THE UTILIZATION OF HOUSE FLY
(Musca domestica) MAGGOT MEAL
AS REPLACEMENT FOR FISHMEAL
IN THE DIET OF Heterobranchus
bidorsalis ♀ x Clarias gariepinus ♂
HYBRID FINGERLINGS
BY
OWIREDU, KOFI ANTHONY
AGR 0405857
A RESEARCH WORK SUBMITTED
TO
THE DEPARTMENT OF FISHERIES,
IN
PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE AWARD
OF BACHELOR OF AGRICULTURE
(HONS.) DEGREE IN FISHERIES,
UNIVERSITY OF BENIN,
BENIN CITY.
DEDICATION
…to God Almighty and my lovely mum Mrs. Comfort A. Owiredu.
1
ACKNOWLEDGEMENT
My greatest appreciation goes to God, the ultimate source of my being and inspiration, for
His grace, guidance and provision.
In love, I thank my lovely Dad, Mr. A.K. Owiredu, for being a visible God to me through
his loving care, emotional and financial support. You’re the best Dad!
To my other self, I mean my treasured siblings (Ama, Sheila, Kwesi and Aku), I thank
greatly for the priceless gift of emotional support, love and understanding offered to me in life.
My gratitude goes to my project supervisor Mr. B. S. Aliu and to all my lecturers especially
Dr. J. O. Abolagba, Dr. F. A. Oguzie, Dr. V. A. Okonji, Mrs. F. A. Ehigiator, Dr. E. E. Obano, Prof.
A. Obi and Prof. J.A.O. Oronsaye for their professional, inspirational and emotional support
during the just concluded programme.
My profound appreciation goes from the bottom of my heart to my dear friends especially
Nneka (my best friend), Adesuwa, Efeturi, Faruk, Kunmi, Jacob, Mary, Maureen, Samson,
Michael, Courage, Justus, Chidera, Stella, Ibh, Kizzie, The Isaiah family, Vincent, Efe (class rep), …
you will always remain treasured in my mind.
May you all remain in the favour of God, benefiting from His blessings beyond the
imagination of your desires … Amen.
2
TABLE OF CONTENTS
Title Page
Title Page
Certification
Dedication
Acknowledgement
Table of Contents
List of tables
List of figures
List of plates
CHAPTER ONE
1.0
1.1
1.2
1.3
1.4
Introduction
The relevance of an ideal substitute for fishmeal
A review into maggot meal production, maggot culture, harvesting and processing
techniques.
Justification of study
Objectives of study
CHAPTER TWO
2.0
2.1
2.2
2.3
2.4
2.5
2.6
Literature Review
The suitability of maggot meal as substitute for fishmeal
The effect of maggot meal inclusion on the growth performance and the feed utilization
efficiency of culture fish species.
The digestibility of maggot meal based diets
The effect of processing techniques on the nutritional potency and utilization of maggot
meal.
The microbial composition of maggot meal: Issues for concern.
Economics of maggot meal utilization in fish diets
CHAPTER THREE
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
Materials and Methods
Experimental system and design
Experimental diets
Proximate analysis of maggot meal, fishmeal and experimental diet
Experimental fish and feeding
Water quality management
Sampling of experimental fish
Evaluation for growth response, feed utilization and economic benefit analysis
Statistical analysis of data
CHAPTER FOUR
3
4.0
4.1
4.2
4.3
Research results
Comparative proximate composition of fishmeal, maggot meal and experimental diets
Growth response, feed utilization and levels of haematological components of experimental
fish fed maggot meal base diets for 70days
Economic benefits of maggot meal utilization as substitute for fishmeal.
CHAPTER FIVE
5.0
5.1
5.2
5.3
Discussion.
Comparative proximate composition of fishmeal, maggot meal and experimental diets.
Growth response, feed utilization and hematological component of experimental fish.
Economic benefits of maggot meal utilization as substitute for fishmeal in the diet of hybrid
catfish fingerlings.
CHAPTER SIX
6.0
6.1
6.2
Conclusion and recommendation.
Conclusion.
Recommendation
References
4
LIST OF TABLES
Table 1:
Comparative Amino Acid Profile of Hydrolyzed House-fly larvae meal (HFLM) and
other traditional ingredients
Table 2:
Haematocrit, Haemoglobin, plasmal cortisol and glucose concentration of
Oreochromis niloticus fingerlings fed magmeal based diets at different inclusion rates
Table 3:
Total mean plate count of microbial isolates from freshly prepared and stored
magmeal.
Table 4:
Gross Composition (%) of Experimental Diets fed to hybrid Fingerlings for 70days.
Table 5:
Comparative proximate composition of fishmeal, magmeal and experimental diets
Table 6:
Growth response, nutrient utilization and levels of haematological components of
catfish hybrid fingerlings subjected to magmeal based diets for 70 days.
Table 7:
Economic benefits of utilizing dietary levels of magmeal as replacement for fishmeal
in diets of hybrid catfish fingerlings
5
LIST OF FIGURES
Fig. 1:
Weekly growth pattern of Heteroclarias (Heterobranchus longifilis x Clarias gariepinus) fed
magmeal based diets for 70 days.
Fig 2:
Weekly weight pattern of hybrid catfish fingerlings fed magmeal based diet for 70 days.
Fig 3:
Weekly RGR pattern for hybrid catfish fed magmeal based diets for 70 days
Fig 4:
Weekly mean FCR for hybrid catfish fingerlings fed magmeal based diet for 70 days
Fig 5:
Weekly mean per for hybrid catfish fingerlings fed magmeal based diet for 70 days
Fig 6:
Weekly PCV levels for hybrid catfish fed magmeal based diets for 70 days.
Fig 7:
Weekly mean haemoglobin levels of hybrid catfish fingerlings fed magmeal based diet for
70 days
Fig 8:
Weekly mean glucose level for hybrid catfish fingerlings fed magmeal based diet for 70
days
6
LIST OF PLATES
Plate 1:
Haematological test kit and device
7
ABSTRACT
A 70-day feeding trial was conducted to study the effects of fishmeal replacement with
dietary housefly maggot meal on the growth responses, feed utilization, hematological
components and the economic benefits in the culture of Heterobranchus bidorsalis ♀ x Clarias
gariepinus ♂ hybrid fingerlings. Isonitrogenous diets with fishmeal replacement levels of 0%, 25%,
50%, 75% and 100% were formulated at 40% CP. Seven (7) fingerlings (initial average weight of
1.25  0.01g) were stocked per tank (39cm x 26cm x 23cm) and fed twice daily on triplicate basis.
Parameters studied showed varied significant difference with specific parameters. Diets T100
reported the highest weight values of 23.87% and 20.34% for weight gain and RGR (relative
weight gain) respectively, as compared to control diet. No significant difference in FCR and PER
was observed for fingerlings feed control diet and those fed magmeal based diets.Optimum range
of haematological components were obtained for all groups of fingerlings. Findings therefore
indicated that magmeal compared favourably and can totally replace fishmeal in diets of hybrid
fingerlings without growth inhibition or any physiological stress at an economic cost.
