title: Detection of QTL controlling feed efficiency and excretion in chickens fed a wheat-based diet.
abstract: BACKGROUND
  Improving feed efficiency is a major goal in poultry production in order to reduce production costs, increase the possibility of using alternative feedstuffs and decrease the volume of manure. However, in spite of their economic and environmental impact, very few quantitative trait loci (QTL) have been reported on these traits. Thus, we undertook the detection of QTL on 820 meat-type chickens from a F2 cross between D- and D+ lines that were divergently selected on low or high digestive efficiency at 3 weeks of age. Birds were measured for growth between 0 and 23 days, feed intake and feed conversion ratio between 9 and 23 days, breast and abdominal fat yields at 23 days, and the anatomy of their digestive tract (density, relative weight and length of the duodenum, jejunum, ileum, and ratio of proventriculus to gizzard weight) was examined. To evaluate excretion traits, fresh and dry weight, water content, pH, nitrogen to phosphorus ratio from 0 to 23 days, and pH of gizzard and jejunum contents at 23 days were measured. A set of 3379 single nucleotide polymorphisms distributed on 28 Gallus gallus (GGA) autosomes, the Z chromosome and one unassigned linkage group was used for QTL detection.
  
  
  RESULTS
  Using the QTLMap software developed for linkage analyses by interval mapping, we detected 16 QTL for feed intake, 13 for feed efficiency, 49 for anatomy-related traits, seven for growth, six for body composition and ten for excretion. Nine of these QTL were genome-wide significant (four for feed intake on GGA1, one for feed efficiency on GGA2, and four for anatomy on GGA1, 2, 3 and 4). GGA16, 19, and 26 carried many QTL for different types of traits that co-localize at the same position.
  
  
  CONCLUSIONS
  This study identified several QTL regions that are involved in the control of digestive efficiency in chicken. Further studies are needed to identify the genes that underlie these effects, and to validate these in other commercial populations and for different breeding environments.
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. sandrine.grasteau@tours.inra.fr.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Mignon-Grasteau
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. nicole.rideau@laposte.net.
authors.forename: Nicole
authors.initials: N
authors.lastname: Rideau
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. irene.gabriel@tours.inra.fr.
authors.forename: Irène
authors.initials: I
authors.lastname: Gabriel
authors.affiliation: INRA, LABOGENA, Domaine de Vilvert, 78352, Jouy en Josas Cedex, France. celinechantry@gmail.com.
authors.forename: Céline
authors.initials: C
authors.lastname: Chantry-Darmon
authors.affiliation: INRA, LABOGENA, Domaine de Vilvert, 78352, Jouy en Josas Cedex, France. marie-yvonne.boscher@paris.inra.fr.
authors.forename: Marie-Yvonne
authors.initials: MY
authors.lastname: Boscher
authors.affiliation: INRA, UE1295 PEAT, 37380, Nouzilly, France. nadine.sellier@sophia.inra.fr.
authors.forename: Nadine
authors.initials: N
authors.lastname: Sellier
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. marie.chabault@tours.inra.fr.
authors.forename: Marie
authors.initials: M
authors.lastname: Chabault
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. elisabeth.lebihan@tours.inra.fr.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Le Bihan-Duval
authors.affiliation: INRA, UR83 Recherches Avicoles, 37380, Nouzilly, France. agnes.narcy@tours.inra.fr.
authors.forename: Agnès
authors.initials: A
authors.lastname: Narcy
mesh_terms: D000273:Adipose Tissue; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development*; D004032:Diet; D005243:Feces / Q000737:chemistry; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000254:growth & development; D008040:Genetic Linkage; D040641:Quantitative Trait Loci; D014908:Triticum / Q000378:metabolism