1. Introduction

African chicken production survives by scavenging and, other than the occasional feeding of household garbage to the chickens and under other circumstances, with the addition of grain to the feed. Due to low input levels and numerous issues with village chicken production, the entire standard of chicken production in developing nations like Ethiopia is primarily of the scavenging type and is typically inefficient [1]. Chickens are a simple way to generate family income and opportunities for job creation with relatively low resource investment and readily available family labor because of their tendency to adapt to most regions of the world, their rapid growth rate, their quick breeding rate compared to most other livestock, or the short generation span. When compared to other domestic animals, chicken is an incredible resource for chicken farming and for household usage as a protein-rich source of animal food for human consumption [2]. The production of chicken is challenged by various factors. The major problem that affects the poultry industries in the tropics is the increasing cost of feed ingredients, such as maize and soya bean meal. The seasonal instability in the supply of conventional feed ingredients requires alternative energy sources to be explored to ensure optimum performance of the chickens [3].

The main challenges for livestock production in the tropics and sub-tropical countries are inadequate feed sources and low quality of existing feed resources [4]. Due to insufficient production of conventional feedstuffs for livestock feeding, the majority of developing nations struggles to provide their animals with enough to feed. Both humans and animals compete over the few amounts of concentrated feedstuffs they produce each year. As a result, the production of livestock in these nations frequently faces a significant problem due to the lack of feed resources [5]. The use of non-conventional feedstuffs in animal feeding can help to solve this problem. In this regard, alternative feed ingredients have been used in animal feeding, including cassava root meal [6, 7] and sweet potato meal [8, 9, 10, 11, 12]. The use of cassava as an alternative to conventional energy feed stuffs like maize could help to reduce feed costs [13].

2. Cassava (Manihot esculenta) in chicken diet

Crops with starchy roots, tubers, rhizomes, corms, or stems are known as root and tuber crops. They are mostly utilized to make animal feed, human food (either raw or processed), starch, alcohol, and fermented drinks like beer. A root is an organ that grows from the root tissue and is a small, frequently enlarged storage organ with hairy stalks. A root is also a tuber. It grows from a rhizome, or a prolonged stem tissue; therefore, it is probably an enlarged storage organ. Consequently, a plant may also be a root, whereas a tuber is a root crop. For instance, potatoes, sweet potatoes, and yams are edible tubers, whereas carrots and cassava are root vegetables. There are differences between the growth patterns of edible tubers and edible root crops or plants. Since the plant’s edible tubers and root vegetables are what fuel its above-ground growth, they are rich in starchy nutrients. While most vegetables grow above ground, root and tuber vegetables are the components of the plant that grow below the soil or on the soil surface. Rhizomes that grow underground can run parallel to or just below the soil’s surface and can also run horizontally. Simply, a swelling portion of one of these rhizomes makes up the tuber. It may be possible to extract nutrients from these bloated chunks. In order for the plants to create healthy new growth in the spring, they want to store nutrients for them [14].

Cassava (Manihot esculenta) is grown for its underground starchy tuberous roots in tropical and subtropical regions. Over 800 million people worldwide eat mostly cassava roots, commonly known as cassava tubers [15]. Cassava roots are low in protein but abundant in calories because they are mostly constituted of starch and soluble carbohydrates. It is anticipated that more than 60% of the cassava grown in Africa will be consumed, with the other third being used to make secondary products [16]. The rising and expensive cost of feed ingredients has been a hindrance to global chicken production for many years. The majority of the time, different cereal crops are used as a conventional feed source for chickens. The competition between human and animal food and feed, as well as the use of these components in other industries, may be to blame for the ongoing increase in these feed ingredients. As a result, a substitute for the conventional energy and protein elements in chicken feed must be affordable and easily accessible and have an adequate nutritious composition and should have no discernible impact on chickens. Accordingly, Cassava (Manihot esculenta) is one such alternative. A common root tuber known as cassava is high in calcium, vitamins B and C, vital minerals, and carbohydrates, making it a viable substitute for maize in the diets of chickens. Cassava’s low protein content, imbalanced amino acid profile, dustiness, and presence of anti-nutritional elements, however, limit its utilization in chicken diets. However, these flaws can be solved through proper processing and the inclusion of feed additives in the diet [17].