8
CHAPTER ONE
1.0
INTRODUCTION
The outstanding level of growth and intensification witnessed in modern aquaculture is
challenged by the absence of a perfect substitute for fishmeal. A possible explanation for this
stems from the concentrated exploitation of plant protein sources, with lesser attention given to
more suitable animal sources of protein. More so, fishmeal is being adjudged variously as a
superior protein supplement in fish feed production, an opinion that stands in the way of
sustained profitability. Therefore, the need for an ideal choice is imperative in the search for
suitable alternatives to fishmeal.
1.1
THE RELEVANCE OF AN IDEAL SUBSTITUTE FOR FISHMEAL
Protein intake and its utilization is quite critical in fish nutrition (De Silva and Anderson,
1995; Sogbesan et al., 2006a), hence protein supplements constitute the most expensive but
indispensable components of a quality fish feed. However, the high cost of production implicated
in the use of fishmeal, (an ultimate protein source), consequent upon its limited supply,
competitive demand and concomitant effect on feed cost has triggered the need to consider
carefully, its inclusion in fish diets as a viable means to cost effectiveness (Food and Agricultural
Organization (FAO) 2002; Delegado et al., 2003; AIFP 2004).
Ideally, a realistic approach to cost reduction in fish feed production has been the partial to
total substitution of less expensive protein sources for more expensive forms (Allan et al., 2000;
Ogunji and Wirth, 2001; Keremeh and Green, 2005; Sogbesan and Ugwumba, 2008). Although,
isolated studies such as Okoye (2003); and Muzinic et al. (2006), opined the nutritional superiority
of fishmeal, trials on its replacement reported success. (Bekibele and Wuyep, 2005; Nweke and
Ugwumba, 2005).
The limited suitability of plant based ingredients, owing to factors such as low protein
content (Oresegun and Alegbeleye, 2001; Haruna, 2003), amino acid imbalance (Eyo, 2001;
Sogbesan et al., 2006a) and the presence of antinutrients (El Sayed et al., 2000; Eyo, 2001) has
instigated the need for research efforts aimed at accessing the potentials of non conventional feed
resources which have been identified to be nutritionally suitable and cost effective. In view of this,
the suitability of maggot meal (magmeal) protein supplement has been confirmed in fish diets
(Ugwumba et al., 2001; Madu et al., 2003).
1.2
MAGGOT MEAL PRODUCTION: MAGGOT CULTURE, HARVESTING AND
PROCESSING TECHNIQUES
Maggot meal, otherwise known as ‘magmeal’ is a processed derivative of housefly larvae
(maggot), usually available in dry and ground form. Maggot defines the larval stage of the
common housefly (Musca domestica). The sack method is commonly used in the culture of maggots
(Awoniyi, 2001a). Suitable substrates for the proliferation of coprophagous insects include
livestock manure and other forms of organic by-products like cattle blood and wheat bran. The
nutrient composition and biomass of maggot generated per unit mass of culture substrate is
influenced by integral factors, a few of which include nature of substrate, time of harvesting and
season (Atteh and Ologbenla, 1993). Maggots harvested by screening or floatation techniques can
be processed into meals by drying or hydrolysis (Fasakin et al., 2003; Sogbesan et al., 2006b).
The utilization of magmeal in aquafeed production affords fish nutritionists an effective
means of ameliorating the implications of high feed cost.
9
1.3
JUSTIFICATION OF STUDY
The suitability of magmeal had been confirmed for trout, tilapia and pure strains of clariid
catfish (Spinelli et al., 1979; Fashina-Bombata, 1997; Adesula and Mustapha, 2000; Fasakin et al.,
2003; Ajani et al., 2004). Essentially, information on nutritional requirement, utilization and
physiological response to feed ingredients as well as consequent growth is species specific.
Although studies by Sogbesan et al. (2005) and Sogbesan et al. (2006b), demonstrated the use of
magmeal on H. longifilis x C. gariepinus hybrid, a critical assessment reveals that the extent of its
utilization by H. bidorsalis x Clarias gariepinus hybrid (a genetically unique and superior culture
candidate) is yet to be established. In addition, the high cost associated with the use of fish meal as
a protein ingredient cannot be ignored. Hence, the need for a search for cheap and suitable
alternatives and thus the essence of this study.
1.4
OBJECTIVES OF STUDY
The general objective of this study is to evaluate the suitability of maggot meal as an
alternative protein source for Heterobranchus bidorsalis x Clarias gariepinus hybrid fingerlings. The
specific objectives are to:
1. compare the proximate composition of fishmeal and
magmeal.
2. assess comparatively, the growth performance of H. bidorsalis x C. gariepinus hybrid fed diets
containing dietary levels of magmeal as substitute for fishmeal.
3. compare the feed utilization efficiency for diets containing dietary levels of magmeal relative
to fishmeal based diets.
4. determine comparatively, levels of haematological indicators of malnutritionally induced
stress in H. bidorsalis x C. gariepinus fed dietary levels of magmeal,so as to affirm the suitability
of magmeal as substitute for fishmeal.
5. evaluate the cost benefit of magmeal utilization relative to the use of fishmeal in diets of hybrid
catfish fingerlings.
10
CHAPTER TWO
2.0
LITERATURE REVIEW
The utilization of maggot meal in fish diet has been accorded a significant outlook in the
recent past. Findings aimed at evaluating and accessing its nutritional potentials have laid
emphasis on its suitability, effect on culture fish, its digestibility, processing techniques, microbial
composition and associated risk, in addition to the cost benefits of its utilization.
2.1
THE NUTRITIONAL SUITABILITY OF MAGMEAL AS A SUBSTITUTE FOR
FISHMEAL
The nutritional suitability of a protein source is a function of its capacity to produce upon
effective digestion, essential amino acids, in adequate quantities that meet the nutritional
requirements of target fish species. The potentials of magmeal as a feasible protein source in
qualitative and quantitative terms is not in doubt.
Qualitatively, magmeal has an appreciable profile of amino acids that corresponds to the
nutritional requirements of fish for somatic and reproductive activity (Adesula and Mustapha,
2000; Akinwade et al., 2002). Ogunji et al. (2006), reported that no essential amino acid was limiting
in maggot meal, with the protein capable of providing growth rates and feed conversion levels
equivalent to fishmeal at substitution levels ranging from 25 – 100%. In addition to a balanced
leucine to isoleucine ratio, Aniebo et al. (2008), observed that levels of commonly limiting amino
acids were comparatively higher in hydrolysed magmeal (housefly larvae meal) relative to other
conventional protein sources. (Table1)
Table 1:
Comparative Amino Acid Profile of Hydrolyzed House-fly larvae meal (HFLM)
and other traditional ingredients
Amino acid
HFLM* FISHMEAL** SOYABEAN**
BLOODMEAL**
Lysine
6.04
4.55
2.62
5.99
Histidine
3.09
1.36
1.02
3.96
Threonine
2.03
2.60
1.66
3.47
Arginine
5.80
3.99
2.90
3.19
Valine
3.61
3.09
2.06
6.41
Methionine
2.28
1.68
0.52
0.91
Isoleucine
3.06
2.97
2.07
0.90
Leucine
6.35
4.45
3.29
10.1
Phenyalanine
3.96
2.35
2.12
5.47
Tryptophan
0.69
0.65
1.02
Cystine
0.52
0.82
0.74
1.31
Tyrosine
2.91
1.98
1.27
1.73
Source: **NRC (1977); *Aniebo et al. (2008)
Quantitatively, a gross analysis of the nutrient density of magmeal reflects an adequate
spectrum of nutrient combination. The proximate composition analysis revealed a composition of
43.3 – 47% CP, 25.3% crude fat, 7.5% crude fibre and 6.25% ash at a dry matter level of 92.7%
(Madu and Ufodike, 2003; Aniebo et al., 2008). Interestingly, Teotia and Miller (1973), confirmed
the presence of adequate levels of phosphorus and B-complex vitamins (protein enhancing factors,
PEF) in magmeal. A gross energy value of 2114.85kcal/100g and an increase in metabolizable
11
energy (ME) as dietary levels of magmeal increased in hybrid catfish diets has been recorded.
