Fat Deposition in a Broiler Sire Strain: 2. Comparisons Among Lines Selected for Less Abdominal Fat, Lower Feed Conversion Ratio, and Higher Body Weight after Restricted and Ad Libitum Feeding

Abstract

Four lines were selected from a broiler sire strain. Selection criteria were sib selection for a low amount of abdominal fat relative to body weight (AF line), individual selection for feed conversion (feed consumed/weight gain) from 21 to 42 days of age (FC line), individual selection for body weight after restricted feeding (GR line), and individual selection for body weight after ad libitum feeding (GL line). In the fifth generation lines were compared at 6 weeks of age for body weight, percent abdominal fat, feed conversion, slaughter yield, and chemical composition. Rankings of lines reared in groups on litter and in individual cages were the same for all traits examined. Lines GR and GL hardly differed, whereas lines AF and FC, compared with line GL, had, respectively, significantly lower body weights (−293 g and −228 g),less abdominal fat (−1.45% and −1.00%), better feed conversions (−.11 and −.17), and higher griller yields (.50% and .70%).Selection for body weight after restricted feeding was not effective in reducing fat deposition. When compared at the same age with the line selected for body weight after ad libitum feeding, sib selection against abdominal fat and selection for a better feed conversion reduced abdominal fat, improved feed conversion, and increased slaughter yields.