Dietary Spirulina effects in Eimeria-challenged broiler chickens: growth performance, nutrient digestibility, intestinal morphology, serum biomarkers, and gene expression.

This study investigated the growth performance, nutrient utilization, and intestinal health responses of Eimeria-challenged broiler chickens to dietary Spirulina (Arthrospira platensis). On d 1, birds were assigned to 2 diets supplemented with Spirulina (0 or 5 g/kg) in a randomized complete block design. The birds within each diet were divided into 2 Eimeria challenge groups (challenge or no-challenge) and that resulted in a 2 × 2 factorial arrangement with 2 levels each of Spirulina and challenge on d 14. On d 15, the birds in the challenge or no-challenge groups were orally gavaged with a solution containing Eimeria oocysts or 1% PBS, respectively. Samples were collected on d 21 and 26 (6- and 11-days post infection; dpi). Data collected from d 1 to 26 were analyzed using the MIXED procedure of SAS. Birds that were fed Spirulina-supplemented diets had increased (P < 0.05) BW gain, gain to feed ratio, and total tract retention nitrogen from d 14 to 21. The ileal villus perimeter and area, serum catalase, HMOX1 and SOD1 jejunal abundance were all increased (P < 0.05) in birds fed Spirulina-supplemented diets on d 21 (6 dpi). However, there was no effect on bone ash or oocyst count. From d 21 to 26, there was a tendency (P = 0.059) for a Spirulina × challenge interaction on the BW gain of birds. Moreover, dietary SP addition increased (P < 0.05) serum catalase, total antioxidant capacity, ileal villus perimeter, tibia bone ash, and the relative mRNA expression of HMOX1, SOD1, claudin 1 and TNFα in the jejunal mucosa of birds on d 26 (11 dpi). On both 6 and 11 dpi, the Eimeria challenge negatively (P < 0.05) impacted growth performance, gut morphology, and the relative mRNA expression of genes. Overall, assessing the impact of Spirulina in broilers revealed its positive antioxidant, immune-modulating, and health benefits. However, its dietary addition did not completely reverse the Eimeria-induced effects in these birds. Ultimately, this study outlines the positive properties of dietary Spirulina beyond its use in the diet of healthy broiler chickens.