Prolactin Gene and Laying Performance in Aseel Birds

Egg productivity is the most important economic trait in egglaying poultry. Endocrine and environmental factors such as length of photoperiod and feeding allowance can influence egg production [1]. However, a genetic factor would be a prerequisite. Egg production is a polygenic inheritance trait with low to moderate heritability depending on the period involved, a major opportunity for improvement in this trait lies in the period after 40 weeks of age [2,3]. In traditional breeding, genetic improvement based on estimated breeding values requires extensive data from a variety of sources. Prolactin (PRL) is a polypeptide hormone which plays a key role in egg production. Onset of incubation behavior is induced by an increase in PRL secretion, which results in regression of ovary & loss of egg production [4]. Polymorphism in the promotor region specially those that result in change of promoter binding sites, most likely influence mRNA expression and thus influence incubation behaviour and egg production [5]. The Asil or Aseel is a breed of chicken originating from South Punjab/Sindh area of Pakistan and India. The Aseel breed is known for its stamina, pugnacity, majestic gait, and dogged fighting qualities [6]. This breed is characterized by its hardiness and ability to thrive under adverse climatic conditions, and its meat is considered to have a desirable taste and flavor. The superiority of Aseel on other indigenous breeds is due to its hardiness, resemblance to Cornish and larger body size [7]. Almost all the varieties of Aseel are characterized with heavy body weight and poor egg production potential thus leading to low progeny size due to erratic ovulation, short or erratic clutches and broodiness. Due to different biological activities attributed to PRL and PRLR, they can be used as the major candidate genes in molecular animal breeding programs. There is scarce data in case of breeds like Aseel, thus present study was planned. Materials and Methods