Domestic Chicken Literature Review

Chapter 2: Literature Review

2.1 The Gallus gallus

Amongst all domestic animals, the domestic chicken (Gallus gallus domesticus) is recognized as the most important and prevalent of animal species worldwide. Domestic chicken are an important animal protein source in human diets. The world’s chicken population is approximately 16.2 billion (Bushra et al., 2012) and approximately 49.3 million of this population is from Ethiopia with 97.3%, 2.32% and 0.38% being indigenous, exotic, and hybrid chickens respectively, manufacturing 72300 metric tons of chicken meat and 78000 of eggs (CSA, 2011). Originally, the Red Jungle Fowl (Gallus gallus) comes from the Southeast of Asia (Oka, Ino et al. 2007) (FuMIHITO, Miyake et al. 1994) (Hillel, Groenen

2011). Indigenous chickens harbor vital genetic resources that need to be conserved against production extortions and replacement with commercial hybrids (Muchadeyi, Sibanda et al. 2005) (Muchadeyi, Wollny et al. 2007). A numerous amount of indigenous chicken breeds is potentially prone to extinction if not already extinct. For instance, in Thailand the RJF is now only found in forested hills or within national parks (Akaboot, Duangjinda et al. 2012). Disease outbreaks also pose serious threats in human diets especially in developing countries where not only malnutrition is a problem but humans are in desperate need of quality protein (Mengesha 2012). According to natural selection, since indigenous chickens can survive in harsh environmental pressures, with low-feed intake and poor management (Farrell 2000), they are considered more robust and fit towards diseases, thus disease resistant (Minga, Msoffe et al. 2004). Therefore, the characterization of indigenous chicken genetic resources is essential for the identification and operative management and use of South African indigenous chicken, thus conservation of domestic chickens. Several of indigenous chicken institutions have developed conservation programs, such as the Fowl for Africa Project initiated by the Agricultural Research Council. This program houses four native chicken breeds as conservation flocks of the genetic diversity of indigenous chickens (Van Marle-Koster and Nel