Genetic architecture of quantitative traits associated with performance and carcass yield in domestic fowl

Author(s)

Millor Fernandes do Rosário

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2008-01-24

Examining board members

Antonio Augusto Franco Garcia; Antonio Augusto Domingos Coelho; Jozivaldo Prudêncio Gomes de Morais; Ana Silvia Alves Meira Tavares Moura; Irineu Umberto Packer

• Advisor: Antonio Augusto Franco Garcia; Luiz Lehmann Coutinho

Abstract

Understanding the genetic architecture means to describe the genetic and environment factors that affect a quantitative trait, together with the estimation of individual genetic effects and its interactions. The aim of this work was to understand the genetic architecture of quantitative traits associated with performance and carcass yield of a chicken reference population created from crosses between a layer line (CC) and a broiler line (TT) genotyped for microsatellite markers that were associated with body weight at 42 days in its reciprocal cross on chromosomes 1, 3 and 4. Three specific topics were presented: 1) to characterize genotypically two reference populations (TCTC and CTCT); 2) to construct linkage maps in the CTCT population and 3) to map QTL associated with performance and carcass yield in CTCT population, using Composite Interval Mapping (CIM). The results showed that the two parental lines (CC and TT) created reciprocal F1 generations with suitable polymorphic information content values and observed heterozygosity, as result of the satisfactory number of alleles. This implies that the reciprocal F2 populations, derived from both F1 generations, are appropriated to map QTL associated with performance and carcass yield. The linkage maps from CTCT population were similar to its reciprocal population and to the Chicken Consensus Linkage Map. Estimating confidence intervals for distances between loci allowed the elucidation of the causes for differences both on chromosome sizes and on order loci. Finally, there were advantages in using CIM, mainly on QTL number and location. The regions where QTLs were mapped in this study not only corroborated some results from TCTC reciprocal population, but also suggested that other genome regions on chromosomes 1, 3 and 4 may control such traits. On chromosome 4 two regions were defined that were not previously described in the literature: one associated with weight gain (MCW0240-LEI0063) and another one with feed intake (LEI0085-MCW0174) at 35- 41 days. The results of this study can be explored through fine mapping, searches in silico for candidate genes and by validation in commercial populations, in order to implement marker assisted selection in poultry breeding programs. (AU)