The impact of restricted rationing upon growth, food conversion efficiency and body composition of rainbow trout

1995 ◽  
Vol 31 (10) ◽  
pp. 219-223 ◽  
Author(s):  
M. Tomec ◽  
Z. Teskeredžic ◽  
E. Teskeredžic ◽  
M. Hacmanjek ◽  
E. McLean

Juvenile rainbow trout, Oncorhynchus mykiss, maintained under commercial conditions, were subjected to four different feeding regimes. Duplicate groups of fish were fed to satiation 3 times/d for either 7, 3, 2 or 1 d/wk over a 10 wk period. At the end of the trial, evaluations were made of group growth performance, body composition, and feed conversion efficiency (FCE). At the end of the experiment, no differences were discerned between fish fed either daily or 3 times/wk with respect to growth, FCE or body composition. Animals placed upon the two lowest rations were significantly smaller (P<0.05) than those fed daily and exhibited decreased condition factors and body lipid levels (P<0.05) and increased moisture content (P<0.05). Food conversion was least efficient in those fish provided the largest ration.

2016 ◽  
Vol 24 (1) ◽  
pp. 53-57 ◽  
Author(s):  
Matin Shakoori ◽  
Hamed Gholipour ◽  
Samira Naseri ◽  
Hossein Khara

Abstract The effects of substituting fishmeal (FM) with different quantities of silkworm pupae (SP) on the growth, survival, and body composition of rainbow trout, Oncorhynchus mykiss (Walbaum), were investigated over the course of a 60-day experiment. A total of 360 fingerlings (55±3.42 g) were randomly allotted to four treatment groups (T1 – fish fed 52.5% FM; T2 – fish fed 5% SP + 47.5% FM; T3 – fish fed 10 % SP+ 42.5% FM; T4 – fish fed 15% SP + 37.5% FM). Each treatment group was divided into three replicates of 30 fish per replicate. One group served as the control. At the end of the experiment, the results showed that 10% of FM can be replaced with SP without any adverse effects on the values of the feed conversion ratio (FCR), specific growth rate (SGR), weight gain percent (WG), condition factor (CF), survival rate (SR), protein content, lipid content, or nutrition protein utilization (NPU).


Animals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 187 ◽  
Author(s):  
Paulo Rema ◽  
Subramanian Saravanan ◽  
Benjamin Armenjon ◽  
Constant Motte ◽  
Jorge Dias

Insects are emerging as a sustainable alternative to fishmeal and fish oil in aquafeeds. This study assessed the effect of graded incorporation levels of defatted yellow mealworm (Tenebrio molitor) protein meal on juvenile rainbow trout (Oncorhynchus mykiss) growth performance, body composition, and apparent nutrient digestibility. The trial comprised five dietary treatments: control diet with 25% fishmeal, and four experimental diets with yellow mealworm protein meal at 5%, 7.5%, 15%, or 25%, which corresponded to a fishmeal replacement of 20%, 30%, 60%, or 100%, respectively. After 90 days, the graded incorporation of insect protein meal led to a significant stepwise increase in final body weight, and a significant improvement of specific growth rate, feed conversion ratio, and protein efficiency ratio compared to the control treatment. Regardless of the incorporation level, the insect protein meal had no effects on fish whole-body composition and apparent digestibility coefficients of dry matter, protein, fat, phosphorus, and energy. Protein, phosphorus, and energy retention significantly increased in fish fed the diets with an insect protein meal. In conclusion, the yellow mealworm protein meal could effectively replace 100% of fishmeal in the diet of juvenile rainbow trout with positive effects on its overall zootechnical performance.


Author(s):  
Philip Niclas Just ◽  
Bernd Köllner ◽  
Matthew James Slater

AbstractPrecisely analysing and optimising feeding regimes is central to salmonid growth performance and delivery of special diets. The current study developed novel video surveillance methods and analysis techniques to assess individual feed intake and minimum pellet intake (MPI) in individually identified juvenile rainbow trout, Oncorhynchus mykiss. Three trials were conducted to test the impact of short-term starvation (N=112 [16 tanks, 7 fish per tank], average weight=27.1±3.4g, age= 119 days), portion numbers per feeding (N=105 [15 tanks, 7 fish per tank], average weight=22.8±2.1g, age= 99 days) and varied numbers of daily feeding events (N=84 [12 tanks, 7 fish per tank], average weight=32.4±3.3g, age= 133 days). All trails were carried out in a recirculating aquaculture system with 20 tanks held at 15 ± 0.5°C. All individuals were code-tagged and high quality video images were taken and analysed to identify all feeding interactions. Individual trout feeding activity under different feeding regimes could be precisely analysed with the video methods developed. Moving from one to two daily feeding events doubled pellet intake per fish from 27.4 ± 5.8 to 52.8 ± 11.5 pellets. Pellet intake (58.8 ± 24.2 pellets) did not increase at three daily feeding events but became more variable across fish. MPI nearly doubled to 30 pellets in fish receiving two daily feeding events (MPI30: chi-squared = 8.74, df = 2, p = 0.01). Short-term starvation had no influence on intake (28 ± 8 pellets/fish) or MPI. Increasing portion number from one (27.8 ± 7.4 pellets fish−1) to two (31.1 ± 7.4 pellets fish−1) or more did not significantly increase the number of ingested pellets. Adjusting the feeding regime by increasing daily feeding events to two, possibly combined with multiple portions, can increase pellet intake and reduce the heteroscedasticity of pellet intake. The methods presented in this study are viable for analysing feeding regimes for juvenile rainbow trout and controlled feedstock/supplement delivery. Implications for analyses with other species and for vaccination optimisation are discussed.


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