(Sogbesan et al., 2006b)
Furthermore, Eyo (2005), reported better acceptability for maggot meal based diets than
soyabean based diet. The minimal fibre composition, presence of protein enhancing factors and
relatively high level of fat are indicators possibly high digestibility and consequently enhanced
utilization of the ingredient. In addition to its biological value, a consideration of its cost
effectiveness and availability is a confirmation that magmeal is not just nutritionally suitable but
constitutes nature’s most - nearly – perfect substitute for fishmeal.
2.2
THE EFFECT OF MAGGOT MEAL BASED DIETS ON THE RELEVANT PHYSIOLOGY
OF CULTURE FISH
Trials on the utilization of magmeal in fish diets have recorded success (Akinwade et al.,
2002; Eyo 2005; Oyelese 2007). Analysis of growth response parameters, feed utilization efficiency
and carcass composition, as well as studies on stress indicators have reflected positive results.
2.2.1 THE EFFECT OF MAGMEAL INCLUSION ON THE GROWTH PERFORMANCE AND
FEED UTILIZATION EFFICIENCY OF CULTURE FISH
Ajani et al. (2004), reported a total replacement of fishmeal with magmeal in diets of
Oreochromis niloticus without any growth inhibition, observing that the protein produced an
equivalent level of growth performance. Interestingly, Sogbesan et al. (2006b), revealed that
Heterobranchus longifilis x Clarias gariepinus fed maggot meal substituted diets responded with
comparatively higher weight gain than those fed fishmeal based diets (fig 1).
12
Source: Sogbesan et al.(2006b)
Fig. 1: Chart showing weekly growth pattern of Heteroclarias (Heterobranchus longifilis x
Clarias gariepinus) fed magmeal based diets for 70 days.
Sogbesan et al. (2006b), recorded same feed conversion ratio of 1.97 for hybrid catfish fed
magmeal and fishmeal based diets. The study reported a comparatively higher productive protein
value for magmeal (6.12) relative to that of fishmeal based diet (6.03).
2.2.2 THE EFFECT OF MAGMEAL BASED DIETS ON THE CONCENTRATION OF
HAEMATOLOGICAL PARAMETERS AND CARCASS COMPOSITION OF FISH
13
Nutritional deficiency has been identified as a major stressor of culture fish species
(Martins et al., 2002). A stressor defines any intrinsic or extrinsic stimulus that is capable of
interfering with the dynamic equilibrium (homeostasis) of an organism’s metabolism (Chrousus
and Gold, 1992). A stated by Wendelaar (1997), adaptational syndromes of malnutritionallyinduced stress in fish include decreased haematocrit (PCV) levels, depressed haemoglobin (Hb)
levels, elevated levels of cortisol and hyperglycaemia. In view of this Ogunji et al. (2007a), reported
that concentration levels of the aforementioned haematological indicators of stress in O. niloticus
fingerlings fed magmaeal based diets were within safe limits, suggesting that no incidence of
physiological stress is associated with the use of magmeal in fish diets. Interestingly, the study
revealed that the lowest haemoglobin concentration (5.96gdl-) occurred in fish group fed fishmeal
based diets (Table 2)
Table 2:
Haematocrit, Haemoglobin, plasmal cortisol and glucose concentration of
Oreochromis niloticus fingerlings fed magmeal based diets at different inclusion
rates
Experimental
Haemoglobin (Hb)
Haematocrit
Cortisol
Glucose
-1
Diets
(gdl )
(%)
(mgml )
(mgdl-)
1
5.96
32.67
9.16
43.01
2
6.49
35.00
30.71
40.96
3
6.72
32.67
32.75
43.73
4
6.95
35.22
31.83
40.25
5
6.91
37.44
34.25
41.96
6
6.97
33.11
25.67
36.44
7
6.76
36.57
14.12
37.07
Source: Ogunji et al. (2007)
The carcass composition of fish has been reported to vary with changes in dietary inclusion
of maggot meal. Ozoria et al. (2009), observed an increase in lipid composition in muscle of fish
fed diets containing high lipid. However, Ogunji et al. (2009), reported that the crude fat and crude
protein decreased significantly with increasing magmeal inclusion. The study also observed an
increase in ash content of fish muscle, with an increase in dietary magmeal inclusion; suggesting
increased availability of essential minerals to human who consume fish fed magmeal based diets.
2.3
THE DIGESTIBILITY OF MAGMEAL
The biological value of a protein source does not only depend on its amino acid profile but
also on its digestibility. The digestibility of an ingredient gives a relative measure (in quantitative
terms) of the extent to which it is digested by a fish species under consideration.
Ogunji et al. (2007b), observed the digestibility of magmeal in fish to be species specific. The
study reported the digestibility coefficient of 80% and 87% for Oreochromis niloticus and Cyprinus
carpio respectively. Ogunji et al. (2009) identified low digestibility of maggot meal as a factor
responsible for reduced growth performance of Cyprinus carpio (common carp) fed magmeal based
14
diets. The presence of enhancers of digestibility has been reported in magmeal (Teotia and Miller,
1973).
2.4
THE EFFECT OF PROCESSING TECHNIQUES ON THE NUTRITIONAL POTENCY
AND UTILIZATION OF MAGMEAL
A rational exploitation of magmeal in fish diets demands a critical consideration of
processing techniques and their effects on its nutritive value and the relevant aspects of its
utilization. This is crucial as the nature of processing techniques employed in magmeal production
determine its digestibility, ensure the bioavailability of essential nutrients, suppress the effects of
probable antinutrients and eliminate microbial contaminants that may inhibit optimum utilization
of its nutritive value.
Although, no form of antinutrient has been reported in maggotmeal, its nutritive value and
utilization in fish is influenced variously by processing method. Wilson and Walker (2000),
reported that hydrolysis destroys tryptophan residues in magmeal and chemically modifies
glutamine and asparagines to their corresponding acid. In addition, Fasakin et al. (2003), observed
that the processing method of defattening and drying influenced the nutrient density of
maggotmeal with crude protein values ranging between 43.30% and 46.70% for full-fat sundried
and hydrolysed(defatted) oven dried maggotmeal respectively.
