Protein and energy utilization and the requirement

Authors: Igor Pirozzi Mark A Booth Geoff L Allan

Publish Date: 2008/12/25

Volume: 36, Issue: 1, Pages: 109-121

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Abstract

This study describes the digestible protein DP and digestible energy DE utilization in juvenile mulloway and determined the requirements for maintenance This was achieved by feeding triplicate groups of fish weighing 40 or 129 g held at two temperatures 20 or 26°C on a commercial diet 214 g DP mJ DE−1 at four different ration levels ranging from 025 of its initial body weight to apparent satiation over 8 weeks Weight gain and protein and energy retention increased linearly with increasing feed intake However energy retention efficiency ERE and protein retention efficiency PRE responses were curvilinear with optimal values depending on fish size approaching or occurring at satiated feeding levels Maximum predicted PRE was affected by body size but not temperature PRE values were 050 and 050 for small mulloway and 041 and 043 for large mulloway at 20 and 26°C respectively ERE demonstrated a similar response with values of 042 and 043 for small and 032 and 034 for large mulloway at 20 and 26°C respectively Utilization efficiencies for growth based on linear regression for DP 058 and DE 060 were independent of fish size and temperature The partial utilization efficiencies of DE for protein k p and lipid k l deposition estimated using a factorial multiple regression approach were 049 and 075 respectively Maintenance requirements estimated using linear regression were independent of temperature for DP 047 g DP kg−07 day−1 while maintenance requirements for DE increased with increasing temperature 442–496 kJ DE kg−08 day−1 Relative feed intake was greatest for small mulloway fed to satiation at 26°C and this corresponded to a greater increase in growth Large mulloway fed to satiation ate significantly more at 26°C but did not perform better than the corresponding satiated group held at 20°C Mulloway should be fed to satiation to maximize growth potential if diets contain 214 g DP mJ DE−1The authors would like to thank Paul Beavers Ben Doolan Luke Cheviot Ian Russell and Luke Vandenberg for technical assistance during this experiment Dr Stewart Fielder and the marine fish team at PSFI produced the mulloway used in this experiment The authors also thank Anthony O’Donohue Dr Mark Porter and Dr Richard Smullens for their contributions This research forms part of the Australian Aquafin CRC project and receives funds from the Australian Government’s CRC program the FRDC and other CRC participants

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