Replacement of maize meal by toasted African breadfruit (Treculia africana) seed meal in the diet of Clarias gariepinus (Burchell 1822) fingerlings

S O Obasa, W O Alegbeleye, A A Akinyemi, A A Idowu, N A Bamidele* and A N Adesanya

Department of Aquaculture and Fisheries Management, Federal University of Agriculture, PMB 2240, Abeokuta, Nigeria.
* Institute of Food Security, Environmental Resources and Agricultural Research, Federal University of Agriculture Abeokuta, PMB 2240, Abeokuta, Nigeria
samoluobasa@yahoo.com

Abstract

A feeding trial was conducted to investigate the effect of toasted African breadfruit (TAB), Trecullia africana on growth performance, nutrient utilization, survival and blood parameters of Clarias gariepinus fingerlings. One hundred and fifty (150) fingerlings of C. gariepinus of average weight of 5.96±0.13g were stocked and fed at 5% body weight per day for 56 days. Five iso-nitrogenous diets containing 40% crude protein in which maize meal was replaced by toasted African breadfruit seed meal at 0% (TAB0), 25% (TAB25), 50% (TAB50), 75% (TAB75) and 100% (TAB100) were formulated and prepared.

Weight gain (WG) and feed conversion ratio (FCR) were not different from 22.0g and 1.71 respectively in fish fed diet TAB50. Also, protein efficiency ratio (PER) was not different from fish fed diets TAB0 (1.51) and TAB50 (1.53) respectively. Then, PER decreased as TAB increased in the diet. Packed cell volume was highest in fish fed TAB75 (33.0%) and was higher than 28.0% of fish fed TAB100.  From the above results, yellow maize could therefore be replaced by toasted African breadfruit seed meal at 50% level without affecting growth and nutrient utilisation and 75% without affecting the blood profile in the diet of African mud catfish, C. gariepinus fingerlings.

Keywords: aquaculture, blood parameters, by-product, nutrient utilization

Introduction

The growth in aquaculture production in the last decade, and the need for cost-efficient feed have resulted in increased demand for alternative feed sources of similar qualities to fully or partly replace conventional feed ingredients. Thus, the increasing needs to investigate and utilize more of the locally available unconventional feedstuffs for fish feed formulation. According to Okoye and Sule (2001), nutrient values estimated from locally available conventional and non-conventional plant sources are high. This appears to justify continuous investigation and utilization of their nutritional potentials to enhance economic fish production.

The major source of metabolisable energy in most compounded diets for fish and livestock is maize (Balogun and Fagbenro 1995). However, the increasing prohibitive cost of this commodity as a result of its many competing uses especially in developing African countries and the decline in recent years, in the local production has led to attempts to replace or supplement the maize component of fish feed with cheaper non conventional energy sources. Examples of some of these are: cassava (Manihot esculentus) meal, (Olurin et al 2006), and tigernut (Cyperus esculentus) meal, (Alatise et al 2006).

Treculia africana (African breadfruit) is a member of the Moracea family. It is widely grown in Southern Nigeria for its seeds. It is a common forest tree known by various tribal names in Nigeria. Such names include “afon” (Yoruba), “barafuta” (Hausa), “Ize” (Binis) “eyo” (Igala) “edikang” (Efik) and “Ukwa” (Igbo) (Irvine 1961). T. africana is commonly called African breadfruit because of its large compound fruit. The fruit is hard and spongy in texture when ripe and contains numerous seeds like orange pips embedded at various depths in the flesh pulp (Enibe 2001). Investigations by various authors have shown that Treculia africana seeds (TAS) are rich in amino acids, minerals and fatty acids (Adeparusi 2001). The seeds also often contain  anti nutritional factors like hydrocyanic acid, oxalates, phytates and tannins which are deleterious to man and animals, interfering with metabolic processes so that growth and bio-availability of nutrients are negatively influenced. These anti nutritional factors can be reduced/ removed by extensive washing, toasting, autoclaving, soaking and fermentation of the seeds or seed meal prior to use in the diet (Fasasi et al 2003).

