Differences in amino acid catabolism by gut microbes with/without prebiotics inclusion in GDDY-based diet affect feed utilization in rainbow trout

Abstract

There is the need to enhance feed efficiency and growth of rainbow trout to reduce production costs of cultured fish. This study conducted a 3 x 4 factorial experiment with three graded levels of grain distiller dried yeast (GDDY) protein (0%, 50%, 75%) as replacement for fishmeal and four different prebiotics inclusion levels (0% (control), 0.4%, 1% mannooligosaccharides (MOS), and 1% GroBiotic A). The feeding trial was conducted for 12 weeks during which fish were fed daily to apparent satiation. Growth of rainbow trout was not affected by replacement of fishmeal with GDDY, but feed conversion ratio (P<0.0001) was greater at the highest level of GDDY inclusion. Increasing GDDY inclusion significantly increased feed intake (P<0.00015), which resulted in poor feed utilization. Acetic (P=0.1994), propionic (P=0.8037), butyric (P=0.6268), valeric (P=0.5877), and isovaleric (P=0.5919) acids profiles did not differ by diet nor with inclusion of MOS or GroBiotic A. Whole shotgun metagenomic analyses of the gastrointestinal tract (GIT) microbiota revealed enrichment in the fungal phyla Ascomycota and Basidiomycota and the bacterial phylum Actinobacteria in the GDDY-fed fish compared to those fed the control fishmeal-based diet, which may be reflective of the species endogenous in GDDY. Microbial genes involved in branched-chain amino acid metabolism (glutamate, glutamine, aspartate) (P=0.028) and glutamate dehydrogenase clusters (P=0.0192), were also elevated in the fish fed the 75% GDDY-based diet. The results from this study indicate the potential for microbially-mediated catabolism of the non-essential amino acids, and suggest this activity may significantly influence efficient utilization of dietary nitrogen in the yeast-based protein diet.

Haematological and intestinal health parameters of rainbow trout are influenced by dietary live yeast and increased water temperature

“…Fish fed yeast resulted in negative effects on fish growth performance, which suggests that replacing 40% of fishmeal protein with live yeast is not viable for rainbow trout, at either water temperature. In contrast, previous studies have successfully replaced up to 40-50% of fishmeal protein with yeast in diets for rainbow trout [1][2][3][4].…”

“…Yeast is a sustainable protein source since it is a byproduct from ethanol and brewing industries and can be grown on organic waste substrates. Yeasts, such as Saccharomyces cerevisiae, have successfully replaced up to 40-50% (112-289 g kg -1 ) of fishmeal protein in salmonid diets without reducing growth performance of rainbow trout (Oncorhynchus mykiss) [1][2][3][4], Atlantic salmon (Salmo salar) [5], Arctic charr (Salvelinus alpinus) [6] and lake trout (Salvelinus namaycush) [7]. However, most of these studies produced diets with heat-extrusion that inactivates high counts of live yeast in the diet [1], thus reducing the production of secretory metabolites that benefit the intestine as a live probiotic [8].…”

“…Previous studies have shown that cold-pelleted diets have lower digestibility than steam and heat-extruded diets [69,70]. In addition, extruded diets of yeast have lower protein digestibility than fishmeal when fed to salmonid fishes [4,6,71]. Therefore, lower inclusion levels of live yeast in cold-pelleted or extruded diets are recommended in future studies to improve diet digestibility and maintain fish growth performance.…”

Probiotic potential of Bacillus velezensis JW: Antimicrobial activity against fish pathogenic bacteria and immune enhancement effects on Carassius auratus

“…Notably, branched chain amino acids (BCAA) biosynthesis pathway was presented in the genome. Microbial BCAA metabolism in the rainbow trout gut is reported to have significant influence on the utilization of dietary nitrogen in the yeast-based protein diet [24]. The second largest function group is related to carbohydrates metabolism.…”

Psychobiotic Therapy: Method to Reinforce the Immune System

“…Prebiotics are “ingredients not metabolized by the host and fermented by the gut microbiota that have specific activities in maintaining the healthy intestine microbiota, which confer well-being and health of the host” [ 17 ]. In 2018 Betiku and collaborators reformulated the concept of prebiotics to: “Prebiotics, which are feed ingredients that are not endogenously digestible by the host but selectively stimulate the growth of beneficial microbes in the host” [ 18 ]. These substances are converted in the gut to other active molecules, including tryptophan and serotonin and these metabolites affect the immune system and/or host central nervous system [ 16 , 17 ].…”