Genetic and phenotypic relationships between and within support and demand tissues in a single line of broiler chicken

Abstract

1. With commercial selection for increased broiler performance there has been a correlated increase in the incidence of several metabolic disorders. A study was undertaken to investigate the balance between the unselected support tissues (including the heart, liver, spleen and the components of the gastrointestinal tract (GIT)) which drive growth in the selected demand tissues (eviscerated body mass) by assessing the genetic correlations between these traits. 2. Data were collected on 483 broiler birds taken from a commercial male broiler line with pedigree information. 3. Genetic parameters were estimated by restricted maximum likelihood with an individual animal model. Heritability estimates for the production traits ranged between h2 = 0.48 and 0.59 for leg and breast mass, respectively. The support tissues were generally associated with low to moderate heritabilities ranging between h2 = 0.19 for proventriculus to h2 = 0.38 for duodenum mass, although moderately high heritability estimates (h2 = 0.51 to 0.54) were associated with the spleen and gizzard. 4. The genetic correlations between production traits and support organs were generally low, however, heart mass was positively correlated with all carcase components of the lean tissue mass; the genetic correlations ranged between r(g) = 0.55 with breast mass to r(g) = 0.64 with eviscerated body mass. 5. In general, there were strong positive genetic correlations between the different components of the GIT. Organs that have been implicated in the development of metabolic disorders such as ascites (for example, the heart) could theoretically be used in commercial selection indices due to moderate heritabilities (heart: h2 = 0.30) and favourable correlations with commercially important traits.

Effect of the infection with Eimeria acervulina, E. maxima and E. tenella on pigment absorption and skin deposition in broiler chickens

“…The female birds had significantly higher skin pigmentation, even though the males showed greater pigment consumption. This finding is in agreement with the reports by Sirri et al (2010) and Muñoz-Díaz et al (2012) and it is attributed to higher deposition of subcutaneous fat in the females, which is related to genetic and hormonal factors (Le Bihan-Duval et al 1998, Rance et al 2002.…”

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

“…The phenotypic correlations between BRE and the other traits were positive and moderate to high (0.378 to 0.832), except for the correlation between BRE and FAT, which was positive but low (0.188). Other studies showing important phenotypic correlations among performance, carcass and body composition traits are also reported (Rance et al, 2002;Vayego et al, 2008). However, there is a limitation in the evaluation of the obtained correlation coefficients: they only indicate the magnitude and the direction of a linear association between the traits (Kaps and Lamberson, 2004) without revealing the cause-effect relationships.…”

“…The phenotypic individual selection is usually accomplished in juvenile ages (Bijma et al, 2000), when called pre-selection, which can be used especially for traits previously identified as being favorably associated with breast weight may facilitate early removal of broilers with poorer quality. These associations may be evaluated by phenotypic correlations (Cheverud, 1988;Rance et al, 2002), since the confounding of genetic and environmental effects on phenotype are low. Such situation can be assumed in poultry evaluation, because the individuals are reared in environmentally controlled housing (Willis et al, 1991;Morris and Pollott, 1997).…”

Growth Performance, Carcass Characteristics and Meat Quality of Griller-Type Broilers of Four Genetic Lines

“…According to Le Bihan-Duval et al (1998), there is a positive correlation (0.76) between body weight and breast meat yield, indicating that heavier chickens produce greater breast yield. According to Rance et al (2002), there is a negative correlation (-0.65) between breast yield and leg yield. Furthermore, there is a mathematical relationship in parts yield: the lower the breast yield, the higher the yield of other parts, such as that of legs, back and wings.…”