2.5
THE MICROBIAL COMPOSITION OF MAGGOT MEAL: ISSUES FOR CONCERN
The utilization of magmeal in fish diets has aroused a serious concern due to the common
knowledge that organic substrate in which maggots develop harbour a wide variety of pathogenic
microbes which are transmissible to culture species and man. Banjo et al. (2005), showed that the
culture subtrates, external (body surface) and internal (gut) tissues of housefly larvae harbour
characteristically distinct loads pathogenic and non-pathogenic microbes.
The possibility exists that a carry-over of potential pathogens of substrate into the
harvested and processed product cannot be completely eliminated, especially when the keeping
quality of the product is uncertain. In a study focused on isolating, characterizing and identifying
the microbial composition of freshly processed and stored magmeal, Awoniyi et al. (2004),
identified bacterial species that consisted of Bacillus cereus, Corynebacteria pyogenes, Pseudomonas
aeruginosa Staphylococcus aureus and Streptococcus faecalis. Fungal isolates identified included
Aspergillus flavus, Fusarium monoliformis, Aspergillus. parasiticus. In addition, Vibro spp has been
observed in maggot cultured with poultry droppings.
2.5.1 RISK AND HAZARDS ASSOCIATED WITH THE MICROBIAL LOAD OF MAGMEAL
The fact that magmeal is laddened with loads of potential microbes indicates issues for
concern. The implication herein is relevant to both culture species and man who are respectively
the direct and indirect consumers of the protein and also to the keeping quality of the product.
a.
Implications on the health status of culture species and man
As reported by Eyo (2001) and Haruna (2003), Aspergillus flavus and Fusarium spp are
toxigenic moulds that are capable of producing mycotoxins such as aflatoxins, orchratoxin and
citrinin which have toxic effect on fish fed to contaminated feed. Although chances of disease
transmission from fish to man are rare due to hard cooking techniques, observation confirmed
that direct contact with source of pathogens (fresh fish and culture water) via open wounds on
15
skins, body cavity mucous membrane have led to microbial contamination, colonization and
disease outbreak. The latter mode of transmission puts informal workers within a fish farm at
high risk. Charmish (1996), observed that individual pricked by tilapia spines were infected by
Vibrio vulnificus, a condition which later caused amputation of fingers.
Pathological cases associated with similar microbes found in magmeal have been reported
in humans. Joanne et al. (2008), identified Fusarium monoliformis, Corynebacteria spp, Pseudomonas
aeruginosa and Streptococcus faecalis as the causative agents of esophageal cancer, diphtheria,
urinary tract infection and necrosis of cutaneous tissues respectively in humans. Bacillus cereus and
Staphylococcus aureus have been implicated in acute food poisoning (Boran and Finegold, 1990).
Staphylococcus aureus have been identified to be the causal agent of toxic shock syndrome (TSS) in
human.
b.
Implications on the keeping quality of maggot meal
Awoniyi et al. (2004), observed a significant variation in microbial load of maggot meal over
storage period as moisture level increased from 7.37% (fresh product) to 23.09% (stored). Table 3
Table 3: Total mean plate count of microbial isolates from freshly prepared and stored
magmeal.
Fresh prepared mm
Stored maggotmeal
-1
3
Bacterial count (cfug )
2.56 x 10
1.1 x 103
Fungal count (cfug-1)
0.25 x 103
3.0 x 103
Source: Awoniyi et al. (2004)
According to Effiong and Eyo (2003), A. flavus with a minimum moisture level of 14.5% is
the significant species involved in mold infestation. Temperature elevation accompanying this
initial attack favours the proliferation of the second species (A. candidus) that raises the moisture
level of the stored feed to values higher than 17%. At such moisture level, A. flavus activity
becomes intense and the wholesomeness of the feed is completely lost.
2.5.2 QUALITY CONTROL AND SAFETY MEASURES IN THE PROCESSING, STORAGE
AND UTILIZATION OF MAGMEAL
The susceptibility of magmeal to fungal and bacterial activity is attributable to interactive
factors identified to include its high lipid composition, prevalence of moisture over storage period
coupled with high microbial load. Allielo and Mays (1998), noted that fungal growth and
associated toxicity are favoured by the storage of fatty feeds under moist condition. Therefore, to
ensure unaltered quality in composition of magmeal, it is essential to adopt measures that avert
the activity of spoilage organisms and processes.
Hygienic procedures such as proper handling, washing of freshly harvested maggot in
addition to proper drying to 3.9% moisture level eliminate potential microbes (Awoniyi et al.,
2004). The washing of harvested maggot with clean water in advance to processing sterilizes the
protein without altering its nutritional potency. The use of anti-mould additives to suppress
fungal growth and associated mycotoxins has been recommended (Effiong and Eyo, 2003).
Adopted precautions include the use of facial mask when handling maggotmeal in feedmill
to avoid transmission of diphtheria (an airborne disease caused by Corynebacteria spp). Pond
16
workers should avoid direct contact between cuts on skin and pond water during management
operation to avoid bacterial contamination, colonization and subsequent infection.
2.6
ECONOMICS OF MAGGOT MEAL UTILIZATION
The high feed cost associated with the use of fish meal negates the development of
commercial aquaculture as it stands in the way of sustained profitability. Feed cost account for at
least 60% of the total cost of production. Ibiyo et al. (2004), asserted that the potentials of nonconventional feed resources constitutes viable tools for fish feed manufacturers at an economic
cost.
Magmeal is readily available free from man’s competitive needs and has been produced at
relatively zero cost (Awoniyi, 2000). In addition, Oyelese (2007), reported that magmeal utilization
offers effective, efficient and productive means of disposing organic wastes at an economic
benefit. Sogbesan et al. (2008), reported an increase in cost benefit ratio from 2.92 to 4.73 with
increasing dietary inclusion of magmeal. A 40% reduction in feed cost has been reported with the
use of maggot meal in fish diets (Oyelese, 2007).
Moreso, Gabriel et al. (2007) and Sogbesan et al. (2005), asserted that the use of locally
available ingredients such as maggot meal in fish feed production offers high prospects for the
growth of indigenous aquaculture. The mass production of magmeal promises a sustainable
solution to the unbearable cost of fish feed, as it affords a feasible means needed to realize the
ultimate objective of fish nutritionists.
17
CHAPTER THREE
3.0
3.1
MATERIALS AND METHODS
EXPERIMENTAL SYSTEM AND DESIGN
Experimental system consisted of fifteen (15) experimental units, each represented by a
rectangular glass tank measuring 39cm x 26cm x 23cm filled with water to two-third (2/3) its
volume, with experimental units designed to hold a total of a hundred and five (105) hybrid
fingerlings (at a stocking rate of 7 fingerlings per tank) over an experimental period of 70 days
during which fingerlings were subjected to five (5) treatments (experimental diets) with 3
replications in a Complete Randomized Design (CRD).
3.2
EXPERIMENTAL DIETS
As shown in table 4, experimental diets consisted of five (5) isonitrogenous feeds
formulated at 40% crude protein level using practically available ingredients, with maggotmeal
replacing fishmeal at 0%, 25%, 50%, 75% and 100% levels.
Table 4:
70days.
