fiFEED RESTRICTION AND MUSCLE FIBRE CHARACTERISTICS OF PECTORALIS MAJOR IN BROILER CHICKENS

The aim of the study was to evaluate the effect of one-week quantitative feed restriction (in days 8–14 of age) on histological characteristics of musculus pectoralis major in broiler chickens during the fattening period. Cockerels of Ross 308 (1215 chicken) were divided into 3 groups: ad libitum fed (AL; 3 × 135), restricted 80% of AL (R80; 3 × 135), and with limited feed intake 65% of AL (R65; 3 × 135). Eight cockerels per group were slaughtered in weekly intervals from day 14 of age till the end of experiment at 35 days to determine changes in the muscle fibre characteristics. The number of muscle fibres in pectoralis major decreased (P ≤ 0.001) with increasing age. Fibre cross sectional area was significantly (P ≤ 0.027) affected by the interaction of group and age. At the end of feed restriction at 14 days all groups had similar fibre area (519–539 μm^2), the differences between groups were observed at 35 days of age with the largest fibre area in R65 chickens (2296 μm^2), while R80 did not differ from AL (1728 μm^2 and 1667 μm^2). There was no effect of feeding regime on giant muscle fibre incidence.