The effect of dietary energy and protein level on feather, skin and nodule growth of the ostrich (Struthio camelus).

Accurate diet formulations are required to fulfil the nutrient requirements of birds in order to achieve optimal production. Knowing how the skin, nodule and feather production characteristics vary with diets of different nutrient densities will help in least-cost modelling. Feather growth and nodule development are factors that were previously neglected in ostrich diet formulation, both of which are essential for the development of a predictive production model. In this trial, 120 birds were placed in 15 pens. Varying energy regimes (high, medium and low) and accompanying protein and amino acid profile levels (level 1-5) were assigned 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. During the slaughter, each bird was weighed, stunned, exsanguinated, defeathered and eviscerated. Feathers from four regions of the skin were plucked and weighed. The shaft diameter of the wing feathers was measured. The nodule size of the tanned skin was measured for each slaughter age. The data were transformed to natural logarithms and regressed against the total feather weight and the total featherless empty body protein weight to set up allometric growth equations. A prediction equation to determine nodule size of the live bird was proposed. Feed cost optimisation is paramount, and results from this study will aid in setting up least-cost optimisation (simulation) formulation models.