Gross Composition (%) of Experimental Diets fed to hybrid Fingerlings for
EXPERIMENTAL DIETS
T0
T25
T50
T75
T100
INGEDIENTS
MAGGOT MEAL
FISHMEAL
SOYABEAN
WHEAT CAKE
MAIZE
BONE MEAL
VITAMIN PREMIX
VITAMIN E
25.00
31.49
15.05
16.00
4.00
0.40
0.06
6.25
1.75
31.49
15.05
16.00
4.00
0.40
0.06
12.50
12.50
31.49
15.05
16.00
4.00
0.40
0.06
18.75
6.25
31.49
15.05
16.00
4.00
0.40
0.06
25.00
31.49
15.05
16.00
4.00
0.40
0.06
PALM OIL
8.00
8.00
8.00
8.00
8.00
KEY
T0
=
T25 =
T50 =
T75 =
T100=
DIETS WITH NO MAGGOTMEAL, WITH FISHMEAL
ACTING AS SOLE ANIMAL PROTEIN.
DIETS WITH MAGMEAL REPLACING FISHMEAL AT 25%
LEVEL OF REPLACEMENT
DIETS WITH MAGMEAL REPLACING FISHMEAL AT 50%
LEVEL OF REPLACEMENT
DIETS WITH MAGMEAL REPLACING FISHMEAL AT 75%
LEVEL OF REPLACEMENT
DIETS WITH MAGMEAL TOTALLY REPLACING FISHMEAL
Maggot meal obtained from the Songhai farms in Delta State were mixed with other milled
ingredients to ensure homogeneity. Thereafter, gelatinized corn starch was used as binder and the
moist feed so formed pelleted using a pelleting machine. Pelleted feed collected in flat trays were
to be sun-dried for 18hrs over 2 days and then stored under water-proof conditions.
18
3.3
PROXIMATE ANALYSIS OF MAGMEAL, FISHMEAL AND EXPERIMENTAL DIETS.
Proximate analysis of experimental diets was done in duplicates, following the method of
the Association of Analytical Chemist, AOAC (2000).Moisture content was determined by drying
feed samples in an oven to a constant weight and a difference in weight of sample taken. Crude
protein was determined indirectly from the analysis of total nitrogen (crude protein = N x 6.25)
using the kjehdahl method while crude fat was was determined after the soxhlet extraction of
dried sample with1.25% H2SO4 and 1.25% NaOH Ash content was obtained by ashing about 2g of
feed samples contained in a porcelain crucible using a muffle furnace of 5500C for 16hrs.
3.4
EXPERIMENTAL FISH AND FEEDING OF EXPERIMENTAL FISH
A total of 115 hybrid catfish fingerlings of average weigth of 1.25 + 0.05g were purchased
from Nikseq fish farms in Benin City. Fingerlings were acclimated for two (2) weeks in plastic
tanks in the main laboratory of the Faculty of Agriculture of the University of Benin. This was
followed by the weighing and random stocking of over-night starved fingerlings at a rate of 7
fingerlings per tank.
Experimental diets were administered at 5% body weight of fish per day, with daily rations
halved and fed to fish at 08.00 – 09.00hrs and 15.00 -16.00hrs. Quantity of feed administered was
adjusted to suit corresponding weight gain and prevalent conditions over the experimental
period.
3.5
WATER QUALITY MANAGEMENT
The only water quality management technique employed involved changing water on daily
basis to ensure adequate dissolved oxygen simply, reduced ammonia and nitrite problems and
elimination of waste matter.
3.6
SAMPLING OF EXPERIMENTAL FISH
The initial weights of fingerlings were determined at the
commencement of the experiment. Fingerlings were sampled on weekly basis to determine weight
gain using the METTLER PM 4500 Delta Range electronic beam balance in the laboratory of the
Faculty of Agriculture, University of Benin. Blood samples were collected on weekly basis for
haematological studies. Blood samples were obtained from the caudal region using Lancets and
heparinised capillary tubes. Haemoglobin (Hb) and
Packed Cell Volume (PCV) were determined by the microhaematocrit method in which blood
samples were either centrifuged for 5 minutes at 10000rpm or allowed to settle down under
gravity over a period of 16rhs in capillary tubes held by plastacine in upright position as described
by Wedemeye and Yasutake (1977). Blood glucose level was determined using the Onetouch
Digital electronic glucose meter. (See plate 1)
19
Plate 1:
Haematological test kit and device
3.7
EVALUATION FOR GROWTH RESPONSE PARAMETERS, NUTRIENT
UTILIZATION EFFICIENCY AND COST BENEFIT ANALYSIS
Recorded weight relationship and quantity of feed consumed was used to compute for
growth response indices (SGR, RGR), nutrient utilization and cost benefit analysis following the
method of Oliva-Teles and Gondoves (2001) as follows:
[A]
GROWTH RESPONSE PARAMETERS
Specific Growth Rate (SGR)g = logeWf – logeWi
t
 W f  Wi
Relative Growth Rate (RGR) = 

Wl
(g/fish/day)
x
100 
%
1 
Where Wf = Final weight
Wi = Initial weight
Loge = Natural logarithm
t = time period in days
[B]
FEED UTILIZATION
(i)
Feed Conversion Ratio (FCR) = Feed intake
Weight gain
(ii)
Protein Efficiency Ratio (PER) = Mean weight gain
Protein intake
20
=Mean weight gain
Feed intake (%CP)
[C]
COST BENEFIT ANALYSIS
Feed and feed cost was based on current market price at the feed ingredient market in
Benin City, Nigeria. Economic evaluation was done following the method of Sogbesan and Madu
(2008), as follows:
(i) Investment Cost = cost of feed + cost of fingerlings stocked (N)
(ii) Profit index
= Value of fish (N)
Cost of feed (N)
(iii) Incidence of cost
=
Cost of feed (N) _ _ _ _ _ _ _
Mean weight of fish produced (g)
(iv) Benefit cost ratio
= Total cost of fish cropped (N)
Total expenditure (N)
3.8
(N/g)
STATISTICAL ANALYSIS OF DATA
Analysis of variance (ANOVA) was used to analyze collected data. Duncan multiple range
test was used to separate means at 5% probability level, using Genstat 8 software package of
Windows 2001.
21
CHAPTER FOUR
RESEARCH RESULTS
4.1
COMPARATIVE PROXIMATE COMPOSITION OF FISHMEAL, MAGGOTMEAL
AND EXPERIEMNTAL DIETS.
The proximate analysis of fishmeal and maggot meal revealed a significant variation in
terms of gross chemical composition. As shown in table 5, differences in proximate composition of
the aforementioned ingredients strongly influenced the gross chemical composition of
experimental diets due to difference in relative inclusion levels of fishmeal and magmeal.
