Abstract
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.
Highlights
Ostriches are primitive, flightless birds that were originally domesticated to produce feather plumes, which were popular in the fashion industry
The energy level of the diet was found to influence the average intake in the pre-starter, grower and finisher phases, with feed intake decreasing from the low- to high-energy regimes (p < 0.05)
The empty body protein weight (EBPW) of the ostriches was regressed over the slaughter ages and analysed according to the dietary energy and http://www.jsava.co.za protein levels
Summary
Flightless birds that were originally domesticated to produce feather plumes, which were popular in the fashion industry. Depending on the quality of the product, feathers can potentially contribute up to 40% of the income generated by a bird, with leather and meat contributing 35% and 25%, respectively Skin nodules are the result of feather follicles that expand around the quill on the ostrich skin. Cloete et al (2004) reported that the age of the bird has an effect on some nodule traits for birds up to 14 months of age. Mellet, Fisher and Bohme (1996) reported that nodule size increases with an increase in age, with an optimum nodule size being achieved only at 14–16 months of age. The skin of the ostrich grows tougher with age and skins from younger birds are used for producing more delicate leather products http://www.jsava.co.za
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