Application of egg powder in diets and its effect on serum parameters of juvenile rainbow trout

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.

Download Full-text

Sublethal effects of terbium and praseodymium in juvenile rainbow trout

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.146042 ◽

2021 ◽

pp. 146042

Author(s):

Houda Hanana ◽

Zofia E. Taranu ◽

Patrice Turcotte ◽

Christian Gagnon ◽

Joanna Kowalczyk ◽

...

Keyword(s):

Rainbow Trout ◽

Sublethal Effects ◽

Juvenile Rainbow Trout

Download Full-text

Video surveillance methods to evaluate individual feeding response in rainbow trout (Oncorhynchus mykiss, Walbaum)—implications for feeding regime optimisation

Aquaculture International ◽

10.1007/s10499-021-00671-z ◽

2021 ◽

Author(s):

Philip Niclas Just ◽

Bernd Köllner ◽

Matthew James Slater

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Video Surveillance ◽

Average Weight ◽

Short Term ◽

Feeding Regime ◽

Daily Feeding ◽

Juvenile Rainbow Trout ◽

Feeding Regimes ◽

The Impact

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.

Download Full-text

Influence of Testosterone and/or Luteinizing Hormone Releasing Hormone Analogue on Precocious Sexual Development in the Juvenile Rainbow Trout 1

Biology of Reproduction ◽

10.1095/biolreprod29.1.137 ◽

1983 ◽

Vol 29 (1) ◽

pp. 137-142 ◽

Cited By ~ 71

Author(s):

Laurence W. Crim ◽

D. M. Evans

Keyword(s):

Rainbow Trout ◽

Luteinizing Hormone ◽

Sexual Development ◽

Hormone Analogue ◽

Luteinizing Hormone Releasing Hormone ◽

Releasing Hormone ◽

Juvenile Rainbow Trout

Download Full-text

Changes in Habitat Use and Feeding Chronology of Juvenile Rainbow Trout (Oncorhynchus mykiss) in Fall and the Onset of Winter in Silver Creek, Idaho

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-237 ◽

1993 ◽

Vol 50 (10) ◽

pp. 2119-2128 ◽

Cited By ~ 64

Author(s):

Michael D. Riehle ◽

J. S. Griffith

Keyword(s):

Rainbow Trout ◽

Habitat Use ◽

Oncorhynchus Mykiss ◽

Density Distribution ◽

Stomach Contents ◽

Early Morning ◽

Invertebrate Drift ◽

Juvenile Rainbow Trout ◽

Rainbow Trout Oncorhynchus Mykiss

We assessed changes in density, distribution, and microhabitat of age-0 rainbow trout (Oncorhynchus mykiss) in Silver Creek, a partially spring-fed stream, by periodic snorkeling in August 1987 through January 1988. We examined trout stomach contents and invertebrate drift samples in diel collections in August, September, October, and January to test if the period of feeding shifted from daytime to nighttime, concurrent with a transition to day concealment. In late September, fish aggregated briefly during the day and then began to conceal themselves in macrophyte beds, undercut banks, and submerged sedges and grasses along streambanks as temperature dropped below 8 °C in early October. Fish emerged from concealment at night, and numbers of trout visible were greatest 30–60 min after sunset and about 30 min before sunrise. Periods of peak feeding changed from afternoon and evening in August and September, when fish were day active, to mainly at night in October after the initiation of day concealment. Trout did not feed upon abundant chironomids in the daytime drift in October. In January, fish fed at 1–4 °C on mayflies, and stomachs were fullest in the early morning. Observations suggest that Silver Creek trout experienced a metabolic deficit that began in September.

Download Full-text