Spray-dried porcine plasma protein improves the performance of Atlantic salmon (Salmo salar) during sea-water transfer

The dietary inclusion of spray‑dried plasma proteins has been shown to improve animal performance in terrestrial livestock under challenging conditions, but evidence in fish is inconsistent. This 87‑day trial evaluated the effect of 5% Proglobulin®, a spray‑dried porcine plasma protein, in the diet of juvenile Atlantic salmon (Salmo salar) during seawater transfer. Fish (initial weight 53.8 ± 5.9 g) were stocked at 29 fish per 200-L tank (six replicate tanks per diet) in a recirculating aquaculture system. The trial comprised a 17‑day freshwater phase followed by a 70‑day seawater phase (salinity 31.8 ppt). Control and test diets were formulated to similar crude protein (52%) and lipid (19%) levels. Fish were fed automatically eight times daily to excess, with uneaten feed collected and weighed weekly to determine feed intake. Sampling occurred at trial start, before seawater transfer, and at trial end. Compared with controls, fish fed the plasma‑supplemented diet showed a 61% higher feed intake, greater weight gain (62.1 ± 5.4 g vs. 46.0 ± 3.2 g), higher SGR (1.01 ± 0.07% vs. 0.82 ± 0.04%), but not significantly improved survival after seawater transfer (94.7 ± 3.2% vs. 90.2 ± 5.5%). The results indicate that dietary spray‑dried plasma protein can enhance feed intake and growth of Atlantic salmon during the critical seawater transfer period.