Abstract
A 63 day experiment was conducted to determine the effect of varying dietary levels of cocoa bean meal (CBM) on the body growth, gonadal development, and blood lipid profile of Clarias gariepinus catfish. Four hundred C. gariepinus post-fingerlings were randomly assigned to five treatments with eighty fish per treatment. Each treatment was replicated four times with 20 fish per replicate in a randomized completely block design (RCBD) with sex as a block. Diets (35% crude protein) containing 0, 10, 20, 40, and 50% CBM were formulated to be fed to the fish in treatments 1, 2, 3, 4, and 5 respectively. Before the commencement of feeding the experimental diet, ten fish (five males and five females) were randomly collected from the various treatments, weighed, dissected, and the gonads (ovaries and testes) harvested and fixed in a bouins fluid. The fixed samples were them taken to the laboratory for histologic and histomorphometric studies. After three weeks of feeding the experimental diets, eight fish (four males and four females) were randomly selected from the various treatments. The gonads were also harvested and fixed for laboratory studies. Further random selections of the fish for laboratory studies were done on fortnightly basis till the 9th week of the study. At the end of the study, four fish from each treatment were selected and blood samples were collected from them for haematology and blood lipid profile. Body weights and lengths measurements were made and recorded on weekly basis. Feed was given to the fish at 5% bio mass and the water changed weekly to ensure freshness. Results of the study showed that the average final standard length, average standard length gain, average final total length, and total length gain were not significantly (P≥0.05) different among the treatments. The average total weight and total weight gain however differed significantly (P<0.05) among the treatments.T2 (10% CBM) had the highest average weight gain value (8.44g). T1 (control) had value (3.59g) which was significantly (P<0.05) lower than T2. T5 (50% CBM) has the lowest value (0.98g) which was also significantly (P<0.05) lower than T2 and the control. T3 and T4 had values (5.55, and 3.59g respectively) which did not differ significantly (P≥0.05) from those of T2 and the control. Also, ovarian weight, testicular weight and GSI values were shown to be significantly (P<0.05) different among the treatment groups. T2 females had the highest ovarian weight and GSI values (2.356g and 6.22) which significantly (P<0.05) different from T3 (0.58g and 1.65 respectively), T1 (0.358g and 1.124 respectively), and T5 (0.36g and 1.21 respectively) which had the least values. T4 had values (1.27g and 3.95 respectively) which did not differ significantly (P≥0.05) from the other groups. Similar result was obtained for the males. T2 and T4 had the highest testicular weight and GSI values. The least values were reported for T5. T3 and the control were found not to differ significantly (P<0.05) from other groups. The results obtained for the histology and Histomorphology showed that the gonads of fish in T2 and T4 were better developed than those of the other groups. T5 was least developed as indicated by lower GSI, tubular diameter and oocyte stages and diameters. Results of the haematology showed there were no significant (P≥0.05) different in the haematological indices of Packed cell volume, haemoglobin, red blood cells, monocyte, eosinophil, and basophil. However, the white blood cell count, neutrophil, and lymphocyte were significantly (P<0.05) different among the treatment groups. The blood lipid profile showed that low density lipoprotein, total cholesterol, and triglyceride differed significantly (P<0.05) among the treatment groups. High density lipoprotein was however not significantly (P≥0.05) different. From the result, it was therefore concluded that feeding cocoa bean meal up to 40% dietary inclusion improved growth and gonadal development. Above this level however (i.e. at 50%), the fish were adversely affected. 20 and 40% CBM dietary inclusion is hence recommended if improved reproductive development and performance is of interest.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of study
It has long been recognized that shortage of animal protein is one of the limiting factors in attainment of food security in Nigeria. It is also established that the minimal protein requirement of an individual is 75g/person/day of which 40g should be from animal source (Federal Ministry of Agriculture and Rural Development: FMARD, 2011). According to FAO (2014) current animal protein consumption in Nigeria is given at 7g/person/day indicating a less than 16% contribution of animal protein to the cumulative protein consumption. The situation worsens with the ever increasing population of the country (FMARD, 2011) leaving a bleak future for human nutrition in Nigeria if animal protein sources should be left to conventional farm animals alone.
