Modulation of the growth performance, amino acid digestibility, and jejunal integrity of broiler chickens by dietary inclusion of raw potato starch or high-amylose corn starch in a mixed-Eimeria challenge model

A mixed Eimeria spp. challenge model was used to evaluate the potential ameliorative effects of dietary resistant starches (RS) on growth performance, ileal amino acid digestibility (AID), and gut integrity in broiler chickens during Eimeria challenge. A total of 1,056 day-old male broiler chicks were assigned to 8 treatments in a 4 × 2 factorial arrangement. Diets included 0 RS (control), 25, or 50 g/kg raw potato starch (RPS), or 50 g/kg high-amylose corn starch (HCS), with or without Eimeria challenge. On d 13, challenged birds were orally inoculated with mixed oocysts of E. maxima, E. acervulina, and E. tenella. There were no Eimeria × diet interactions for performance traits. During the starter phase (d 0 - 9), birds fed 25 g/kg RPS had higher (P = 0.047) weight gain (WG) than the control. In the pre-inoculation (d 9 -13) and prepatent (d 13 -16) phases, the WG and final weight gain (FBW) were greater (P < 0.05) in birds fed 50 g/kg HCS. Eimeria challenge decreased (P < 0.05) the WG and elevated (P < 0.05) the feed conversion ratio (FCR) during acute infection (d 16 - 19) and compensatory growth phases (d 28 - 35). The challenged birds also had shorter villi (P < 0.05), deeper crypts (P = 0.001), and increased intestinal permeability (P < 0.05). No significant diet × infection interaction nor main effect of diets was observed for the AID of amino acids, except for Trp and Cys. Trp had higher (P = 0.018) digestibility in birds fed 50 g/kg HCS than the control, and Cys digestibility was greater (P = 0.005) in birds fed diets with 25 g/kg RPS or 50 g/kg HCS than the control. However, Eimeria challenge depressed (P < 0.05) the AID of Ala and that of most indispensable amino acids. In conclusion, dietary RS improved the early growth performance, possibly via modulation of intestinal microbiota and metabolites, inducing a shift in digestion trajectory, but had limited effects post-infection.