Feeding for Well-Being: Porcine Blood Hydrolysate Supplementation Improves Metabolic and Welfare-Related Traits in Farmed Gilthead Sea Bream (Sparus aurata)

TL;DR

Adding porcine blood hydrolysate to fish feed improves metabolism and welfare in gilthead sea bream.

Contribution

This study shows PBSH as a novel functional feed ingredient with benefits for fish health and performance.

Findings

PBSH reduced liver fat and stress indicators like cortisol and glucose in fish.

Fish fed PBSH showed improved swimming performance and faster weight recovery after fasting.

PBSH altered gut bacteria, increasing genera like Aureimonas and Halomonas.

Abstract

The revalorization of animal by-products, such as porcine blood, is a key strategy for sustainable aquaculture and circular economy practices. This study aimed to fill the existing knowledge gap on the effects of spray-dried porcine blood hydrolysate (PBSH), assessing its potential as a functional feed ingredient for gilthead sea bream. Two practical diets were formulated: a control diet containing 5% blood meal, and a PBSH diet including 5% PBSH previously characterized in vitro. The results indicated that the PBSH diet promoted lower hepatosomatic index, a down-regulation of key hepatic lipogenic enzymes (scd1b, hl, lpl), and a better stress condition with lower circulating levels of glucose and cortisol and a reduction in aggressive attacks. Positive findings were also achieved in energy management, obtaining lower metabolic rates along with an enhanced swimming performance (20% increase in the critical speed) and a quicker weigh recovery after a fasting period. The PBSH diet also shaped the intestinal bacterial composition, determining a redistribution of abundant genera including Aureimonas and Halomonas. Ultimately, this study demonstrated that PBSH would act as a functional ingredient capable of enhancing fish energy management and resilience in the face of stressful events, exhibiting a transient transcriptional modulation, yet persistent physiological and welfare benefits.

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