Of all the sources of animal proteins, fish is the cheapest and these fishes are abundantly found in nearly all aquatic environments spawning up to 31,900 species making it the largest of all classes of vertebrates in species diversity (Oyinlola, 2011). Due to poor supply and high cost of animal protein in Nigeria (Ampofo-Yeboah, 2013), fish consumption has been reported to constitutes about 41% of the total animal protein intake and about 22% of the total protein intake (FAO,
2011). According to FAO (2012), fish provides more than 1.5 billion people with almost 20 percent of their average per capita animal protein intake, and 3.0 billion people with at least 15% of such protein. Fish farming has grown strongly as an effective way of generating food and income from dwindling land space, as fish supplies from open water and lagoons continue to fall and human population increases (Adebayo and Adesoji, 2008). Despite domestic supply from both capture and culture fisheries of less than 0.7 million metric tons per annum in Nigeria, about
0.7 million metric tons of fish is imported annually to augment the dietary requirement of its citizens, making Nigeria the largest importer of frozen fish in Africa (FMARD, 2011). This as stated by the Federal department of Fisheries (FDF) (2007) to create huge foreign exchange demands on the economy. Fish and fisheries products are essential component of the economic and social health wellbeing of many countries and societies, and aquaculture has been identified as the next viable solution in reducing importation (Oyinlola, 2011; Pepple and Ofor, 2011).
African catfish (Clarias gariepinus; Burchell, 1822) is a major aquaculture species in the list of culturable species which has gained widespread recognition as a promising species in
aquaculture production in Nigeria (Taiwo, 2008; Lenient et al., 2008). It is an economically important food fish, cultured primarily in freshwater ponds in tropical countries (Babalola and Apata, 2006). The reasons for the preferential use of catfish in Nigeria include its omnivorous feeding manner; fast growth rate; high yield potential; high fecundity; air-breathing characteristics; good market potentials; and high degree of tolerance to diseases, as well as harsh and poor environmental conditions; (Ayinla et al., 1994; Rad et al., 2003; Anyanwu et al., 2007).
In artificial breeding of fish, efforts are channeled towards obtaining breeding stock with quality sperm and ripe ovary for the production of large number of good quality fries (Oyinlola, 2011). Although recent efforts have been made in increasing the multiplication and supply of seeds (as seen in the catfish seed multiplication project of West Africa Agricultural Productivity Programme: WAAPP), it is still faced with several challenges. Estimates by the United Nations development project (UNDP) assisted base line study gave the annual fingerlings requirement for Nigeria to be 250 million while domestic supply stood at 7.2 million (Nwokoye et al., 2007). Among the factors affecting fish seed quality as stated by Conyurt and Akhan (2008) and Dada and Ebhodaghie (2011) are genetic; broodstock fertility, nutrition (quality and quantity) and outcomes of modern agricultural practices which introduce chemical residues (fertilizers and insecticides) into natural water sources used for culture. Also of importance are the negative effects of common hatchery practices like transportation, cleaning, handling, and use of chemicals, poor water quality and crowding of fishes which are stressors on reproduction (Billard et al., 1995). These factors affect fertilization in artificial reproduction resulting in the production of low quality fish seeds and thus prompting research into various ways of mitigating their effects and producing high quality fish seeds (Oyinlola, 2011). In order to improve culture techniques, it is extremely important to understand the mechanism linking gonad development and reproductive performance (Cek and Yilmaz, 2007). According to Saka et al. (2015), histology is an important tool used in assessing fish reproductive health and to show the initial signs of lesions or alterations not easily identifiable during the macroscopic examination of fish tissue. Many researchers (Schulz et al., 1997; Yalcin et al., 2001; Cek and Yilmaz, 2007; Saka and Adeyemo, 2015; Saka et al., 2015) have greatly studied the gonadal development in C. gariepinus and their maturation. This has given rise to an in-depth exposé on the reproductive biology of this species. Attempts have been made to improve growth and maturation in order to increase productivity in catfish seed production. The continuing expansion of aquaculture and
perhaps the advocates of organic farming and minimal use of chemicals in crop and animal production, because of their implications, for man has engineered a shift from synthetic drugs and chemical to natural plants (neutraceutical) to aid artificial breeding in fishes (Dada and Ajilore, 2009). Hence medicinal plant/phytochemicals which were then little thought of are now researched, evaluated and developed into additives or drugs with little or no side effects (Adedeji et al, 2006). Medicinal plants and other plant products and by-products are now being used as fertility enhancers in production of Clarias gariepinus spp. (Oyinlola, 2011). Gonadal development in all species of animals is influenced by gonadotropic hormones produced as a response of hypothalamus to environmental cues such as photoperiods, feeding and temperature (Al-Khamees, 2009). Ugwu and Ugwuoke (2013) from their research reported that some of these plants which are known to contain phytoestrogens have more pronounced effect on reproductive structures than on other body tissues.
