Preliminary evaluation of raw Alchornea cordifolia seeds as feed ingredients for broilers

O O Emenalom, A B I Udedibie, N U Okehie and B I Onwuka

Department of Animal Science and Technology, Federal University of Technology Owerri, P.M.B. 1526, Owerri, Nigeria
emenalom2000@yahoo.com

Abstract

Some chemical and anti-nutritional characteristics as well as the feeding value of the seeds of Alchornea cordifolia plant on broilers were investigated. The mature dried seed contains 13.7% crude protein, 5.10% crude fibre, 4.90% crude fat, 4.90% ash and 60.7% carbohydrates. It also contains phytic acids, saponins, tannins, cardiac glycosides, steroids, flavonoids, alkaloids, and anthraquinone but not cyanides.

 Inclusion of raw Alchornea seed meal at 5, 10 and 15% in starter broiler diets, fed 0 – 28 days of age caused progressive reductions in growth and by 28 day, broilers fed 15% Alchornea diet weighed 32.8% of control. Feed intakes and feed conversion ratios declined significantly (P<0.05) among the Alchornea seed diet groups relative to control. At 5% level, Alchornea seed promoted much better growth, feed intake and feed conversion ratio than 15% but the values were significantly (P<0.05) less than control. The enzyme alanine aminotransferase (ALT) were higher, and alkaline phosphatase (ALP) and aspartate aminotransferase (AST) tended to be lower, for Alchornea seeds compared with control.

It is concluded that raw Alchornea cordifolia seed is toxic to broiler chicks and depressed their performance at 5 – 10% dietary levels. Further studies on processed Alchornea seeds are worthwhile considering its high seed yield in most tropical countries.

Keywords: proximate composition, performance, serum chemistry, toxic factors

Introduction

Alchornea cordifolia is a tropical browse plant that is little known and used in the feeding of non-ruminant animals. It is valuable in subsistence agriculture because its foliage are frequently fed to grazing animals or processed into leaf meal for non-ruminants. However, it produces large quantities of seeds in the wild that has been neglected from production to processing and use.

The very limited scientific literature indicates that Gorillas and Chimpanzees eat the pith and fruits of Alchornea cordifolia and A. floribunda in the Republic of Guinea (Sebater 1977), Equatorial Guinea (Sugiyama and Koman 1992) and Japan (Huffman 2002). Another report indicated that the leaves are cherished by ruminants and are used by subsistence farmers who harvest them for their livestock (Udedibie and Opara 1998: Okoli et al 2003). The leaves have also been reported to be high in xanthophylls and when incorporated into broiler or layer diets result in yellow colouration of the shank and egg yolks, respectively (Udedibie and Opara 1998).

Unfortunately many browse plant produces seeds that contain a number of anti-nutritional factors that limit their use as food for humans and animals. Only the alkaloids; alchornine and alchornidine (Huffman 2002) have been reported in Alchornea plants. In general, the literature concerning the toxic factors and usefulness of Alchornea seeds as feedstuff for animal is very limited and its use as an energy source in poultry diets not documented.

The present study was therefore designed to determine the nutritional and anti-nutritional characteristics of the seeds of Alchornea cordifolia as well as the performance and blood chemistry of broiler chicks fed graded levels of the seed meal. This we believe will encourage its processing for improvement and use in non-ruminant rations.

Materials and methods 

Processing of Alchornea seeds

Matured Alchornea cordifolia seeds were harvested from the wild in bushes around the Federal University of Technology, Owerri, Nigeria, where this experiment was conducted. The harvested seeds were sun dried on a concrete slab for 4 days, separated from the stalks and crushed into meal using a hammer mill. The meal was sent for proximate and phytochemical analysis at the National Institute for Veterinary Research Vom, Jos, Nigeria. The energy value of the seeds was estimated (in kj) by multiplying the percentage of crude protein, crude fat and carbohydrates by the factors 16.7, 37.7 and 16.7, respectively.

Experimental diets

Four experimental diets were evaluated. All the experimental diets were fed as a meal, and all major ingredients, including Alchornea were ground in a hammer mill and mixed manually. In the experimental diets; 5, 10 and 15% Alchornea seeds were added to the diets, partially replacing maize (Table 1) as an energy feedstuff.

Experimental birds and design

One hundred and twenty day-old mixed sex Anak broiler chicks were used in the experiment. The birds were housed in 2 x 3m half-walled floored pens in an open-sided, naturally ventilated house with black polythenes to control heat and winds. Wood shavings were used for bedding and 24 hour of light/day was used. Each pen was heated by an electric bulb/lantern and stove and provided with waterer and feeder.

The chicks were divided into 12 groups of 10 chicks each. Three pens were assigned to each of the four treatments: 0, 5, 10, and 15% ASM. A completely randomized design was used in the experiment. The birds were weighed at the beginning of the experiment and weekly thereafter. Feed intakes were recorded daily. The experiment lasted for 28 days.

