In the present study, the effects of the addition of different concentrations of the GHRP-6 peptide, a ghrelin analogue, to a commercial diet of gilthead seabream (Sparus aurata) on growth performance and intermediate metabolism of cultured animals were analysed. Juvenile fish (~20 g initial mean body mass) were fed in a medium/long term feeding period with three different diets: i) Control, non-supplemented (CTRL); ii) D100, supplemented with 100 μg GHRP-6/kg feed; and iii) D500, supplemented with 500 μg GHRP-6/kg feed. Sea breams were maintained in the experimental facilities of the Servicios Centrales de Investigación en Cultivos Marinos (SCI-CM, University of Cádiz) in an open system with constant water temperature (19 ºC) and salinity (36 ‰), and fed ad libitum during 97 days. At the end of the trial, different biometric, somatic and feed efficiency indexes were concomitantly analysed with Gh plasma levels, as well as several parameters related to the metabolic status of the animals. Our results demonstrated the existence of an overall improvement of growth performance in fish fed with diets supplemented with both doses of GHRP-6, and these effects were slightly mirrored by plasma Gh levels. Moreover, the GHRP-6 peptide does not generate physiological or metabolic alterations in fish fed the supplemented diets, although promotes a better aerobic management by the specimens fed the D100 diet as denoted by the lowering effect observed in plasma lactate. Taking together, our results strongly suggest the potential beneficial impact of GHRP-6 peptide on the aquaculture industry, as well as in fed producers for this and others cultured species.

J.A. Martos-Sitcha and J.M. Mancera belong to the Fish Welfare and Stress Network (AGL2016-81808-REDT) supported by the Spanish Ministry of Economy, Industry and Competitiveness.

Trabajo presentado en el XIII Congreso de la Asociación Ibérica de Endocrinología Comparada, celebrado los días 16 y 17 de septiembre de 2021