International Journal of ISSN: 2574-9862 IJAWB

Avian & Wildlife Biology
Research Article
Volume 3 Issue 1 - 2018
Prolactin Gene and Laying Performance in Aseel Birds
SK Maurya1* and BM Yadav2
1Narendra Deva University of Agriculture & Technology, India
2Nawab Wajid Ali Shah Zoological Garden, India
Received: December 29, 2017 | Published: February 15, 2018
*Corresponding author: SK Maurya, Deparment of Veterinary Physiology & Biochemistry, College of Veterinary Science & Animal Husbandry, Narendra Deva University of Agriculture Technology, Kumarganj, Faizabad- 224 229 (UP) India, Tel: +919415720187; Email:
Citation: Maurya SK, Yadav BM (2018) Prolactin Gene and Laying Performance in Aseel Birds. Int J Avian & Wildlife Biol 3(1): 00058. DOI: 10.15406/ijawb.2018.03.00058


Prolactin gene polymorphism at exon 5 of prolactin receptor gene (PRLR5) was studied in Aseel birds along with its interaction with laying performance. Laying performances were recorded as age at first laying (AFE), Body Weight at First Egg (WFE), Mean Egg Weight (MEW) and Total No. of Eggs at 90 days of laying (TEN). DNA was isolated from 2- 3 ml not clear of Blood from 40 birds collected from wing vein. PRLR5 locus was amplified by PCR and the product was restriction digested with Bam HI and resolved on 2% Agarose gels for genotyping. The AFE (d), WFE (Kg), MEW (g) and TEN of Aseel birds in the present study were found to be 188.40±0.22, 1.57±0.03, 43.61±0.36 & 35.48±0.40 respectively. The prolactin gene locus PRLR5 showed two alleles A & B. The frequencies of A and B alleles at this locus were 0.60 and 0.40 respectively. There was no interaction of various laying performances found with alleles of PRLR5.

Keywords: Egg production performance; Kadaknath; Prolactin; Polymorphism; Birds


MEW: Mean Egg Weight; WFL: Weight at First Laying; AFH: Age of Hens; MEW: Mean Eggs Weight; TEN: Total Number of Eggs


Egg productivity is the most important economic trait in egg-laying 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.

Material and Methods

Birds and production data

The birds from the poultry farm of College of Veterinary Science & Animal Husbandry, Narendra Deva University of Agriculture & Technology, Kumarganj, and Faizabad were used for the present study. Forty female birds of Aseel breed nearing their age of laying were taken for the present study. Birds were kept in separate cages for the ease of sample & data collection and were fed ad libitum. The weights at first egg (WFE) were recorded in kg with a balance on the day when they gave their first egg. Age at first egg (AFE) was calculated from the records. Mean weight of eggs (MEW) was taken as average of daily egg weights over a period of 90 days of laying and recorded in g with the help of a monopan balance. Total no. of eggs (TEN) represented the number of eggs laid over the study period of 90 days.

Blood Collection and DNA isolation

Two to three ml of blood was collected from wing vein of each bird in a vacutainer tube containing EDTA. DNA was isolated from 2-3 ml of blood using High salt method of Montgomery and Sise [8] with slight modifications.

Polymerase chain reaction

Polymerase chain reaction was carried out in a Bio-Rad CFX96 Real Time system. Primer pair for PRLR5 was used as described by Rashidi et al. [9], to amplify a fragment of 250 bp from exon 5 of prolactin receptor gene. The sequence of primers is as follows:



PCR was performed in a final volume of 50 μl containing:100 ng of genomic DNA, 0.5μM of each primer, 0.2 mm of each dNTPs, 1.5 mM MgCl2, 1.0 U Taq DNA polymerase and 1× reaction buffer. The cycle conditions for PCR included-Initial denaturation of 5 min at 94°C; followed by 35 cycles of 94 °C for 30s, annealing at 59 °C for 60 s, extension at 72 °C for 60 s followed by a final extension of 5 min at 72 °C. The PCR product was resolved on to a 2% Agarose gel.

Restriction digestion

The fragment amplified by PRLR5 contains GGATC sequence for BamHI endonuclease. Thus, restriction enzyme BamHI was used. The restriction digestion was performed in 20μl volume having 1 X restriction enzyme buffer and 4-5 units of enzymes. The reaction tubes were incubated overnight at 37 °C.