Different parts of cassava can be supplemented into diets of chickens. As a result, cassava tubers can be consumed boiled, mashed, deep-fried, and so on, and there are many food products based on cassava such as tapioca (cassava starch), a worldwide food ingredient; fufu (cassava flour boiled in water); and garri (fermented cassava mash), the two last popular foods in West and Central Africa [18]. The basic cassava products used in animal feeding are chips and pellets, which can partially or completely substitute the cereal grain in poultry feed [19]. The finger-like leaves, which are consumed as vegetables or used as animal feed, as well as different byproducts from the cassava processing industries, such as pomace and peels from starch, ethanol, and cassava food production, which can be used as livestock feed, are examples of other cassava products. Cassava flour, which should not be consumed by humans, can be used to make livestock feed [20]. Livestock feeding accounts for more than a third of the cassava crop’s production [21]. Before being powdered or pelletized for use in commercial livestock feed, cassava tubers are first cut into slices and dried. Cassava chips can be made using basic household or village procedures as well as on a big, mechanized scale, and the processes utilized at various sizes of chip and pellet manufacturing are connected. The amount of cassava that needs to be processed, the cost of labor and capital, as well as the accessibility of relatively cheap energy, all influence the technology that is selected [22]. The availability of a better source of protein and the inclusion of enough methionine in the diet to meet both body requirements and cyanide detoxification are two factors that will determine whether utilizing cassava powder as a maize alternative in poultry feed is feasible [23]. While attempts have been made to reduce the dirtiness with the addition of oil and supplementation with suitable amounts of methionine and lysine amino acids, it has been beneficially observed that cassava root meal can replace up to 30% of maize in a broiler ration [24]. In a layer’s diet, cassava root meal can completely replace maize [25]. Compared to chicken-fed rations with cassava chips or maize, broiler chicken-fed rations containing cassava pellets exhibited improved feed consumption [26]. For growing Japanese quail, about 35% cassava meal-based ration is suggested [27]. Cockerel starter birds can tolerate only about 28% level of cassava sievate in their ration [28]. Cassava root sievate and wet maize milling waste [29] can successfully replace maize by up to 35% without impacting the growth and feed utilization of finisher broilers.

The majority of research findings demonstrates that adding cassava to chickens’ diets results in attractive responses in their behavior. For instance, substituting a 4:1 mixture of cassava root meal and leaves for maize in the diet of chickens can lower feed costs without affecting the layers’ ability to gain weight or produce eggs [30]. Feeding broilers cassava chips supplemented with Moringa oleifera leaf meal at levels of 5 and 10% showed that cassava chips replacing maize at levels of 55.56% and 83.33%, respectively, in the diets had no negative effects on production and blood parameters [31]. Depending on dry matter consumption and growth performance of broilers, cassava root chips can completely substitute maize grain in broiler rations as an energy feed source [32]. On the other hand, based on the results of yields of major edible meat parameters, cassava root chips could replace maize grain by less than 50% in broilers diet, and 50% cassava root chips or 5% Moringa olifera meal, or a mixture of both can successfully be used in the ration of layers, substituting maize grain and soybean meal. The final body weight gain, total body weight gain, and daily body weight gain of broiler chickens were enhanced by substitution of noug seed cake with cassava leaf meal at a 4% substitution level. Thus, cassava leaves can be a good protein source to substitute the expensive Noug seed cake in the broiler ration [33].

