Sesbania spp.

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General information

Sesbania sesban (L) Merrill is a short-lived fodder shrub or small tree. This legume can tolerate wide temperature ranges, acidic soils and waterlogging, as well as soil salinity. S. sesban grows rapidly and is useful as fodder and green manure. This species has long been used for feeding livestock and for soil improvement in India and Africa.

Productivity and nutrient composition

Biomass production of Sesbania sesban has been reported to be 4.8 t / ha and N in the above-ground biomass to be 0.1 t / ha (Creamer and Baldwin, 2000). S. aculeata yields in the range of 1 to 1.5 t / ha of seeds (see Hossain and Becker, 2001).

The crude protein contents of Sesbania species (Table 5) are higher than those reported for conventional legumes, such as chickpea, mungbean and cowpea. Sesbania sp. are, however, deficient in essential amino acids except for leucine, tryptophan and histidine (see Table 10). Sesbania sp. are generally a good source of essential fatty acids (Hossain and Becker, 2001).

The organic matter digestibility of Sesbania seeds ranges from 67 - 72 per cent and nitrogen solubility in alkali from 81 - 89 per cent (Hossain and Becker, 2002).

Antinutrients

A potent antinutrient in Sesbania sp. in addition to the ones presented in Table 6 are the non-starch polysaccharides (NSP). The seeds contain about 30 - 42 per cent endosperm, 75 per cent of which is made of an NSP, galactomannan (Chandra and Farooqui, 1979).

Soaking overnight in water followed by autoclaving has been shown to be effective in significantly bringing down levels of various antinutrients in Sesbania seed meal (Table 7).

Fish feeding trials

Hossain et al. (2001a, 2002) observed that untreated Sesbania aculeata seed meal could be added to the diets of common carp and Nile tilapia up to a level of 10 per cent without compromising growth. Even after considerably reducing various antinutrients by soaking and soaking + autoclaving (Table 8), growth in carp fed diets containing Sesbania seed meals could not reach levels observed with a fishmeal based diet (Hossain et al., 2001b). The NSP, galactomannan was later found to be the substance primarily responsible for retarding growth in both carp and tilapia (Hossain et al., 2001c and unpublished data). More research is needed as to whether removal of the galactomannan rich endosperm would enable higher inclusion of Sesbania seed meal in fish diets