Genotyping and statistical analysis

Genotypes were manually scored based on the bands resolved on the gel. Frequencies of various alleles were calculated using the following formula:

Frequency of an allele = ( 2 x No.of Homozygote )+ ( No.of Heterozygote ) 2 x Total no.of Individuals ( N ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqbacbaaaaaaa aapeWaaSaaaOqaaKqbaoaabmaak8aabaqcLbsapeGaaGOmaiaaccka caWG4bGaaiiOaiaad6eacaWGVbGaaiOlaiaad+gacaWGMbGaaiiOai aadIeacaWGVbGaamyBaiaad+gacaWG6bGaamyEaiaadEgacaWGVbGa amiDaiaadwgaaOGaayjkaiaawMcaaKqzGeGaey4kaSIaaiiOaKqbao aabmaak8aabaqcLbsapeGaamOtaiaad+gacaGGUaGaam4BaiaadAga caGGGcGaamisaiaadwgacaWG0bGaamyzaiaadkhacaWGVbGaamOEai aadMhacaWGNbGaam4BaiaadshacaWGLbaakiaawIcacaGLPaaaaeaa jugibiaaikdacaGGGcGaamiEaiaacckacaWGubGaam4Baiaadshaca WGHbGaamiBaiaacckacaWGUbGaam4Baiaac6cacaWGVbGaamOzaiaa cckacaWGjbGaamOBaiaadsgacaWGPbGaamODaiaadMgacaWGKbGaam yDaiaadggacaWGSbGaam4CaiaacckajuaGdaqadaGcpaqaaKqzGeWd biaad6eaaOGaayjkaiaawMcaaaaaaaa@818F@

Alleles frequency and their accordance to Hardy-Weinberg equilibrium were calculated from Graphpad Prism software version 5.0. The following linear equation was applied to analyze the genetic effects of PRL24:

Yij = μ + Gi + Hj + eij, MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY=Hhbbf9v8qqaqFr0xc9pk0xbb a9q8WqFfeaY=biLkVcLq=JHqpepeea0=as0Fb9pgeaYRXxe9vr0=vr 0=vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaKqzGeaeaaaaaa aaa8qacaWGzbGaamyAaiaadQgacaqGGaGaeyypa0JaaeiiaiabeY7a TjaabccacqGHRaWkcaqGGaGaam4raiaadMgacaqGGaGaey4kaSIaae iiaiaadIeacaWGQbGaaeiiaiabgUcaRiaabccacaWGLbGaamyAaiaa dQgacaGGSaaaaa@4ABC@

Where Yij is the average performance of ith genotype in jth hatch, μ is mean of the population, Gi is fixed effect of ith genotype (i=1,2,3), hj is fixed effect of jth hatch (j=1,2,3), and eij is random residual error.

Results and Discussion

The AFE in days in Aseel hens ranged from 184 to 194, whereas the Mean±SEM was found to be 188.40±0.22. The weight at first laying (WFE) in Kg among Aseel hens ranged from 1.20 to 2.20; the mean±SEM being 1.57±0.03. The mean egg weight (MEW) ranged from 39.97 g to 49.62 g and the mean±SEM values were found to be 43.61±0.36. Total number of eggs (TEN) varied from 29 to 41; the mean being 35.48±0.40. The age at first laying (AFE) in the present study was higher than the studies of Mohan et al. [10] (2008a, b); where they reported it to be 154 d. The body weights of Aseel hens (WFE) in the present study were better than the study of Gurung & Singh [11]; where they reported the body weights (g) to be 1133±1.52 at an age of 6 months. This difference might be due to the fact that they studied this breed reared by the farmers/ localities as unorganized farms; whereas in the present study, birds were kept in organized farm of the University.

