Supplementation with nucleotides and seaweed meal enhances immunity, growth performance and resistance to Vibrio parahaemolyticus in pacific white shrimp

Acute hepatopancreatic necrosis disease (AHPND) is a bacterial disease mainly caused by Vibrio parahaemolyticus which produces high mortality rates in Pacific white shrimp (PWS). Dietary nucleotides (NU) and seaweed products contain bioactive compounds with reported benefits in PWS. Our objective was to evaluate the effects of NU, a Macrocystis integrifolia seaweed meal (SM), and their combination on PWS performance and survival upon AHPND challenge. A feeding trial (1250 PWS; 56 days) was performed using diets supplemented with 500 ppm NU (NU500), 500 ppm SM (SM500), 500 ppm NU and 500 ppm SM (NU500SM500), 334 ppm NU and 666 ppm SM (NU334SM666) or no supplementation (Control). A challenge trial (720 PWS; 10 days) was also performed using the same diets plus an additional non-challenged, non-supplemented group. Compared to Control, in the feeding trial all supplemented groups showed significantly higher final mean weight, final biomass, mean weight gain, average daily gain and specific growth rate; and NU334SM666 featured a significantly higher feed intake than all other groups. In the challenge trial, a non-significantly increased survival rate vs the challenged Control (30.63 ± 4.70 %) was seen with NU500 (33.95 ± 9.62 %), SM500 (41.02 ± 3.17 %) and NU500SM500 (45.00 ± 13.54 %), while NU334SM666 achieved a significantly higher survival rate (59.61 ± 9.55 %). Hyaline cells were significantly increased with NU334SM666 in both the feeding and challenge trials. In conclusion, NU and SM exhibit synergistic effects, enhancing PWS immune response and growth performance while reducing post-challenge mortality. These findings support their potential as a sustainable, immunomodulatory nutritional alternative to conventional AHPND management strategies.