3. Limitations on using cassava meal

The physical properties of cassava root meal, such as dustiness, poor pelleting quality, and poor pigmentation, tend to also limit the use of cassava as a feed ingredient in animal diets, in addition to the antinutritional factors and nutrient deficiencies inherent in raw and unprocessed cassava root. It has been noted that these physical restrictions, particularly in poultry, can lower feed intake and have an impact on body weight gain and feed conversion ratio. Animals fed a diet based on cassava that does not contain oil or that is fed as mash have also been shown to exhibit crop impaction and respiratory system irritation [34].

A cassava-based diet’s dustiness is typically correlated with the form in which the feed is given to the animal. High levels of cassava meal in mash feed often produce dusty feed. Through proper pelleting, dustiness problems in cassava-based mash diets might be resolved, which would increase feed consumption and poultry performance. Pelletizing a cassava-based diet produces a diet that is denser, more homogeneous, and less dusty [35]. Diets based on cassava are about one-third less bulky after pelleting, which solves the dustiness problem. However, methods like the addition of oil or molasses can be used to address difficulties with dustiness in unpelleted chicken feed on farms without pelleting machinery.

To reduce dustiness, wet mashed feed can also be given to the birds; however, moist mashed feed should not be kept for an extended period of time to prevent contamination and deterioration. Lack of pigmentation is a further physical characteristic that restricts the use of cassava as a feed element for animals, particularly poultry. The color of cassava root meal is white (it does not have any pigmentation). It has been noted that feeding layers and broilers large amounts of cassava root meal causes pale meat and egg yolks, respectively. Due of minimal consumer appeal, it has been stated that these eggs and chicken flesh are sold for low prices.

When using a lot of cassava meal, the product quality should be improved by adding leaf meal or other pigmenting agents to the diet. Cassava root meal’s lack of pigmentation can be avoided by adding at least 30–50 g of leaf meal per kg of poultry food. Leaf meals including those from young grass, ipil-ipil (leucaena) leaves, sweet potato leaves, and cassava leaves have been shown to be successful [35].

4. Methods to raise the nutritional value of cassava

Various processing techniques have been employed for many years to improve the nutritional content of cassava for use by humans and fowl. All of these techniques aim to remove different ANFs that are present in raw cassava, including hydrogen cyanide, phytate, saponin, and alkaloids [36]. These processing techniques have also been utilized to address physical issues like dustiness and a lack of pigmentation that tend to decrease performance and product quality and raise mortality when unprocessed cassava is used as a food or feed ingredient, as well as nutrient shortages. There are two types of cassava processing techniques: traditional [37] and modern [38]. Traditional cassava processing techniques include drying; boiling; parboiling/cooking; steaming; frying; roasting; addition of oil, molasses, and leaf meal; and utilization of natural fermentation processes in order to improve the nutritional composition and decrease the anti-nutrient content. HCN losses from these procedures range from 25 to 98% [39]. The addition of feed additives, such as nutrient supplements with amino acids, vitamins, and minerals; the addition of pigmentation agents; pelleting; the addition of synthetic enzymes; the microbial fermentation of cassava roots; and the genetic modification of the cassava plant are examples of contemporary methods of cassava processing [40].

5. Conclusion

Feed resources for chickens mainly come from activities directed toward human food production. The potential sources of feed for chicken production are mainly cereal crops and their byproducts. Shortage of conventional feed resources and continuous increment in its cost have been challenging chicken production in the tropics. Utilization of alternative feed resources is mandatory to overcome this challenge in the poultry sector. Root and tuber crops can be added in chicken diets. Cassava is among the root crops and can be included in chickens’ ration. Thus, the tuber of cassava can be included in broilers diet and substitute up to 50% maize in the ration without harming the performances of both broiler and layer chickens. The use of cassava in chicken diet is limited by the presence of some anti nutritional factors. These factors can be reduced by different methods. In conclusion, cassava can be included in chickens’ diet without causing negative impact on the performances of chickens.

Konstantinos Pougouras

Chapters authored

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