Fish live in very intimate contact with their environment, and are therefore very susceptible to physical and chemical changes which may be reflected in their blood components (Wilson and Taylor 1993). In fish, exposure to chemical pollutants can result in either increases or decreases in haematological levels. A decrease in the erythrocyte count or in the percent of haematocrit indicates the worsening of an organism state and developing anaemia. Furthermore, it should be noted that haematological indices are of different sensitivity to various environmental factors and chemicals (Vosylienë 1999). Previous haematological studies of nutritional effects, infectious diseases and pollutants (Rehulka 2002) brought knowledge that erythrocytes are the major and reliable indicators of various sources of stress (O’neal and Weirich 2001).

Catfish of the genus Clarias are widely distributed in Africa and have been the focus of long-term aquaculture interest. A variety of species of the genus Clarias and their hybrids were cultured for reasons of their high growth rate, disease resistance and ability to adapt to high density culture, excellent adaptation to ambient climate and very efficient feed conversion ratio, ability to mature and remain gravid throughout the year in captivity, acceptance of relatively cheap feeds, high fecundity, potential for all year round induction of final oocyte maturation and high consumers’ acceptance  (Huisman and Richter 1987). Furthermore, the high nutritional quality of T. Africana seed necessitated the need to evaluate its utilisation as a substitute for maize in the diets and implication on the health of African mud catfish (C. gariepinus) fingerlings.

Materials and methods

The feeding trial was conducted in 15 circular plastic tanks (40L) in the wet laboratory of the Department of Aquaculture and Fisheries Management, Federal University of Agriculture, Abeokuta Nigeria. Each tank was filled to 2/3 of its volume with water supplied from the university’s water reservoir. The system was a flow-through with water exchange rate of about 1.5L/ minute in order to sustain optimal culture environment.

One hundred and fifty (150) fingerlings of catfish, C gariepinus fingerlings with average weight of 5.96±0.13g were obtained from a reputable fish hatchery in Abeokuta, Ogun State, Nigeria. The fish were transferred to the wet laboratory and acclimatized for one week being fed with a commercial feed of 0.8mm particulate size. They were then starved for 24 h prior to being placed on experimental diets. Five randomly selected samples were sacrificed for proximate analysis before the commencement of the completely randomized (CRD) experiment.

Five iso-nitrogeneous diets were formulated to contain 40% crude protein. Maize (10.81% crude protein) was replaced with toasted African breadfruit meal (TAB) (12.69% crude protein) at 0% (TAB0), 25% (TAB25), 50% (TAB50), 75% (TAB75) and 100% (TAB100). The formulation was done using the Pearson square method. Table 1 shows gross percentage composition of the experimental diets. The African breadfruit was purchased from the local market and toasted on fire until it turned light brown. The TAB and all the other ingredients were milled with hammer mill and sieved through a 595µm to remove chaff and ensure homogenous size profile. The ingredients for each diet were mixed thoroughly in a bowl and pelletized in a locally fabricated manually-operated pelletizer. The moist pellets were oven-dried at 80˚C for 12hours, packaged in tagged air-tight polythene bags and stored in dry place at room temperature.

C. gariepinus fingerlings were randomly distributed into 15 plastic tanks representing five treatments replicated thrice, at the rate of 10 fish per tank. All the experimental fish were fed the experimental diets twice daily at 5% of total biomass, between the hours of 07:00 – 08:00 and 16:00 – 17:00 for eight weeks. Fish were batch weighed weekly with a sensitive electronic balance (METTLER TOLEDO, PB602). Mortality was monitored daily. Water temperature (⁰C) was monitored daily using mercury-in glass thermometer; dissolved oxygen (DO) was measured using Jenway DO meter model 9071 while the pH was measured using glass electrode pH meter (E520) metrolin model.

