The nutritional profile of pigeon pea is interesting for poultry, with values close to field pea. Antinutritional factors are present but in a lesser quantity than for other legume seeds, leading to higher nutritive value (Nwokolo et al., 1985; Ologhobo, 1992). For example the toxicity assessed by the effect of pigeon pea on organ weights or blood parameters was generally low (Ologhobo, 1992). However, a high variability in nutritional value is reported in the literature, with some low digestibility values (Chrysostome et al., 1998; Nwokolo, 1987; Yamazaki et al., 1988). This can be due to several factors:
Variation in composition and antinutritional factors. For example there are claims that white-seeded varieties have a higher nutritional value than dark ones (Odeny, 2007), although earlier experiments failed to confirm this (Nwokolo et al., 1985).
Diet formulation. In some cases the level of amino acids (particularly methionine) is deficient in experimental diets, which can lead to a mis-interpretation of results (Babiker et al., 2006).
Treatments. Heat treatments seem to have a positive effect on protein digestibility and energy value (Chrysostome et al., 1998; Onu et al., 2006).
Although the results are not always consistent between experiments, it is generally observed that pigeon pea lowers performance (Oso et al., 2012; Onu et al., 2006). High inclusion rates, above 20% of the diet, reduce performance (Amaefule et al., 2011; Ani et al., 2011; Etuk et al., 2003), but a reduction also occurs at rates as low as 5 to 10% (Babiker et al., 2006; Saeed et al., 2007; Oso et al., 2012). This effect seems to be higher in starter than in finisher broilers (Igene et al., 2012; Ani et al., 2011). Feed intake is often unaffected or even increased, which suggests that pigeon pea does not induce palatability problems (Tangtaweewipat et al., 1989). However, in some trials feed efficiency was reduced. In other trials growth performance was maintained with 10 to 20% raw pigeon pea in the diet (Ologhobo, 1992; de Oliveira et al., 2000; Tangtaweewipat et al., 1989; Iorgyer et al., 2009).
Many trials tried to improve performance by treating the seeds with the use of heat (roasting or cooking), soaking, fermentation or dehulling (Onu et al., 2006; Abdelati et al., 2009). In most cases the growth rate of broilers was improved, with no clear advantage to one particular process, except that fermentation did not confer any advantage (Oso et al., 2012). Optimization of thermal treatments showed that over-processing (e.g. autoclaving at 120°C for 30 min) led to decreased performance (Pezzato et al., 1995). Toasted pigeon pea supported growth, when included at up to 27% of the diet for finishers. However, performance was reduced (although not significantly) in younger birds (Ani et al., 2011). Amino acid balance is important: several authors improved performance by adding methionine to the diet (but not lysine) (Amaefule et al., 2011; Babiker et al., 2006). This could be linked to the deficiency of pigeon pea in sulphur-containing amino acids (methionine and cystine), coupled with the low digestibility of protein in raw pigeon pea. Amino acid deficiency could also explain the increased feed intake in some situations.
In summary, the general recommendation in broilers would be to limit incorporation to 10% pigeon pea in the diets of young birds. With processed (e.g. toasted) pigeon pea and in older birds, higher incorporation rates, up to 20%, could be used. In less intensive conditions, higher rates could be tested if pigeon pea is available at low cost. However, feed efficiency can be lowered. In all cases, particular attention should be paid to amino acid supply, particularly methionine.
Feeding pigeon pea often led to reduced performance in laying hens. Hen-day egg production tended to decrease with raw pigeon pea (Amaefule et al., 2007b; Agwunobi, 2000; Tangtaweewipat et al., 1989), although in some experiments production was maintained with 20% pigeon pea in the diet (Udedibie et al., 1989). Feed intake increased, which led to a degradation of feed efficiency (Amaefule et al., 2006c; Amaefule et al., 2007a). Delayed start of lay has been recorded (Amaefule et al., 2006c; Amaefule et al., 2007a). Heat treatments such as toasting or boiling can improve performance, following the same recommendations as with broiler finishers (Amaefule et al., 2006c; Amaefule et al., 2007b). Pigeon pea can be used in diets for pullets (Amaefule et al., 2004; Amaefule et al., 2006b).
The overall recommendation for layers is to use pigeon pea with care to avoid a degradation of feed efficiency. It should be safe to use 10% pigeon pea in layer diets, but addition of methionine may be necessary. Higher rates (20%) can be tested, especially if the seeds have undergone heat treatment.
In quails, toasted pigeon pea allowed good growth performance at up to 20-30% in the diet. However, increased feed consumption led to a degradation of feed efficiency (Yisa et al., 2013).