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

Abstract

The purpose of the study was to investigate effects of different inoculation dosages of <i>E. tenella</i> 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 <i>E. tenella</i> oocysts were inoculated via oral gavage to fourteen-day-old broilers. Inoculation of <i>E. tenella</i> linearly increased FCR (<i>p</i> < 0.05), and feed intake was quadratically increased on 6 days post-infection (dpi; <i>p</i> = 0.08) and 7 dpi (<i>p</i> = 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 <i>E. tenella</i> infection on 6 dpi (<i>p</i> < 0.01). <i>E. tenella</i> infection deepened cecal crypts depth on 6 dpi (CD; <i>p</i> < 0.05). Gastrointestinal permeability tended to be linearly increased (<i>p</i> = 0.07). <i>E. tenella</i> infection tended to linearly reduce duodenal VH (<i>p</i> = 0.1) and jejunal VH on 9 dpi (<i>p</i> = 0.09). Different dosages of <i>E. tenella</i> modulated the tendency of fecal moisture content and oocyst shedding. Therefore, <i>E. tenella</i> infection impaired feed efficiency and small intestinal health mainly by reducing cecal VFA production and deepening cecal CD in broilers.