Production and body composition traits of broilers in relation to breast weight evaluated by path analysis

Abstract

Breast weight has great economic importance in poultry industry, and may be associated with other variables. This work aimed to estimate phenotypic correlations between performance (live body weight at 7 and 28 days, and at slaughter, and depth of the breast muscle measured by ultrasonography), carcass (eviscerated body weight and leg weight) and body composition (heart, liver and abdominal fat weight) traits in a broiler line, and quantify the direct and indirect influence of these traits on breast weight. Path analysis was used by expanding the matrix of partial correlation in coefficients which give the direct influence of one trait on another, regardless the effect of the other traits. The simultaneous maintenance of live body weight at slaughter and eviscerated body weight in the matrix of correlations might be harmful for statistical analysis involving systems of normal equations, like path analysis, due to the observed multicollinearity. The live body weight at slaughter and the depth of the breast muscle as measured by ultrasonography directly affected breast weight and were identified as the most responsible factors for the magnitude of the correlation coefficients obtained between the studied traits and breast weight. Individual pre-selection for these traits could favor an increased breast weight in the future reproducer candidates of this line if the broilers' environmental conditions and housing are maintained, since the live body weight at slaughter and the depth of breast muscle measured by ultrasonography were directly related to breast weight. Key words: animal breeding, multivariate analysis, phenotypic correlation, poultry, pre-selection Características de produção e de composição corporal de frangos em relação ao peso de peito avaliada por análise de trilha RESUMO: O peso do peito possui grande importância econômica na indústria de frangos, podendo estar associado a outras variáveis passíveis de seleção. Estimaram-se correlações fenotípicas entre características de desempenho (peso vivo aos 7, 28 dias e ao abate e profundidade de músculo peitoral por ultra-sonografia), carcaça (peso eviscerado e de pernas) e composição corporal (peso do coração, do fígado e da gordura abdominal), em uma linhagem de frangos, e quantificou-se a influência direta e indireta destas variáveis sobre o peso do peito. Para tanto, utilizou-se a análise de trilha, desdobrando-se a matriz de correlações parciais em coeficientes que forneceram a influência direta de uma variável sobre a outra, independentemente das demais. A manutenção das variáveis peso vivo ao abate e peso eviscerado na matriz de correlações pode ser prejudicial à análise estatística que envolve os sistemas de equações normais, como a análise de trilha, devido à multicolinearidade observada. O peso vivo ao abate e a profundidade do músculo peitoral por ultra-sonografia apresentaram efeitos diretos importantes sobre o peso de peito e foram identificadas como as principais responsáveis pela magnitude dos coeficientes de correlação obtidos. Assi...

Use of the correlation coefficient in agricultural sciences: problems, pitfalls and how to deal with them

“…One can use partial correlations to establish such pathways, but this can be a very laborious process in the absence of prior intuition about the variables and a descriptive approach would be better. In fact, partial correlations are seldom encountered in agricultural applications (for an example see Lorentz et al 2011), the opposite being the case in psychology (e.g., Rosmarin et al 2011).…”

Saanen Oğlaklarının Canlı Ağırlıkları Üzerine Vücut Ölçümleri İçin Path Analizi

“…Path analysis is used to describe the directed dependencies among a set of variables [3] . Therefore, application of path analysis in animal breeding practices began to increase [4][5][6][7][8][9][10][11][12][13] . Also, there are some studies which examined the direct and indirect effects of body measurements on body weight [14][15][16][17] .…”

Genetic variability in ultrasound records of breast muscle in a broiler breeding program

“…Sibs from an elite flock that underwent selection for the development of a broiler male line were investigated using different approaches [5][6][7][8] and selected to emphasize performance and carcass traits. Pedigree chicks were wing-banded at hatching and housed and raised as rec-ommended by the company guidelines for nutritional planning, management conditions and vaccination.…”

“…US1 was gauged along the keel, and US2 was gauged over the coracoid bone. Data collection was performed at 35 d of age from Nov. 1999 to Jan. 2001 [5] [7,8]. Previous studies considered the average of the breast muscle depth in the longitudinal and transverse directions (US) in the ultrasound record [7,8].…”

“…Previous studies estimated the genetic parameters of performance traits in a male broiler line to specify the impact of ultrasound usage in the broiler breeding program [5][6][7][8]. Current approaches enable us to better appreciate the efficiency of the breast muscle ultrasound as a selection criterion in addition to genetic relationships with body composition and meat quality traits.…”