73 Akintola et al / Advances in Agricultural Biotechnology 1 (2011) 73-76 EFFECT OF OESTROGEN ON EGG PRODUCTION AND EGG QUALITY TRAITS IN SEC- OND YEAR LAYERS An experiment was conducted to determine the effects of graded levels of oestrogen on egg laying performance and egg quality traits in second cycle layers. Sixty (60) Brown Lohmann breeds of laying birds of 69 weeks old were randomly assigned to four treatment groups of 15 birds per treatment and three replicates of 5 birds per group in a completely randomized design (CRD). Graded dosage levels of oestrogen (0µg, 10 µg, 20 µg and 30 µg) were administered for eight (8) weeks. Statistical analysis of the data col- lected on egg production and egg quality traits revealed that oestrogen had significant influence (P<0.05) on egg production better than the control and the other treatments group. No significant difference (P>0.05) were observed on egg quality traits (egg weights, shell thickness, yolk and albumen weights) among the treatment groups. It was therefore concluded that oestrogen admin- istered at dosage rate of 10µg had significant improvement on egg production performance on second cycle layers. © 2011 woaj Ltd. All rights reserved Akintola, O.A 1 , Ajuogu, P.K 2 . and Ajayi, F.O 2 . 1 Department of Animal Science Rivers State University of Science & Technology, Oroworokwu, Nigeria 2 Department of Animal Science & Fisheries University of Port Harcourt, Port Harcourt, Nigeria . Article history: Accepted: Available online: 4 October 2011 Keywords: Laying performance, egg quality, oestrogen ARTICLE INFO ABSTRACT Advances in Agricultural Biotechnology 1 (2011) 73-76 1. Introduction Oestrogen is a steroid hormone produced by the developing follicles in the ovaries. It is one of the pri- mary steroid hormones which are lipophilic and poorly soluble in water [11]. The most common oestrogens are oestrone, oestrodiol-17 and oestroil. Oestrone and oes- trodiol-17 are the most important steroids because they are physiologically effective at lower concentrations than other steroids found in the environment. It is specu- lated that reproductive hormones can improve egg lay- ing performance in laying birds especially at old age, when the adult laying birds decline in production and also the shell quality deteriorate [7]. Oestrogen controls the female sexual development; it is also known to cause fertilization in man [5]. In birds, oestrogen is the differ- entiating hormone for gonadal development, its presence in the female is the differentiation antigen for the het- erogametic gonad in the avian ovary. This gene product is present in both sexes and activated by exposure to embryonic oestrogen. This makes avian sexual reversal from male to female possible, including expression of H -W antigen through the administration of oestrogen to the genetically male egg during the critical stage of em- bryonic development [4]. When oestrogen is absent, the gonad develops into testes, but when present for the * Corresponding author. email address: folsaade_ajayi@yahoo.coml 2011 woaj Ltd. All rights reserved Available at woaj Advances in Agricultural Biotechnology Journal homepage: www.woaj.org/AAB