| dc.description.abstract | Least-squares estimates of the parameters of the Bertalanffy growth equation, adjusted for six sources of variation, were obtained for oryx, eland and zebu cattle.
Values for asymptotic weight were lower than the mature weights normally given for the species, particularly eland and cattle, owing to management constraints. The figures for females brought into the project were considered the most representative of the species in general. For this category of oryx, eland and zebu cattle respectively, the estimates were as follows: the coefficients of growth rate were 0·136, 0·112 and 0·114; asymptotic weights (W∞) were 146, 277 and 395 kg; and ages at maturity (0·98 W∞) were 33, 41 and 39 months. For females born on the project estimates of birth weights were 14·5, 24·1 and 28·7 kg; and of ages at zero weight were 3·55, 3·80 and 5·18 months prepartum, for oryx, eland and zebu cattle respectively.
When differences in size, and therefore metabolic rate were discounted, oryx grew at 3·2, eland at 3·1 and zebu cattle at 3·4 g/kg W∞0·75/day. Comparison with mean values for water turnover (ml/l0·82/day) on the same project revealed that oryx used about one third of the water required by eland and cattle, for the same amount of growth (g/kg W∞/day).
Significant sources of variation for W∞ were species, sex, and mode of entry into the project (capture or birth), all at P < 0·005. Season of birth was also significant at P < 0·01, with oryx born 2 months before a wet month achieving the largest W∞ whereas the highest average growth rate occurred when birth was 1 month before a wet month. The only significant source of variation obtained for growth rate was year of entry (P < 0·005). | en_US |