Similar findings regarding WFE were reported by Ahmad et al. [12], in Peshawari variety of Aseel; whereas, mean eggs weight (MEW) and TEN in the present study, were better than previous study [11,13,14]. These differences might be due to the difference in breed of Aseel hens and managemental conditions. There was present of only two alleles: one where the restriction site was present and other where restriction site was absent. The individuals showing no restriction site for the enzyme were designated as of BB genotypes; whereas AA genotypes were cut by the enzyme. The frequency of A allele was higher (0.60) than B allele (0.40) at PRLR5 marker site. These results are in concurrence with the findings of Rashidi et al. [9] where they reported the frequencies of AA and BB genotypes to be 0.72 and 0.28 respectively. The age of hens at their first laying (AFE) in the genotypes AA & BB were 186.8±0.69 & 188.1±0.79 respectively. The mean body weight at 1st laying of hens (WFE) having genotypes AA & BB were 1.60±0.05 & 1.53±0.04 respectively. Birds showing mean egg weight (MEW) having genotypes AA & BB were 43.20±0.45 and 44.11±0.60 respectively. All birds showing mean total no. of egg (TEN) having genotypes AA & BB were 36.14±0.48 & 34.67±0.63 respectively.


Statistically, there was no significant difference was found between the means of various laying traits with genotypes and this finding is in contrary to the findings of Zhang et al. [15], where they found that polymorphism of the PRLR gene is significantly associated with egg production traits in the Erlang Mountainous chicken. This difference might be attributed to breed of birds used in the study. Based on the findings of current study, it can be concluded that though PRLR5 shows polymorphisms in Aseel hens, statistically there is no association of laying performance with polymorphism at this locus of Prolactin.



Conflict of Interest

Author declares there is no conflict of interest.


  1. Lewis PD, Gous RM (2006) Effect of final photoperiod and twenty-week body weight on sexual maturity and early egg production in broiler breeders. Poult Sci 85(3): 377-383.
  2. Emsley A (1997) Integration of classical and molecular approaches of genetic selection: egg production. Poult Sci76(8): 1127-1130.
  3. Luo PT, Yang RQ, Yang N (2007) Estimation of genetic parameters for cumulative egg numbers in a broiler dam line by using a random regression model. Poult Sci86(1): 30-36.
  4. Sharp PJ (1997) Immunological control of broodiness. World Poult Sci J 53: 23-31.
  5. Cui JX, Du HL, Liang Y, Deng XM, Li N, et al. (2006) Association of polymorphisms in the promoter region of chicken prolactin with egg production. Poult Sci 85(1): 26-31.
  6. Panda B, Mahapatra SC (1989) Common breeds of poultry in Poultry Production. ICAR, New Delhi, India, pp. 6-18.
  7. Bhatti MA, Qureshi MS, Ahmad A (1991) Comparative study on the performance of various genetic groups of Aseel and its crosses with exotic breeds of poultry under controlled & field conditions in Second Annual Report, Pakistan. Agric Res Council Islamabad, Pakistan.
  8. Montgomery GW, Sise JA (1990) Extraction of DNA from sheep white blood cells. New Zealand J Agric Res 33(3): 437-441.
  9. Rashidi H, Rahimi Mianji GH, Farhadi A, Gholizadeh M (2012) Association of prolactin and prolactin receptor gene polymorphisms with economic traits in breeder hens of indigenous chickens of Mazandaran province. Iranian Journal of Biotechnology Thatching10(2): 129-135.
  10. Mohan J, Sastry KVH, Tyagi JS (2008) Production and other characteristics of Aseel Peeladesi hens under normal rearing system. Ind J Poult Sci 43: 243-246.
  11. Gurung BS, Singh M (1999) Network project on Survey of poultry (Aseel) genetic sciences. ICAR Terminal Report, India.
  12. Ahmad S, Hussain J, Akram M, Aslam F, Mahmud A, et al. (2013) Comparative study on productive performance and hatching traits of three age groups of indigenous Mushki Aseel chickens. Agricultural Advances 2(5): 146-149.
  13. Singh CB, Singh CV (2008) Selection indices for genetic improvement of broiler. Ind J Ani Res 42(2): 125-127.
  14. Haunshi S, Padhi MK, Niranjan M, Rajkumar U, Shanmugam, et al. (2013) Comparative evaluation of native breeds of chicken for persistency of egg production, egg quality and biochemical traits. Ind J Anim Sci 83(1): 59-62.
  15. Zhang L, Li DY, Liu YP, Liu Y (2012) Genetic effect of the prolactin receptor gene on egg production traits in chickens. Genet Mol Res 11(4): 4307-4315.
© 2014-2018 MedCrave Group, All rights reserved. No part of this content may be reproduced or transmitted in any form or by any means as per the standard guidelines of fair use.
Creative Commons License Open Access by MedCrave Group is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at
Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version | Opera |Privacy Policy