In Uganda, the JPS are unused feed resource and are readily available for livestock feeding. Currently, the JP fruits are mainly eaten by children who climb trees for fun and collect the fruits, which they enjoy eating. However, the JPS left after using the pulp are of little importance and are always discarded as waste (Ndyomugyenyi et al., 2008). The JPS can be widely produced in Uganda, because JP trees thrive very well in a variety of soils including loam, marl, and sandy soils (Morton, 1987). The seeds are a potential energy source, because they are rich in carbohydrates (Pankaj, 2003). Compared to maizewithastarchcomponentof 68% (Ewing, 1997), JPS contain 41% starch (Morton, 1987). However, JPS have an advantage of being less costly and less competed for than maize. If the treated JPS meals would replace a larger proportion of maize meal, not only feed costs could reduce, but also competition between humans and livestock for maize.

Despite the availability of JPS, little work has been conducted to include the seeds in poultry diets. An attempt to include Java plum seed meal (JPSM; when JPS were boiled for 50 minutes) in broiler chick diets caused retarded growth of the chicks due to the presence of anti-nutrients (Ndyomugyenyi et al., 2008). Therefore, the ability to include JPS in poultry diets could depend on the processing techniques that eliminate anti-nutrients from the seeds. Although some anti-nutrients in JPS were identified (Ndyomugyenyi, 2008), little effort has been made to eliminate them. In addition, little work has been done to include the adequately processed JPSM in poultry diets. Therefore, this study was conducted to evaluate the nutritional value of soaked-boiled-fermented Java plum seed meal in broiler chick diets.The Java plum seeds (JPS) are producedbyJavaplum (JP)tree,belongingtoMyrtaceaeplant family (Kurt, 2005). The JPS are enclosed in a dark, red-purple, ovaloid fruit (Figure 1). The seeds are mainly dispersed by birds and mammals (Whitinger, 2004). In Uganda, the seeds are dispersed mainly by birds, which eat the fruit pulp and discard the seeds at variable distances from the source (Ndyomugyenyi, 2008). The seedlings from fallen seeds grow naturally under mother trees and thorny bushes, if available in the area, are good cover for the young seedlings (Chhotu et al., 2003). The seeds and leaves of JP are popular livestock feeds in some areas of India (Pankaj, 2003). The JP tree is utilized by humans as food and medicine, and the ripe JP fruit is eaten as a preserve (Okuto and Ouma, 2009; Hutchinson, 2003). The JP fruit pulp is very juicy with a sweet to stringent flavour in poorer varieties and is used to make jelly, jam, squash, wine, and vinegar (Pankaj, 2003). Pods are often fermented to make beer (Chhotu et al., 2003). The seeds were reported to possess anti-inflammatory, anti-arthritic, anti-pyretic, carminative, and astringent properties (Duane et al., 2004; Hutchinson, 2003).

In Uganda, the JPS are unused feed resource and are readily available for livestock feeding. Currently, the JP fruits are mainly eaten by children who climb trees for fun and collect the fruits, which they enjoy eating. However, the JPS left after using the pulp are of little importance and are always discarded as waste (Ndyomugyenyi et al., 2008). The JPS can be widely produced in Uganda, because JP trees thrive very well in a variety of soils including loam, marl, and sandy soils (Morton, 1987). The seeds are a potential energy source, because they are rich in carbohydrates (Pankaj, 2003). Compared to maizewithastarchcomponentof 68% (Ewing, 1997), JPS contain 41% starch (Morton, 1987). However, JPS have an advantage of being less costly and less competed for than maize. If the treated JPS meals would replace a larger proportion of maize meal, not only feed costs could reduce, but also competition between humans and livestock for maize.

Despite the availability of JPS, little work has been conducted to include the seeds in poultry diets. An attempt to include Java plum seed meal (JPSM; when JPS were boiled for 50 minutes) in broiler chick diets caused retarded growth of the chicks due to the presence of anti-nutrients (Ndyomugyenyi et al., 2008). Therefore, the ability to include JPS in poultry diets could depend on the processing techniques that eliminate anti-nutrients from the seeds. Although some anti-nutrients in JPS were identified (Ndyomugyenyi, 2008), little effort has been made to eliminate them. In addition, little work has been done to include the adequately processed JPSM in poultry diets. Therefore, this study was conducted to evaluate the nutritional value of soaked-boiled-fermented Java plum seed meal in broiler chick diets.

Nutrient composition of JPSM

The nutrient composition of raw and processed JPSM is shown in Table 2. The composition of maize is also included for comparison purposes. The dry matter (DM) and calculated ME of raw and processed JPS were comparable to those of maize. The MEn of the processed JPS was also comparable to that of maize (Cilliers et al., 1994). However, NFE of raw and processed JPS was higher than that of maize. The NFE of raw and processed JPSM was also higher than the 752 g/kg reported by Ndyomugyenyi et al. (2008). Processing increased CP and NFE contents of JPSM by 8.11 and 0.230%, respectively. The CP of raw JPSM was lower than the 63 to 85 g/kg reported by Morton (1987).

Despite the MEn of the processed JPSM being lower than that of common energy sources such as cassava meal (14.9 MJ/kg) and wheat (15.1 MJ/kg) (Ewing, 1997), it is still within an acceptable range for use as energy feedstuff. Additionally, the seeds are readily available; face little competition between humans and livestock. Condensed tannins reduced by 62.4% after processing JPS indicating that processing by soaking-boiling-fermentation was not effective in removing tannins from the seeds.

