Dietary protein complexity modulates growth, protein utilisation and the expression of protein digestion-related genes in Senegalese sole larvae

Molecular Ontogeny of First-Feeding European Eel Larvae

“…Gaining knowledge regarding digestive physiology during larval development for fish species, which are of interest to aquaculture, is essential for identifying adequate feeding strategies leading to improved production of healthy offspring. As such, several studies have utilized the recent advances in molecular tool availability in order to explore the molecular digestive system functionality and capacity in fish species such as Atlantic halibut, Hippoglossus hippoglossus ( Murray et al, 2006 ), Atlantic cod, Gadus morhua ( Kortner et al, 2011 ), catfish jundia, Rhamdia quelen ( Silveira et al, 2013 ), blunt snout bream, Megalobrama amblycephala ( Ping et al, 2014 ), Atlantic salmon, Salmo salar ( Sahlmann et al, 2015 ), Atlantic bluefin tuna, Thunnus thynnus ( Mazurais et al, 2015 ) and Senegalese sole, Solea senegalensis ( Canada et al, 2017 ). Similarly, intensive scientific inquiry has been conducted to identify the molecular functionality and capacity of the digestive tract in Japanese eel larvae during the transition from endogenous to exogenous feeding, where it was demonstrated that expression levels of genes encoding the major pancreatic enzymes (such as trypsin, amylase and lipase), arise prior to or at initiation of exogenous feeding ( Kurokawa et al, 2002 ; Pedersen et al, 2003 ; Murashita et al, 2013 ).…”

Fish muscle hydrolysate obtained using largemouth bass Micropterus salmoides digestive enzymes improves largemouth bass performance in its larval stages

“…These reports also agree with previous studies that had indicated a rapid and efficient absorption of low molecular weight protein fraction such as FAA, peptides, and hydrolyzed proteins in larval fish as opposed to intact protein [ 31 – 36 ]. It is generally accepted that larval ability to digest dietary intact protein increases gradually throughout ontogeny in parallel with the ongoing maturation of the digestive tract and subsequent increase in enzymatic activities [ 17 , 28 , 36 , 37 ]. More specifically, after metamorphosis is completed, fish go through a process referred to as “enzymatic maturation” of the intestine, characterized by a decrease in cytosolic activity (measured as leucine-alanine peptidase activity) and an increase in the activity of brush border membrane enzymes (measured as aminopeptidase N and alkaline phosphatase activity) [ 37 ].…”

“…Ovissipour et al [ 48 ] and Cahu et al [ 15 ] reported that an incorporation of a moderate dietary level of fish protein hydrolysate promotes the onset of the “adult mode of digestion” in developing Persian sturgeon ( Acipenser persicus ) and sea bass larvae, respectively. However, larval capacity to digest dietary components of different molecular weights changes throughout its development [ 17 ]. Our study found that the in vitro hydrolysis method using carp intact muscle and LMB digestive tracts incubated at both acid and alkaline pH (to mimic digestive process of LMB) yielded a wide range of low molecular weight fractions (peptides) as opposed to the non-hydrolyzed muscle protein or muscle treated only with acid pH or alkaline pH without enzymes from LMB digestive tracts, which were comprised of large molecular weight fractions (polypeptides above 150 kDa).…”

“…It is widely known that the inclusion of pre-digested protein in the form of protein hydrolysates improves larval growth performance [ 14 – 16 ]. However, larval capacity to digest dietary components of different molecular weights changes throughout its development [ 17 ] and therefore, the right balance between different sizes of protein fractions in diets is critical to induce positive growth responses in larval fish.…”

Effects of dietary protein levels on activities of protease and expression of ingestion and protein digestion‐related genes in Nile tilapia juveniles

“…To efficiently formulate diets, some previous knowledge of the digestive process of the animal is required, which may be developed by investigating digestive enzyme activity (Canada et al, 2017). Proteases are enzymes that specifically break peptide bonds between amino acids in proteins (Rust, 2002), with trypsin and chymotrypsin being the most relevant in the gastrointestinal tract of fish (Santigosa et al, 2008).…”