Effects of protein hydrolysate in weaning diets for Atlantic cod (Gadus morhuaL.) and Atlantic halibut (Hippoglossus hippoglossusL.)

Abstract

Predigested dietary protein may enhance the utilisation of formulated diets at weaning, and also stimulate intestinal maturation. In this study, Atlantic cod (Gadus morhua L.; 41 days post hatch (dph)) and Atlantic halibut (Hippoglossus hippoglossus L.; 63 days post first feeding (dpff)) were weaned onto diets with graded levels of where varying parts of the protein was substituted with pepsin hydrolysed protein, exchanged with dietary protein. By increasing dietary content of hydrolysed protein from none to 40 %, cod increased the rate of survival from 7±1 % to 18±2 % (82 dph; Regression, P=4*10 -7 ). In halibut, the survival rate decreased from 57±9 % to 22±7 % as the content of hydrolysed protein increased from none to 45 % (119 dpff; Regression, P=8*10 -5 ).Growth was not affected in any of the species. A 3-fold higher specific activity of leucine aminopeptidase (LAP) in cod was found in the groups fed 20 and 30 % hydrolysed protein than in the group fed non-hydrolysed protein (82 dph; ANOVA, P<0.05), indicating a more mature intestine in the former groups. In halibut, specific activity of alkaline phosphatase (AP) was 3-6-fold higher in the groups receiving nonand 15 % hydrolysed protein than in the groups receiving 30 and 45 % hydrolysed protein (91+119 dpff; ANOVA, P<0.05). The lower preference optimal level offor hydrolysed protein in halibut than in cod is suggested to mainly be caused bydue to a slower feeding habit practice in halibut which allow more extensive nutrient leaching before ingestion.3

Fish larval nutrition and feed formulation: knowledge gaps and bottlenecks for advances in larval rearing

“…In carp (Cyprinus carpio) and European seabass (Dicentrarchus labrax) larvae, substitution of 60 and 250 g kg )1 , respectively, of the dietary protein with hydrolysed protein was found to be optimal (Cahu et al 1999;Carvalho et al 2004). In an experiment with cod (Gadus morhua), supplementation of pepsin hydrolysed protein up to 400 g kg )1 protein improved survival rates compared with lower levels of supplementation, while a similar experiment with Atlantic halibut (Hippoglossus hippoglossus) did not give improved performance with hydrolysed protein supplementation (Kvåle et al 2009). Inclusion levels above 500 g kg )1 of the protein seem to be detrimental to several fish species (gilthead seabream, Kolkovski & Tandler 2000;carp, Carvalho et al 1997;Dicentrarchus labrax, Cahu et al 1999; although not to all (Solea solea, Day et al 1997;turbot, Psetta maxima, Oliva-Teles et al 1999).…”

“…2004). In an experiment with cod ( Gadus morhua ), supplementation of pepsin hydrolysed protein up to 400 g kg −1 protein improved survival rates compared with lower levels of supplementation, while a similar experiment with Atlantic halibut ( Hippoglossus hippoglossus ) did not give improved performance with hydrolysed protein supplementation (Kvåle et al. 2009).…”

“…Until a gastric digestion is attained (not the case of agastric fish), fish larvae digestion relies mainly on pancreatic enzymes with an optimum of activity at a neutral or alkaline pH, conditioning the range of proteins that fish larvae are able to digest. In larval fish diets and weaning diets, part of the protein fraction is usually supplied in the form of hydrolysate (Carvalho et al 1997;Cahu et al 1999;Kvåle et al 2009;Nankervis & Southgate 2009). This is a way to facilitate digestion and to increase the availability of peptides and amino acids absorbed within the larval gut.…”

Effects of dietary size-fractionated fish hydrolysates on growth, activities of digestive enzymes and aminotransferases and expression of some protein metabolism related genes in large yellow croaker (Larimichthys crocea) larvae

“…Fish hydrolysate is promising as a core material in microdiet since it typically consists of low molecular-weight peptides resulting from protein pre-digestion, which are more likely to be absorbed by enterocytes compared to high molecular-weight macromolecules (Önal and Langdon, 2009). The nutritional value of fish hydrolysate has been evaluated in diets for rearing marine fish larvae and improved growth and/or survival rate has been reported (Han et al, 2010;Kvåle et al, 2009;Liu et al, 2010). Furthermore, fish hydrolysate contains various molecular weight compounds ranging from dozens to thousands of Da which may affect the absorption capacity and rate of passage of the diet through the gastrointestinal tract (Espe and Lied, 1999).…”

Impact of dietary protein hydrolysates on skeleton quality and proteome in Diplodus sargus larvae

“…Modulating the solubility and molecular size of proteins presented in artificial diets has been shown to affect larval quality of different fish species (Zambonino Infante et al., 2005). For instance survival, growth, development of the digestive tract and/or the occurrence of skeletal deformities were improved by the inclusion of dietary protein hydrolysates (PH) in larvae of various fish species such as European seabass (Zambonino Infante et al., 1997; Cahu et al., 1999), rainbow trout (Dabrowski et al., 2003), Atlantic cod and Atlantic halibut (Kvåle et al., 2009), and gilthead seabream (Gisbert, 2010). However, including PH in aquafeeds deserves further attention as some inclusion levels of dietary peptides and/or free AA (FAA) have been shown to have a detrimental effect on growth performance (Cahu et al., 1999; Kolkovski and Tandler, 2000; Carvalho et al., 2004; Tonheim et al., 2005).…”