Effects of divergent selection for body weight at a fixed age on histological, chemical and rheological characteristics of rabbit muscles

The aim of this study was to investigate the main carcass traits, and some of the histological, chemical and rheological characteristics of two muscles in two lines of rabbits divergently selected for body weight at 63 days of age. At slaughter, live body weight (+ 13%) and weights of semitendinosus (ST) and longissimus lumborum (LL) muscles (+ 13 and + 8%, respectively) were heavier in the heavy line (HW) than in the light line (LW). At the same time, mean cross-sectional area of constituent myofibers was 6% larger in ST muscle from HW compared to LW lines; however, the number of myofibers remained steady in both lines. Shear force value was increased by 20 and 8% in ST and LL muscles, respectively, in HW compared to LW lines. Ultimate pH values in both muscles were similar for both lines. No effect of selection was denoted for intra-muscular fat content of ST muscles. This study suggests that selection for live body weight at a fixed age of slaughter affected muscle weight by myofiber hypertrophy and caused slight modifications of rheological properties of the muscles. (C) 2002 Elsevier Science B.V. All rights reserved.