Ž . Animal Feed Science and Technology 72 1998 283–293 Determination of energy, protein and amino acid requirements for maintenance and growth in ostriches S.C. Cilliers a , J.P. Hayes b , A. Chwalibog c , J. Sales b, ) , J.J. Du Preez b a Little Karoo Agricultural Centre, PO Box 313, Oudtshoorn, 6620, South Africa b Department of Animal Science, UniÕersity of Stellenbosch, Stellenbosch, South Africa c DiÕision of Animal Nutrition, Department of Animal Science and Animal Health, Royal Veterinary and Agricultural UniÕersity, BulowsÕej 13, 1870 Frederiksberg C, Denmark Received 3 March 1997; accepted 21 November 1997 Abstract Requirements for maintenance and the utilization of dietary true metabolisable energy, Ž . Ž . corrected for nitrogen N -retention TME , effective energy, corrected for N-retention, protein n Ž . and amino acids were assessed in 44 young ostriches 7 months of age by means of a Ž comparative slaughter technique. Response in nutrient gain energy, lipid, protein and amino . acids in feathers, legs, hides and carcasses were separately studied by scarifying 8 birds at the beginning and 12 birds at the end of a 21-day feeding period. TME required for maintenance was n Ž . 0.75 0.425 MJrempty body weight EBW , kg rday or 7.96 MJrday, while maintenance require- ments for effective energy, corrected for N-retention, amounted to 0.311 MJrEBW, kg 0.75 rday or Ž 8.90 MJrday. Utilisation efficiencies for TME were estimated as 0.414 "0.006 MJrEBW, n 0.75 . Ž . kg rday and 0.443 "0.016 MJrday , whereas a value of 0.568 "0.009 was determined for effective energy, corrected for N-retention. Digestible maintenance protein requirements of 0.678 "0.027 grEBW, kg 0.75 rday was found, and by altering this estimate to requirement for total dietary protein, 1.05 "0.038 grEBW, kg 0.75 rday was calculated. Maintenance requirements for lysine, methionine qcystine, threonine and valine compared favourable to literature values for poultry, but substantially higher values than for poultry, however, were determined for leucine, arginine and histidine. Net utilisation estimates for digestible amino acids varied between Ž . 0.948 "0.025 for the slow turnover amino acids arginine and 0.569 "0.015 for the fast turnover ) Corresponding author. Queensland Poultry Research and Development Centre, PO Box 327, Cleveland, QLD 4163, Australia. Tel.: q61-07-3824-3081; fax: q61-07-3824-4316. 0377-8401r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. Ž . PII S0377-8401 97 00188-0