<i>Laminaria japonica</i> Polysaccharides Improves the Growth Performance and Faecal Digestive Enzyme Activity of Weaned Piglets

The aim of this experiment was to investigate the effect of <i>Laminaria japonica</i> polysaccharide (LJP) supplementation at levels of 100, 200, or 400 mg/kg on the growth performance, faecal digestive enzyme activity, and serum biochemistry and amino acids of weaned piglets. One hundred and twenty weaned piglets (Barkshire × Licha Black, 21 days old, 6.13 ± 0.16 kg) were randomly divided into four groups with five replicates of six piglets in each group based on body weight. Piglets were fed with different levels (0, 100, 200, and 400 mg/kg) of LJP for a 21-day trial. On day 21, faecal and blood samples were collected from one piglet per pen. The results showed that the supplementation of the 200 and 400 mg/kg LJP significantly increased average daily gain (ADG) and average daily feed intake (ADFI) compared to the control group (<i>p</i> = 0.007; <i>p</i> = 0.002), and dietary LJP linearly increased ADG and ADFI (<i>p</i> = 0.002; <i>p</i> < 0.001). In addition, the supplementation of the 200 and 400 mg/kg LJP significantly increased faecal amylase activity (<i>p</i> < 0.001) compared to the control group, and dietary LJP linearly increased faecal amylase and lipase activities (<i>p</i> = 0.001; <i>p</i> = 0.037). Moreover, dietary LJP at 400 mg/kg increased serum histidine content compared to the other groups (<i>p</i> = 0.002), and dietary LJP linearly increased the contents of serum histidine and asparagine in piglets (<i>p</i> < 0.001; <i>p</i> = 0.046). In conclusion, supplementation of 200 and 400 mg/kg LJP could enhance growth performance and faecal digestive enzyme activity and modulate the serum amino acid content of weaned piglets, potentially contributing to the health of weaned piglets.