Abstract: Haematological changes in Clarias gariepinus fed the diets containing raw sunflower and sesame seed meal substituting soybean meal was evaluated in a seventy day feeding trial. Seven isonitrogeneous and isocaloric diets containing sunflower and sesame seed meal replacing soybean meal at a rate of 15, 30 and 45% were prepared. A diet without replacement of soybean meal served as control. The result of fish fed test diets showed significant (p<0.05) difference over the fish fed control diet with respect to PCV and Mean Corpuscular Volume (MCV). Fish fed control diet had the lowest Hb, PCV, WBC, RBC, MCV, MCHC and ESR. There was no significant difference (p>0.05) in the fish fed control diet and test diets with respect to MCH, MCHC and ESR. Hence, it can be concluded that the haematological parameter of Clarias gariepinus is not significantly (p>0.05) changed with increase dietary inclusion of raw sunflower and sesame seed meal.
INTRODUCTION
Catfish farming and indeed aquaculture offer strong potential for growth to meet the natural fish demand thereby reducing importation, provides employment, alleviates poverty and helps to meet the millennium development goals (Williams et al., 2007). There are many culturable catfish species which are but not limited to Clarias gariepinus, Clarias anguillaris, Heterobranchus bidorsalis, Heterobranchus longifilis, Clarias isheriensis, Clarias submarginatus, Chrysichthys nigrodigitatus, Bagrus sp., Synodontis sp. But Clarias gariepinus is the most cultured fish in Nigeria and indeed Africa (Garibaldi, 1996). Its hardness, omnivory, ability to understand adverse condition, high fecundity and mass artificial seed technique also ease its culture (Haylor, 1992; Hecht et al., 1996).
Ichthyohaematological investigation serves mainly for diagnostic purpose; apart from this main purpose, it can be used to appraise the suitability of feeds and feed mixture pellets, to examine the effect of stress situation etc. (Svobodova et al., 1991). As with all animal production, disease is considerable constraint in production, development and expansion in the aquaculture industry. There can be a wide variation in the quality of diet received by farmed fish. Factors include the poor availability of suitable constituents, poor formulation and processing, lack of knowledge and understanding of dietary requirement or in appropriate storage (Southgate, 1993). Soybean Meal (SBM) is currently the most commonly used plant protein source in fish feed (El-Sayed, 1999). However, other plant protein sources which are less expensive would be beneficial in reducing feed cost when made to replace soybean meal (Barros et al., 2002).
Blood analysis is a valuable means of evaluating the physiological condition of cultured fish with respect to determining the effect of diets and other stress factors on fish health. Changes in haematology of fish in response to stressing agents are indicators of the stressful stage of fish, producing useful information to curb any unfavourable condition that may affect the fish health. (Bello-Olusoji et al., 2006). Adeparusi and Ajayi (2004) reported that analysis of blood is an important factors that could be considered in fish feed assessment. The use of haematological values as indices of diagnosing diseases and stress induced condition as well as for feed assessment is well documented (Fagbenro et al., 1993; Adeparusi and Ajayi, 2004; George et al., 2007; Yue and Zhou, 2008; Akintayo et al., 2008). Hence, this study investigates the haematological characteristic of Clarias gariepinus fed with sesame and sunflower meal based diets replacing soybean meal based diet.
MATERIALS AND METHODS
Sources and processing of ingredients: A seventy day feeding trial was conducted on Clarias gariepinus using dehulled seeds of raw sunflower and sesame which were obtained from a farm in Kebbi State, Nigeria. They were ground in a hammer mill and the oil therein was removed using the pressure generated from locally made screw press (cassava-presser type). The cakes therefore were analyzed for their proximate composition (AOAC, 1985). Fish meal, soybean meal and other feedstuffs obtained from commercial sources in Nigeria were separately milled screened to fine particles size and triplicate samples were analyzed for their proximate composition (AOAC, 1985). Based on the nutrient composition of the protein feed stuff (Table 1), a control diet and six test diets (40% crude Protein, 12% crude Lipid, 18 MJ energy) were formulated. The control diets contained soybean meal, providing 50% of the total protein. Three of the test diets contained sunflower meal protein at a replacement levels of 15, 30 and 45% for the soybean meal to serve as test diets RSF15, RSF30 and RSF45, respectively while the other three contained sesame meal protein at the same replacement levels for the soybean meal to serve as test diets RSM15, RSM30 and RSM45, respectively (Table 2). The feedstuffs were blended, moistened, steam pelleted and oven dried for 24 h.
Culture condition: Clarias gariepinus fingerlings were acclimated to experimental condition for 7 days prior to the feeding trial. Groups of 15 catfish fingerlings (3.38±0.015 g) were stocked into aquaria comprising 60 L capacity rectangular plastic tanks.
| Table 1: | Proximate composition of carcass of protein feed ingredients |
| NFE: Nitrogen free extract | |
| Table 2: | Gross and proximate composition (g/100 g dry matter) of experimental diets fed to Clarias gariepinus at varying replacement levels of raw samples of sunflower and sesame seed meal based diets |
| NFE: Nitrogen free extract | |
Each diet was fed to the catfish in triplicate tanks twice daily (09.00, 16.00 h) at 5% b.wt. for 70 days. Fish was removed from each tank every 14 days and batch-weighed and the amount of feed was adjusted accordingly. Eight catfish and 6 catfish per treatment were respectively sacrificed at the beginning and end of the feeding trial, respectively.
HAEMATOLOGICAL STUDIES
The blood analyses were determined according to the method described by Svobodova et al. (1991). The following were done.
Blood analysis: 5-10 mL blood samples were collected from cardiac puncture using 2 mL disposable heparinised syringe treated with EDTA as anti-coagulant.
