Quantitative trait loci for bone traits segregating independently of those for growth in an F₂ broiler × layer cross

Abstract

An F₂ broiler–layer cross was phenotyped for 18 skeletal traits at 6, 7 and 9 weeks of age and genotyped with 120 microsatellite markers. Interval mapping identified 61 suggestive and significant QTL on 16 of the 25 linkage groups for 16 traits. Thirty-six additional QTL were identified when the assumption that QTL were fixed in the grandparent lines was relaxed. QTL with large effects on the lengths of the tarsometatarsus, tibia and femur, and the weights of the tibia and femur were identified on GGA4 between 217 and 249 cM. Six QTL for skeletal traits were identified that did not co-locate with genome wide significant QTL for body weight and two body weight QTL did not coincide with skeletal trait QTL. Significant evidence of imprinting was found in ten of the QTL and QTL × sex interactions were identified for 22 traits. Six alleles from the broiler line for weight- and size-related skeletal QTL were positive. Negative alleles for bone quality traits such as tibial dyschondroplasia, leg bowing and tibia twisting generally originated from the layer line suggesting that the allele inherited from the broiler is more protective than the allele originating from the layer.

Genetic parameters and mapping quantitative trait loci associated with tibia traits in broilers

“…Sharman et al (2007) also described a QTL region for the femur weight very close to this QTL region.…”

“…These markers have been previously associated with QTL for tibia plateau angle (Sharman et al, 2007) and femur bone mineral density (Rubin et al, 2007). In this same region, two candidate genes associated with performance traits, fat deposition and carcass percentage are mapped: insulin-like growth factor 1 (IGF1) and lysine (K)-specific demethylase 5A (KDM5A) (Boschiero et al, 2013).…”

“…In this same region, two candidate genes associated with performance traits, fat deposition and carcass percentage are mapped: insulin-like growth factor 1 (IGF1) and lysine (K)-specific demethylase 5A (KDM5A) (Boschiero et al, 2013). Sharman et al (2007) also mapped QTL for tibia weight on GGA1, in the region flanked by markers MCW0297 and LEI0146. Nones et al (2012) mapped QTL for carcass chemical composition on GGA1 using the same population as that used in the current study and they mapped QTL region for fat/dry matter flanked by markers MCW0297-LEI0146 and QTL for fat flanked by markers LEI0146-LEI0174.…”

“…Ambo et al (2009), studying the same population of broilers, mapped QTL for body weight traits at 35 and 41 days of age on the GGA4, exactly in the same chromosome region where QTL for tibia width and weight were mapped (MCW0240-LEI0063). Within this chromosome region, Baron et al (2011) mapped QTL for drums and thighs; Schreiweis et al (2005) for tibia area, length, and width; and Sharman et al (2007) for tibia bone mineral density, and femur weight.…”

“…Some authors have mapped QTL for bone traits (Schreiweis et al, 2005;Sharman et al, 2007), such as tibia and femur length (Tsudzuki et al, 2007;Zhou et al, 2007;Gao et al, 2010). According to Araújo et al (2012), studying traits inherent to bone structures and properties will help to improve our understanding of locomotor disorders, and provide possibilities for effective solutions.…”