COMPARATIVE STUDY ON THE GROWTH, REPRODUCTIVE, AND CARCASS CHARACTERISTICS OF ARCHACHATINA MARGINATA SNAIL FED THREE DIFFERENT AQUATIC PLANTS

Chapter one

Introduction

1.1 Background to the Study

Snail farming, scientifically known as heliciculture, has become a vibrant and rapidly expanding sector within Nigeria’s agricultural framework, propelled by a surging demand for snail meat as a high-quality, cost-effective source of animal protein. This demand is deeply rooted in both nutritional and cultural dimensions. Snail meat is celebrated for its exceptional nutritional composition, boasting approximately 15-20% protein, a robust profile of essential amino acids such as lysine and methionine, vital vitamins including A, B-complex, and E, and key minerals like iron, calcium, and phosphorus, all while maintaining a low fat content of less than 2% (Okpeze, 2020). These characteristics position snail meat as a healthier alternative to red meat or poultry, particularly appealing to health-conscious consumers and critical for rural Nigerian communities where access to affordable protein sources is often limited. The meat’s low cholesterol and high digestibility further enhance its appeal, making it suitable for diverse dietary needs, including those of children and the elderly. Culturally, snail meat is a cornerstone of Nigerian cuisine, particularly in southern regions like Rivers, Delta, and Edo states, where it is a prized delicacy in dishes such as pepper soups, egusi stews, and grilled preparations. Its rich, earthy flavor and tender texture have made it a staple in both household meals and festive occasions, driving consistent demand in urban markets such as Lagos, Port Harcourt, and Enugu, where supply shortages are common due to seasonal fluctuations and production constraints.

Among the various snail species cultivated in Nigeria, the African giant snail, Archachatina marginata, stands out as the preferred choice for commercial heliciculture due to its superior biological and market attributes. This species is notable for its substantial size, frequently reaching weights of 100-150 grams at maturity, and its rapid growth rate, achieving market-ready size within 6-12 months under optimal conditions (Adebayo, 2023). Its reproductive efficiency is equally impressive, with each snail capable of producing 5-20 eggs per clutch and a relatively short incubation period of 20-30 days, enabling farmers to maintain a steady supply of breeding stock. The robust, calcium-rich shell of A. marginata, which constitutes 20-30% of its body weight, enhances its resilience to environmental stressors and physical handling, making it well-suited to Nigeria’s tropical climate, characterized by high humidity and temperatures ranging from 25-30°C. Consumer preference for A. marginata is driven by its larger size and tender, flavorful meat, which commands premium prices, often 20-30% higher than those for other species like Achatina achatina, fetching ₦500-₦800 per kilogram in urban markets (Okeke, 2023). These traits collectively position A. marginata as the backbone of Nigeria’s snail farming industry, playing a pivotal role in addressing food security by providing an accessible protein source and fostering economic empowerment through income generation for smallholder farmers, who dominate the sector.

Despite its immense potential, snail farming in Nigeria faces significant obstacles that limit its scalability and profitability, with the high cost of feed being the most formidable challenge. Feed expenses account for 60-70% of total production costs, placing a heavy financial burden on smallholder farmers who often lack the capital to manage these expenses (Okpeze, 2020). The conventional feed of choice, soybean (Glycine max), is highly effective due to its rich protein content of 35-40%, balanced amino acid profile, and moderate levels of vitamins and minerals, which support optimal snail growth, reproduction, and shell development. However, soybean’s high cost, driven by its frequent importation and susceptibility to global market price volatility, renders it increasingly unaffordable. Between 2020 and 2023, the price of soybean meal surged by over 50%, exacerbated by Nigeria’s economic challenges, including foreign exchange fluctuations and supply chain disruptions (Eze, 2021). Local soybean production, while growing, remains insufficient to meet the demands of multiple livestock sectors, including poultry and aquaculture, which intensifies competition and drives up costs. This economic constraint restricts smallholder farmers’ ability to expand their operations, perpetuating cycles of poverty and undermining the sector’s potential to contribute significantly to Nigeria’s agricultural economy, which accounts for approximately 25% of the nation’s GDP.

