Spray-Dried Porcine Plasma Promotes the Association Between Metabolic and Immunological Processes at Transcriptional Level in Gilthead Sea Bream (Sparus aurata) Gut.

This study aimed to unveil the biological mechanisms modulated in response to the dietary administration of SDPP in the gilthead sea bream gut. Fish (BWi = 10.6 0.1 g, n = 400, mean standard deviation, SD) were fed during 95 days with C and SDPP diets using automatic feeders (ARVO-TEC T Drum 2000; Arvotec, Huutokosk, Finland) at a rate of 2.5% of the stocked biomass, which approached apparent satiation. The daily feed ratio was evenly distributed in 7 meals per day from 08:00 to 18:00 h. During the trial, water temperature and pH (pH meter 507; Crison Instruments, Barcelona, Spain), salinity (MASTER-20T; ATAGO Co., Ltd., Tokyo, Japan), and dissolved oxygen (OXI330; Crison Instruments) was measured. The water flow rate was maintained at approximately 9.0–10.1 L/min in a recirculation system (IRTAmar; Spain) that provided the experimental tanks with adequate water quality (total ammonia and nitrite) through UV, biological, and mechanical filtration. Photoperiod followed natural changes according to the season of the year (November to February; 40°37'41'' N). Fish were regularly sampled monthly to evaluate their growth in BW and adjust the feeding ratio to stocked biomass. At the end of the trial, fish were anesthetized as described above. All fish in experimental tanks were measured for final BW and SL as indicated. Then, 10 fish per tank were sacrificed with an overdose of MS-222 (200 mg/L) for tissue sampling purposes. The intestinal cavity was exposed, and the intestine was removed with a scalpel. A small piece of the anterior intestine (0.5 cm) was dissected and immediately transferred into RNAlater (Ambion) incubated at 4 C overnight and frozen at -80°C until further RNA extraction.