Table 5:
Comparative proximate composition of fishmeal, magmeal and experimental diets
COMPOSITION
MOISTURE
CONTENT
CRUDE
PROTEIN
CRUDE FIBRE
ASH
ETHER
EXTRACT
NFE
DRY MATTER
FISHMEAL
MAGMEAL
3.32
5.72
EXPERIMENTAL DIETS
T0
T25
T50
T75 T100
4.33
4.69
4.92
4.96
5.03
70.62
39.82
40.23
40.45
40.12
40.69
30.00
1.03
16.04
5.96
8.60
9.25
18.66
1.93
10.25
9.01
2.06
9.92
12.72
2.94
8.19
15.79
3.24
6.25
16.15
3.96
5.92
18.02
3.03
96.68
17.55
94.28
34.25
95.67
30.16
95.31
28.04
95.08
28.67
95.04
27.02
94.97
From the table above, fishmeal had a comparatively higher crude protein (70.62%) and a
lower crude fiber component (1.03%) than magmeal, the latter having a lower CP of 39.82% and
high fiber composition of 8.60%. Although, the crude protein composition of experimental diets
remained relatively the same ( 40.00  0.05%), the crude fibre and ether extract composition of
experimental diets varied with relative levels of magmeal and fishmeal inclusion. However,
fishmeal was found to contain a comparatively higher ash content. On the contrary, NFE value
was higher in magmeal than for fishmeal, causing an increase in dietary levels of NFE with
increasing levels of magmeal inclusion.
GROWTH RESPONSE, NUTRIENT UTILIZATION AND LEVELS OF HAEMATOLOGICAL
COMPONENT FOR HYBRID CATFISH
FINGERLINGS FED MAGMEAL AS REPLACEMENT FOR FISHMEAL
FOR 70 DAYS.
Table 6 below profiles the summary of research findings on growth response, feed
(nutrient) utilization and levels of haemotological indicators of malnutritionally induced stress in
hybrid catfish fingerlings fed dietary magmeal as replacement for dietary fishmeal.
22
GROWTH
RESPONSE
INDICATORS
SGR (g/fish/day)
0.03a
0.03a
0.04a
0.04a
0.03a
0.01
RGR (%)
11.42b
14.08b
13.88b
20.50a
20.34a
2.21
FEED (NUTRIENT)
UTILIZATION
Growth response, nutrient utilization and levels of haematological components of
catfish hybrid fingerlings subjected to magmeal based diets for 70 days.
PARAMETER(S)
EXPERIMENTAL DIETS
S.E.D
T0
T25
T50
T75
T100
c
b
a
a
WEIGHT (g)
16.25 17.48
18.47
23.34
23.87a
0.50
FCR
1.41a
1.48b
1.61a
1.59a
1.61a
0.39
PER
1.70ab
1.69ab
1.41b
2.22a
1.70ab
0.30
FEED INTAKE (g)
2.33c
3.25bc
4.25ab
5.04a
2.07c
0.61
HAEMATOLOGICAL
PARAMETERS
Table 6:
PCV (%)
38.58a
38.42a
37.88ab
37.73ab
37.20b
0.51
Hb (g/dl)
12.82a
12.84a
12.57ab
12.58ab
12.42b
0.71
Glucose (mg/dl)
44.54a
42.88b
40.99c
38.65d
37.45e
0.34
All means with superscripts with different alphabets are significantly different (P < 0.05); based on
horizontal column.
4.2.1 GROWTH RESPONSE
The weight response of hybrid catfish fingerlings to levels of magmeal inclusion as
replacement for fishmeal over a 70 day feeding trial is shown in figure 2.
23
60
T100
T25
T50
T75
To
50
30
)
Weight(g)
40
20
10
0
1
2
3
4
5
6
Time(week)
7
8
9
10
FIG 2: Weekly weight pattern of hybrid catfish fingerlings fed magmeal for 70 days.
A positive weight response was observed for all treatments. However, a significant
difference in mean weight of fingerlings was observed with respect to dietary treatments at 5%
probability level. Results revealed a comparatively higher increase in weight of fingerlings with
increasing levels of magmeal inclusion (Table 6). Fingerlings subjected to treatment T100 and T75
gave the highest mean weight values of 23.87g and 23.34g respectively with T57 giving a
comparatively higher weight at the end of the 10th week of experiment (figure 2). On the contrary,
control diet (T0) gave the least mean weight gain over the experimental period, with T25 and T59
giving respective intermediate mean weight values of 17.48g and 18.47g.
Although findings reflected no significant difference with respect to Specific Growth Rate
(SGR), the Relative Growth Rate (RGR) was shown to vary with respect to treatments with diets
T75 and T100 having the highest mean values of 20.50% and 20.34% respectively, with no
significant difference between the latter (i.e. highest mean values of RGR). The control diet (T0)
had the least mean RGR value of 11.42% a value which showed no significant difference for
treatment T25 and T50 (Figure 3)
24
70
T100
T25
T50
T75
To
60
50
RGR(%)
40
30
20
10
0
1
2
3
4
5
6
7
8
9
10
-10
Time (weeks)
Fig 3: Weekly RGR pattern for hybrid catfish fed magmeal diets for 70 days
NUTRIENT OR FEED UTILIZATION
25
FIG 4: WEEKLY MEAN FCR FOR HYBRID CATFISH FINGERLINGS FED MAGMEAL
FIG 5:
WEEKLY MEAN PER FOR HYBRID CATFISH FINGERLINGS FED MAGMEAL
FOR 70 DAYS
Figures 4 and 5 show respectively, weekly mean values of Feed Conversion Ratio (FCR)
and Protein Efficiency Ratio (PER) obtained over the experimental period. As shown in table 6,
there was a relative significant difference in FCR with respect to treatments. The control diet (T0)
had a superior FCR of 1.41, although this was not significantly difference from mean values of
FCR reported for T25 which had a mean value of 1.48. Diets T100 and T50 had a comparatively
higher but similar mean values of 1.61 and hence no significant difference between the two
treatments. Treatment T75 gave the lowest mean value of 1.59, relative to all experimental diets
containing maggotmeal, although this was not significantly different from the effects of treatment
T100 and T50 as indicated in Table 6.
Furthermore, Protein Efficiency Ration (PER) for control diet (T0), diets T25 and T100 was
found not to be significantly different, respectively having mean PER values of 1.70, 1.69 and 1.70.
Interestingly, T75 gave a superior PER values mean value of 2.22, a value of outright significant
difference with respect to the means of other treatment at probability level of 5% (Table 6). The
least feed intake was reported for control diet (T0) as against the comparatively higher intake
observed in T75.
4.2.2 LEVELS OF HAEMATOLOGICAL INDICATORS OR MALNUTRITIONALLY
INDUCED STRESS IN HYBRID CATFISH FINGERLINGS FED MAGMEAL IN PLACE
OF FISHMEAL FOR 70 DAYS.
As shown in Table 6, there was significant difference in mean Packed Cell Volume (PCV),
with respect to dietary treatments. Result showed a gradual decrease in mean PCVs with
increasing levels of dietary magmeal. Control diet (T0) and T25 gave imperatively higher mean
26
PCV levels of 38.58% and 37.73% respectively. Although, statistical analysis revealed no
significant difference of PCV levels in fingerlings subjected to control treatment and treatment
T25, these was significant difference between PCV levels obtained from treatments T0 and T100.
Figure 6 shows the weekly values of PCV in hybrid fingerlings fed magmeal in place of fishmeal
for 70 days.
