title: Improving the efficiency of feed utilization in poultry by selection. 1. Genetic parameters of anatomy of the gastro-intestinal tract and digestive efficiency.
abstract: BACKGROUND
  Feed costs represent about 70% of the costs of raising broilers. The main way to decrease these costs is to improve feed efficiency by modification of diet formulation, but one other possibility would be to use genetic selection. Understanding the genetic architecture of the gastro-intestinal tract (GIT) and the impact of the selection criterion on the GIT would be of particular interest. We therefore studied the genetic parameters of AMEn (Apparent metabolisable energy corrected for zero nitrogen balance), feed efficiency, and GIT traits in chickens.Genetic parameters were estimated for 630 broiler chickens of the eighth generation of a divergent selection experiment on AMEn. Birds were reared until 23 d of age and fed a wheat-based diet. The traits measured were body weight (BW), feed conversion ratio (FCR), AMEn, weights of crop, liver, gizzard and proventriculus, and weight, length and density of the duodenum, jejunum and ileum.
  
  
  RESULTS
  The heritability estimates of BW, FCR and AMEn were moderate. The heritability estimates were higher for the GIT characteristics except for the weights of the proventriculus and liver. Gizzard weight was negatively correlated with density (weight to length ratio) of duodenum, jejunum and ileum. Proventriculus and gizzard weights were more strongly correlated with AMEn than with FCR, which was not the case for intestine weight and density.
  
  
  CONCLUSIONS
  GIT traits were largely dependent on genetics and that selecting on AMEn or FCR would modify them. Phenotypic observations carried out in the divergent lines selected on AMEn were consistent with estimated genetic correlations between AMEn and GIT traits.
authors: INRA, UR83 Recherches Avicoles, F-37380, Nouzilly, France.
authors: Hugues
authors: H
authors: de Verdal
authors: Agnès
authors: A
authors: Narcy
authors: Denis
authors: D
authors: Bastianelli
authors: Hervé
authors: H
authors: Chapuis
authors: Nathalie
authors: N
authors: Même
authors: Séverine
authors: S
authors: Urvoix
authors: Elisabeth
authors: E
authors: Le Bihan-Duval
authors: Sandrine
authors: S
authors: Mignon-Grasteau
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D004063:Digestion; D004435:Eating / Q000502:physiology*; D005260:Female; D041981:Gastrointestinal Tract / Q000033:anatomy & histology* / Q000254:growth & development; D005895:Gizzard, Avian / Q000033:anatomy & histology / Q000254:growth & development; D040582:Inheritance Patterns; D008099:Liver / Q000033:anatomy & histology / Q000254:growth & development; D008297:Male; D009929:Organ Size; D010641:Phenotype; D011531:Proventriculus / Q000033:anatomy & histology* / Q000254:growth & development; D012641:Selection, Genetic