Phenylalanine and Tyrosine as Feed Additives for Reducing Stress and Enhancing Welfare in Gilthead Seabream and Meagre

Abstract

Increased aquaculture production is associated with a growing interest in improving fish welfare. For this reason, the search for strategies to mitigate stress has intensified, one of these strategies being food supplementation with amino acids. The objective of this study was to evaluate the effects of dietary phenylalanine (Phe) and Tyrosine (Tyr) on the stress response and metabolism of juvenile gilthead seabreams (Sparus aurata) and meagres (Argyrosomus regius). Fish batches were fed a control diet and two diets supplemented with 5% Phe or Tyr for seven days. At the end of the experiment fish were stressed by air exposure for 3 min and then sacrificed for the extraction of blood and brain. Classical plasma stress markers were analyzed (glucose, lactate, proteins, cortisol), as well as hormones derived from those amino acids (adrenaline, noradrenaline and dopamine). Despite interspecific differences, fish fed the diets supplemented with Phe or Tyr showed a reduction on several stress markers. However, interspecific differences were detected for many indicators. Concretely, hormonal stress markers were significantly attenuated in meagres fed the enriched diets. Moreover, the stress condition favored a mobilization of amino acids towards the brain, especially in supplemented diets, hence this amino acid excess could be used as an energy substrate to cope with stress.

Effects of Dietary Phenylalanine and Tyrosine Supplements on the Chronic Stress Response in the Seabream (Sparus aurata)

“…Plasma cortisol only showed differences in non-stressed specimens at 30 and 90 days between the control and the specimens fed amino acid diets and between the specimens fed with Phe and with other treatments, respectively. It is probable that enriched foods could attenuate the cortisol increase related to the stress response since it only varied significantly between basal and stress states in the Phe treatment; in this sense, previous studies have demonstrated that the cortisol levels did not show differences in seabreams (S. aurata) which were fed with Phe and Tyr supplemented diets (Salamanca et al, 2021). As the present experiment was based on chronic stress, the absence of cortisol changes after 3 months could have been expectable due to the acclimation of the hypothalamic-pituitary-interrenal (HPI) axis (Montero et al, 1999;Procarione et al, 1999;Haukenes and Barton, 2004;Barton et al, 2005).…”

Understanding Nutrition and Metabolism of Threatened, Data-Poor Rheophilic Fishes in Context of Riverine Stocking Success- Barbel as a Model for Major European Drainages?

“…Aromatic AAs (phenylalanine + tyrosine), in addition to their conventional roles as key precursors of hormones and neurotransmitters [ 31 ], have recently been recognized for stress abatement in fish, particularly phenylalanine [ 81 ]. Due to their dynamic and fast-flowing habitat, rheophilic cyprinids may depend more on such stress abatement AAs.…”

Development of Polypyrrole Modified Screen-Printed Carbon Electrode Based Sensors for Determination of L-Tyrosine in Pharmaceutical Products

“…The negative effects that affect the health of the individual caused by the new coronavirus can be partially or completely treated with pharmaceuticals containing a compound, which acts on the central nervous system, namely tyrosine (Tyr), the target compound of this study. Tyr is a chemical compound discovered in 1846 by German chemist Justus von Liebig, an important compound for a healthy nervous system as it is the precursor of the main neurotransmitters, respectively dopamine, adrenaline, and noradrenaline [ 4 , 5 ]. Low levels of Tyr in human bodies can lead to diseases such as albinism and alkaptonuria whereas high levels of Tyr can lead to different emotional disorders, fits of depression, and even Parkinson’s disease [ 6 , 7 , 8 ].…”