RESUMO
Major objectives of the poultry industry are to increase meat production and to reduce carcass fatness, mainly abdominal fat. Information on growth performance and carcass composition are important for the selection of leaner meat chickens. To enhance our understanding of the genetic architecture underlying the chemical composition of chicken carcasses, an F(2) population developed from a broiler × layer cross was used to map quantitative trait loci (QTL) affecting protein, fat, water and ash contents in chicken carcasses. Two genetic models were applied in the QTL analysis: the line-cross and the half-sib models, both using the regression interval mapping method. Six significant and five suggestive QTL were mapped in the line-cross analysis, and four significant and six suggestive QTL were mapped in the half-sib analysis. A total of eleven QTL were mapped for fat (ether extract), five for protein, four for ash and one for water contents in the carcass using both analyses. No study to date has reported QTL for carcass chemical composition in chickens. Some QTL mapped here for carcass fat content match, as expected, QTL regions previously associated with abdominal fat in the same or in different populations, and novel QTL for protein, ash and water contents in the carcass are presented here. The results described here also reinforce the need for fine mapping and to perform multi-trait analyses to better understand the genetic architecture of these traits.
Assuntos
Galinhas/crescimento & desenvolvimento , Galinhas/genética , Carne/análise , Locos de Características Quantitativas , Animais , Composição Corporal , Mapeamento Cromossômico , Feminino , Masculino , FenótipoRESUMO
An F(2) population established by crossing a broiler male line and a layer line was used to map quantitative trait loci (QTL) affecting abdominal fat weight, abdominal fat percentage and serum cholesterol and triglyceride concentrations. Two genetic models, the line-cross and the half-sib, were applied in the QTL analysis, both using the regression interval method. Three significant QTL and four suggestive QTL were mapped in the line-cross analysis and four significant and four suggestive QTL were mapped in the half-sib analysis. A total of five QTL were mapped for abdominal fat weight, six for abdominal fat percentage and four for triglyceride concentration in both analyses. New QTL associated with serum triglyceride concentration were mapped on GGA5, GGA23 and GG27. QTL mapped between markers LEI0029 and ADL0371 on GGA3 for abdominal fat percentage and abdominal fat weight and a suggestive QTL on GGA12 for abdominal fat percentage showed significant parent-of-origin effects. Some QTL mapped here match QTL regions mapped in previous studies using different populations, suggesting good candidate regions for fine-mapping and candidate gene searches.
Assuntos
Adiposidade/genética , Galinhas/genética , Fenótipo , Locos de Características Quantitativas/genética , Abdome/anatomia & histologia , Animais , Mapeamento Cromossômico/veterinária , Cruzamentos Genéticos , Genótipo , Triglicerídeos/sangueRESUMO
An F(2) resource population, derived from a broiler x layer cross, was used to map quantitative trait loci (QTL) for body weights at days 1, 35 and 41, weight gain, feed intake, feed efficiency from 35 to 41 days and intestinal length. Up to 577 F(2) chickens were genotyped with 103 genetic markers covering 21 linkage groups. A preliminary QTL mapping report using this same population focused exclusively on GGA1. Regression methods were applied to line-cross and half-sib models for QTL interval mapping. Under the line-cross model, eight QTL were detected for body weight at 35 days (GGA2, 3 and 4), body weight at 41 days (GGA2, 3, 4 and 10) and intestine length (GGA4). Under the half-sib model, using sire as common parent, five QTL were detected for body weight at day 1 (GGA3 and 18), body weight at 35 days (GGA2 and 3) and body weight at 41 days (GGA3). When dam was used as common parent, seven QTL were mapped for body weight at day 1 (GGA2), body weight at day 35 (GGA2, 3 and 4) and body weight at day 41 (GGA2, 3 and 4). Growth differences in chicken lines appear to be controlled by a chronological change in a limited number of chromosomal regions.
Assuntos
Galinhas/crescimento & desenvolvimento , Galinhas/genética , Ração Animal , Animais , Peso Corporal/genética , Galinhas/anatomia & histologia , Mapeamento Cromossômico , Ingestão de Alimentos/genética , Feminino , Genótipo , Hibridização Genética , Intestinos/anatomia & histologia , Masculino , Locos de Características Quantitativas , Aumento de Peso/genéticaRESUMO
With the objective of mapping quantitative trait loci (QTLs) for performance and carcass traits, an F2 chicken population was developed by crossing broiler and layer lines. A total of 2063 F2 chicks in 21 full-sib families were reared as broilers and slaughtered at 42 days of age. Seventeen performance and carcass traits were measured. Parental F(0) and F1 individuals were genotyped with 80 microsatellites from chicken chromosome 1 to select informative markers. Thirty-three informative markers were used for selective genotyping of F2 individuals with extreme phenotypes for body weight at 42 days of age (BW42). Based on the regions identified by selective genotyping, seven full-sib families (649 F2 chicks) were genotyped with 26 markers. Quantitative trait loci affecting body weight, feed intake, carcass weight, drums and thighs weight and abdominal fat weight were mapped to regions already identified in other populations. Quantitative trait loci for weights of gizzard, liver, lungs, heart and feet, as well as length of intestine, not previously described in the literature were mapped on chromosome 1. This F2 population can be used to identify novel QTLs and constitutes a new resource for studies of genes related to growth and carcass traits in poultry.
Assuntos
Galinhas/genética , Cromossomos , Locos de Características Quantitativas , Animais , Brasil , Galinhas/anatomia & histologia , Galinhas/crescimento & desenvolvimento , Mapeamento Cromossômico , Cruzamentos Genéticos , Feminino , Marcadores Genéticos , Genótipo , Masculino , Repetições de MicrossatélitesRESUMO
O experimento teve como objetivo avaliar a degradabilidade "in situ" da matéria seca (MS), proteína bruta (PB) e fibra em detergente ácido (FDA) do caraço de algodäo integral (CAI) em substituiçäo ao farelo de algodäo, empregando silagem de sorgo (SS), como único volumoso. Além disso, avaliaram-se alteraçöes no pH e cinética de fermentaçäo ruminal de 9 bovinos, machos, com fístulas no rúmen. Os tratamentos foram: A = 0 por cento CAI, B = 6,6 por cento CAI e C = 15 por cento CAI; a silagem de sorgo entrou na proporçäo de 70 por cento em todos os tratamentos. As raçöes eram isonitrogenadas, com aproximadamente 12 por cento de PB na MS. Houve diferença estatística (p < 0,05) para a degradaçäo de MS no tempo 48 horas (A = 54,4 por cento; B = 54,2 por cento e C = 58,7 por cento), de PB às 12 horas (A = 40,3 por cento; B = 47,7 por cento; e C = 53,1 por cento) e de FDA às 48 horas (A = 40,3 por cento; B = 41,2 por cento e C = 45,6 por cento), ocorrendo maiores taxas de degradaçäo com aumento do nível de CAI na dieta. Os demais parâmetros (volume ruminal, "turn over" do digesto ruminal e pH do conteúdo ruminal) näo mostraram diferenças significativas entre tratamentos. O emprego crescente de CAI, até 15 por cento da MS da raçäo, aumentou a degradaçäo da MS, da PB e da FDA desse produto