Changes in gene and protein expression related to feed intake and thermoregulation in broilers challenged with different doses of mixed Eimeria spp

The objective of the study was to investigate the effects of Eimeria infection on expression of genes and proteins related to feed intake and core body temperature in broilers. A total of 750 fifteen-day-old male broilers were distributed to five experimental groups in a completely randomized design (CRD) with 6 replicates of 25 birds per pen. The five experimental groups included (1) unchallenged control (UNC); (2) Eimeria challenge 1 (EC1): challenged with 31,250 E. acervulina, 6,250 E. maxima, 6,250 E. tenella; (3) Eimeria challenge 2 (EC2): 2 × EC1; 4) Eimeria challenge 3 (EC3): 2 × EC2; and 5) Eimeria challenge 4 (EC4): 2 × EC3. Feed intake was linearly decreased by increased doses of Eimeria spp. in broilers at 6 days post inoculation (dpi) (P < 0.05). Core body temperature was linearly reduced by higher doses of Eimeria spp. in broilers (P < 0.05). Relative mRNA expression of agouti-related protein (AGRP) (P < 0.05), interleukin 18 (IL18) (P < 0.05), motilin receptor (MR) (P < 0.01), and proopiomelanocortin (POMC) (P < 0.01) was linearly decreased by higher doses of Eimeria spp. in the brain. Relative mRNA expression of cholecystokinin (CCK), motilin, neuropeptide Y (NPY), neuropeptide Y receptor Y1 (NPYY1) was linearly decreased by higher doses of Eimeria spp. in the duodenum (P < 0.05). Higher doses of Eimeria spp. significantly increased relative mRNA expression of cold-inducible RNA-binding protein (CIRBP), hypoxia inducible factor 1 subunit alpha (HIF1A), and heat shock protein 70 (HSP70) in the duodenum. Higher doses of Eimeria spp. linearly and quadratically decreased relative mRNA expression of CCK (P < 0.01), and relative mRNA expression of motilin and NPYY2 was linearly decreased by higher doses of Eimeria spp. in the jejunum (P < 0.05). Higher doses of Eimeria spp. linearly increased protein concentration of CCK in the serum (P < 0.05). Hence, Eimeria infection modulated expression of genes and proteins related to feed intake and core body temperature in broilers.