Preparation, Structural Analysis, and Growth‐Promoting Effects of Amomum longiligulare Polysaccharide 1‐Mg (II) Complex

In this study, Amomum longiligulare polysaccharide 1 (ALP1) is used to chelate with magnesium (Mg) to synthesize the ALP1‐Mg (II) complex (ALP1‐Mg). Based on Box‐Behnken response surface design, the optimum technological conditions are 22 mg mL−1 trisodium citrate, 2.10 mol L−1 MgCl2, reaction at 70 °C for 2.9 h, resulting in a maximum Mg content of 2.13%. Next, the physicochemical properties and structural characteristics of ALP1 and ALP1‐Mg are characterized, and the results show that the morphology, conformation, crystallinity, and thermal stability of ALP1‐Mg are changed. In addition, dietary supplementation of 500 mg kg−1 ALP1‐Mg significantly reduces the feed conversion ratio during the grower (15–35 d). Meanwhile, the villus height/crypt depth of the duodenum and ileum are significantly increased, and the relative abundance of Lactobacillus is significantly elevated. Taken together, the results suggest that ALP1‐Mg is a potential growth‐promoting feed additive.