Moreover, the reliance on soybean exposes farmers to additional risks, such as seasonal shortages and quality inconsistencies, which can lead to suboptimal snail performance, including slower growth rates and reduced reproductive output. For instance, inadequate protein or calcium in diets can decrease body weight gain by up to 30% and lower egg production, directly impacting farm profitability (Nwosu, 2021). Other challenges in the sector include limited access to high-quality breeding stock, which affects farm productivity, and inadequate extension services, leaving farmers without the training or technical support needed to adopt modern farming practices or access markets effectively. These barriers collectively hinder the growth of heliciculture, despite its potential to produce an estimated 10,000 tons of snail meat annually, a figure that falls short of meeting Nigeria’s growing demand, projected to increase by 5-7% annually due to population growth and urbanization (Okeke, 2023).

To overcome these challenges, researchers and farmers are increasingly turning to alternative feed sources that are cost-effective, locally abundant, and nutritionally comparable to soybean. Aquatic plants, including duckweed (Lemna minor), Azolla pinnata, and water hyacinth (Eichhornia crassipes), have emerged as highly promising candidates due to their availability in Nigeria’s extensive network of rivers, lakes, and wetlands, which span over 70,000 kilometers of waterways. These plants require minimal inputs for cultivation, such as land or fertilizers, and their rapid growth rates enable frequent harvesting, aligning with the principles of a circular economy. This approach emphasizes resource efficiency, waste reduction, and environmental sustainability by repurposing locally available materials to address agricultural needs. By leveraging these aquatic plants, farmers can reduce dependency on expensive, imported feeds, lower production costs, and enhance the environmental sustainability of snail farming, thereby supporting both economic and ecological goals.

Duckweed (Lemna minor), a small, floating aquatic plant, is particularly notable for its exceptional growth rate, capable of doubling its biomass in just 2-3 days under nutrient-rich conditions. It boasts a crude protein content of 30-40% on a dry matter basis, rivaling soybean, and is rich in essential amino acids like lysine and methionine, which are critical for muscle development and growth in snails. Duckweed also contains significant levels of vitamins (A, B, E) and minerals (calcium, phosphorus), supporting shell formation and overall health. Its high digestibility and low fiber content make it an ideal feed for livestock and aquaculture, with studies demonstrating its ability to maintain or improve weight gain and feed efficiency in species like tilapia and poultry (Islam, 2024). Duckweed’s ability to thrive in diverse aquatic environments, including wastewater systems, further enhances its appeal as a low-cost, sustainable feed option. For smallholder farmers, duckweed can be cultivated in simple ponds or containers, requiring minimal investment and yielding high returns. However, its application in snail farming, particularly for Archachatina marginata, is underexplored, with limited data on its impact on growth, reproduction, and carcass quality, necessitating further research to validate its efficacy (Adebayo, 2023).

Azolla pinnata, a nitrogen-fixing aquatic fern, offers another compelling feed alternative due to its robust nutritional profile and low-input cultivation requirements. It contains 25-35% crude protein, slightly lower than duckweed but still substantial, and is rich in vitamins (A, B, E) and minerals such as calcium, phosphorus, and potassium, which are essential for snail shell development and reproductive health. Azolla’s unique ability to fix atmospheric nitrogen through its symbiotic relationship with cyanobacteria not only enriches its nutritional content but also contributes to soil fertility when its residues are used as organic fertilizer, providing an additional environmental benefit (Chatterjee, 2023). With a biomass yield of up to 20 tons per hectare annually, Azolla is a cost-effective option for farmers with access to small ponds or wetlands, requiring only basic water management to cultivate. Its efficacy in poultry and fish diets has been well-documented, with studies showing improved growth rates and feed efficiency without increasing costs (Kumar, 2022). However, its use in snail farming remains largely unstudied, with gaps in understanding its effects on Archachatina marginata’s performance, particularly in terms of egg production and hatchability. Potential challenges, such as palatability and the presence of secondary metabolites like tannins, which could affect digestibility, require empirical validation to ensure its suitability as a feed alternative.

Water hyacinth (Eichhornia crassipes), an invasive aquatic plant, presents a unique opportunity to transform an ecological challenge into a valuable resource. Despite its lower protein content of 15-20%, it provides significant fiber, calcium, and potassium, making it a viable supplementary feed for snails. Its widespread abundance in Nigerian waterways, where it clogs rivers and lakes, causing flooding and oxygen depletion, makes it a virtually cost-free resource in many regions. Water hyacinth’s rapid growth rate, doubling in 5-7 days, ensures a consistent supply, but its use requires processing—such as washing, drying, and grinding—to improve palatability and reduce anti-nutritional factors like tannins and oxalates, which can impair digestibility or affect snail health (Osman, 2022). Repurposing water hyacinth as feed not only reduces production costs but also mitigates its environmental impact, aligning with sustainable ecosystem management by clearing waterways and restoring aquatic biodiversity. Studies in livestock diets, such as those for cattle and goats, have shown promise for processed water hyacinth, but its application in snail farming is limited, necessitating research to assess its impact on Archachatina marginata’s growth, reproduction, and meat quality (Okeke, 2023).

