Improving the mechanical characteristics of faecal waste in rainbow trout: the influence of fish size and treatment with a non-starch polysaccharide (guar gum)

Abstract

This study (3 × 2 randomized factorial design) describes differences in the mechanical properties of faeces from rainbow trout of three size classes (small ≈40 g, mid‐size ≈150 g, large ≈650 g) and assesses the effects of a non‐starch polysaccharide binder (guar gum). Observations made at the macroscopic level were reinforced by rheological measurements of viscosity and elastic modulus. Mid‐sized fish excreted mechanically the most stable faeces, roughly twice as stable as those of small fish and three times more stable than faeces from large fish. The addition of 3 g kg−1 of guar gum saw some mechanical characteristics improve by about 700%. Faeces from large‐ and mid‐sized fish were more easily stabilized than those of small fish. Mechanical recovery potential for faecal samples disrupted by water turbulence was determined. Stability differences observed for different fish size had no significant effect but the improvements imparted by guar gum reduced postfiltration effluent load to about 35% for large fish, about 24% for mid‐size and about 22% for small fish. Faecal leaching decreased significantly with increasing stability. Guar gum was shown to have significant potential for improving the treatability of fish faecal waste.

Evaluation of feed and feeding regime on growth performance, flesh quality and fecal viscosity of Atlantic salmon (Salmo salar L.) in recirculating aquaculture systems

“…HY groups showed better growth and the fish with higher body weight showed worse fecal viscosity. This result was in line with study on rainbow trout (Brinker, 2009). …”

“…There also existed studies with no such dependency (Chen et al, 1993;Merino et al, 2007). Differences among fecal properties may be the results of the changes in digestive physiology of fish or the composition of the diets or a combination of them (Brinker, 2009). Simultaneously, fish digestive physiology is related to fish size and dietary composition (Guillaume et al, 2001).…”

“…Feces sampling for rheological measurements were carried out between June 1 and 6 according to Brinker (2009). Five fish were sampled daily from each tank from 8:40 to 10:00.…”

Biological responses in mullet Mugil liza juveniles fed with guar gum supplemented diets

“…Some studies have evaluated the addition of guar gum to fish diets, yet most have only observed the physical attributes of the feces (Amirkolaie et al, 2005;Brinker, 2007Brinker, , 2009Brinker and Reiter, 2012), nutrient digestibility (Leenhouwers et al, 2006), oxidative status, gastrointestinal tract morphology (Enes et al, 2012), and the effects on glucose and lipid metabolism (Enes et al, 2013). However, the mechanisms by which guar gum acts on body composition and modulates the microbial community in the tract remain uncertain.…”

Impact of replacement of soybean meal with guar korma meal on growth performance and some physiological parameters of the Nile Tilapia (Oreochromis niloticus) fingerlings.

“…The increase in digesta viscosity may also be responsible for impairment of macronutrient digestibility, thus leading to growth and feed efficiency depression. Inclusion of small amounts of guar gum (0.3 %) in rainbow trout Oncorhynchus mykiss diets enhanced feces stability in water, indicating that soluble NSPs may improve processing of fecal wastes in this species (Brinker et al, 2005and Brinker 2007, 2009). On the contrary, in the Nile tilapia Oreochromis niloticus, guar gum reduced feces stability due to its high water-binding capacity, thus not acting as appropriate feces binder in this species (Amirkolaie et al, 2005).…”