T100
T25
T50
T75
T0
50
45
40
30
)
PCV(%)
35
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9
10
Time(week)
FIG 6: Weekly PCV levels for hybrid catfish fed magmeal diets for 70
days
Haemoglobin (Hb) levels varied similarly, showing a gradual decrease with increasing
levels of magmeal inclusion shown in Figure 7. Mean blood glucose levels were significantly
different with respect to all treatments (Table 6), as there was a gradual decrease in mean levels of
total blood glucose as dietary levels of magmeal increased in fish diets. Diet TO gave the highest
mean value (44.54mg/dl), where as diet T100 gave the lowest mean blood glucose level of
37.45mg/dl. The weekly total glucose level obtained over the experimental period is shown in
figure 8.
27
16
14
12
T100
T25
T50
T75
To
Hb(mg/l)
10
8
6
4
2
0
1
2
3
4
5
6
7
8
9
10
Time (week)
FIG 7:
Weekly mean haemoglobin levels
fingerlings fed magmeal for 70 days
28
of
hybrid
catfish
60
T100
T25
T50
T75
T0
50
40
Glucose(mg/l)
30
20
10
0
1
2
3
4
5
6
7
8
9
10
Time (week)
FIG 8:
Weekly mean glucose level for
fingerlings fed magmeal for 70 days
4.3
hybrid
catfish
ECONOMIC BENEFITS OF MAGMEAL UTILIZATION AS SUBSTITUTE FOR
FISHMEAL IN THE DIETS OF HYBRID CATFISH FINGERLINGS
Table 7 details the summary of fingerlings on the benefits of replacing fishmeal with
dietary levels of magmeal in diets of hybrid catfish fingerlings.
29
Table 7:
Economic benefits of utilising dietary levels of magmeal as replacement for
fishmeal in diets of hybrid catfish fingerlings
ECONOMIC PARAMETERS
BENEFIT COST RATIO
T0
0.05b
EXPERIMENTAL DIETS
T25
T50
T75
T100
b
b
ab
0.04
0.04
0.06
0.08a
S.E.M
0.01
COST OF FEED (N)
231.34
207.59
183.59 159.99 136.34
0.00
INCIDENCE OF COST (N/g)
12.59a
8.87ab
6.18bc
3.24c
2.90c
1.73
VALUE OF FISH (N)
8.80C
11.84bc
13.15b
22.25a
21.54a
1.33
PROFIT INDEX
0.04c
0.06bc
0.07b
0.14a
0.16a
0.01
301.34
277.59
INVESTMENT COST
253.59 229.99 206.34
0.00
All superscripts with different alphabets are significantly different (P < 0.05); based on horizontal
comparison.
As shown in table 7, benefits of magmeal utilization in place of fishmeal showed
significant differences with respect to dietary treatments. A total reduction in feed cost was
observed with increasing levels of magmeal inclusion. T100 gave the least feed cost value of N
136.34 against the height cost of fed (N231.34) obtained for control diet (T0). Diet T100 and T75
had comparatively higher Benefit Cost Ratio (BCR) of 0.08 and 0.06 respectively, while diets T50,
T25 and T0 gave the least mean BCR values of 0.04, 0.04 and 0.05 respectively, with no significant
difference between BCR values for the latter 3 treatments at the set level of probability. However,
T100 showed significant difference with respect to other treatments. On the other hand, incidence
of cost and investment cost was found to be decreasing with increasing inclusion levels of
magmeal, with diets T100 giving the least incidence of cost and investment cost of 2.90 N/g and N
206.34 respectively. Control diet yielded the least mean value of fish and a comparatively low
profit index of 0.04 (Table 7).
30
CHAPTER FIVE
DISCUSSION
5.1
THE COMPARATIVE PROXIMATE COMPOSITION OF FISHMEAL, MAGMEAL
AND EXPERIMENT DIETS.
The comparatively higher crude protein content of fishmeal (70.62%) as shown in Table 5 is
not surprising as fishmeal is conventionally recognized as the most desirable animal protein
ingredient in aquaculture diets due to its high protein quality (Muzinic et al.,2006). The crude
protein content of maggotmeal (39.82%) relatively agrees with values reported by Gado et al.
(1982); Atteh and Ologbenla (1993) and Fasakin (2003), who had earlier reported a crude protein
value of 45%, but totally at variance with the findings of Calvert et al. (1971) and Teotia and Miller
(1974), that reported extremely high values of about 63% CP. This variation in findings may be
due to the fact that the gross chemical composition of housefly larvae meal has been reported by
several studies to be influenced by the substrate medium used for maggot culture, geographical
location, differences in analytical procedures employed, sub-species of housefly, age of larvae, in
addition to the time of harvesting, (Atteh and Ologbenla, 1993; Teguia et al., 2002). Although the
crude protein of fishmeal and magmeal varied considerably, experimental diets were found to be
of fairly uniform crude protein content ( 40.00 + 0.05).This is probably due to the fact that the
diets were formulated as isonitrogenous diets at 40% CP.
The crude fat (ether extract) of magmeal (18.66%) although higher than that of fishmeal
(5.96%) was found to be comparatively lower than the range (20.7 – 25.3%) reported by Atteh and
Ologbenla (1993), a condition obviously attributable to the aforementioned factors identified to
influence the gross nutrient composition of the protein. The comparatively high crude fat reported
in the present study agrees with the assertion of Chapman (1971), which stated that, the major
food reserves for insect are triglycerides. Hence, there existed a directly proportional relationship
between the fat content of experimental diets and the inclusion levels of magmeal (Table 5). The
high level crude fat composition of magmeal may likely have a positive effect in the acceptability
and growth response of fingerlings subjected to magmeal based diets. Earlier, Eyo (2005), stated
that magmeal has a high lipid profile which contributes to its characteristics flavour, thus the
inducement to accept magmeal based diets in preference to diets of plant based ingredients,
affirming the preference of catfish juveniles to animal lipids with desirable flavour than their plant
counterparts.
On the other hand, of great concern is the comparatively higher crude fiber content of
magmeal (8.60%) relative to that of fishmeal (1.03%) which was found to be higher than that
reported by Aniebo et al. (2008), who reported value of 7.0%. The increasing value of crude fibre
associated with increasing inclusion levels of magmeal as shown in Table 5 cannot be ignored as
Ozoria et al., (2009) noted that magmeal contains an Acid Detergent Fiber (ADF) at concentration
levels of 137.8 kg-1. This triggers an issue of great concern to the inclusion levels of magmeal in fish
diets in that most catfish can tolerate up to 8% fiber in their diets, beyond which growth
depression sets in, as effective digestibility and feed utilization may be seriously impaired.
The ash content of fishmeal (16.04%) was found to be higher than that of magmeal (9.25%).
This is understandable due to the comparatively higher bone-material composition possibly found
in fishmeal. Magmeal being a larva lacks bone materials and as such contains quite an
insignificant composition of mineral materials as opposed to the high ash content found in
fishmeal.
31
Generally, the variable gross chemical composition of fishmeal and magmeal influenced the
relative difference in proximate composition of the experimental diets.
