Cashew (Anacardium occidentale) nuts and by-products

Cashew nut meal (CNM)

Discarded cashew nuts, usually called cashew nut meal, is an energy and nutrient rich product that can be used at relatively high levels in ruminant diets, though one should pay attention to its high oil content. Most trials have taken place in Brazil.

Dairy cows

Up to 24% cashew nut meal (i.e. 7 kg/day) was included in a concentrate to supplement a sugarcane-based diet (Pimentel et al., 2007). Cashew nut meal was included at 50% of the dietary DM in a total mixed ration based on maize silage (Pimentel et al., 2012a). In both experiments, including CNM did not change milk yield compared to the control diet (Pimentel et al., 2012a; Pimentel et al., 2007). CNM inclusion (24%) in a sugarcane-based diet decreased milk fat content from 36.8 g/kg to 26.6 g/kg. In a maize silage-based diet, CNM had no effect on DM intake (21.3 kg/day) (Pimentel et al., 2012a). However, its inclusion at 24% of a sugarcane-based diet significantly reduced the DMI of the sugarcane from 7.7 to 7.05 kg DM/day, and overall diet DMI from 14 to 13.22 kg DM/day (Pimentel et al., 2007). The form in which cashew is offered (separately or mixed into the diet) may explain those contradictory results. The inclusion of cashew nuts in the ration did not affect rumen fermentation parameters (Pimentel et al., 2012b). In the semi-arid conditions of North-East Brazil, CNM included at 20% in dairy cow diets decreased the interval between post-partum and first ovulation (Brasil, 2003).

Sheep

Cashew nut meal can be safely introduced into sheep diets provided that the dietary lipid content is kept below 6-7%, as higher values will decrease fibre digestibility, DMI and forage digestibility (Silva et al., 2013). CNM was included at 13-18% of DM in a concentrate fed (1.2% BW) to supplement hay in breeding rams. It had no negative effect on sperm quality (Medeiros, 2005; Oliveira et al., 2014). CNM included at 12 or 24% of the DM into a concentrate fed to adult ewes as a supplement to hay had variable effects, depending on the inclusion rate. At the lower level, no deleterious effect was observed. At 24% inclusion, CNM increased the number of degenerated oocytes and lowered the proportion of viable oocytes. It was thus recommended to limit its inclusion in ewes (Fernandes et al., 2014).

Table 1. Summary of trials in which cashew nut meal (CNM) was fed to small ruminants

Cashew bagasse

Most trials with cashew bagasse have taken place in Brazil, usually with sheep. It is not always clear whether the product tested is the bagasse (by-product of the juice extraction) or only the non-extracted pulp.

Nutritive value

Cashew bagasse has a low in vitro DM digestibility (46%), probably due to its high fibre and lignin content (Pereira et al., 2008). Ensiling up to 36% cashew bagasse with elephant grass improved the nutritive value of the silage compared to elephant grass alone, and provided better conservation (Ferreira et al., 2004). Treating cashew bagasse with urea improved its nutritive value (Dantas Filho, 2010).

Sheep

Including 19% dried cashew bagasse in diets containing elephant grass, sorghum and soybean meal for growing sheep resulted in the best fermentation parameters (Rogerio et al., 2009). In Brazil, a mixture of equal proportions of dried cashew pulp and leucaena leaf meal was found to be suitable for growing sheep (Leite et al., 2005). Fed alone, fresh or dried cashew bagasse as forage had no effect on animal performance or age of puberty (Rodrigues et al., 2010). Dried cashew bagasse ensiled with elephant grass improved silage DM intake and growth of young sheep (Ferreira et al., 2004). Dried cashew bagasse replaced 50% of tropical forage in the diet of gestating and lactating ewes or of young growing male lambs without negative effects on the reproductive performance of ewes or on the age of puberty of lambs (Rodrigues et al., 2010; Rodrigues et al., 2011). Used as forage for fattening lambs, dried cashew bagasse improved feed conversion ratio and resulted in better carcass characteristics (Silva et al., 2011).

Cattle

In India, sun-dried cashew bagasse partly replaced (50%) groundnut meal in a concentrate offered to Gir dairy cows, to supplement a forage-based diet, without modifying milk yield (Sundaram, 1986).

Table 2. Summary of ruminant trials with dehydrated cashew bagasse (DCB) or pulp (DCP)

Cashew nut shells

In Nigeria, cashew nut shells included at up to 20% of diet to West African dwarf goats fed an elephant grass-based diet resulted in lower feed intake, digestibility, daily weight gain, and degraded feed conversion ratio. However, they had no impact on blood parameters, even at 30% of the diet, and could reduce feed costs (Ocheja et al., 2014; Okolo et al., 2012).

Cashew Nut Shell Liquid (CNSL)

It has been suggested that CNSL may reduce methane emissions from ruminants (Kobayashi, 2012). An in vitro experiment showed that CNSL could favourably alter rumen microbes and inhibit methane production. In dairy cows, CNSL increased the production of propionate both in vitro and in vivo when fed at 4 g/100 kg BW, but not at lower levels (Coutinho et al., 2014).

Cashew tree leaves

Cashew tree leaves are not a good supplement. They have a high concentration of tannins and lignin, which explained the low values observed for DM intake and DM digestibility in goats (Reddy et al., 2008). In India, cashew tree leaves offered as a supplement (300 g/d) to male goats fed ad libitum with elephant grass (Pennisetum purpureum), failed to improve diet DM digestibility (Reddy et al., 2009). In Nigeria, cashew leaves fed alone to lambs did not meet their nutritional requirements and caused nitrogen losses (Anugwa et al., 1987).