Determination of energy, protein and amino acid requirements for maintenance and growth in ostriches

Requirements for maintenance and the utilization of dietary true metabolisable energy, corrected for nitrogen (N)-retention (TMEn), effective energy, corrected for N-retention, protein and amino acids were assessed in 44 young ostriches (7 months of age) by means of a 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. TMEn required for maintenance was 0.425 MJ/empty body weight (EBW), kg0.75/day or 7.96 MJ/day, while maintenance requirements for effective energy, corrected for N-retention, amounted to 0.311 MJ/EBW, kg0.75/day or 8.90 MJ/day. Utilisation efficiencies for TMEn were estimated as 0.414±0.006 (MJ/EBW, kg0.75/day) and 0.443±0.016 (MJ/day), 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 g/EBW, kg0.75/day was found, and by altering this estimate to requirement for total dietary protein, 1.05±0.038 g/EBW, kg0.75/day was calculated. Maintenance requirements for lysine, methionine+cystine, 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 0.948±0.025 for the slow turnover amino acids (arginine) and 0.569±0.015 for the fast turnover amino acids (cystine) with a mean value of 0.747. Results in the present study presented essential information for the establishment of requirement estimates for ostriches.