AUTHOR=Goo Doyun , Choi Janghan , Ko Hanseo , Choppa Venkata Sesha Reddy , Liu Guanchen , Lillehoj Hyun Soon , Kim Woo Kyun 

TITLE=Effects of Eimeria maxima infection doses on growth performance and gut health in dual-infection model of necrotic enteritis in broiler chickens

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1269398

DOI=10.3389/fphys.2023.1269398

ISSN=1664-042X

ABSTRACT=<p>The objective of this study was to investigate the effects of the different doses of <italic>Eimeria maxima</italic> (<italic>EM</italic>) oocysts on growth performance and intestinal health in broiler chickens challenged with a dual infection model of necrotic enteritis (NE) using <italic>EM</italic> and NetB<sup>+</sup><italic>Clostridium perfringens</italic> (<italic>CP</italic>). A total of 432 fourteen-d-old male Cobb 500 broiler chickens were divided into 6 groups with 6 replicates each. The six different groups were as follows: Control, non-challenged; T0<sup>+</sup>, challenged with <italic>CP</italic> at 1 × 10<sup>9</sup> colony forming unit; T5K<sup>+</sup>, T0<sup>+</sup> + 5,000 <italic>EM</italic> oocysts; T10K<sup>+</sup>, T0<sup>+</sup> + 10,000 <italic>EM</italic> oocysts; T20K<sup>+</sup>; T0<sup>+</sup> + 20,000 <italic>EM</italic> oocysts; and T40K<sup>+</sup>; T0<sup>+</sup> + 40,000 <italic>EM</italic> oocysts. The challenge groups were orally inoculated with <italic>EM</italic> strain 41A on d 14, followed by NetB<sup>+</sup><italic>CP</italic> strain Del-1 on 4 days post inoculation (dpi). Increasing <italic>EM</italic> oocysts decreased d 21 body weight, body weight gain, feed intake (linear and quadratic, <italic>p</italic> &lt; 0.001), and feed efficiency (linear, <italic>p</italic> &lt; 0.001) from 0 to 7 dpi. Increasing <italic>EM</italic> oocysts increased jejunal NE lesion score and intestinal permeability on 5, 6, and 7 dpi (linear, <italic>p</italic> &lt; 0.05). On 7 dpi, increasing the infection doses of <italic>EM</italic> oocysts increased jejunal <italic>CP</italic> colony counts (linear, <italic>p</italic> &lt; 0.05) and increased fecal <italic>EM</italic> oocyst output (linear and quadratic, <italic>p</italic> &lt; 0.001). Furthermore, increasing the infection doses of <italic>EM</italic> oocysts decreased the villus height to crypt depth ratios and the goblet cell counts (linear, <italic>p</italic> &lt; 0.05) on 6 dpi. Increasing <italic>EM</italic> oocysts downregulated the expression of MUC2, B<sup>0</sup>AT, B<sup>0,+</sup>AT, PepT1, GLUT2, AvBD3 and 9, LEAP2, and TLR4, while upregulating CLDN1, CATHL3, IL-1β, IFN-γ, TNFSF15, TNF-α, IL-10, and Gam56 and 82 on 6 dpi (linear, <italic>p</italic> &lt; 0.05). Additionally, increasing <italic>EM</italic> oocysts decreased Pielou’s evenness and Shannon’s entropy (linear, <italic>p</italic> &lt; 0.01). In conclusion, increasing the infection doses of <italic>EM</italic> significantly aggravated the severity of NE and exerted negative impact on intestinal health from 5 to 7 dpi.</p>