Abstract

This study was carried out on the microbiological analysis of dry cassava peel used in the preparation of pigs feed. Since the nutritional compositions of the peels were tremendously improved, it follows that other non conventional feed ingredients which are readily available can be improved upon using this method. Consequently, inclusion of such into livestock feeding will imply reduced cost of production.

The findings also indicated that fermentation of the cassava peels with Pleurotus ostreatus might be an effective means of detanninfying and improving its nutritional value for use as animal feed.

CHAPTER ONE

INTRODUCTION

1.1     Background of the study

Manihot esculenta with common names ‘‘cassava’’, is a woody shrub of the spurge family, Euphorbiaceae native to South America. It is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates. Cassava can also be classified into different species which include M. aesculifolia (AES), M. Brachyloba (BLO), M. Carthaginensis (CTH), M. Esulenta subsp,  M. Tristis (TST). However, it contains cynogens (1.3%) depending on cultivars (Stupak et al., 2006) and large amount of cyanogenic glucosiders in the cassava flour (Cumbane et al., 2007) which could limit cassava root utilization for consumption and for livestock feeding. Cassava appears to have originated in Brazil and Paraguay, but has spread throughout tropical areas of south and Central America long before the arrival of Columbus. Cassava is now one of the most important food crops in counties throughout the world.

It ranks as the 6th most important food crop worldwide, even though in Western countries it is little known or used. The tubers of cassava or ‘’Yuca’’, as the plant is commonly known in South America, are extremely rich in starch infact, it is the richest sources of starch of any food plant (it contains up to 10times as much starch as corn and twice as much as potatoes). The large tubers, which can weight can weigh up to 5kg provide 30% of their dry weight as starch. However, the entire plant is poisonous if consumed raw, due to its linamarin content, a pre-cursor of cyanode glycosides.  Nigeria is the world’s largest producer of cassava while Thailand is the largest exporter of dried cassava.Cassava roots play an important role in the African diet and they are processed using simple traditional methods into products such as “gari” and fufu, or lafun flour, some of which are fermented products (Odunfa, 1985). As a rough estimate, about

10 million tons of cassava are processed for gari annually in Nigeria alone (Okafor, 1992).

In the processing of fermented cassava products, the roots are normally peeled to rid them of two outer coverings: a thin brown outer covering, and a thicker leathery parenchymatous inner covering (Obadina et al., 2006).  These peels are regarded as wastes and are usually discarded and allowed to rot. With hand peeling the peels can constitute 20-35% of the total weight of the tuber (Odunfa, 1985).

The wastes generated at present pose a disposal problem and would even be more problematic in the future with increased industrial production of cassava products such as in gari production, cassava flour and dried cassava fufu (Obadina et al, 2006). Since these peels could make up to 10% of the wet weight of the roots, they constitute an important potential resource if properly harnessed by a biotechnological system (Obadina et al, 2006).

Cassava peels continue to constitute waste in the cassava processing industry

(Eustace and Dorothy, 2001).  This is in spite of the potential of the use of the byproduct as an animal feedstuff. Considerable evidence has emerged for the possibility of using processed cassava peel as an energy source for pigs and poultry (Longe et al, 1983). Higher inclusion of the by-product in monogastric feed or formulation of diets with cassava peels, as sole energy source is limited because of its fibrous nature.

Fakolade (1997) and Arowora et al (1999) have reported the occurrence of high amounts of non-starch polysaccharides in cassava peels. Degradation of these carbohydrate compounds to simple sugars will further increase the energy value of cassava peels. Since the monogastric industry constitutes the largest consumer of commercial livestock feeds in Africa, it is imperative to find alternative feed sources to the expensive energy ingredients like the cereals (Arowora et al, 1999).

The use of fungi for the conversion of lignocelluloses into food and feed rich in protein offers an alternative for developing unconventional source of proteins as food or feed (Vijay et al, 2007).  Yeast and algal proteins for example require sophisticated techniques and heavy inputs to produce whereas the beauty of mushroom cultivation lies in its ability to grow on cheap lignocellulose materials with minimum inputs and a high yield of valued food protein for direct human consumption and may also provide a rich source of animal feed (Vijay et al, 2007).