At 28 day of age, blood samples were drawn from the brachial wing vein between 8.00 and 9.00am. The blood samples were analysed for AST, ALP and ALT at the Federal Medical Centre Owerri, Nigeria.

Data collection and analysis

The initial body weight of all replications was noted and weekly body weight and feed consumption were recorded throughout the experiment. The chick performance data on weight gain, feed consumption, feed conversion (FCR) and survivability were calculated from the records of body weight, feed consumption and mortality, respectively.

Data on performance and blood chemistry were subjected to Analysis of Variance (ANOVA) (Steel and Torrie 1960). Differences between treatment means were separated by applying the standard error of means (Snedecor and Cochran 1978). Statements of statistical significance were based on (p<0.05).

Results 

Proximate and anti-nutritional characteristics

The proximate compositions of Alchornea cordifolia seed meal is presented in table 2.

Raw Alchornea seed meal contains 13.7% crude protein, 4.90% crude fat, 60.8% carbohydrate, and 3406 kcal/kg energy. The phytochemical compositions (table 3) shows the presence of phytic acids, saponins cardiac glycosides, tannins, flavonoids, steroids, alkaloids and anthraquinone but not cyanides.

Growth, feed intake and feed conversion

Addition of raw Alchornea seed meal to starter broiler diets at levels of 5, 10 and 15% caused 49.6, 54.6 and 67.2% reductions in growth rate and 37.8, 42.4 and 48.5% reduction in feed intakes, respectively (Table 4) that were statistically significant when compared with the control.

There was marked deterioration in feed conversion values of broilers fed Alchornea seed meal diets. Values for mortality were not significantly different but increased with increasing dietary inclusion level of Alchornea seeds in the diets

Blood chemistry

Of the blood analysis done (Table 5) there were decreases in plasma levels of alkaline phosphatase (ALP) and aspartate aminotransferase (AST), and an increase in alanine aminotransferase (ALT) in chicks fed Alchornea seed diets.

Discussion 

Little is known about the proximate composition and anti-nutritional factors in Alchornea seeds or the effect of processing procedures such as heating or fermentation on the compounds. This remains for future research. But based on chemical analysis alone, Alchornea seeds are a valuable source of carbohydrates for monogastric animals such as poultry and pigs. However, no systematic research has been done in the nutritional quality and phytochemical properties of Alchornea seeds for any monograstric species.

In the present study, it was found that  raw Alchornea seed meal contain toxic substances notably phytic acids, tannins, saponins, among others (table 3) and had negative effects on body and blood chemistry of broiler chicks. The relatively high content of phytic acids (Table 3) in the seed is undesirable for non-ruminant animals. Phytic acids are a phosphoric acid derivative of myo-inositol with the ability to chelate essential mineral ions such as calcium, magnesium and certain trace elements (Nolan et al 1987). The insoluble complexes so formed are known to resist breakdown in the digestive tract resulting in reduced availability to these mineral element for monogastric animal (Reddy et al 1982: Reddy and Pierson 1994).

Tannins occurring in sorghum grains and faba beans depressed growth and caused toxicity in chicks (Iji et al 2004). Annongu et al (1996) reported significant improvements in feed intake, feed efficiency and growth rate as well as hematological variables such as haematocrit, erythrocyte number,  leucocytes count and haemoglobin concentration of broilers when the tannin concentration in sheanut meal was reduced by 57%  through fermentation (i.e. wet incubation of the meal) . The biological significances of tannins in animal nutrition are related to their characteristic ability to form complexes both with metal ions and with macro-molecules such as proteins and polysaccharides (De Bruyne et al 1999). Dietary tannins reduced weight gain and voluntary fed intake in chicks (Armstrong et al 1974, Ahmed et al 1991), which is in line with the result of the present study.

Saponins are glycosides containing a polycyclic aglycone moiety of either C₂₇ steroid or C₃₀ teriterpenoid (collectively termed sapogenins) attached to a carbohydrate (Haralampidis et al 2002). They are widely distributed in the plant kingdom and have a characteristics bitter taste and foaming properties (Agarwal and Rastogi 1974). The anti-nutritional effects of saponins have been mainly studied using alfalfa saponins. In non-ruminants (poultry, rabbits, rats and pigs) retardation of growth rate primarily due to a reduction in feed intake is probably the major concern (Cheeke and Shull 1985). Other negative effects have been ascribed to several properties of saponins such as reduced feed intake caused by the bitter taste (Cheeke 1971) or astringent and irritating effects on the membrane of the mouth and throat (Oleszek et al 1994), reduction in protein digestibility (Shimoyamada et al 1998) probably by the formation of saponin-protein complexes (Potter et al 1993)  and damage to the intestinal membrane (interact with lipid bilayer) thereby increasing its permeability (Johnson et al 1986) that facilities uptake of substances that are normally not absorbed (e.g. toxins, microbes, allergens) and inhibition of active mucosal nutrient transport (Francis et al 2002).  Saponins have also been shown to have haemolytic activity toward red blood cells (Khalil and Eladawy 1994) as well as complexing minerals such as iron, zinc and calcium (Milgate and Roberts 1995) thereby rendering them  unavailable to the animals.

