The effect of time-restricted demand feeding on feeding activity growth and feed conversion in rainbow trout (Oncorhynchus mykiss)

Abstract The effect of restricted access to a demand feeding system was evaluated for cage-reared rainbow trout with an initial weight of 0.46 – 0.61 kg during 4 summer months. The purpose was to find the access time that produced optimal levels of food supply, as assessed by measurements of growth rate and feed conversion. Following a period during which fish had 24 h access to food per day, feeding regimes were reduced to 3, 5 or 7 h of access to the feeder per day for treatment groups. The time available for feeding within each restricted regime was divided into two feeding periods during each day. Fish held under the control feeding regime were given unrestricted access to the demand feeder (24 h/day). Restricted access time to the demand feeders resulted in a significantly reduced number of feeder actuations and thus lowered food supply compared with the unrestricted regime. Restricted access to the feeder also resulted in a decreased growth rate during the first 28 days after the transition from unrestricted feeding. This was particularly obvious for the trout allowed to feed for only 3 h per day. Following the initial period of low growth rate, specific growth rates increased in the restricted groups and became similar under all the feeding regimes, at about 1.1% per day. The feed conversion (FC) varied with food access time. The self demand food supply was used most efficiently by fish fed for 3 h per day (FC = 1.0) and least efficiently by fish fed on the unrestricted regime (FC = 1.6). Trout on the other two regimes, with 5 and 7 h feeding, showed intermediate conversion of 1.1 and 1.2, respectively. The results suggest that two feeding periods per day, each of about 2 h duration, are sufficient for optimal growth of large (0.5 – 2 kg) rainbow trout adapted to demand feeders. The number of bites per day was correlated with the water temperature. Biting activity peaked at 16 °C. After 2–3 h of feeding, trout on the time-restricted feeding regimes exhibited a significantly lower bite activity, probably due to the fish becoming satiated.

[1]  J. Tipping,et al.  Use of Demand Feeders on Large Steelhead Rearing Ponds , 1986 .

[2]  G. A. Kindschi,et al.  Effect of intermittent feeding on growth of rainbow trout, Salmo gairdneri Richardson , 1988 .

[3]  T. Storebakken,et al.  Growth rate estimates for cultured Atlantic salmon and rainbow trout , 1987 .

[4]  T. Storebakken,et al.  Nutrient partitioning in rainbow trout at different feeding rates , 1991 .

[5]  J. R. Brett,et al.  6 – Physiological Energetics , 1979 .

[6]  William Rowan,et al.  The Study of Instinct , 1953 .

[7]  R. Hardy.  Practical Feeding—Salmon and Trout , 1989 .

[8]  C. Webster,et al.  Seasonal production of rainbow trout, Oncorhynchus mykiss (Walbaum), in ponds using different feeding practices , 1991 .

[9]  C. B. Cowey,et al.  A system for the quantitative study of the learning capacity of rainbow trout and its application to the study of food preferences and behaviour , 1973 .

[10]  G. Davey.  Ecological Learning Theory , 1989 .

[11]  G. Kindschi.  Notes on Two Feed Types and Methods for Steelhead Trout Production , 1984 .

[12]  D. Grove,et al.  Satiation amount, frequency of feeding and gastric emptying rate in Salmo gairdneri , 1978 .

[13]  M. Bres.  A new look at optimal foraging behaviour; rule of thumb in the rainbow trout , 1986 .

[14]  A. Alanärä.  Demand feeding as a self-regulating feeding system for rainbow trout (Oncorhynchus mykiss) in net-pens , 1992 .

[15]  D. Statler.  Use of Self-Feeders for Rearing Steelhead Trout at Dworshak National Fish Hatchery , 1982 .

[16]  S. J. Vies.  Comparative performance of juvenile rainbow trout, Salmo gairdneri Richardson, fed to satiation with simulated ‘standard’ and ‘high energy’ diet formulations , 1989 .

[17]  T. Thorslund,et al.  Effects of Constant Temperatures and Diel Temperature Fluctuations on Specific Growth and Mortality Rates and Yield of Juvenile Rainbow Trout, Salmo gairdneri , 1977 .

[18]  S. Kaushik,et al.  Influence of bacterial protein incorporation and of sulphur amino acid supplementation to such diets on growth of rainbow trout, Salmo gairdnerii Richardson , 1980 .

[19]  P. J. Landless.  Demand-feeding behaviour of rainbow trout , 1976 .

[20]  F. Beamish,et al.  Effects of feeding frequency on food intake, growth and body composition of rainbow trout (Salmo gairdneri) , 1977 .

[21]  W. Wurtsbaugh,et al.  Effects of temperature and ration level on the growth and food conversion efficiency of Salmo gairdneri, Richardson , 1977 .