Green leaves and pods
No specific information (as of 2017) seems available in the international literature on the use of Parkia spp. leaves or green pods in rabbit feeding. Pharmacological studies conducted with rabbits have identified in Parkia leaves anti-diarrhoeal and immuno-stimulating activities (Agunu et al., 2005; Yapo et al., 2010). Since the leaves and pods are widely used for ruminants, they could be considered as potential feed source for rabbits. Young trees (7-8 years old) can be pruned 2 to 4 times a year and provide cut-and-carry forage, which could be valuable for rabbits (Sabiiti et al., 1992). Direct experiments with rabbits would be welcome.
African locust bean trees sometimes host the semi-parasite mistletoe (Phragmanthera nigritana or Tapinanthus bangwensis). These potential sources of green forage can be used in rabbit feeding. When compared to Tridax procumbens distributed ad libitum in addition to a concentrate, these two types of mistletoe leaves completely replaced the control forage in rabbit breeding does feeding, without any deleterious effect on their performance or those of their young (Alemede et al., 2013; Alemede et al., 2014).
Pod pulp and husks
No information seems available in the international literature on the use of this pulp in rabbit feeding (as of 2017). As the pulp is used successfully to feed humans, livestock and poultry, it could be considered a potential source of energy in rabbit feeding but with a lower protein content (5%) than that of cereals. Direct experiments about the inclusion of this pulp in rabbit diets would be welcome, before recommendation of its use. The dried pod husks (24% crude fibre) could also be considered a potential source of fibre in rabbit feeding.
Seeds
Raw African locust bean seeds are very palatable for rabbits and are used in some commercial feeds (mixture of non-ground ingredients) for European pet rabbits (Lowe, 2010). However, this direct utilization remains questionable since some intestinal obstructions in pet rabbits were associated with the ingestion of intact Parkia seeds (Harcourt-Brown, 2007). After grinding, raw African locust bean seeds were introduced, without alteration of performance, in growing rabbits diets at up to 25-26% and so saving some maize and all the groundnut cake of the diet (Balogun et al., 1983; Daniel, 2015). Different treatments of the raw seeds before grinding, such as water extraction, autoclaving (Balogun et al., 1983), boiling, natural fermentation (Daniel, 2015; Akpet et al., 2012), and roasting (Akande, 2015), are able to improve the growing rabbits performance after introduction of the treated seeds at 12 to 25% of the diet. This improvement is generally explained by the reduction of some anti-nutritional compounds contained in the seeds, such as trypsin inhibitors, hydrocyanic acid or tannins (Esenwah et al., 2008; Daniel, 2015). For example, roasted African locust bean seeds (4-5 min at 80°C) were introduced in place of soybean meal and part of the dietary maize, up to 30% of rabbit diets, without significant alteration of dry matter, protein or fibre digestibility (Akande, 2015).
The growth rate improvement obtained by using the treated seeds in balanced diets is generally 10 to 20%, in comparison to raw seed utilisation or control diet (Balogun et al., 1983; Akpet et al., 2012; Daniel, 2015). However, any treatment represents an increase of the product cost, in comparison with raw seeds. In addition, treatments imply frequently a reduction of the dry matter mass of the treated seeds, particularly after fermentation. This loss of mass is demonstrated for traditional fermentation by the increase of the content of dry matter in protein (+20%) or ether extract (+30%), and the concomitant decrease of 32% of the total carbohydrates in the fermented seeds, in comparison with raw seeds (Esenwah et al., 2008). Direct experiments would be welcome to assess if the performance increase is sufficient to economically justify the feed ingredients cost increase, knowing that no physiological or health problem is associated with the use of raw African locust bean seeds in rabbit balanced diets.
Raw or processed locust bean seeds can be considered a suitable ingredient for rabbits due to their high content in protein and lipids and low fibre content. Proteins are rich in lysine (about 130-135% of growing rabbit requirements), but deficient in sulphur-containing amino acids (less than 70% of requirements) (Hassan et al., 2005; Lebas, 2013). For the lipids, fatty acids composition is characterized by a high level (20%) of behenic acid (C22:0), and close to 50% of linoleic acid with very few linoleic acid (Balogun et al., 1985), a situation which will largely influence the rabbit lipid composition (Lebas, 2007).