Alkaloids are basic nitrogenous compounds, which can form salt with acids. Peterson et al (1991) identified three groups’ namely true alkaloids, pseudoalkaloids and protoalkaloids. The occurrence and chemistry of alkaloids, in tropical legumes has been reported by Smolenski and Kinghorn (1981). Alkaloids in most animal species are known to course chronic lesions of the liver and damage to the lungs, kidneys and other organ (Seifert 1992) and may have similar effects on broilers fed Alchornea seed, meal diets.

Alchornea seeds also contain cardiac glycosides, anthraquinone, steroids and flavonoids whose actual effects on non-ruminant animals have not been totally elucidated. The presence of these compounds among others (table 3) in Alchornea seeds may partially explain total freedom from insect attack, which the plants enjoy. But Janze et al (1977) observed that the effects of these compounds in seeds are dosage dependent and their concentrations in the seeds have also been reported to drop below detectable levels following processing (Udedibie and Nwaiwu 1988).

Body weight and feed intake were substantially depressed when adding any of 5, 10 or 15% Alchornea seed to rations consumed by broiler chicks to four weeks of age with an extreme depression produced by feeding 15%.  The growth depressing factor (s) present in Alchornea seeds are unknown but could be blamed on some of the anti-nutritional/toxic factors identified in the seeds (table 3).  Tannins and saponins have been associated with reduced protein digestibility and retardation of growth (Sathe and Salunkhe 1984, Cheeke and Shull 1985, Iji et al 2004) and may have contributed to the depressed growth of the birds. The presence of these anti-nutritional factors is one of the major drawbacks according to Kumar and D’ Mello (1995) limiting the nutritional and food qualities of browse plants and seeds from forage crops and legumes.  Again part of the negative effect on growth may be explained by lack of knowledge about nutrient availability, especially amino acids in Alchornea seeds, as there was no available data in literature.

 Feed intake was severely affected by the treatments. Broilers fed Alchornea seeds consumed appropriately 2 times less feed. It is therefore clear that the birds were consuming nutrients much below their daily requirements. Apparently there was a depressive effect on appetite, which increased with increasing dietary inclusion level of the seed meal. Unfortunately there are no data on poultry in the literature to support these results but Iji et al (2004) observed reductions in voluntary feed intakes in non-ruminants fed plant materials containing tannins, saponins or alkaloids. If that is the case, the presence of these compounds among others in Alchornea seeds may have contributed to the low feed intake and subsequently the poor weight gain of broilers fed the diets.

Feed conversion ratio was markedly affected in Alchornea diet groups, thus reflecting the depressive effects on growth. This observation, coupled with the mortalities recorded in the Alchornea seed diet groups suggest a dosage related effect of the anti-nutritional factors on the birds and may argue more strongly for the negative effect of the toxic factors on the broilers.

Dietary raw Alchornea seed caused several changes in blood chemistry. The enzymes alkaline phosphatase (ALP) and aspartate aminotransferase (AST) decreased while alanine aminotransferase (ALT) increased with increasing dietary inclusion of Alchornea seeds. The enzyme ALT is a cytoplasmic enzyme whose increase in blood plasma frequently signals either liver or muscle damage (Lumeij 1997). It increased in chicks fed raw Alchornea seeds despite the depressed weight of the chicks. On the other hand ALP another indicator of liver damage (Kramer and Hoffman 1997) and AST both decreased with increasing dietary inclusion levels and decreasing weights of the chicks. Therefore a factor in Alchornea seeds apparently causes either hepatic or muscle damage and needs further investigation. Similar variables in haematocrits, erythrocyte number, leucocytes count and hemoglobin concentration as well as the complexing of minerals such as iron, zinc and calcium have been reported in broilers fed diets containing saponins or tannins (Milgate and Roberts 1995: Annongu et al 1996), thus confirming the adverse negative effects of toxic compounds on blood compositions of birds whose livers and other organs could not properly detoxify them.

Conclusion 

• The present research shows that the raw unprocessed Alchornea cordifolia seed meal is low in protein, contains toxic substances and depressed growth performance of starter broilers at 5- 15% dietary inclusion levels. The enzymes alkaline phosphatase and aspartate aminotransferase decreased while alanine aminotransferase increased with increasing levels of Alchornea seed meal.

  
  

• There is need for further research on the relative effect of processing on the   nutritional / toxic properties of Alchornea seeds as well as the potential benefit to be gained from using such seed meals in monogastric animal rations.

Acknowledgement 

The authors are grateful to the National Institute for Veterinary Research Vom, Jos, Nigeria, for carrying out the phytochemical analysis and Mrs G.S. Adaka of the Federal Medical Centre ,Owerri for the blood analysis.

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Received 29 August 2008; Accepted 29 January 2009; Published 5 August 2009

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