IN-VITRO GAS FERMENTATION PATTERN OF MAIZE STRAW SUPPLEMENTED WITH CASSAVA PEEL-BASED DIETS

ABSTRACT

The increasing scarcity and high cost of conventional livestock feed resources in developing countries have intensified the search for alternative and sustainable feed materials for ruminant production. Agricultural by-products such as maize straw and cassava peels are abundant in Nigeria and possess significant potential as low-cost feed resources when properly processed and supplemented. This study evaluated the in-vitro gas fermentation characteristics of maize straw supplemented with cassava peel-based concentrate diets with or without oil inclusion. The experiment was designed to assess the nutritive value, degradability, methane production, and fermentation efficiency of the formulated diets using rumen fluid inoculum under laboratory conditions.

Six dietary treatments consisting of varying inclusion levels of cassava peel concentrate and oil supplementation were formulated and analyzed. Chemical composition analyses revealed that cassava peel concentrate possessed higher crude protein and lower fibre fractions compared to maize straw. Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) values were observed to be higher in maize straw than in cassava peel concentrate, indicating improved digestibility potential in the supplemented diets. In-vitro gas production parameters showed significant variations among treatments, particularly in methane production, dry matter degradability (DMD), and fermentation efficiency. Diets supplemented with oil demonstrated reduced methane output at lower supplementation levels, suggesting the potential of oil inclusion as a methane mitigation strategy in ruminant nutrition.

The findings indicate that cassava peel-based supplements can effectively improve the fermentation characteristics and nutritional quality of maize straw-based diets for ruminants. Furthermore, the inclusion of oil in the diets contributed to reduced methanogenesis, thereby offering environmental and nutritional benefits. The study therefore recommends the utilization of cassava peels and other agro-industrial residues as sustainable feed alternatives for improving livestock productivity and reducing feed costs in Nigeria and other developing countries.

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Livestock production plays a vital role in food security, income generation, and rural livelihoods across sub-Saharan Africa. In Nigeria, ruminant animals such as goats, sheep, and cattle constitute important sources of animal protein and contribute significantly to the agricultural economy. However, one of the major challenges confronting livestock production is the persistent shortage of quality feed resources, particularly during the dry season when natural pastures decline in quantity and nutritional quality (Akinfemi et al., 2010).

The increasing competition between humans and livestock for conventional feed ingredients such as maize, soybean, and groundnut cake has further escalated feed costs, thereby limiting profitable livestock production. Consequently, there has been growing interest in the utilization of non-conventional feed resources and agricultural residues that are inexpensive, readily available, and environmentally sustainable (Makkar, 2000). Among such residues, maize straw and cassava peels have attracted considerable attention due to their abundance and potential nutritional value for ruminants.

Maize straw is a fibrous agricultural residue generated after harvesting maize grains. Although it is widely available in tropical regions, its utilization in animal feeding is constrained by low crude protein content, high fibre concentration, poor digestibility, and low voluntary intake by animals (Reddy et al., 2003). Similarly, cassava peels are major by-products of cassava processing industries and households. Nigeria, being one of the world’s largest producers of cassava, generates substantial quantities of cassava peels annually. Unfortunately, a significant proportion of these peels are discarded as waste, contributing to environmental pollution despite their potential use in animal nutrition (Aro et al., 2010).

Recent advancements in ruminant nutrition have focused on improving the feeding value of fibrous agricultural wastes through supplementation and feed processing technologies. Supplementation with cassava peel-based concentrate has been reported to enhance microbial activity in the rumen, improve nutrient availability, and increase feed utilization efficiency (Fievez et al., 2005). Additionally, dietary oil inclusion has emerged as a promising strategy for reducing methane emissions from ruminants while improving energy utilization. Methane production during rumen fermentation represents not only a loss of feed energy but also contributes significantly to greenhouse gas emissions and climate change (Beauchemin et al., 2008).

The in-vitro gas production technique has become an important laboratory method for evaluating the nutritive value and fermentation characteristics of feed resources. The method estimates the extent and rate of feed degradation through measurement of gas produced during microbial fermentation under anaerobic conditions. Compared to in-vivo feeding trials, the in-vitro gas production technique is faster, less expensive, and requires smaller quantities of feed samples (Menke & Steingass, 1988). Furthermore, parameters such as methane production, organic matter digestibility, short-chain fatty acid production, and fermentation kinetics can be effectively assessed using this technique.

Despite the abundance of maize straw and cassava peels in Nigeria, information on their combined utilization as ruminant feed supplements, particularly under oil supplementation, remains limited. There is therefore a need to investigate the fermentation characteristics and nutritional potential of maize straw supplemented with cassava peel-based diets in order to enhance sustainable livestock feeding systems.