Blood cell count: Haemocytometer was used in blood cell count. The blood diluting fluid was prepared as described by Svobodova et al. (1991). The blood cells were counted on the counting chamber of haemocytometer with the aid of compound microscope:
| • | RBC = No of cells counted x3x10x200 (106 mm3) |
| • | WBC = No of cells counted x0x25x10x20 (104 mm3) |
Haemoglobin estimation: Haemoglobinometer was used for haemoglobin estimation based on acid haematin method (SAHLI):
Packed cell volume: The packed cell volume was measured after placing sealed micro-haematocrit tube in a centrifuge at 10,500 rpm using micro-haematocrit reader and expressed as percentage.
Erythrocyte sedimentation rate (ESR): ESR was determined the procedures of Svobodova et al. (1991). The volume of ESR with the given time interval is the difference between 100% and the percentage part presented by the corpuscle volume.
Mean corpuscular volume (MCV): MCV was calculated from the haematocrit value (PCV, % and the Erythrocyte count (Er mm3):
Mean corpuscular haemoglobin concentration (MCHC): This was obtained using the formula:
Mean corpuscular haemoglobin (MCH): This was expressed in picograms (ρg):
Statistical analysis: Data obtained from the experiment was expressed in Mean±SD and it was subjected to one way Analysis of Variance (ANOVA) using SPSS 16.0 version. Where the ANOVA reveals significant difference (p<0.05) and Duncan multiple range test was used to compare differences among individual treatment means.
RESULTS AND DISCUSSION
The summary of comparison of haematological parameters of Clarias gariepinus fed sunflower and sesame meal based diets replacing soybean meal at different levels is presented in Table 3.
| Table 3: | Haematological profile of blood of Clarias gariepinus fed raw sunflower and sesame meal based diets |
| Figures in each row with different superscript are significantly different at p<0.05. Figures in rows without superscripts are not significantly different at p>0.05. Hb: Haemoglobin content, PCV: Packed cell volume, WBC: White blood count, RBC: Red blood count, MCHC: Mean corpuscular haemoglobin concentration, MCV: Mean corpuscular volume, MCH: Mean corpuscular, haemoglobin, ESR: Erythrocyte sedimentation rate and HSI: Hepatosomatic index | |
The Erythrocyte count (Er) ranges between 10.85 in fish fed RSM15 to 4.7 in fish fed diet CTR. Er increases with increment in levels of sunflower inclusion and decreases with level of sesame seed meal inclusion. The highest value of Er was recorded in the blood of fish fed RSF45 while the lowest value was recorded in fish fed CTR. A measurable increase in the haematological parameter observed in the fish fed test diets with respect to fish fed control diets was also observed by Akintayo et al. (2008) who fed the toasted sunflower seed meal to Clarias gariepinus and Yue and Zhou (2008) who fed cotton seed meal to juvenile hybrid Tilapia, Barros et al. (2002) for channel catfish and El-Saidy and Gaber (2004) for Nile Tilapia. Although, the result trend deviates from the trend reported by Adeparusi and Ajayi (2004) who fed Lima bean to Oreochromis niloticus. Other researchers who have also reported a decrease in haematocrit and haemoglobin with increase level of ingredients are (Blom et al., 2001; Dabrowski et al., 2001; Richard et al., 2003). However, there was no significant (p>0.05) difference in the Er of fish fed control diet and the fish fed test diets. The Leucocytes counts also ranges between 6.6x106 mm3 in fish fed diet RSM15 and 3.6x106 mm3 in fish fed diet CTR. Same pattern as recorded for Er was observed for WBC. There was no significant (p>0.05) difference in fish fed control diet and fish fed test diets with respect to MCH, MCHC, ESR. However significant (p<0.05) variation existed in the Packed Cell Volume (PCV) and Mean Corpuscular Volume (MCV) of fish fed the control diets and other test diets. The highest PCV was obtained in the blood of fish fed diet RSF45 while the lowest PCV was obtained in the fish fed diet CTR. However there was no significant difference (p>0.05) in the PCV of the blood of fish fed diets RSF15 RSF30, RSF45, RSM15, RSM30 and RSM45. The highest MCV was obtained in the blood of fish fed RSF30 while the lowest was in the fish fed diet CTR. There was no significant (p>0.05) variation in the MCV of fish fed other test diets apart from RSM30. Akinwande et al. (2004) opined that a measurable increase in white blood count of fish or any animal is a function of immunity and animals’ resistance to some vulnerable illness or disease. This increase might indicate that the fish under study had high immunity or resistance to disease. George et al. (2007) observed that when 50% fish meal was replaced by soybean meal in the diet for Clarias gariepinus, there was increase in PCV, HB and RBC of the fish fed the diet. High value of Erythrocyte count recorded in this study was also observed by Fagbenro et al. (1993) and Akintayo et al. (2008) which indicates high oxygen absorption and transportation capacity of the cells of the fish under study. Hecht et al. (1996) reported the hardiness of Clarias gariepinus to be due to the presence of arborescent air-breathing organ. The decrease in haematological parameter with increasing level of incorporation of sesame meal might not be unconnected to the presence of tannin and phytate present in the seed meal. Wedemeyer and Yasutake (1977) reported that blood infection might reduce haematocrit value and erythrocyte count. The result agreed with the observation of Blom et al. (2001), Dabrowski et al. (2001), Richard et al. (2003). But the presence of these anti-nutrients was not to a level to induce pathological changes in the fish.
CONCLUSION
Hence it can be concluded that the haematological parameter of Clarias gariepinus is not significantly (p>0.05) changed with increase dietary inclusion of raw sunflower and sesame seed meal. Therefore, not much stress is placed on the health of Clarias gariepinus even when fed at higher level of inclusion (45%).