Authors: Nathaniel W. Farris, Florence Perera Willora, Dmitri Hendrik Blaauw, Shruti Gupta, Ester Santigosa, Ian Carr, Kyla Zatti, Saraswathy Bisa, Viswanath Kiron, Iversen Martin Haugmo, Viviane Verlhac-Trichet, Mette Sørensen

Published in Aquaculture Reports Volume 36, June 2024

Highlights

• Schizochytrium-derived oil in diet did not negatively impact the growth of Atlantic salmon.
• The oil in the diet did not compromise osmoregulation-related parameters in salmon.
• The dietary oil did not disturb plasma osmolality of the fish.
• Schizochytrium-derived oil can support salmon during the winter signal period.
  
  

Abstract

The aim of this study was to investigate the impact of progressive replacement of fish oil with Schizochytrium-derived oil from Veramaris® (VMO) in the diets of Atlantic salmon, focusing on its effect during the pre-adaptation to smoltification phase of parr, with an emphasis on the winter signal period. Substitution of fish oil with VMO during this critical developmental phase of salmon (pre-adaptation to smoltification phase) can contribute to the goal of reducing dependence on wild fisheries as a primary source of essential fatty acids in aquafeeds. Three isoproteic, isolipidic and isoenergetic diets were formulated; a control diet containing 5% fish oil and 12% plant oil (0VMO) and two other diets, in which 50% and 100% of the EPA+DHA from fish oil were replaced with VMO, henceforth referred to as 50VMO and 100VMO, respectively. The fish were exposed to a 12 L:12D photoperiod over a 49-day window with samples collected at five time points, including a 48-h salt water challenge to evaluate the effects on common smoltification-related biomarkers including the expression of two genes coding for the two protein isoforms of the NKA alpha catalytic subunit (nkaa1a, nkaa1b), the gene coding for NA+/K+Cl⁻ co-transporter (nkcc1) in the gills as well as osmolality, Cl-, Mg2+, Ca2+, cortisol, growth hormone, and insulin-like growth factor-1 in plasma. The results showed non-significant differences in growth performance and only minor differences in smoltification-related parameters between the dietary treatment groups. Overall, the unconventional source of EPA+DHA was not detrimental to growth, hypoosmoregulatory ability or general welfare, suggesting that the progressive substitution of fish oil with Schizochytrium-derived oil in diets for Atlantic salmon parr is a viable option for adoption by the aquaculture industry.