The nutritional potential of these aquatic plants has been extensively documented in other livestock sectors, such as aquaculture and poultry farming, where they have demonstrated comparable or superior performance to conventional feeds like soybean (Hasan, 2023). For example, duckweed and Azolla have been shown to support weight gain and feed conversion efficiency in fish species like tilapia and carp, while water hyacinth has been used as a low-cost supplement in ruminant diets. However, their application in heliciculture, particularly for Archachatina marginata, remains a largely uncharted frontier. Critical knowledge gaps exist regarding the effects of these feeds on key performance metrics, including growth (body weight gain, feed conversion efficiency, body length, and width), reproductive performance (egg number, weight, circumference, hatchability, and incubation period), and carcass quality (edible meat yield and shell strength). Additionally, the organoleptic properties of snail meat—flavor, texture, juiciness, and consumer acceptability—are pivotal for market success in Nigeria, where sensory qualities drive consumer preference. These properties may be influenced by feed type, particularly due to differences in fat content, amino acid profiles, or plant-derived compounds like volatiles or tannins, but their impact remains understudied in the context of aquatic plant-based feeds (Ibrahim, 2024). These gaps limit farmers’ ability to adopt alternative feeds confidently, as they lack evidence-based guidance on their nutritional efficacy and market implications.

This study is strategically aligned with global sustainability priorities, notably the United Nations Sustainable Development Goals (SDGs), including SDG 2 (Zero Hunger), SDG 1 (No Poverty), and SDG 13 (Climate Action). By promoting low-cost, locally sourced feeds, the research enhances food security by making snail farming more accessible to smallholder farmers, who constitute over 70% of Nigeria’s agricultural workforce and play a critical role in rural economies (Eze, 2021). The adoption of aquatic plants reduces dependency on expensive, imported feeds like soybean, lowering production costs by up to 40% and increasing profitability, thereby supporting poverty alleviation in resource-constrained communities. Environmentally, the use of aquatic plants, particularly invasive species like water hyacinth, contributes to ecosystem restoration by reducing their proliferation in waterways, mitigating issues like flooding and biodiversity loss. The focus on Archachatina marginata ensures practical relevance, as its dominance in Nigeria’s snail market—accounting for over 80% of commercial production—maximizes the study’s impact on the sector (Adebayo, 2023). By addressing both economic and environmental challenges, this research offers a transformative pathway to scale heliciculture sustainably, enhancing its contribution to Nigeria’s agricultural economy, which employs over 35 million people, and aligning with global efforts to promote sustainable agriculture and food systems.

Furthermore, the study’s emphasis on empirical evaluation of alternative feeds addresses critical research gaps identified in the literature, such as the lack of comprehensive data on the nutritional and economic viability of aquatic plants for snail farming (Adebayo, 2023). By comparing duckweed, Azolla pinnata, and water hyacinth to soybean, the research provides actionable insights for farmers, policymakers, and extension services, enabling the development of targeted interventions, such as training programs and subsidies, to promote sustainable feed adoption. The inclusion of organoleptic evaluation ensures that alternative feeds do not compromise the sensory qualities of snail meat, safeguarding consumer acceptance and market competitiveness in Nigeria’s vibrant food sector, where snail meat is a delicacy valued for its unique taste and cultural significance (Ibrahim, 2024). Ultimately, this research not only advances the science of heliciculture but also contributes to Nigeria’s broader agricultural development goals, fostering resilience, sustainability, and inclusivity in the face of economic and environmental challenges.

1.2 Statement of the Problem

The profitability of snail farming in Nigeria faces significant hurdles due to the high cost of conventional feeds, particularly soybean, which is often imported or subject to unpredictable price swings. This economic burden falls heavily on smallholder farmers, who dominate the sector but lack the resources to manage these costs, limiting their ability to scale operations. The reliance on soybean, despite its high protein content, restricts the growth of heliciculture as a sustainable source of income and nutrition, especially for rural communities where affordable protein sources are scarce.

