Influence of Krill Meal on the Performance of Post-Smolt Atlantic Salmon That Are Fed Plant-Based and Animal-Based Fishmeal and Fish Oil-Free Diets

Abstract

The purpose of this study was to determine the influence of krill meal (KM) inclusion at various levels (0%, 2.5%, 5%) in plant-based and animal-based feeds, that were fishmeal (FM) and fish oil (FO) free, on Atlantic salmon growth. A FM/FO feed containing 0% KM was the control. Using a 2 × 3 factorial approach, diets were randomly assigned to one of 28 0.5 m3 flow-through tanks (n = 4 tanks per diet) initially stocked with 60 fish (148.4 ± 12.9 g; 23.6 ± 0.8 cm; condition factor (K) = 1.16 ± 0.08) each. Salmon were fed for 90 days using automatic feeders ad libitum. On day 45, stocking densities were reduced to 45 fish per tank by the random removal of 15 individuals to remove any potential of density affecting growth through the trial end. Water temperature, oxygen saturation, pH, and salinity throughout the trial were 11.8 °C, 103.5%, 7.38, and 32.0 g L−1, respectively. Fish fed plant-based feed without KM were lighter (p < 0.05) than all other groups at day 45 and 90, but those fed a plant-based feed with KM had comparable growth and feed intake compared to that of fish fed the control diet. Irrespective of the presence of KM, animal-based feeds achieved comparable weight growth (p > 0.05) to the control and 5% KM plant-based groups, with KM increasing feed intake (p < 0.05). Between day 45 and 90, feed conversion ratios increased in all groups except the control and 0% KM plant-based group, while specific growth rates (SGRs) decreased for all except the 0% KM plant-based diet. Between-group differences (p < 0.05) were also noted for the thermal growth coefficient. No differences were recorded in visceral or intestinal weight, and whole-body lipid levels were identical, proportional for all groups. Although differences (p < 0.05) were apparent in the concentrations of individual fillet fatty acids between groups, a 75 g serving size of any treatment would be sufficient to exceed daily intake recommendations for EPA + DHA. This trial determined that benefit, in terms of feed intake and growth performance, was gained when KM was added to plant-based feeds. However, no such advantage was observed when KM was used with animal-based feeds.

The Impact of Marine Resource-Free Diets on Quality Attributes of Atlantic Salmon

“…K = condition factor; HG wt = headed and gutted weight. For comprehensive diet formulations see [6]. Diet had a significant impact on SL, with fish fed the P1 and A3 diets being shorter than those fed the FM/FO-based diet (Table 3).…”

“…The fish employed in the present study were derived from a 90-day growth trial which was undertaken to assess the response of Atlantic salmon to dietary krill meal (KM) inclusion. The results of these experiments, which evaluated seven diets, have been presented previously [6], and this study is a further examination of morphological, functional, and consumer acceptance attributes of the fish that were not originally addressed. Four fish were randomly taken from four replicated tanks for each of the seven diets, which comprised a control FM/FO-based feed (C1), plant-based feeds incorporating 0% (P1), 2.5% (P2), and 5% (P3) KM, and animal-based formulas that incorporated 0% (A1), 2.5% (A2), and 5% (A3) KM (n = 16 fish per dietary treatment).…”

“…SL = standard length; RFW = relative fin width; RFH = relative fin height; RFI = relative fin index; FW = fray width; #F = number of frays. For comprehensive diet formulations see [6]. Data in a row displaying different superscripts were significantly different (p < 0.05).…”

“…The impact of various dietary treatments on mean (±SD) stable isotope concentrations of δ 13 C and δ 15 N and δ 13 C: δ 13 N ratios in fillets of post-smolt Atlantic salmon. For comprehensive diet formulations see [6]. Data in a row displaying different superscripts were significantly different (p < 0.05).…”

“…The reduction in FM/FO has been facilitated, to a certain extent, by an improved understanding of salmon nutrition, genetic selection, advances in feed technologies, and innovation in feed delivery methods [2][3][4][5]. Other attributes driving the reduction in the use of FM/FO have been the rising price of both commodities in the international marketplace [6] and the emergence of a more refined and opinionated consumer. Prices for FM/FO have risen as competition for both resources has increased while availability has generally weakened.…”