The effect of varying dietary nutrient densities on the relative growth of ostrich body components

The influence of varying dietary protein and energy levels on the relative growth of body components of ostriches was evaluated over a 244-day growth period. One hundred twenty 1-day-old ostrich chicks were randomly assigned to 15 pens. Three varying energy regimes (high, medium and low) and five protein levels (1–5) were supplied ad libitum to each pen. A randomly selected bird from each pen was slaughtered at 1, 35, 63, 103, 159, 168 and 244 days of age. Each bird was weighed, stunned, exsanguinated, defeathered and eviscerated. Individual body components were dissected and weighed at every slaughter age. Proximate analysis was performed on these components, which were ground with the remainder of the carcass, excluding gut content, but including blood and feathers. Based on the analysis of ostrich feathers and the known mass of the feathers, the protein mass contribution of the feathers was deducted from the protein accretion of the bird. All the data were transformed to natural logarithms and regressed against the featherless body protein growth. Intercepts and slopes were compared to determine differences in growth rate ascribed to nutrient densities. Neither dietary energy nor dietary protein level had a significant effect on the relative growth of the measured components in this study. Allometric coefficients were established, which could be helpful to improve the accuracy of simulation modelling attempts for ostrich nutrition.