Growth of the femur and tibia of a commercial broiler line.

The objective of this experiment was to characterize the relationship between growth and skeletal development in commercial broilers as a function of both age and BW. From hatch through 43 d, birds were randomly selected weekly from the same commercial flock for measuring BW, tibia, and femur characteristics. Final BW was 1.8 kg for females and 2.1 kg for males. The fat-extracted weight of the tibia and femur increased proportionately with BW through 43 d of age. Length and width measures as a proportion of their final values at 43 d increased more rapidly than relative changes in BW. The length of the femur as a function of BW reached a plateau at 1.5 kg (35 d of age), whereas the length of the tibia did not plateau through 43 d of age. Differences in width measures between the two long bones were not apparent as BW increased through 43 d of age. The ash percentage of the diaphyseal region (mid-10% of bone) was consistently greater in the tibia than the femur from 15 to 43 d (P < or = 0.05). Differences in mineralization rates and growth characteristics suggest that the functionality and integrity of the femur should not be assumed solely from tibia measurements.