Lignocellulytic enzymes also have significant potential applications in various industries including chemicals, fuel, food, brewery and wine, animal feed, textile and laundry, pulp and paper, and agriculture (Howard et al, 2003).

1.2     The problem statement

Cereals have remained the major energy source in livestock diets with maize being the most common and the major ingredient contributing about 60-80% (Damisa et al., 2007). Inadequate supply and prohibitive prices of these cereal grains particularly corn and consequent increase in the cost of livestock products have led animal nutritionists to search for cheaper alternative sources of energy to feed livestock (Adebowale, 1981). The need to find alternative and cheaper ingredients to replace the expensive ones is inevitable since cost of feed accounts for 70-80% of the cost of poultry production in Nigeria. Feed cost alone according to Sastry and Thomas (1976) accounts for 67.2% of the total pig production cost. It is therefore pertinent to scout for cheaper and readily available sources for compounding swine rations. In recent times, cassava or tapioca meal has been extensively used as a replacement ingredient to corn (Damisa et al., 2007).

Two important biological wastes that may cause damage to the environment are generated during the traditional processing of cassava storage roots for 'gari' production in Africa, namely, the cassava peels and the liquid squeezed out of the fermented parenchyma mash (Oboh, 2006). Cassava peels derived from gari processing are normally discarded as wastes and allowed to rot in the open, thus resulting in health hazards (Oboh, 2006).

As a rough estimate, about 10 million tons of cassavas are processed into gari annually in Nigeria alone (Oboh, 2006). Since these peels could make up to 10% of the net weight of the roots, they constitute an important potential resource for animal feeds if properly processed by a bio-system (Antai and Mbongo, 1994).

 A bout 60% of the cassava produced all over the world is used for human consumption (Obadina et al, 2006). Cassava peels are the major by-product of the cassava processing industry and these peels are largely underutilized as livestock feed in Nigeria (Annan, 1998). The waste peels are found to contain 42.6% carbohydrate, 1.6% protein, 12.1% ether extract, 5.0% total ash and 22.5% crude fibre (Obadina et al, 2006).

With the advent of biotechnology approaches, there are opportunities for economic utilization of agro industrial residues such as cassava peel waste.

1.3     Objectives of project

The objectives of the study is;

1.    To enumerate the microbial content of dried cassava peel

2.    To isolate and identify the potential spoilage organism of this product

3.   To make recommendation on how to preserve the peels before consumption by the livestock.

1.4     Justification of the problem statement

Feed represents a major portion of the over all production cost in the poultry and livestock industry in the country. A major constraint in the poultry industry in Nigeria is the availability of feed ingredients all the year round at economic prices. This problem is further compounded by the fact that most of these ingredients are imported at high foreign exchange costs. Therefore, alternative sources of energy for animal feeds which are nutritionally adequate and cheap must be found locally to reduce the cost.

One source of great potential which is increasingly being used for animal feed is cassava which can completely replace maize and other cereals in livestock and poultry feed-formulation. Cassava peels contain high amount of non-starch polysaccharides, mostly non- digestible carbohydrates such as cellulose and hemicelluloses (Oke, 1992).

These are poorly digested and bio-utilized by livestock. The digestibility of cassava peels as feed for both ruminants and non-ruminants tends to decrease with crude fibre content (Fakolade, 1997). Pleurotus ostreatus is known to reduce this high fibre content by degrading the hemicelluloses, cellulose and lignin components of the peels and also improve the low protein content of the peels as animal feed (Hadar et al., 1992).

 Thus through the fermentation process, the two major limitations associated with the use of cassava peels as animal feed are catered for and also environmental pollution by agro-wastes such as cassava peels is minimized.

1.5     Scope of the study

This study will cover the production processing and storage of cassava peel for livestock consumption (pig) and the limitation will include inadequacy of current literature tone and financial constrain.

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