Effects of Infection on Key Parameters for Feed Efficiency in Broiler Chickens.

The purpose of the study was to investigate effects of different inoculation dosages of on growth performance, gastrointestinal permeability, oocyst shedding, intestinal morphology, fecal consistency, ileal apparent digestibility, antioxidant capacity, and cecal VFA profile in broiler chickens. Five different dosages (T0: 0, T1: 6250, T2: 12,500, T3: 25,000, and T4: 50,000) of oocysts were inoculated via oral gavage to fourteen-day-old broilers. Inoculation of linearly increased FCR ( < 0.05), and feed intake was quadratically increased on 6 days post-infection (dpi; = 0.08) and 7 dpi ( = 0.09). Cecal lesion score of each treatment was T0: 0; T1: 0.39 ± 0.14; T2: 0.93 ± 0.21; T3: 1.25 ± 0.16; and T4: 1.58 ± 0.2. Cecal total VFA production was linearly reduced due to infection on 6 dpi ( < 0.01). infection deepened cecal crypts depth on 6 dpi (CD; < 0.05). Gastrointestinal permeability tended to be linearly increased ( = 0.07). infection tended to linearly reduce duodenal VH ( = 0.1) and jejunal VH on 9 dpi ( = 0.09). Different dosages of modulated the tendency of fecal moisture content and oocyst shedding. Therefore, infection impaired feed efficiency and small intestinal health mainly by reducing cecal VFA production and deepening cecal CD in broilers.