Comparative Efficacy of Monobutyrin, Tributyrin, Sodium Butyrate, and Poly-β-hydroxybutyrate on Growth, Intestinal Health, and Nitrite Stress Resistance in Penaeus monodon.

Intestinal health is crucial for the growth and stress resistance of shrimp. Butyrate, a beneficial metabolite of intestinal microbiota and the primary energy substrate for enterocytes, exerts regulatory effects on intestinal health. Butyrates exist in various chemical forms, yet their application in shrimp remains limited. Therefore, in this study, Penaeus monodon were fed diets supplemented with 1% four types of butyrate (monobutyrin, MB; tributyrin, TB; sodium butyrate, SB; poly-β-hydroxybutyrate, PHB) for 56 days, followed by 48 h of acute nitrite stress. A systematic investigation into their influences on the shrimp growth, intestinal health and nitrite stress resistance was conducted. The results showed that the four butyrate types significantly increased the weight gain rate of the shrimp by more than 25% and improved the survival rate under nitrite stress by more than 28% when compared with the control group (p < 0.05). They also improved intestinal mucosal integrity, and enhanced intestinal antioxidant and immune capacities through the activation of the Nrf2 pathway and the upregulation of immune gene expression. Specifically, T-AOC and SOD activities, as well as the expression levels of Nrf2, GPx, Trx, ALF, Pen3, and serP genes, were significantly upregulated in all four butyrate groups, while MDA content was significantly decreased (p < 0.05). In addition, LPO content, CAT and ASC activities, and the expression of HO1, SOD, Crus, and proPO genes exhibited differential changes among the four butyrate groups. Furthermore, the intestinal microflora structure was reshaped by all four butyrate variants, with notable reductions in pathogenic Vibrio alongside elevated abundances of advantageous taxa including Rhodobacteraceae. In conclusion, butyrate can facilitate the growth and anti-stress capacity of P. monodon by improving intestinal health, with the overall efficacy ranked as TB, PHB, MB and SB under the present study conditions.