ABSTRACT
Mass production of freshwater rotifer, Branchionuscalyciflorus was carried out using different food types (Chlorella sp., Spirulina sp., and Baker’s yeast). Rotifer stock culture was prepared using NPK + urea (50g: 2.5g) and chicken droppings with freshly grown alga. Different food concentrations (150, 300, 650 and 1000 mg/ml) and feeding intervals (2x and 3x per day) were used to grow B. calyciflorus in a Batch culture method. Optimum pH (7.02±0.06), dissolved oxygen (6.68±1.23 mg/l) and temperature (26.00±0.02 °C) were maintained in the course of the experiment. Rotifers were sampled every two days to determine the population and counting of the population was done using calibrated petri-dish wider stereomicroscope. Number of rotifers was expressed in individual/ml. Data obtained showed that there was significant difference in population growth increase in all the variables used in this study (P < 0.05). The highest population growth was attained with 650 mg/ml of Chlorella sp. (213.81±9.94 individuals/ml), followed by Baker’s yeast (196.67±8.18 individuals/ml) and 300 mg/ml of Spirulina sp. (151.90±7.98 individuals/ml). The least population growth of B. calyciflorus was recorded with 150 mg/ml concentration of Chlorella sp. and Spirulina sp. (81.43±6.19 and 75.71±5.12 individuals/ml, respectively), and 1000mg/ml of Baker’s yeast (65.24 ±3.86 individuals/ml). Generally, higher food concentrations (1000 mg/ml and 650 mg/ml) did better with 2x feeding interval (90.16±3.47 and 176.19±9.57 individuals/ml) respectively (p < 0.05). The lower concentrations (150mg/ml and 300mg/ml) gave the best population growth of B. calyciflorus with 3x feeding interval. The peak population growth was attained on day 8 of the experiment (p < 0.05). The present study indicated that the quantity and quality of food have a significant role on the rotifer production and Chlorella sp. at 650 mg/ml appears most suitable to feed rotifers for maximal production.
TABLE OF CONTENTS
Title Page
Table of Contents
List of Tables
List of Figures
List of Plates
Abstract
CHAPTER ONE: INTRODUCTION AND LITERATURE REVIEW
1.1 Introduction
1.2 Justification of the Study
1.3 Objectives of the Study
1.4 Literature Review
1.4.1 Biology of rotifers
1.4.2 Classification
1.4.3 Morphology
1.4.4 Reproduction in rotifer
1.4.5 Cyst production
1.4.6 Differences among rotifer strains
1.4.7 Predator feeding success
1.4.8 Physical and chemical requirements for mass
production of freshwater rotifers
1.4.9 Food requirements for mass production of
freshwater rotifer
1.4.10 Nutritional value of rotifers
CHAPTER TWO: MATERIALS AND METHODS
2.1 Procurement of Rotifer Species
2.2 Preparation of Stock Culture
2.3 Experimental Setup
2.4 Sampling of Rotifers
2.5 Statistical Analysis
CHAPTER THREE: RESULTS
3.1 Physico-chemical Parameters of the Experimental Medium
3.2 Overall effect of Food type on Rotifer Population
3.3 Combined Effect of the Different Food type and Concentrations
on the Population Growth of Rotifer
3.4 Combined Effects of Foodtype and Feeding Interval on
Population Growth of Rotifer
3.5 Combined Effect of Foodtype and Duration on Population
Growth of Rotifer
3.6 Combined Impact of Food Type, Food Concentration, Feeding Interval
and Duration on Rotifer Growth
CHAPTER FOUR: DISCUSSION AND CONCLUSION
4.1 Discussion
4.2 Conclusion
References
Appendix
CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
1.1 Introduction
Owing to the high rate of fish consumption in our society today, it’s social, economic and health wise impact, the need for improvement in fish rearing especially the hatchery sector arise. Fish contain essential nutrient called fatty acid in which the popularly known omega-3 and 6 is gotten from. Unfortunately, fish cannot synthesize this nutritive component (n-6 and n-3) by itself. Hence one or both of these fatty acids must be supplied preformed in the diet, depending on the Essential Fatty Acid (EFA) requirements (NRC, 1993).
The preferred live food organisms for larvae fish are those in their natural diets, such as algae; however, Rotifer and Brine shrimp (Artemia) are the only zooplankton produced in mass quantities (Kazietal., 2010). Variations of nutritional quality, primarily (n-3) polyunsaturated fatty acid (PUFA) content, exist among sources of zooplankton from different geographical origins and culture conditions (Dhertetal., 1992). Many fish larvae are very sensitive to a deficiency of n-3 PUFAs (Dhertetal., 1992). Thus, the composition and amounts of fatty acids in zooplanktonic food affects growth and survival of larvae fish.
In current fish culture practices, Larviculture is of the main bottlenecks in the promotion of the production of fish and crustaceans. In Nigeria, larviculture is yet to be stabilized due to insufficient supply of reliable live food within the locality. Ashraf et al., (2010) stated that Larvae fish depend on the nutrients stored in the yolk sac for the first few days and on completion of yolk sac absorption, they demand immediate external food for nourishment. They respond best to motile prey organisms, which are important food as well as enzyme source to digest food (Ashraf etal., 2010). Hence culture of live food is an important component of a successful fish hatchery (Lee et al., 2002). Non-availability of appropriate food at this stage is a major cause of larval losses.
Rotifers (wheeled animals) are micro-zooplankton that have been widely used as essential food source in raising freshwater and marine fish larvae due to its unique characteristics (Lubzens, 1987; Dhert, 1996). It is easily digestible, has appropriate size, can survive in high stocking densities and swims slowly giving an ample opportunity to its predator for prey (Qie et al., 1997; Lubzens et al., 2001). It possesses apposite biochemical composition that suites the nutritional requirements of larval fish. Moreover, it has the potential for enrichment with fatty acids and vitamins and various therapeutants for
Rotifers by themselves have little nutritional value, they serve as a “nutrient container” (they are what they eat). In other words, they get the essential nutrient from algae on which they feed. Lubzensetal. (2001) stated that, to the fish grower, rotifers are live food capsules that deliver essential nutrients for growth and survival of fish larva. This means that the nutritional value of rotifer for larval fish, shrimp and crab depends on the rotifers food source. Rotifers actively graze the water column feeding on particles approximately 1 to 30 microns in sizes. Apart from pure algae, there is a number of yeast or algae-based rations suitable for culturing rotifers that are commercially available (Watanabe, 1993; Chew and Lim, 2006).
Rotifers have a life span of 12-15 days but are only reproductive on the first 2-5 days. They reproduce both sexually and asexually but under optimal culture conditions, reproduce by parthenogenesis. They are cultured using a wide variety of culture systems, including batch, semi-continuous and continuous (feedback) culture. In this work, batch culture will be used.
Shiriet al. (2003) reported that Branchionuscalycifloruscould be used efficiently as starter feed for Burbotlotalota. But very little is known about the culture, nutrition and population dynamics of the B.calyciflorus
1.2 Justification of the Study
In Nigeria, larviculture is yet to be stabilized due to insufficient supply of reliable live food within the locality. And since larviculture is of the main bottlenecks in the promotion of the production of fish and crustaceans, the need for stable source of live feed for larvae fish arise. The production of live food within the locality will reduce high loss of larvae fish and input cost, which are the main challenges faced by Aquaculturist in aquaculture production. Hence, the mass production of rotifer (Branchionuscalyciflorus) for aquaculture.
1.3 Objectives of the Study
The Objectives of this study were to:
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