Growth pattern of Chianina bulls from 6 to 24 months fed two different diets. 2. Tissues.

Sixty-nine Chianina young bulls were fed two unifeed diets to ad libitum intake from six months of age (H and L diet, 0.94 and 0.76 UFV/kg DM respectively), and were serially slaughtered at nine two-month intervals from 8 to 24 months of age. A further eight calves were slaughtered at six months as an initial reference. Sides were anatomically dissected into total muscle (TSM), fat (TSF), bone (TSB) and other tissues (TSOT). Statistical analysis used the allometric equation, and variation in the growth coefficients was tested by the log-log relationship of the second or third degree. Overall, relative to cold side weight (CSW), TSM and TSOT were nearly in isauxesis (b = 0.97 and 1.05 respectively), TSF had late development (b= 1.55) and TSB was in bradiauxesis (b = 0.79). The allometric coefficient of TSM was lower (0.95 versus 0.99) and that of TSF was higher (1.68 versus 1.41), in H diet bulls than in L diet bulls. In relation to TSB weight, the allometric coefficient of TSM (for H and L bulls) and of TSF (only for H bulls) varied along the developmental range and the TSM growth rate did not differ between diets. The average growth coefficient of TSM and TSF relative to TSB peaked at about 18 months. The multiple relationships of the average daily gain of tissues relative to BW and to daily weight gain (DWG) showed that lean gain varied linearly with BW and DWG, while fat and bone gain were sensitive to an interaction between BW and DWG.