**2. Global overview of intensive livestock farming systems**

Livestock farming throughout the world is becoming increasingly intensive as a result of the increased demand for beef, milk, eggs, and dairy by-products. The estimated population whose livelihood depends on agriculture makes up 42% of the total world population [10]. Therefore, this sector plays a vital role in the process of economic development of any country by ensuring a flow of essential food products,

#### *Alternative Animal Feeding for Intensive Livestock Farming Systems and Their Impact… DOI: http://dx.doi.org/10.5772/intechopen.106061*

which contribute to food security. Also, livestock farming contributes draught energy and manure for crop production and appears to be the key food and cash security available to many people living in developing countries [4, 11].

It has been reported that the world's population is expected to increase by 2% annually reaching 9.1 billion by 2050, while food demand is projected to increase by 59% in the coming decades. These projections challenge farmers to use proper methods, systems, and technologies to maximize productivity so that they can respond effectively to human consumption needs [12]. Since a majority of rural households live in areas where poverty and deprivation are the most severe and depend on agriculture for their survival, it might seem obvious that livestock needs to be intensive, modern, efficient, and competitive so that its contribution can reduce poverty and transform the economies of the countries [13]. Therefore, efficient and sustainable livestock farming systems in the whole world seem to be a priority for both small and large farmers [14].

Livestock farming worldwide is practiced in three different systems: extensive, semi-intensive, and intensive systems. In extensive livestock farming, mostly practiced in developing countries, the land is individually owned and the animals are heavily dependent on vegetation composed of wild plant species for grazing, which compromises the faster growth of animals and reduces their productive performance [12]. In this system, the animals are only brought indoors and fed meals during lambing and calving seasons or the winter. Although it is a less efficient system, it presents some advantages in terms of sustainability as it returns most of the animal manure directly to the soil, thereby contributing to increased crop production and nutrient cycling [11]. Also, animals can be raised in the semi-intensive systems, where they graze for some period during the day and in the evening, they feed on supplements. Both extensive and semi-intensive systems are practiced by smallholder farmers, and they are more suitable for ruminants such as cattle, goats, and sheep [15].

Currently, in the whole world, more so in developed countries, farmers are practicing intensive system-based management so that they can provide beef, milk, and eggs throughout the year. In this system, also described as factory farming, animals are enclosed in zero-grazing units where are fed and provided water to yield high productivity (beef, dairy produce, and poultry) from limited land available by raising large numbers of animals indoors. Under this system, diet, breeding, and disease are managed precisely and in consequence, meat, milk, and other products are produced in large quantities [16]. However, confined animals are usually fed based on concentrates composed of very expensive feedstuffs which makes this system the most expensive, requiring high initial costs to develop the activity [17]. One of the key strategies to make intensive livestock farming cheaper would be the adoption of food alternatives based on locally available and low-cost by-products such as coconut meal, palm kernel cake (PKC), palm fiber, cottonseed meal, and other vegetable and fruit wastes [18].
