The influence of feeding frequency on the metabolic rate of perch Perca fluviatilis L.
Abstract
The aim of the study was to determine the impact of feeding frequency (one, two or three feeds and continuous feeding) on the magnitude of oxygen consumption (OC, mg O2 kg-1 h-1) and ammonia excretion (AE, mg TAN kg-1 h-1) by juvenile perch. The study was conducted during routine rearing in a recirculating system. No significant impact of the applied feeding schedules (P > 0.05) on the average diurnal values of OC and AE was confirmed. The values ranged from 165.88 mg O2 kg-1 h-1 (one feed) to 188.48 mg O2 kg-1 h-1 (continuous feeding) and from 5.51 mg TAN kg-1 h-1 (two feeds) to 6.44 mg TAN kg-1 h-1 (continuous feeding). The feeding schedule had a significant influence on the diurnal fluctuations of oxygen consumption and ammonia excretion and was especially evident in the latter. The AEmax/AEaverage ratio in the group of fish fed once was 2.46, but the AEmax/AEmin ratio was 19.01. AE variability over a twenty-four hour cycle was much lower in other feeding schedules. The course of the diurnal profiles of OC and AE was characteristic for each of the applied experiment variants. Statistically significant dependencies were confirmed between ammonia excretion and oxygen consumption (P < 0.001) and were specific to each experiment group. Correlation coefficients of the linear regression equation that describes the AE – OC relation ranged from 0.57 (three feeds) to 0.94 (two feeds). The values of OFR (kg O2 kg-1 feed fed day-1) and AFR (kg TAN kg-1 feed fed day-1) were not determined by the applied feeding schedule (P > 0.05).
CORRESPONDING AUTHOR:
Zdzisław Zakęś, Instytut Rybactwa Śródlądowego, ul. Oczapowskiego 10, 10-719 Olsztyn; Tel./Fax: +48 89 5240171, +48 89 5240505; e-mail: zakes@infish.com.pl
