Estimates of heritability and genetic correlations for meat quality traits in broilers

Broiler meat quality is one of the primary factors considered by the poultry industry. This study was conducted to estimate heritability and genetic correlation coefficients for meat quality traits in a single male broiler line. The meat ultimate pH (24 h after slaughter) and lightness presented the highest heritability estimates. Given the estimated genetic correlations, the pH measured at 15 min and 24 h after slaughtering, as well as lightness, were characterized by a close and negative genetic relationship with water holding capacity traits. In contrast, meat quality traits exhibited only non-significant genetic correlations with performance and carcass traits. Noticed exceptions were breast weight, which was genetically and favorably associated with the initial pH and thawing-cooking losses, and ultrasound record of pectoral muscle depth, which was genetically and unfavourably associated with the shear force of meat. Meat pH values at 24 h after slaughtering or lightness may be a favorable selection criterion for the poultry industry for improving meat quality, since these traits are associated with the water holding capacity of the meat. Out of the traits studied, lightness is most easily assessed on the industrial slaughtering line. The direct selection for breast weight could improve the initial pH and thawing-cooking losses of meat, even as selection for ultrasound records of Pectoralis major may affect the meat tenderness in this lin

Quantitative-genetic study of muscle fibers of number and diameter in a male broiler line

O presente estudo teve como objetivo estimar parâmetros genéticos e fenotípicos de número diâmetro e área de fibras musculares, bem como de características de desempenho, carcaça e qualidade de carne em uma linhagem de frangos pertencentes a um programa de seleção do tipo sib test, onde foram coletadas informações de carcaça dos irmãos completos dos indivíduos a serem selecionados, oriundos de um rebanho de pedigree, fornecidos pela Agroceres Ross Melhoramento de Aves S.A. Também foram fornecidos pela empresa 73.142 e 34.949 dados de peso à seleção juvenil e medidas de ultra-sonografia do músculo peitoral, respectivamente. As características analisadas foram: peso à seleção (PS), medidas de ultra-sonografia (US), peso de peito (PPEI), medida de pH inicial (pHi), medida de pH final (Phf), teor de luminosidade (L*), teor de vermelho (a*), teor de amarelo (b*), perdas de água por exsudação (EXSU), perdas de água por descongelamento (CONG), perdas de água por cozimento (COZ), força de cisalhamento (FC), número de fibras musculares (NCel), diâmetro de fibras musculares (DIAM) e área de fibras musculares (AREA). Os componentes de (co) variância foram estimados através do método de máxima verossimilhança restrita, utilizando-se o programa MTDFREML. A matriz de parentesco foi composta por 77.474 animais. As estimativas dos coeficientes de herdabilidade foram moderadas a altas para as características número de fibras musculares, peso à seleção juvenil, medida de ultra-sonografia, peso de peito, perda de água por exsudação, teor de luminosidade e teor de vermelho. As estimativas de correlações genéticas do número e diâmetro de fibras musculares com as características de perda de água da carne e força de cisalhamento indicaram a existência de uma importante associação genética entre as características, capazes de apresentar satisfatório potencial de resposta à seleção.This research was conducted to estimate genetic and phenotypic parameters of muscle fibers of number, diameter and area, as well as of performace, carcass and meat quality traits in a male broiler line belonging to a program of selection of the type sib test, in which data from complete brothers of the individuals were selected, bred in a pedigree flock provided by Agroceres Ross Melhoramento de Aves S. A. Also were provided by the company 73,142 and 34,949 data concerning body weight at juvenile selection and ultrasound records of pectoral muscle, respectively. The traits analyzed were: body weight at juvenile selection (PS), ultrasound records of pectoral muscle (US), meat breast weight (PPEI), initial pH measure (pHi), final pH measure (pHf), lightness (L*), redness (a*), yellowness (b*), weep losses (EXSU), drip losses (CONG), shrik losses (COZ), shear force (FC), muscle fibers of number (NCel), muscle fibers of diameter and muscle fibers area (AREA). (Co) variance components were estimated by restricted maximum likelihood method, using the software MTDFREML. The numerator relationship matrix was composed by 77,474 individuals. Heritability coefficients estimates were from moderate to high for muscle fibers number, ultrasound records, meat breast weight, weep losses, lightness and redness traits. Genetic correlation estimates of muscle fibers number and diameter with the measures of meat water losses and shear force traits indicated the existence of an important genetic association between the traits, capable to present potential satisfactory respond to the selection