Lebas, 2010). A study conducted in the Oregon University (USA) with rabbit diets containing 0, 20, 40 or 60% of almond hulls replacing alfalfa hay demonstrate that almond hulls could be successfully incorporated into the diet of growing rabbits up to the level of 40% replacement for alfalfa meal without any adverse effects on performance and nutrient digestibility. With 60% of almond hulls, feed intake was reduced by about 30%, probably because of a nutritional imbalance and/or pellets
too hard (Aderibigbe et al., 1990).

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 86.6 5.2 69.5 91.8 18
Crude protein % DM 6.0 0.9 4.2 7.8 46
Crude fibre % DM 15.2 5.4 10.4 28.5 16
NDF % DM 32.6 3.6 25.1 39.7 42
ADF % DM 26.5 4.2 19.5 34.2 43
Lignin % DM 10.8 2.7 6.3 16.1 37
Ether extract % DM 3.1 0.7 2.3 5.2 37
Ash % DM 7.3 1.9 4.8 11.5 47
Gross energy MJ/kg DM 17.6 2.2 15.1 19.7 4 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 2.9 0.9 2.2 7.0 30
Phosphorus g/kg DM 1.2 0.6 0.6 3.8 33
Potassium g/kg DM 26.2 1.8 22.7 29.0 26
Sodium g/kg DM 0.3 0.1 0.2 0.5 21
Magnesium g/kg DM 1.2 0.5 0.8 3.7 29
Manganese mg/kg DM 18 5 12 31 26
Zinc mg/kg DM 17 6 9 30 25
Copper mg/kg DM 6 4 2 14 20
Iron mg/kg DM 236 104 108 436 25
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 63.4 3.3 56.7 66.7 7
Energy digestibility, ruminants % 59.5 *
DE ruminants MJ/kg DM 10.5 *
ME ruminants MJ/kg DM 8.7 *

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

References

AFZ, 2011; Alibes et al., 1983; Alibes et al., 1990; Arosemena et al., 1995; DePeters et al., 1997; DePeters et al., 2000; Fadel, 1992; Getachew et al., 2004; IAV, 2009; Obradovic, 1969; Tisserand et al., 1989; Weir, 1951

Last updated on 24/10/2012 00:43:36

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 94.5 0.7 93.7 95.3 4
Crude protein % DM 21.4 2.1 18.6 23.6 4
Crude fibre % DM 2.5 0.2 2.2 2.7 4
NDF % DM 5.0 0.4 4.6 5.5 3
ADF % DM 3.3 0.4 2.9 3.6 3
Lignin % DM 0.7 0.2 0.6 0.9 3
Ether extract % DM 57.4 2.9 54.1 60.5 4
Ash % DM 3.3 0.2 3.0 3.4 4
Gross energy MJ/kg DM 30.7 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 2.7 1
Phosphorus g/kg DM 5.2 1
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 86.2 *
DE growing pig MJ/kg DM 26.5 *

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

References

Saura-Calixto et al., 1983; Watt et al., 1950

Last updated on 24/10/2012 00:43:36

Main analysis Unit Avg SD Min Max Nb
Crude protein % DM 10.5 1
Crude fibre % DM 23.5 1
Ether extract % DM 5.5 1
Ash % DM 6.5 1
Gross energy MJ/kg DM 18.9 *
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 53.2 *
DE growing pig MJ/kg DM 10.0 *

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

References

Kneeland, 1958

Last updated on 24/10/2012 00:43:36

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 89.3 1
Crude protein % DM 47.9 1
Crude fibre % DM 4.2 1
Ether extract % DM 4.3 1
Ash % DM 6.4 1
Gross energy MJ/kg DM 20.2 *

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

References

Morgan et al., 1930

Last updated on 24/10/2012 00:43:36

References
References 
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/27 Last updated on September 15, 2020, 18:18