5.2
GROWTH
RESPONSE,
NUTRIENT
UTILIZATION
AND
LEVELS
OF
HAEMATOLOGICAL COMPONENTS IN HYBRID CATFISH FINGERLINGS FED
MAGMEAL BASED DIETS IN PLACE OF FISHMEAL
Mean values of growth response indicators, nutrient utilization and haematological
components showed significant difference with respect to variable treatments.
5.2.1 GROWTH RESPONSE
Research findings revealed a significant positive response in growth pattern of hybrid
catfish fingerlings to dietary levels of magmeals as substitute for fish meal (Figure 2). This
affirmed the suitability of experimental diets, indicating the absence of anti-growth factors in all
diets administered during the experiment. Using weight increase, specific growth rate (SGR) and
relative growth rate (RGR) as indicators for growth determination, an obvious weight increase
was observed between wks 6 – 10, in a directly proportional relationship to dietary levels of
magmeal. This trend of weight gain is not surprising as fingerlings may have required 2 – 3wks to
get acclimated to change in diets, as weight indices showed considerable appreciation from week
5 after fingerlings may have become adapted to experimental diets.
The absence of significant difference and comparatively higher mean values obtained for
fingerlings subjected to treatments T75 and T100 is indicative of a possible synergic effect obtained
from the combination of fishmeal and magmeal proteins in diets T75, with the latter possibly
supplying a superior profile of non-protein nutrient (consisting mainly of essential minerals and
vitamins). This is obviously so, as there seemed to be a form of nutrient fortification when
fishmeal was replaced with magmeal at 75% replacement level, hence the directly proportional
relationship between levels of magmeal inclusion and mean weight values as shown in table 6.
This observation conforms with earlier assertion by Mazid et al. (1997), which stated that
combined protein sources in fish diets offers superior nutritive value than the use of single protein
ingredients. Similarly, Aniebo et al. (2008), recommended the use of magmeal with other protein
sources that are rich in trytophan such that the latter lacks hyptophan (Table1).
The highest mean weight value of 23.87 reported for diets T100 indicates the possibility of a
total replacement of fishmeal with magmeal in fish diet without growth inhibition. This agrees
with the findings of Ajani et al. (2004), and Ogunji et al. (2007a), that reported a total replacement
of fishmeal with magmeal without any observable defect in fish growth and nutrient utilization.
On the other hand, mean values of SGR as given in Table 6 showed no significant
difference, suggesting a relative equality in nutritive quality of magmeal and fishmeal based diets.
However, the significantly different mean values reported for all experimental diets and more
importantly the higher RGR of 20.50% reported for fingerlings subjected to diets T100 further
affirms the superiority of magmeal over fishmeal as observed by Sogbesan et al., (2008). (Fig 3).
5.2.2 FEED UTILIZATION
Control diet T0 had a superior Feed Conversion Ratio (FCR) of 1.41, a value which was
significantly different from mean FCR values obtained for diets T50, T75 and T100. The latter
values although significantly different from each other, was found to be significantly different
from the control diet. The relatively high FCR ratio reported for magmeal based diet may be
32
attributed to the high crude fibre content of the protein. The significant difference reported for
FCR contrasted the findings of Ogunji et al. (2006), who reported no significant difference for feed
utilization for Oreochromis niloticus fed magmeal based diets. This contradictory findings is
expectedly true as the efficiency of feed utilization is in fish is species specific.
The interestingly high protein efficiency ratio (PER) of 2.22 reported for diet T75 be due to
the possible high quality profile of nutrients obtained from the combined use of fishmeal and
maggotmeal ingredients in the fish diets, indicating a possible relationship between the protein
quality and the protein utilization as supported by earlier studies. (Tables 4 and 5)
5.2.3 LEVELS OF HAEMATOLOGICAL COMPONENTS
The study revealed a relative significant difference with respect to dietary treatments,
showing that the nutritional composition of the experimental diet influenced the levels of
haematological indicators of hunger induced stress. There was significant difference between PCV
and Hb levels. Fingerlings subjected to control diets and those fed on exclusive magmeal based
diets.
Although, levels haemtological components fell within the normal range for catfish species,
there was slight decrease in Hb and PCV levels within increasing level of magmeal inclusion. This
disagrees with the findings of Ogunji et al. (2006), who observed increasing levels of PCV and Hb
with increasing levels of magmeal inclusion and corresponding decrease in glucose level in diets
of Oreochromis niloticus. However, the fact that experimental fish had comparable growth rates and
feed utilization efficiency possibly suggests that variation in levels of haematological components
in fish with respect to dietary magmeal is species specific.
5.3
ECONOMIC BENEFITS
The increasing economic benefit associated with increasing dietary magmeal is obviously
due to the reduction in levels of fishmeal relative to that of magmeal. This is not surprising as
magmeal is obtained at a relatively zero cost. This findings also agreed with observations made
by Oyelese (2007) and Aniebo et al(2008),who earlier identified magmeal as an absolutely cheap
and readily available protein ingredient, free from man’s competitive uses, offering effective,
efficient and productive means of disposing organic wastes at an economic cost advantage.
Therefore, the utilization of magmeal in fish feed production offers high prospects for growth
of indigenous aquaculture, while ensuring sustainable income generation and increased
profitability in the subsector.
33
CHAPTER SIX
CONCLUSION AND RECOMMENDATION
5.4
CONCLUSION
This study has shown that magmeal protein is well utilized by hybrid catfish, thus
enhancing growth rates and efficient nutrient utilization. No form of physiological stress is
associated with the use of magmeal at all inclusion levels. Hence, magmeal can adequately replace
fishmeal in the diets of culture species at an economic cost.
On the basis of economic evaluation, it is obvious that the use of magmeal as supplement
for costly fishmeal affords nutritionists and aquaculturists a feasible means to attaining the major
objective of fish nutrition which has always been to meet the nutritional requirement of culture
fish species at the least possible economic cost.
5.5
RECOMMENDATION
On the basis of research findings, the following recommendations can be made relative to
magmeal utilization as substitute for fishmeal in diets of hybrid catfish fingerlings.
The use of magmeal to replace fishmeal at 100% replacement level in catfish diets is
commendable. However, replacement level of 75% is quite ideal, considering the similar weight
performance, comparative cost advantage and the need for nutrient fortification arising from the
use of combine protein sources in fish diets. Hence the use of magmeal at 75% replacement level is
recommended to fish farmers and feed industry.
Subsequent research efforts aimed at assessing the nutritive potentials of housefly magmeal
should concentrate on generating scientific information on the non-protein composition of the
protein, with a view to providing a firm basis for exploiting the qualitative and quantitative
potentials of this protein source.
The utilization of maggot meal ensures the possibility of a pollution free environment by
simply transforming manure wastes into productive protein ingredients for sustainable
aquaculture and other forms of animal husbandry. This can be effectively achieved through the
formulation and implementation of science- oriented policies by the state, local and federal
ministries of environment and other relevant parastatals to enhance this new, improved and
environmentally friendly means of waste elimination at an economic cost.
34
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broilers. International Journal of Poultry Science. 6(11):822-825.
Adesulu, E. A. and Mustapha, A. K. (2000): Use of housefly maggot as a fishmeal replacer in the
tilapia culture: a recent vogue in Nigeria. In: K.Fotzsimmons and J.Filho Rio De
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