At the beginning of the feeding trial, composite samples of ten whole fish and a random sample of five fish per aquarium were analyzed for proximate composition at the end of 56 days experimental period. Nitrogen content was determined by A.O.A.C. (1990) methods and the factor of 6.25 was used to convert the nitrogen to protein. Fat, fibre, ash and moisture content of the diets and composite fish samples were analyzed using A.O.A.C. (1990) method. Blood samples for analyses were collected from the caudal peduncle with a fine syringe and drawn into heamatocrit bottle for analysis. Analysis for the following blood parameters were carried out: Erythrocyte counts (RBC), white blood cell count (WBC) and pack cell volume were analyzed according to Blaxhall and Dalsey (1973). Heamoglobin was according to Roberts (1978) while, mean corpuscular volume (MCV) mean corpuscular heamoglobin concentration (MCHC) and mean corpuscular heamoglobin (MCH) were analyzed according to Meyer et al (1992). Diet performance was evaluated on experimental fish according to Olivera et al (1990). Statistical comparisons of growth performance protein utilization and haematological values were made by using analysis of variance (ANOVA) system (SAS 1988).  Differences among means were also tested for significance (p=0.05) using Duncan Multiple Range Test (DMRT).

Results

Water temperature in the experimental systems ranged from 25.6 – 27.2 ⁰C, dissolved oxygen ranged from 6.3 -8.2 mg/l while pH ranged from 6.17 and 7.16. The proximate composition of diets fed to C. gariepinus fingerlings are presented in Table 2. Moisture content increased as TTA increased in diets while crude protein was highest in diet TAB75 with a value of 40.40% and lowest in diet TAB0 with a value of 39.30%. Lipid content was lowest in diet TAB25 and then increased as TAB increased in diet.

Growth response, nutrient utilisation and survival of C gariepinus fed varying levels of TAB are presented in (Table 3). There were no differences in growth response and nutrient utilisation indices in fish fed diets from TAB0 to TAB50. Then, these indices decreased as TAB increased in diet (Fig. 1). There was no difference in survival of fish fed control diet and those fed diet TAB75.

Table 3: Growth response, nutrient utilization and haematocrit of C. gariepinus fingerlings fed various level of African breadfruit based diets.
Parameters	TAB0	TAB25	TAB50	TAB75	TAB100	SEM	P-value
Initial mean weight (g)	6.27	5.93	5.97	6.03	6.13	0.12	0.063
Final mean weight (g)	28.3ab	31.0a	27.7b	18.9c	16.43c	5.72	0.015
Mean weight gain (g)	22.1ab	26.3a	21.7b	12.9c	10.3c	6.49	0.014
Mean feed intake (g)	36.6a	39.3a	37.1a	25.3b	24.0b	6.49	0.036
Mean protein intake (g)	14.6a	15.7a	12.9a	9.71b	9.58b	2.51	0.012
Feed conversion ratio (g)	1.66bc	1.50c	1.71bc	1.96a	2.33a	0.29	0.000
Protein efficiency ratio	1.51ab	1.67a	1.53ab	0.71c	0.66c	0.44	0.008
Specific growth rate (%)/day	2.82a	2.90a	2.48ab	1.85b	1.63c	0.51	0.001
*App. NPU (%)	59.9a	53.2ab	40.6ab	23.4c	20.5c	15.7d	0.006
Survival (%)	83.3a	83.3a	76.7ab	76.7ab	73.3b	4.00	0.026
NOTE: values without common superscripts in horizontal rows are significantly different (P<0.005) *Apparent net protein utilisation.

Figure 1. Weight gain of C. gariepinus fingerlings fed Toasted African breadfruit seed meal based diets

The proximate composition of the experimental fish is shown in Table 4. Moisture did not maintain any order. Ash content increased as TAB increased in diet while crude protein decreased as TAB content of diet increased from fish fed diet TAB50. Lipid was highest in fish fed diet TAB25, then decreased as TAB increased in diets. 

Table 5 displays the haematological profile of C. gariepinus fingerlings fed toasted African breadfruit seed meal based diets. There were no differences in the values of Packed cell volume and the red blood cells between fish fed the control diet (TAB0) and fish fed diet TAB75, while white blood cells and mean corpuscular volume were higher in fish fed diet TAB100 than in fish fed diets with lower inclusion levels of toasted African breadfruit seed meal.

