Mutual influence of protein and lipid feed content on European catfish (Silurus glanis) growth

Abstract

We wished to determine protein and lipid content in pelleted raw fish food, necessary for optimal growth of European catfish (Silurus glanis). Experiments were set up in 20 cages, each holding 30 young catfish. Fishes in each cage received a different food combination over a 98-day period at favourable physical and chemical water conditions. Food protein content varied between 37.5 and 45%, while lipid content, added in the form of soybean oil, varied between 3 and 11%. The oil contained an adequate x-fatty acids concentration, necessary for fish growth. The main growth indicators determined at the end of experiment were total body gain, specific growth rate and feed conversion ratio. There was a high statistical difference among the experimental groups receiving variable food combinations for each growth parameter (P < 0.001). Both protein and lipid food content affected growth parameters, but in a different manner. Further analysis -percentage of change depending on lipid to protein ratio and bivariate surface analysis -allowed us to recognize the most economical combination: 39.5% protein + 9% lipid content. The addition of 9% soybean oil to the fish food reduces the necessary protein concentration by 5.5%, with resulting identical catfish growth effects.

Effects of dietary protein and cellulose levels on growth performance, antioxidant status, immune response and inflammation in juvenile yellow catfish ( Pelteobagrus fulvidraco )

“…It is also possible that this low‐protein diet may have been less palatable owing to its lower fishmeal content. Similar findings have also been reported in other catfish species, including Asian catfish (Singh et al., 2009), European catfish (Has‐Schön et al., 2004), black catfish (Salhi et al., 2004), bagrid catfish (Giri et al., 2011) and Indian walking catfish (Mir et al., 2020). While insufficient protein can impair growth, fish are generally unable to utilize excessive exogenous protein to facilitate tissue growth and protein synthesis, and as such most exogenous protein is utilized as fuel for metabolic processes (Wu et al., 2015).…”

“…In prior studies, excessive or insufficient protein intake by fish has been associated with poor growth (Kim & Lee, 2009). In catfish, optimal dietary protein levels have been estimated to range from 30% to 55% of total diet, including the hybrid clarias catfish Clarias batrachus × C. gariepinus (36.5% of dry diet) (Giri et al., 2003), the European catfish Silurus glanis (40% of dry diet) (Has‐Schön et al., 2004), the black catfish Rhamdia quelen (37% of dry diet) (Salhi et al., 2004), the African catfish Clarias gariepinus (30% of dry diet) (Ahmad, 2008), the Asian catfish Clarias batrachus (36% of dry diet) (Singh et al., 2009), the bagrid catfish Horabagrus brachysoma (48% of dry diet) (Giri et al., 2011), the yellow catfish Pelteobagrus fulvidraco (42% of dry diet) (Chen et al., 2016) and Indian walking catfish Clarias magur (55% of dry diet) (Mir et al., 2020). Ultimately, optimal dietary protein intake is determined by fish size, environmental factors, the frequency of feeding, and the source and quality of dietary protein (Singh et al., 2009).…”

The Development of the Digestive Tract in Larval European Catfish (Silurus glanis L.)

“…European catfish fry fed with universal starter feed manifested excellent survival but grow slowly (Hamačkova et al., 1997;Prokeš et al., 1999). The optimal concentrations of lipid, proteins and addition of soya bean oil to fish food have beneficial effects on catfish growth indicators and meat quality (Bogut et al., 2002;Has‐Schön et al., 2004).…”

Evaluation of selected feeds differing in dietary lipids levels in feeding juveniles of wels catfish, <I>Silurus glanis</I> L.

“…The optimal level of total protein, in the feed used for catfish fry rearing, has been determined as 40-45% (Mareš et al 2003, Has-Schön et al 2004. Analyzing the results of experiments referring to the feeding of catfish , the aim to determine the optimal crude fat content in the feed is justified.…”

“…They are not only the source of metabolic energy, essential (for fish) fatty acids, hormone precursors, and phospholipids. The latter are important components of cytoplasmic membranes (Has-Schön et al 2004). Fats are also needed as solvents for vitamins (A, D, E and K), necessary for the correct functioning of organisms.…”