Indian Journal of Animal Research 376 RESEARCH ARTICLE Indian Journal of Animal Research, Volume 58 Issue 3: 376-380 (March 2024) Characterization of 24bp Insertion Polymorphism of Prolactin Gene and its Association with Quantitative Traits in Tellicherry Native Chicken Breed Azhaguraja Manoharan 1 , S. Sankaralingam 2 , P. Anitha 2 , Binoj Chacko 2 , T.V. Aravindakshan 2 10.18805/IJAR.B-4479 I NTRODUCTION In birds, prolactin hormone is involves in various physiological functions viz. crop sac development, induction and maintenance of broody behavior and regulation of gonadal function (Kulibaba et al., 2012). Also, it has a crucial effect on egg production in chicken (Cui et al., 2006). It has been observed that most prolactin gene polymorphism occurs at the 5’ flanking region, 3 flanking region and coding region of a signal peptide (Li et al., 2009). Additionally, the 5 flanking region of the avian prolactin gene has been regarded as a magnificent experimental model for studying both tissue-specific and hormonally regulated activation of gene transcription (Wilkanowska et al ., 2014). The sequence variation at the 5 flanking region of prolactin gene possibly will consequence in alters the transcription factor binding sites and contribute to the release of prolactin hormone (Rashidi et al., 2012). A 24 bp insertion at the promoter region of the chicken prolactin gene is associated with suppression of the prolactin gene expression causing non-broodiness in hens, it could be used as a genetic marker against broodiness in chicken (Jiang et al., 2005). Research studies showed the correlation of different allelic variants of the prolactin gene with egg production for the different breeds of chicken (Begli et al., 2010). Modern commercial poultry production is mainly aimed at increase in egg production by inhibition of broody behavior (Xu et al., 2010). Over the past few years, new DNA technologies have been invented in poultry science which gave rise to marker-assisted and genome selection (Wolc et al., 2016). The combination of modern DNA technologies and classic selection approaches paved the way for the creation of highly productive competitive lines and breeds of poultry (Sodhi et al ., 2013). Based on the studies carried out over the few decades, it has been reported that the prolactin gene has a direct and indirect association with various production traits in poultry. Hence, it could be used as a potential marker for the production traits (Wilkanowska et al., 2014). The main objective of the present study was identification of 24 bp insertion-deletion polymorphism at the promoter region of the prolactin gene and to find out its association with quantitative traits in Tellicherry native chicken of Kerala, India. ABSTRACT Background: Over many centuries, the conventional methods of poultry breeding is based on the phenotypic selection of the birds with superior trait in a particular population. Prolactin is a physiological candidate gene that has significant effects on production traits in poultry. The objective of this study was to investigate 24 bp insertion (I) polymorphism of prolactin gene and its association with quantitative traits in Tellicherry native chicken. Methods: A total of 200 blood samples were collected from the randomly selected birds of All India Co-ordinated Research Project (AICRP) on Poultry Breeding, Mannuthy. The isolated DNA samples were subjected to polymerase chain reaction (PCR) by using specific set of primers to amplify the 24 bp insertion polymorphism. PCR amplicons were sequenced to study the polymorphism at nucleotide level. Result: PCR amplification revealed the presence of a specific DNA fragment with 130/154 bp contained 24 bp insertion polymorphism. Based on the polymorphic patterns birds were designated with three genotypes as II, ID and DD. The frequency of I (0.6975) allele was found higher than D (0.3025) allele. Our experimental results revealed that 24 bp insertion polymorphism of prolactin did not have a significant association with production traits viz, age at sexual maturity, egg weight and egg number in Tellicherry native chicken. Key words: Allele, Chicken, PCR, Polymorphism, Prolactin. 1 ICAR- Indian Veterinary Research Institute, Izzatnagar, Bareilly- 243 122, Uttar Pradesh, India. 2 Department of Poultry Science, College of Veterinary and Animal Sciences, Mannuthy, Thrissur-680 651, Kerala, India. Corresponding Author: Azhaguraja Manoharan, ICAR- Indian Veterinary Research Institute, Izzatnagar, Bareilly-243 122, Uttar Pradesh, India. Email: azhagurajamano@gmail.com How to cite this article: Manoharan, A., Sankaralingam, S., Anitha, P., Chacko, B. and Aravindakshan, T.V. (2024). Characterization of 24bp Insertion Polymorphism of Prolactin Gene and its Association with Quantitative Traits in Tellicherry Native Chicken Breed. Indian Journal of Animal Research. 58(3): 376-380. doi: 10.18805/IJAR.B-4479. Submitted: 10-04-2021 Accepted: 21-08-2021 Online: 06-10-2021