GROWTH, FEED-INTAKE AND BODY-COMPOSITION OF OSTRICHES (STRUTHIO-CAMELUS) BETWEEN 10 AND 30 KG LIVE MASS

Data on cumulative feed intake, growth rate and chemical body constitu ents of 24 ostrich chicks, from a comparative slaughter experiment, we re utilized to describe patterns of efficiency of feed utilization, de position rates of protein, fat and body energy, as well as patterns of energy intake over the live mass interval 10-30 kg, by employing the empirical, allometric autoregression growth model. The ratio of daily energy storage in protein accretion to that of fat accretion was 1.3:1 at 20 kg live mass and changed to 1:2 at 30 kg live mass. The change in energetic ratio coincided with a breaking-point in the log-linear r elationship between live mass and cumulative metabolizable energy (ME) intake at 23 kg live mass, thus separating the growth curve into two different growth phases as reflected by different patterns of energy i ntake, growth rate, feed conversion ratio, body composition and the co mposition of growth. The relative apportionment of ME towards total bo dy energy increased almost linearly across both phases and was closely related to deposition rate of body fat and inversely related to energ y loss as heat expenditure. Gross efficiency of protein deposition rem ained constant within growth phases but decreased across phases. In te rms of metabolic body size, the priority for the allocation of ME to t he deposition of body energy in protein or fat, changes and is correla ted with changes in heat production that would alter the maintenance n eeds of the growing animal.