Evaluation of feedstuffs and the metabolisable energy and amino acid requirements for maintenance and growth in ostriches (Struthio camelus)

Thesis (PhD)--Stellenbosch University, 1994.

ENGLISH ABSTRACT: Differences in the digestion and metabolism of ostriches and poultry, require the assessment of nutritional values (especially ME values) of various ingredients to establish a new system for ostrich feed evaluation. These findings are a prerequisite for the determination of nutrient requirements and efficient diet formulations. A number of comparative studies between ostriches and adult roosters were conducted with respect to true and apparent metabolisable energy, corrected for nitrogen retention (TME" and AME") of common ingredients used in diets for ostriches and poultry. Results were obtained by balance method with continuous feeding and total excreta collection. Results obtained for mature ostriches were then compared to those calculated for younger birds (6 months of age). AME" values were determined according to the replacement method, while TME" values were calculated, using the regression method. The theory of ME determinations and the accuracy of determined TME" values of ingredients for ostriches and roosters were evaluated by comparing theoretical and determined TME" values of an experimental diet, comprising various ingredients. Experimental evidence was produced to confirm the suitability of the method used for determining ME in ostriches, for measuring amino acid availabilities. Hence a comparative study was conducted between ostriches and roosters with respect to the true and apparent availabilities of amino acids in an experimental diet. In a response study, nutrient (energy, amino acids, protein, lipid and ash) retentions in feathers, hides, legs and carcasses, was separetly measured by means of comparative slaughter technique. Requirements for maintenance and utilisation efficiencies were established. The potential growth of a flock of ostriches, representative of Oudtshoorn birds, were estimated according to the Gompertz Model. Potential growth, feed consumption figures, carcass characteristics and utilisation efficiencies, were then used to compute dietary requirements for the experimental group of birds (7 months of age) and these results were extrapolated to assess dietary requirements for ostriches from dayold to maturity (day 600).

AFRIKAANSE OPSOMMING: Verterings - en metabolisme verskille tussen volstruise en pluimvee, noodsaak die evaluering van verskeie grondstowwe vir die ontwikkeling van 'n grondstof-valuerings-sisteem vir volstruise. Die resultate is noodsaaklik vir die bepaling van voedingsbehoeftes en doeltreffende rantsoen-formulerings. Verskeie vergelykende studies tussen volstruise en pluimvee is onderneem ten opsigte vir die bepaling van ware en skynbare metaboliseerbare energie waardes, gekorrigeer vir stikstof-retensie (WME" en SME"), vir algemene grondstowwe. Daar is gebruik gemaak van die balans-metode met aaneenlopende voeding en ekskreta-versameling. Resultate wat vir volwasse volstruise verkry is, is oak vergelyk met die van jonger kuikens (6 maande). SME" waardes is bereken volgens die vervangings-tegniek, terwyl WME"-waardes bereken is volgens die regressie-metode. Die teorie en akkuraatheid van bepaalde WME" waardes is bevestig deur 'n vergelykende studie tussen teoretiese en bepaalde waardes van 'n eksperimentele rantsoen vir beide volstruise en pluimvee. Die bruikbaarheid van die balans-tegniek vir energie-bepalings, is ook bevestig vir die bepaling aminosuurbeskikbaarheid by volstruise. Energie-, proteïen-, aminosuur-, vet- en as-retensies in vere, vel, bene en karkas, is met behulp van 'n vergelykende slagproef in volstruise gemeet. Onderhouds-behoeftes en benuttingsdoeltreffendhede kon gevolglik beraam word. Groeikurwes vir 'n verteenwoordigende monster Oudsthoorn-volstruise is oak bepaal volgens die Gompertz-model. Potensiele groei, voerinnames, karkas-eienskappe en benuttingsdoeltreffendhede is gebruik vir die berekening van rantsoen-spesifikasies vir 'n eksperimentele groep kuikens (7 maande) en die gegewens is ge-ekstrapoleer om rantsoen-spesifikasies vir volstruise te beraam van dagoud tot volwassenheid (600 dae).

Doctoral