Organic manganese as a functional micronutrient: Promoting metabolic health and sustainable growth in Litopenaeus vannamei

This study evaluated the effects of five manganese (Mn) sources on Pacific white shrimp ( Litopenaeus vannamei ). Five Mn sources include Mn sulfate (MnSO 4 ·H 2 O), Mn dioxide (MnO 2 ), Mn dioxide nanoparticles (MnO 2 NPs), Mn glycine chelate (Mn-Gly), and Mn chelate of hydroxy analogue of methionine (Mn-MHA). During a 56-d feeding trial, 450 shrimp (1.03 ± 0.02 g) were randomly distributed among five dietary treatments, with each having three replicates. Growth performance and feed utilisation were not observed to be significantly affected by Mn sources ( P > 0.05). However, organic Mn sources (Mn−Gly and Mn−MHA) significantly enhanced Mn deposition ( P = 0.002) and upregulated a key Mn transporter ( zip14 , tmem165 , and fpn1 ) in the hepatopancreas when compared with inorganic MnO 2 source ( P < 0.05). Moreover, dietary organic Mn-MHA significantly enhanced systemic antioxidant capacity (T-AOC and GSH-Px) and innate immune response, as evidenced by increased activities of relevant enzymes (AKP, ACP, and NOS) and upregulation of associated genes ( gpx , cat , sod , nos , and akp ) when compared with MnO 2 ( P < 0.05). Furthermore, the organic Mn sources significantly downregulated genes related to endoplasmic reticulum stress ( perk , atf4 , atf6 , and eif2α ), inflammation ( spz-5 , il-16 , and rab6a ), and apoptosis ( caspase8 , p53 , and caspase3 ), while significantly upregulating the anti-apoptotic gene ( bl-1 ) when compared with MnO 2 ( P < 0.05). Notably, Mn−MHA supplementation significantly reduced hepatopancreatic lipid content ( P = 0.002) by modulating the expression of genes involved in lipid synthesis ( fas and acc ) and lipolysis ( aco and cpt ) ( P < 0.05). In summary, although growth remained unaffected, organic Mn sources, particularly Mn−Gly and Mn−MHA, demonstrated superior bioavailability by enhancing antioxidant status, immune function, and hepatopancreas health as well as by regulating lipid metabolism.