Growth assays

FI, WG, and FCR of broiler chicks decreased (R² ˃ 0.850) with increasing JPSM in the diets (Figure 2). At 80 and 320 g/kg inclusion, FI, WG and FCR were depressed by 16.0 and 34.1%, 20.2 and 42.5%, and 4.90 and 12.5%, respectively. Liver, heart, and pancreas weights relative to body weight were not significantly (P ˃ 0.05) affected by JPSM inclusion (Table 3). However, caecum,gizzard,andintestineweights increased (R² ˃ 0.800), while the heart weight decreased (R² = 0.772) with increasing JPSM in the diets (Figure 3). At 80and320 g/kgJPSMinclusion, weights of caecum, intestine, and gizzard increased by 48.5 and 68.2%, 18.8 and 43.5%, and 9.55 and 19.2%, respectively. Inclusion of JPSM in chick diets adversely (P < 0.05) affected nitrogen retention (NR), nitrogen digestibility (ND), dry matter digestibility (DMD), and excreta water content (EWC) (Table 3). At 320 g/kg JPSM inclusion, NR, ND, DMD, and EWC were depressed by 30.8, 12.6, 0.42, and 2.45%, respectively. No mortality was recorded at 320 g/kg JPSM inclusion. The cost per kg gain of birds increased with increasing JPSM in the diets. The cost increased by 5.5 and 13.8% at 80 and 320 g/kg inclusion, respectively.

The decrease in WG with increasing level of SBF JPSM in the starter diets could be attributed to low FI (Figure 4) and poor nutrient utilization by the birds (Table 3). The low FI was probably due to astringency of JPSM. Tannins were reported to be responsible for the astringent taste and low FI of feedstuffs (Hagerman, 2002; Brown, 2001; Reed, 1995; Van Soest, 1994). According to Hagerman (2002), tannins reduce FI by decreasing palatability and negatively affecting digestion. In the current study, 37.6% tannins remained in JPS after processing (Table 2). Tannins in JPSM could have also caused poor nutrient utilization, hence growth depressionofchicks.Tanninsformcomplexes with carbohydrates (Mahmood et al., 2006) and combine with proteins (Teguia and Beynen, 2005; Van Soest, 1994) in the digestive tract thereby negatively affecting their digestibility. Studies on the effect of sorghum tannins on broiler performance (Kyarisiima, 2002; Okot and Mujabi, 2001) also showed that tannins were responsible for growth depression. However, growth depression in the present study could not entirely be attributed to tannins, because tannin content in the chick diets ranged from 0.734 to 2.93 g/kg catechin equivalent (Table 1). Brown (2001) reported that levels of over 5.0 g/kg tannins in poultry diets cause growth depression. Other anti-nutrients reported in JPS such as saponins, alkaloids, phytic acid, oxalates, and triterpenes (Zdunczy et al., 1997) could have also played a role in depressing FI and growth of the chicks. Saponins were reported to significantly affect growth, FI and reproduction of animals (Francis et al., 2002). Saponins also impair digestion of protein and uptake of vitamins and minerals in the gut (Francis et al., 2002). Phytic acid is known to affect protein and lipid utilization (Kumar et al., 2010), because it inhibits enzymes (such as pepsin, amylases, and trypsin) needed to digest food (Coulibaly et al., 2011; Ramakrishna et al., 2006). Oxalates combine with proteins toformcomplexesthat inhibit peptic digestion (Akande et al., 2010). The FCR of chicks decreased with increasing levels JPSM meal in the diet probably, because of anti-nutritional factors, such as alkaloids and tannins in meal and the effects of continued consumption of these anti-nutritional factors.

No mortality of chicks was recorded at the highest level of JPSM inclusion (320 g/kg) suggesting that lethal effects of JPSM (Ndyomugyenyi et al., 2008) were minimized by SBF treatment. The cost per kg gain of birds increased with increasing JPSM in the diets, because the seeds were obtained from peri-urban areas at a cost (harvesting and transport costs). However, the seeds are readily available in rural areas and will eventually be obtained at low or no cost. The liver, heart and pancreas weights relative to body weight were not significantly affected suggesting healthy chicks. Gizzard weight increased with JPSM inclusion probably, because of JPSM texture which facilitated the increased rate of contraction of the gizzard. The increase in gizzard weight was also reported when whole maize was used for poultry feeding (Engberg et al., 2004; Gabriel et al., 2007; Lu et al., 2011; Roche, 1981). Increment in caeca weight at higher levels of JPSM could be due to stress exerted on these organs as they attempted to extract nutrients from nutrient-impoverished diets due to the presence of anti-nutrients. The avian caecum is a multi-purpose organ whose functioning can be efficient and very important to a bird’s physiology especially during stress periods (Clench and Mathias, 1995). Clench and Mathias (1995) reported that caecal lengths and masses increased when birds were fed on poorer and more fibrous diets. The reason for increment in intestine weight at higher levels of JPSM could not be readily established in the present study.

Including soaked-boiled-fermented Java plum seed meal in diets depressed the performance of broiler chicks. Soaking-boiling-fermentation treatment is not an effective method to improve the nutritional value of Java plum seeds for poultry. Maize remains a better energy source in poultry diets.

The authors have not declared any conflict of interests.

The authors are thankful to Gulu University for the financial support and Okwir, G. and Idibu, J. for the technical support.