This study was conducted to evaluate graded Eimeria challenge on growth performance, apparent ileal digestibility, gastrointestinal permeability, intestinal morphology, gene expression of tight junction protein, and intestinal lesion scores in broiler chickens. There were 5 groups in this study, including a control and 4 different Eimeria treatment doses. A mixed Eimeria spp . solution with 50,000 Eimeria maxima , 50,000 Eimeria tenella , and 250,000 Eimeria acervulina per milliliter was prepared for the high-dose challenge treatment. The 2-fold serial dilution was used to make the medium-high (25,000 E. maxima ; 25,000 E. tenella ; 125,000 E. acervulina ), the medium-low (12,500 E. maxima ; 12,500 E. tenella ; 62,500 E. acervulina ), and the low challenge dose (6,250 E. maxima ; 6,250 E. tenella ; 31,250 E. acervulina ). A total of three hundred sixty 13-day-old male broiler chickens were randomly allocated into 5 treatments with 6 replicated cages. Growth performance was calculated from 0 to 6 D postinfection (DPI) . Intestine lesion was scored on 6 DPI. Gastrointestinal permeability was measured on 3, 5, 6, 7, and 9 DPI. The results indicated significant linear reduction in growth performance, intestinal villi height, and ileal nutrient digestibility in response to the increase of Eimeria challenge dose. Furthermore, gene expression of tight junction protein was linearly upregulated by the increasing challenge doses. Significant linear increases of gastrointestinal permeability were found on 5, 6, and 7 DPI ( P < 0.01). On 9 DPI, the gastrointestinal permeability was recovered back to normal level in the challenge groups. In conclusion, the higher Eimeria doses birds received, the more severe intestine damage was observed in several gastrointestinal health parameters. The medium-low or medium-high levels of mixed Eimeria oocysts is suggested as an optimum Eimeria -challenge dose to establish a subclinical challenge model for future studies evaluating nutritional strategies. Moreover, it is recommended to measure gastrointestinal permeability on 5 DPI with higher oocysts doses and 6 DPI when using the lower oocysts doses.

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The aim of this study was to investigate the effect of heat stress (HS) on digestibility of protein and fat and the expression of nutrient transporters in broilers. Forty-eight male Cobb500 chicks were used in this study. At day 14, birds were randomly divided into two groups and kept under either constant normal temperature (25 °C) or high temperature (35 °C) in individual cages. Five birds per treatment at 1 and 12 days post-treatment were euthanized, and Pectoralis major (P. major) and ileum were sampled for gene expression analysis. At day 33, ileal contents were collected and used for digestibility analysis. The total consumption and retention of protein and fat were significantly lower in the HS group compared to the control group. Meanwhile, the retention of crude protein per BWG was significantly higher in the HS group compared to the control group. In P. major and ileum tissues at day 1, transporters FATP1 and SGLT1 were down-regulated in the HS group. Meanwhile, FABP1 and PepT1 were down-regulated only in the ileum of the HS group. The converse was shown in P. major. The nutrient transporter FABP1 at day 12 post-HS was down-regulated in the P. major and ileum, but GLUT1 and PepT2 were down-regulated only in the ileum, and PepT1 was down-regulated only in the P. major compared with the control group. These changes in nutrient transporters suggest that high ambient temperature might change the ileum and P. major lipids, glucose, and oligopeptide transporters.

Supplementation of broiler diets with feed additives such as chemotherapeutic drugs and antibiotics has side effects, meat residues, and antibiotics resistance complications. Plant-derived natural compounds could be safe and easy substitutes for chemical additives. One of the natural compounds is curcumin, the extract from herbal plant Curcuma longa , known for its antioxidant and antimicrobial properties which may be effective in reducing coccidia infection in poultry. The objective of this study was to evaluate the effects of curcumin on Eimeria challenged ( C ) and nonchallenged ( NC ) Cobb 500 broilers. A total of 360 12-day-old male chicks were housed in 36 cages in a completely randomized design with 6 replicates per treatment of 10 birds each cage. The six corn–soybean meal–based treatment diets were fed from day 12 to 20 to C and NC birds in 3-by-two factorial arrangement: nonchallenged control ( NCC ), NC + 100 mg/kg curcumin, NC + 200 mg/kg curcumin, challenged control ( CC ), C + 100 mg/kg curcumin, and C + 200 mg/kg curcumin. Broilers in C groups were inoculated orally with 50,000 oocysts of Eimeria maxima , 50,000 oocysts of Eimeria tenella , and 250,000 oocysts of Eimeria acervulina on day 14. The intestinal permeability (day 19), growth performance parameters, and intestinal lesion scoring were measured and recorded on day 20. The means were subjected to two-way ANOVA, and main factors effect and their interactions were considered. The growth performance and permeability were higher ( P < 0.001) in the NC and C groups, respectively. However, no interaction was observed between curcumin dose and cocci challenge on both of these parameters. Results from lesion scores and oocyst shedding showed reduction ( P < 0.050) in birds fed C + 200 mg/kg curcumin compared with those fed C + 100 mg/kg curcumin or CC. Curcumin treatment showed higher production of GSH ( P = 0.002) and total glutathione (GSH+2GSSG) ( P = 0.002) but lower GSH/GSSG ratio ( P < 0.001) than the NCC group. Curcumin exhibited some positive responses on antioxidant capacity, lesion score, and oocyst shedding in the present study, suggesting that curcumin alone or a combination with other feed additives could be a dietary strategy to improve gut health in broilers.

Broilers infected with Eimeria brunetti and given dietary zinc were examined for experimental induction of necrotic enteritis. Inoculation with sporulated E. brunetti oocysts at 7 days of age was followed by 5 consecutive days of oral inoculation with cultured Clostridium perfringens. Feed was supplemented with zinc at 1000 ppm. Upon necropsy of broilers 6 days after coccidial inoculation, necrotic enteritis was found in 20% (2/10) of birds given both organisms and dietary zinc. Coccidial lesion scores were also highest in that group. Birds infected with E. brunetti and C. perfringens with no dietary zinc had significantly higher coccidiosis lesion scores (P less than 0.05) than groups inoculated with E. brunetti only, regardless of zinc supplementation. Alpha toxin levels in intestinal contents were low in groups infected with both organisms, regardless of zinc supplementation. Zinc was tested for effects of alpha toxin production in vitro. In the mid-log phase (6 hours incubation), a high level of alpha toxin was produced in zinc-supplemented media, but this was lost quickly in the presence of trypsin. Addition of zinc partly protected the toxin from the action of trypsin.