1.2 Statement of the Problem

The high cost and inadequate availability of conventional livestock feed ingredients remain major constraints to sustainable ruminant production in Nigeria. Most smallholder farmers rely heavily on natural pastures and crop residues, which are often nutritionally deficient, especially during prolonged dry seasons. Maize straw, although abundant, contains high fibre and low protein levels, resulting in poor digestibility and reduced animal performance.

At the same time, large quantities of cassava peels generated from cassava processing activities are underutilized or improperly disposed of, leading to environmental pollution and waste of potentially valuable feed resources. The challenge therefore lies in developing cost-effective and nutritionally efficient feeding strategies that can convert these agro-industrial wastes into valuable livestock feed.

Furthermore, methane emission from rumen fermentation constitutes a significant environmental concern and represents an energy loss to the animal. Although dietary oil supplementation has shown potential in reducing methane production, limited studies have investigated its effects on maize straw and cassava peel-based diets under Nigerian production systems.

This study therefore seeks to evaluate the in-vitro gas fermentation pattern of maize straw supplemented with cassava peel-based concentrate with or without oil inclusion in order to determine its nutritional value, digestibility potential, and methane reduction capacity.

1.3 Aim of the Study

The main aim of this study is to evaluate the in-vitro gas fermentation characteristics of maize straw supplemented with cassava peel-based concentrate diets with or without oil supplementation for improved ruminant nutrition.

1.4 Objectives of the Study

The specific objectives of the study are to:

1. determine the chemical composition of maize straw and cassava peel-based supplements;
2. evaluate the in-vitro gas production characteristics of maize straw supplemented with cassava peel concentrate;
3. assess the effect of oil supplementation on methane gas production during rumen fermentation;
4. determine the dry matter digestibility and fermentation efficiency of the experimental diets; and
5. investigate the potential of cassava peel supplementation in improving the nutritive value of maize straw for ruminant feeding.

1.5 Research Questions

The study seeks to provide answers to the following questions:

1. What is the chemical composition of maize straw and cassava peel-based supplements?
2. How does cassava peel supplementation affect the in-vitro gas fermentation pattern of maize straw?
3. What effect does oil supplementation have on methane production during rumen fermentation?
4. Does supplementation improve the digestibility and fermentation characteristics of maize straw-based diets?
5. Can cassava peels serve as sustainable alternative feed resources for ruminants?

1.6 Research Hypotheses

The following hypotheses were tested in the study:

Null Hypotheses (H?)

1. Cassava peel supplementation has no significant effect on the in-vitro gas production characteristics of maize straw.
2. Oil supplementation has no significant effect on methane gas production during rumen fermentation.
3. There is no significant difference in digestibility among the experimental diets.

Alternative Hypotheses (H?)

1. Cassava peel supplementation significantly affects the in-vitro gas production characteristics of maize straw.
2. Oil supplementation significantly reduces methane gas production during rumen fermentation.
3. Significant differences exist in digestibility among the experimental diets.

1.7 Significance of the Study

This study is significant because it provides scientific information on the utilization of agricultural by-products as alternative feed resources for ruminant production. The findings will contribute to efforts aimed at reducing feed scarcity and lowering production costs in livestock farming.

The study will also promote environmental sustainability through the effective utilization of cassava peels and maize straw that are often discarded as wastes. By converting these residues into valuable feed resources, environmental pollution associated with indiscriminate waste disposal can be minimized.

Furthermore, the study contributes to current research on methane mitigation strategies in ruminant nutrition through dietary oil supplementation. Reduced methane production implies improved feed energy utilization and decreased environmental impact of livestock production systems.

The results of this research will be useful to livestock farmers, animal nutritionists, researchers, feed manufacturers, agricultural extension agents, and policymakers involved in sustainable animal production and feed resource management.

1.8 Scope of the Study

This study focused on the evaluation of the in-vitro gas fermentation characteristics of maize straw supplemented with cassava peel-based concentrate diets with or without oil inclusion. The research covered proximate composition analysis, fibre fraction determination, gas production measurement, methane estimation, and digestibility evaluation under laboratory conditions using rumen fluid inoculum.

The study was limited to in-vitro evaluation and did not include in-vivo animal performance trials.

1.9 Justification of the Study

The increasing demand for affordable livestock products necessitates the exploration of unconventional feed resources capable of improving animal productivity at reduced cost. Maize straw and cassava peels are widely available agro-industrial residues in Nigeria but remain underutilized in animal feeding.

Evaluating their fermentation characteristics and digestibility potential is essential for developing sustainable feeding systems that enhance livestock productivity while reducing environmental pollution. In addition, reducing methane emission from ruminants aligns with global efforts toward climate-smart agriculture and sustainable livestock production.

This study is therefore justified by the need to improve feed resource utilization, reduce feeding costs, enhance environmental sustainability, and support food security through efficient ruminant production systems.

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