Cocoa powder is a product from the beans of tropical plant, Theobroma cacao which is mostly found in West Africa, South and Central America and tropical areas of Asia (Weisburger, 2001). Cocoa and its products (cocoa butter, cocoa powder, dark chocolate, and cocoa liquor) are known to be therapeutic because of their content of important substances as antioxidants (mainly flavonoids, epicatechin, catechin, and procyanids), methylxanthine (caffeine and theobromine), nitrogenous compounds and minerals (Adamson et al., 1999; Visioli et al., 2000; Greer et al.,
2001; Rios et al., 2003; Kelm et al., 2006; Tomas-Barberan et al., 2007; Maleyki and Ismail, 2008; Latif, 2013). Polyphenols (flavonoids) are reported to exhibit multiple biological effects including; anti-oxidant, antiviral, antibacterial, anti-inflammatory, vasodilatory, anticancer, and anti-ischemic in vitro (Procházková et al., 2011). The phenolic agents in cocoa confer it with its resistance attribute to peroxidation in addition to antioxidant and immune regulatory effect (Visioli et al., 2000). In addition, flavonoids are known to have the ability to modulate cytochrome P- 450 activity. Flavonoids and procyanidin exert their effects (both in-vitro and in- vivo) as antioxidants, free radical scavengers and chelators of divalent cations (Adamson et al.,
1999; Vinson et al., 1999; Ampofo-Yeboah, 2013). Diets rich in antioxidants have been reported to reduce the damage free radicals can have on sperm and biological functions, hence chocolate has been recommended for males with fertility issues (www.fertilityassociates.co.nz/boosting- your-fertility.aspx; Yildirim et al., 2014). The antioxidant products found in cocoa have been reported to inhibit the oxidation of low density lipoprotein (LDL-cholesterol); thus, they show a protective effect against heart disease (Weisburger, 2001).
Plant products such as Garcinia kola seed have been reported to improve growth performance in catfish broodstock (Dada and Ikuorowo, 2009). On the other hand, polyphenols including flavonoids, isoflavones, lignins, coumestanes, which are all abundant in plants and plant by- products are phytoestrogens (functionally similar to natural androgens and estrogens) and have been reported to function as endocrine disrupting chemicals (EDC) which exhibits antifertility and abortifacient properties (Ampofo-Yeboah, 2013). Histological studies on fish have shown that some plant products. Pawpaw seeds (Ekanem and Okoronkwo, 2003; Jegede and Fagbenro,
2008), and Moringa oleifera (Bose, 2007) appear to be an effective sterility inducing agent through the disintegration of gonadal cells, preventing testicular and ovarian development into spermatids and oocytes. However, Hostetler et al. (1990) reported no treatment effect on fertility in rats when cocoa powder supplemented diet is fed.
Factors like genetic, nutrition, temperature, photoperiodicity, confinement, handling, use of chemicals, poor water quality and stocking density impose stress on fishes and thus affect their growth and reproductive performance.
1.2 OBJECTIVES OF THE STUDY
The broad objective of this study was to determine the effect of feeding diets supplemented with cocoa bean cake (meal) on body growth, gonadal development, haematology and blood lipid profile of C. gariepinus.
The specific objectives are to determine
The effect of dietary inclusion of cocoa bean meal on the growth performance of C. gariepinus catfish.
The effect of dietary inclusion of cocoa bean meal on the gonadal development of C. gariepinus catfish.
The effect of dietary inclusion of cocoa bean meal on the blood haematology of C. gariepinus catfish.
The effect of dietary inclusion of cocoa bean meal on the blood lipid profile of C. gariepinus catfish.
1.3 JUSTIFICATION OF RESEARCH
The demand and production of fresh fish (especially cultured fish products) have been on the increase particularly with the efforts of the federal government to cut down on importation to
increase foreign exchange earnings. This has given rise to a need for suitable methods of fish seeds production to meet the high demand edible fish (Dada and Ebhodaghe, 2011). On this note it has become extremely important to understand the relationship between gonad development and reproductive performance of fish in order to improve culture techniques. (Cek and Yilmaz, 2007).
The tilting away from the use of synthetic chemicals in animal agriculture in recent times has necessitated research into the use of natural substances in curtailing the negative impacts of these chemical stressors on fish reproduction and hence improving efficiency of artificial fish breeding. The case of poor survival of catfish larvae and frys have been associated with poor quality eggs produced by the females which is more common than male fertility issues. Also coupled with the fact that there is no standard diet for broodstocks or young juveniles reared for breeding purposes, there is need to use plants with antioxidant and medicinal properties to enhance the performance and fertility of broodstocks (Dada and Ebhodaghe, 2011). Cocoa bean meal, although in competitive demand between man and animals and thus somewhat costly when compared to other non-conventional feedstuffs can go a long way being beneficial as it is readily available and will be easy to adopt. Also the extra incurable cost from its use will be made up for by improved reproductive performances. This study therefore seeks to key into this peculiar area of using “neutraceuticals” to improve productive and reproductive development and thus recommend strategies to hatchery operators.
This material content is developed to serve as a GUIDE for students to conduct academic research
GROWTH, GONADAL DEVELOPMENT AND BLOOD PROFILE IN AFRICAN CATFISH (CLARIAS GARIEPINUS, BURCHELL 1822) FED DIETS CONTAINING COCOA BEAN MEAL
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