Aquatic plants like duckweed, Azolla pinnata, and water hyacinth offer a promising solution due to their abundance in Nigeria’s waterways, rapid growth, and nutritional value. These plants are cost-effective and environmentally sustainable, with duckweed and Azolla providing high protein levels and water hyacinth offering a low-cost option despite its invasive nature. However, there is a lack of comprehensive research on how these feeds affect the growth, reproduction, and carcass quality of Archachatina marginata, the preferred snail species, leaving farmers without clear guidance on their viability compared to soybean.

Additionally, the sensory qualities of snail meat—such as flavor, texture, and juiciness—play a critical role in consumer acceptance but remain understudied in relation to these alternative feeds. This study addresses these gaps by comparing the effects of the three aquatic plants against soybean, aiming to provide evidence on their suitability as sustainable feed options. By doing so, it seeks to enhance profitability for smallholders and support environmentally friendly practices, contributing to food security and sustainable agriculture in Nigeria.

1.3 Objectives of the Study

The main objective is to compare the effects of three aquatic plants and soybean on snail growth, reproduction, carcass, and organoleptic properties. Specific objectives are include:

1. To assess the growth performance, including feed intake, body weight gain, body length, and body width, of Archachatina marginata fed duckweed, Azolla pinnata, water hyacinth, and soybean.

2. To evaluate the reproductive performance, including egg number, egg weight, egg circumference, number of hatchlings, incubation period, and mortality, across the four dietary treatments.

3. To determine the carcass characteristics, specifically the weight of edible parts and shell weight, of snails fed the different diets.

4. To investigate the organoleptic properties (flavor, texture, juiciness, and overall accept- ability) of snail meat using a trained taste panel.

1.3 Research Questions

The study seeks to answer the following research questions:

1. How do duckweed, Azolla pinnata, and water hyacinth affect the growth performance (feed intake, body weight gain, body length, and body width) of Archachatina marginata compared to soybean?

2. What are the effects of these aquatic plants on the reproductive performance (egg number, egg weight, egg circumference, number of hatchlings, incubation period, and mortality) of Archachatina marginata?

3. How do carcass characteristics (weight of edible parts and shell weight) differ among snails fed duckweed, Azolla pinnata, water hyacinth, and soybean?

4. What are the organoleptic properties (flavor, texture, juiciness, and acceptability) of snail meat from the different dietary treatments?

1.4 Significance of the Study

This study is significant for several reasons. First, it contributes to the growing body of knowledge on sustainable snail farming by evaluating the potential of aquatic plants as alter- native feeds, which could reduce production costs and enhance profitability Okeke2023. By identifying cost-effective feed options, the study supports smallholder farmers in improving their livelihoods and contributing to food security in Nigeria Eze2021. Second, the findings will provide empirical data on the effects of aquatic plants on snail performance, addressing gaps in the literature Adebayo2023. Third, the organoleptic evaluation will inform strategies for improving the marketability of snail meat, enhancing consumer acceptance Ibrahim2024. Finally, the use of aquatic plants aligns with environmental sustainability goals by repurpos- ing abundant or invasive species like water hyacinth, potentially mitigating their ecological impact Osman2022.

1.6 Scope of the Study

The study focuses on Archachatina marginata snails reared for six months at the Snailery Unit of [Your University Name], Nigeria. It assesses growth parameters (feed intake, body weight gain, body length, and body width), reproductive indices (egg number, egg weight, egg circumference, number of hatchlings, incubation period, and mortality), carcass charac- teristics (weight of edible parts and shell weight), and organoleptic properties (flavor, texture, juiciness, and acceptability). The experimental diets include soybean as the control and three aquatic plants (duckweed, Azolla pinnata, and water hyacinth) as treatments. The study is limited to a controlled experimental setting and does not account for field conditions or long- term effects beyond six months.

1.7 Definition of Terms

i. Heliciculture: The practice of farming or rearing snails for commercial or subsistence purposes.

ii. Growth Performance: Measurable indicators of snail development, including feed intake, body weight gain, body length, and body width.

iii. Reproductive Performance: Parameters related to snail reproduction, such as egg number, egg weight, egg circumference, number of hatchlings, incubation period, and mortality.

iv. Carcass Characteristics: Attributes of the snail after slaughter, including the weight of edible parts and shell weight.

v. Organoleptic Properties: Sensory qualities of snail meat, including flavor, texture, juiciness, and overall acceptability, as assessed by a taste panel.