Raw jatropha products tend to cause morbidity or mortality in different animal species. Toxicity of jatropha as a feedstuff has been studied extensively in several species including mice, rats, goats, sheep, and fish (Adam, 1974; Adam et al., 1975; Ahmed et al., 1979a; Ahmed et al., 1979b; Makkar et al., 1999). This toxicity is mainly due to phorbol esters and curcin (a lectin) (Nesseim et al., 2012). Others substances, such as trypsin inhibitors, lectins and phytate restrict the use of jatropha products in animal feeding. Jatropha platyphylla is free of phorbol esters and hence non-toxic. However, its kernels and kernel meal contain trypsin inhibitors, lectin and phytate (Makkar et al., 2012).
Jatropha species contain lipophilic tetracyclic diterpenoids called phorbol esters, that are present in all parts of the plant, including the seeds, leaves, stems, roots and flowers. The largest concentration (between 2 and 6 g/kg DM) is in the seed kernel. Non-detoxified kernel meal contains from 1 to 3 g/kg phorbol esters, and the oil 2 to 7 g/kg (DM basis) (Makkar et al., 2012). A detoxification process, for example by combining an alkali (NaOH) and an alcohol (methanol) can remove most or all of the phorbol esters (Makkar et al., 2010b). There are low-phorbol genotypes and species, such as Jatropha platyphylla, that may provide a meal where phorbol esters are below the detection level (Makkar et al., 2012).
Phorbol esters are known for their inflammatory action resulting in irritation and toxicity in insect, fish and mammalian species (Goel et al., 2007; Makkar et al., 2009; Nesseim et al., 2012). Jatropha curcas contains one of the most potent of the phorbols: phorbol-12-myristate-13-acetate, which is recognized for its tumor promoting activity (as a co-carcinogen) and is used as a biomedical research tool in models of carcinogenesis. Phorbol esters are toxic to livestock even at very low concentrations (Goel et al., 2007). In calves, mortality and severe liver, digestive, kidney and lung lesions were observed when they were fed diets containing only 0.25 g/kg Jatropha curcas seeds (Ahmed et al., 1979b). The same occured in goats fed similar doses of Jatropha curcas (Adam et al., 1975). In mice, intra gastric absorption of phorbol esters resulted in acute haemorragic gastro-enteritis with LD50 = 27.34 mg/kg live weight (Li et al., 2010).
Jatropha contains lectins or haemaglutinins. These proteins represent 6 to 11% of the seed proteins and they play an important role as deterrents to herbivores (Nesseim et al., 2012). In Jatropha curcas, the lectin curcin has irritative properties. Curcin belongs to a group of proteins called ribosome inactivating proteins, which inactivate ribosomes and, therefore, reduce protein synthesis (Makkar et al., 2011). However, curcin is also found in edible crops such as spinach, beet root and cereal grains where it does not seem to alter protein metabolism (Nesseim et al., 2012).
Jatropha contains trypsin inhibitors that prevent protein digestion and have deleterious effects on growth performance, notably in monogastric animals (Rackis et al., 1981).
Jatropha curcas seeds contain saponins, which are bitter, have haemolytic activity and are toxic, particularly to fish (Cseke et al., 1999). Raw Jatropha curcas kernel meal contains 2-3.4% DM saponins (Makkar et al., 1998; Martinez-Herrera et al., 2006), which is lower than in soybean meal (4.7% DM) and have very mild haemolytic activity (Makkar, personal communication).
Phytates are present in jatropha kernel meal (6-10% DM, Makkar et al., 1998; Martinez-Herrera et al., 2006), but their effect can be alleviated with phytase enzymes (Makkar et al., 2012).