Estimates of genetic trend for carcass traits in a commercial broiler line

Abstract

ABSTRACT. Data from the slaughter of 24,001 chickens that were part of a selection program for the production of commercial broilers were used to estimate genetic trend for absolute carcass (CW), breast meat (BRW), and leg (LW) weights, and relative carcass (CY), breast meat (BRY), and leg (LY) weights. The components of (co)variance and breeding values of individuals were obtained by the restricted maximum likelihood method applied to animal models. The relationship matrix was composed of 132,442 birds. The models included as random effects, maternal additive genetic and permanent environmental for CW, BRW, LW, CY, and BRY, and only maternal permanent environmental for LY, besides the direct additive genetic and residual effects, and as fixed effects, hatch week, parents' mating group and sex. The estimates of genetic trend were obtained by average regression of breeding value on generation, and the average genetic trend was estimated by regression coefficients. The genetic trends for CW (+6.0336 g/generation), BRW (+3.6723 g/generation), LW (+1.5846 g/generation), CY (+0.1195%/ generation), and BRY (+0.1388%/generation) were positive, and they were in accordance with the objectives of the selection program for these traits. The genetic trend for LY (-0.0019%/generation) was negative, possibly due to the strong emphasis on selection for BRY and the negative correlations between these two traits.

Correlated responses and genetic parameters for performance and carcass traits in a broiler line

“…Carcass traits were the weights of carcass (CW), breast (BRW), and legs (LW), and relative weights of carcass (CY), breast (BRY) and legs (LY) ( Table 1). Our results were similar to those found by Gaya et al (2006) and Grosso et al (2009). The coefficients of variation ranged from 10% to 17% for most traits, which indicates the variability in the population for the studied traits.…”

“…This suggests that the weight at seven days has a greater selection response than the weight at older ages. The estimates obtained for performance and carcass traits were moderate to high (Table 2), similar to the results presented in other studies (Le BIHAN-DUVAL et al, 2001;GAYA et al, 2006;N'DRI et al, 2006;GROSSO et al, 2009). BRW and BRY were associated to the highest values of performance and carcass traits and presented the highest potential genetic gains.…”

“…CY, BRY and LY) presented low variation coefficients probably due to selection of animals at slaughter. Nevertheless, low coefficients of variation for CY were also found by N' Dri et al (2006) and Grosso et al (2009), which reported values of 5% and 2.62%, respectively. The mean for CW, BRW, and LW was similar to Grosso et al (2009), and higher than those presented by Rance et al (2002), Zerehdaran et al (2004), Gaya et al (2006) andN'Dri et al(2006).…”

“…Thus, the meat industry like animals with high weights at slaughter and better carcass traits. Genetic relations for some growth and carcass traits have been previously studied (Le BIHAN-DUVAL et al, 1998;Le BIHAN-DUVAL et al, 2001;RANCE et al, 2002;ZEREHDARAN et al, 2004;GAYA et al, 2006;VAYEGO et al, 2008;GROSSO et al, 2009). Although these studies had considered the carcass traits, the genetic relation between carcass traits with body weights were not analyzed, these may limit our understanding on how the animal performance affects carcass traits.…”

Effects of genotype and population density on growth performance, carcass characteristics, and cost-benefits of broiler chickens in north central Nigeria

“…The weights of the thigh, breast, and back were taken as the carcass weight, which was later expressed as percentage of the final live body weight. Similarly, the relative weights of the cut parts (head, neck, shank, wing, thigh, breast, and back) and the organs (liver, heart, lung, kidney, and gizzard) were determined using the formula (Mohamed et al 2008;Grosso et al 2009):…”