Abstract
The intestinal health of weanling pigs is often compromised by harmful bacterial agents, leading to inflammation and reduced intestinal integrity. Limited research exists on the effects of spirulina as a bioactive feed additive on weanling pigs. Hence, this study aimed to investigate the effect of spirulina on the growth performance and intestinal health of pigs using a lipopolysaccharide (LPS) challenge model. On d 0, 128 pigs were assigned to one of four groups in a 2 × 2 factorial arrangement of treatments with 2 levels each of spirulina (0 or 5 g SP/kg) and LPS (challenge or no-challenge). There were 8 replicate pens per treatment and 4 pigs per pen. On d 7, pigs were weighed, and pigs in the LPS challenge group were intraperitoneally injected with 100 µg/kg body weight LPS. The other pigs were injected with saline. On d 14, all pigs were weighed. On d 15, one selected pig per pen was again injected with the same amount of LPS or saline. After 4 h, the selected pigs were euthanized, and samples were collected. Data were analyzed using the MIXED procedure of SAS and evaluated for main effects and interactions. There was no dietary spirulina effect on growth performance. However, the LPS challenge reduced (P < 0.05) the body weight and gain-to-feed ratio of pigs. Dietary spirulina increased (P < 0.05) the apparent total tract digestibility (ATTD) of dry matter regardless of the LPS challenge. There was an SP × LPS interaction effect (P < 0.05) on the jejunal villus height, villus perimeter, and villus area. Additionally, there was an SP × LPS interaction (P < 0.05) on serum tumor necrosis factor alpha. Challenge with LPS reduced (P < 0.05) the serum concentration of catalase but increased (P < 0.05) serum c-reactive protein concentration irrespective of dietary spirulina inclusion level. Dietary spirulina increased (P < 0.05) the mRNA expression of jejunal zonula occludens-1. An SP × LPS interaction (P < 0.05) showed that LPS-challenged pigs fed a spirulina-supplemented diet had the highest jejunal superoxide dismutase 2 mRNA expression relative to pigs in the other groups. In summary, dietary spirulina supplementation enhanced antioxidant activity and reduced intestinal inflammation in pigs during an LPS challenge. Dietary spirulina also improved tight junction integrity and dry matter digestibility, irrespective of the LPS challenge.