Introduction
Japanese quail (Coturnix coturnix Japonica) is an important livestock in Nigeria and in many nations. It is being farmed as the smallest avian species for meat and egg production (Panda and Singh, 1990). Its production is favoured because they are generally accepted, requires less time and space, have rapid growth, earlier sexual maturity, greater laying ability, shorter generation interval and resistance to diseases when compared to chickens. These peculiarities of coturnixs have facilitated its commercial production and rearing; mainly as meat in Europe, eggs in Japan and are often bred as dual-purpose birds in other Asian countries (Minvielle, 1998). They are also used as laboratory animals for researches (Baumgartner, 1994) and for extensive use in many studies (Kayang et al., 2004) such as for growth, selection and breeding. In Nigeria it is used for research purposes and commercially reared mainly for egg production.
Many researchers have focused their genetic studies on improving only economic traits. A broader perspective of improved and efficient genetic study has emerged because selection, breeding and genetic improvement have a marked effect on characteristics of the blood biochemistry; as researchers utilize the biochemical parameters of the blood as markers in livestock species to enhance productivity and reproductive performance (Emmerson, 2003; Nguyen and Tran, 2003). Genetic resources such as serum enzymes, serum proteins and bilirubin have been established as genetic markers in farm animals (Pagot, 1992). Several researches have shown the relationship between poultry birds’ performance and some blood parameters, these includes: plasma Alkaline Phosphatase activity in Rhode Island birds (Orunmuyi et al., 2007), the relationship between growth and blood constituents in Japanese quail by Faraht et al, (2010), and variation of plasma constituents at different ages of female Japanese quail (Hassan, 2010).
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