Digestive capacities, inbreeding and growth capacities in juvenile Arctic charr Salvelinus alpinus

Abstract

Genetic variation in growth performance was estimated in 26 families from two commercial strains of Arctic charr Salvelinus alpinus. Physiological determinants of growth and metabolic capacities were also assessed through enzymatic assays. A relatedness coefficient was attributed to each family using parental genotypes at seven microsatellite loci. After 15 months of growth, faster growing families had significantly lower relatedness coefficients than slower growing families, suggesting their value as indicators of growth potential. Individual fish that exhibited higher trypsin activity also displayed higher growth rate, suggesting that superior protein digestion capacities can be highly advantageous at early stages. Capacities to use amino acids as expressed by glutamate dehydrogenase (GDH) activities were lower in the liver of fast-growing fish (13-20%), whereas white muscle of fast-growing fish showed higher activities than that of slow-growing fish for amino acid metabolism and aerobic capacity [22-32% increase for citrate synthase (CS), aspartate aminotransferase (AAT) and GDH]. The generally higher glycolytic capacities (PK and LDH) in white muscle of fast-growing fish indicated higher burst swimming capacities and hence better access to food.

Digestive tract morphology and enzyme activities of juvenile diploid and triploid Atlantic salmon (Salmo salar) fed fishmeal-based diets with or without fish protein hydrolysates

“…In addition to the area available for nutrient absorption, enzyme activities are expected to influence the efficiency with which nutrients are digested and absorbed, and be linked to feed utilization and growth. For example, there is some evidence for a link between protease activity and growth in salmonids and some other fish species [25,[56][57][58][59][60]. In our study, the low enzyme activities recorded at 875 and 2090 ddPSF (Fig 9) coincided with periods of reduced fish growth (low TGC), including the time of photoperiod manipulation used to induce parr-smolt transformation.…”

“…For example, tryptic activity was much lower at 2090 ddPSF than at the preceding and subsequent sampling times, but chymotrypsin did not show an equivalent trough (Fig 9). A lack of concordance between the activities of trypsin and chymotrypsin has been reported in previous studies in which fish have been provided with feeds differing in nutrient composition, or held under conditions that have induced differences in feed intake and growth [34,35,57,58,62,78]. Although the reasons for the differences in the patterns of the enzymatic activities of trypsin and chymotrypsin remain unclear they have been linked to differences in growth trajectories and feed conversion observed in fish held under different conditions [24,57,61,63].…”

“…On the other hand, enzyme activities were high at 2745 ddPSF, which coincided with a period of high growth. Of the protease enzymes, most attention has been given to a possible link between trypsin or ALP and fish growth, with relationships to enzyme activity and trypsin isozymes having been investigated in several studies [25,[56][57][58][59][60][61][62]. Significant relationships have been reported in a number of growth trials that have used enzyme activity (as a surrogate for digestive capacity) and isozymes as indicators.…”

Impact of environmental factors on the growth and maturation of farmed Arctic charr

“…They found that the two strains had significantly different allelic and genotypic distribution and that the genetic variability was lower in the Quebec domesticated strains than in wild populations of the same species. In a later study (Ditlecadet et al 2009) with the same farmed strains, it was found that faster-growing families had significantly lower relatedness coefficients than slower-growing families. Recently, Nugent et al (2017) presented a single nucleotide polymorphism (SNP) linkage map for Arctic charr based on genetic sequencing of 85 full-siblings, and their parents, from the Fraser strain.…”

“…In Canada, the potential for selective breeding in several strains has been investigated (Ditlecadet et al 2006(Ditlecadet et al , 2009Blackie et al 2011;Norman et al 2011Norman et al , 2014. Two natural populations from geographically distant locations and phylogenetic lineages have been the primary contributors to the Arctic charr being produced in the Canadian industry (Blackie et al 2011): the Nauyuk Lake system in Nunavut and the Fraser River in Labrador.…”