Discussion

The water quality parameters in all the treatments were within the tolerable ranges for catfish culture  (Chuapoehuk 1999). Moreover, fish responded favourably to the experimental diets in all treatments from the beginning to the end of the trial. The present study showed that TAB could replace maize up to 50% level without compromising growth and nutrient utilization. Beyond the 50% inclusion level, there was reduction in growth and nutrient utilization as the meal increased in the diet of African mud catfish, C.gariepinus fingerlings. This trend could be due to the presence of anti nutritional factors like tannins, phytates and oxalate which according to Fasasi et al (2003) might not have been completely removed during toasting. However, the presence of hydrocyanic acid is precluded since it is completely removed in African breadfruit by toasting (Fasasi et al 2003). Moreover, the significant difference in the growth and nutrient utilization indices as TAB increased in the diets of C. gariepinus fingerlings indicated that growth was affected by the inclusion of TAB as a substitute for maize at varying levels.

Although, results of similar studies on African breadfruit are scarce, however, results obtained in this study are comparable with the results similar studies on replacement of maize with other non conventional energy sources. Olurin et al (2006) recommended 50% inclusion level of cassava (M. esculentus) flour in the diet of C.gariepinus fingerlings. Furthermore, Falaye and Oloruntuyi (1998) and Lasisi et al (2008) worked on the replacement of maize by plantain (Musa paradisiaca) peel meal (PPM) and sweet potato peel meal (SPPM) in the diets of C. gariepinus respectively. The authors observed consistent decrease in percentage weight gain with increase in PPM and SPPM inclusion in the diets, and thus concluded that C. gariepinus did not favourably tolerate diets containing PPM and SPPM above 25% inclusion level.

The values of the calculated ME and energy/protein ratio in all diets were within the acceptable ranges for fish culture. Hastings (1979) stated that generally, foods containing less than 3000kcal/kg or 300kcal/100g are low in gross food efficiency, for they contain low fat and high fibre ingredients. He further suggested that a rule of thumbs on gross physiological energy content in fish feed is to provide not less than 8kcal/kg protein in the diet.

The steady decrease in growth performance and nutrient utilization indices above 50% TAB inclusion level might be due to a number of factors which include the presence of anti-nutritional factors like tannins, phytates and oxalate. Mole and Waterman (1987) observed that these anti-nutrients form complexes with protein thereby reducing the digestibility and consequently biological availability of this nutrient. Also, Olaofe and Sanni (1988) stated that the anti-nutritional activity of oxalates and phytin lies in their ability to form complexes with metals like Ca, Zn, Mg and Fe, while phytic acid acts as a strong chelator, forming protein and mineral-phytic acid complexes thereby reducing protein and mineral bioavailability. Van Egmund (1990) observed that tannins interfere with digestion by displaying anti-trypsin and anti-amylase activity, form complexes with vitamin B12 and interfere with the bioavailability of proteins. Also, its presence may predispose the reconstituted flour to the development of astringent taste (PAG 1971). The latter may be responsible for reduced palatability and consequently, lower feed intake recorded in this study as TAB inclusion increased in the diet of C. gariepinus fingerlings.

The absence of significant differences in the values of erythrocytes and heamatocrit (PCV) in fish fed the Control diet and fish fed diet with 75% TAB inclusion is similar to the results obtained by Brucka-Jastrzebska and Protasowicki (2005). They subjected common carp (Cyprinus carpio) to cadmium and nickel exposure for a prolonged period. Although, there was initial erythrocyte system dysfunction as evidenced by haemolytic anaemia observed at the onset of the experiment. This was later followed by a return of homeostasis and levelling off of the haematological parameters at 14 or 30 days after injection. Similar phenomenon might have resulted at the onset of the feeding trial in this work. This probably lead to decrease in growth and nutrient utilization but a levelling off of the haematological parameters in C. gariepinus fingerlings fed high inclusion levels of TAB in the diets. Likewise, Dharam et al (2008) observed increasing values of white blood cells in Channa punctatus as doses of toxicant increased. The increase was attributed to a stimulation of the immune system in response to damage caused by the toxicant. It could therefore be concluded that maize can be replaced at 50% level by toasted African breadfruit seed meal without affecting growth and nutrient utilisation, while replacement can also be achieved at 75% level without any adverse effect on the blood profile in the practical diet of African catfish C. gariepinus fingerlings.

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Received 16 November 2012; Accepted 9 May 2013; Published 2 June 2013

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