ISSR polymorphism of laying hens of broiler parental stock distinguished by rates of growth and productivity indicators

Abstract

Searching for biomarkers of high productivity in chickens is currently one of the relevant tasks facing poultry farming. Thus, the research was aimed at studying genetic traits of laying hens. The hens belonged to parental stock of the «Arbor Acres Plus» hybrid cross and varied according to the productivity abilities. The study was carried out in 2018-2019 at the PRODO Tyumen Broiler factory located in Tyumen, Tyumen region on three groups of chickens numbering from 6000 to 6085 bird units. Raising and evaluation of laying hens were carried out in accordance with the «Arbor Acres Plus» guidelines and standards for breeding of the parental generation and the regulations for the technology of the parent stoсk management and bird weighing which were developed on the basis of those guidelines and standards and adopted at the factory. The practice of raising the «Arbor Acres Plus» hybrid cross revealed a distinct differentiation of laying hens by body weight during the growth period. There were distinguished fast-growing «large» individuals, «small» individuals and «medium» individuals occupying an intermediate position. At the beginning of the experiment, during the 18th week of age the average mass of «small» chickens was 106 g less than that of chickens from the «medium» group. The average mass of chickens from the «medium» group was 139 g less than the indications in the «large» group, and the differences between the «large» and the «small» hens amounted to 245 g. Such differences remained until the 35th week, and then they leveled out substantially. The differences between groups of chickens were observed also in egg production rates, which decreased with increasing the age of laying hens (by 31-33 weeks). The amount of eggs per layer per week averaged out at 71.1 % for “small” hens, 72.8 % for the «medium», and 74.4 % for the «large» ones. To assess the genetic polymorphism of chickens the ISSR-PCR method was applied. Seven primers were used to study the genetic polymorphism of laying hens: (AG)8G, (AG)8T, (CA)8G, (GT)8C, (AC)8T, (TC)8C, (TG)8A. The experimental groups of laying hens differed both in the frequencies of ISSR bands and in the average indicators of polymorphism. Higher parameters of the proportion of polymorphic bands (P), genetic diversity (h), apparent (ne) and effective number of alleles (na) were observed in the group of «large» laying hens, while the «medium» and «small» groups had lower rates and did not significantly differ in the level of polymorphism among themselves. Higher rates of ISSR polymorphism observed in the group of fast-growing («large») laying hens could be a marker of a higher level of genetic diversity in this group compared to chickens from the other two groups. The conducted studies showed that ISSR markers can be recommended as a simple tool for monitoring the genetic diversity of stocks of laying hens.