The intestinal wall has on its surface, protrusions called villi that are responsible for the absorption of nutrients. Commonly, these structures have their dimensions measured to related more area surface with better absorption. However, the measurement of these villi neglects the inflammation and the presence of immature cells that increase the surface area but affect negatively the absorption and compromise the animal performance. The measurements of villi/crypt are traditional tools in animal research; however, they may overlook alterations that impact the mucosal functionality. This study aimed to compare the morphometry of the intestinal villi/crypt with the I See Inside (ISI) scoring methodology, exploring their correlation with zootechnical performance. Therefore, broilers were grouped as nonchallenged (NC) and challenged with Eimeria (CH) and jejunum samples were collected at 22 d for histological analysis. The same villi were submitted to the ISI methodology, which is based on the scoring of 8 parameters related to the inflammatory process, and the measurements of villus height (VH), villus width (VW), crypt depth (CD), crypt width (CW), VH:CD ratio and villi absorptive surface (VAS). The CH group presented higher ISI total score, VW, CD, CW and lower VH, VH:CD, and VAS in comparison to the NC group. While the villi/crypt morphometry did not exhibit correlations with performance, the presence of Eimeria oocysts and the ISI total score was positively correlated (P < 0.05) with the feed conversion ratio (FCR), demonstrating a statistical interaction between high ISI scores and worse performance. In conclusion, a larger villus is not related to better intestinal functionality when this enlargement is unleashed by the immune processes occurring inside. The scoring system that evaluates the type of alteration observed has a direct impact on the animal's zootechnical performance which is not observed with the single metric surface evaluation.

• The ISI was applied to evaluate histologic alterations specific of Eimeria infection. • The ISI histological score show high correlation with broilers performance. • The higher the ISI scores the worse are the performance results of birds challenged.

We evaluated the effects of a protease supplementation on the growth performance and intestinal health of broilers. Cobb chicks (392; 1-42 d) were divided into four treatments (seven replicates of 14 birds each). There were two feed formulations: a standard diet (SD) and a low crude protein and digestible amino acids diet (Low CP&AA). The two diets were either supplemented (+P) or not (−P) with a protease (Jefo Protease; 1.25 g kg⁻¹). Performance was evaluated by feeding phases (1-7, 8-21, 21-35, and 35-42 d). On day 28, ileum samples were analyzed by a morphometric index for histological alterations (I See Inside Scoring System – ISI). Broilers fed the Low CP&AA had a poor feed conversion ratio (FCR); however, the addition of the protease to the Low CP&AA positively affected FCR and body weight gain and promoted a performance similar to the group fed SD−P. Birds fed diets supplemented with the protease presented the best ISI morphological index, mainly as a result of the low number of alterations regarding the lamina propria, epithelial thickness, and enterocyte proliferation. It is possible to conclude that the enzyme improves feed conversion and lamina propria, epithelial thickness, and proliferation of enterocytes index of broiler chickens when added to a standard diet or with a low crude protein and digestible amino acids diet.

The effect of feeding spray-dried plasma (SDP) during the starter period was evaluated with a commercial broiler integrator on performance and overall health of broilers. The I See Inside (ISI) methodology assessing gut health in broilers was used as a tool to evaluate the impact of dietary interventions under commercial conditions. One hundred farms with approximately 1.1 million broilers were used at a Brazilian broiler integrator. Two groups of farms were fed either a control or an SDP diet containing 1% SDP, from 0 to 10 d of age. Diets were formulated to have similar nutritional density, containing zinc bacitracin and CuSO4 from 0 to 28 d. After 10 d, both groups were fed common commercial diets. Performance data were analyzed together or by type of ventilation system: positive pressure or negative pressure. Birds were sent to market as they reached 3.05 kg; therefore, age at slaughter (AS) was evaluated as a dependent variable along with other performance measures. From the 100 farms in the trial, 35 (16 control and 19 SDP farms) were selected for the assessment of broilers health, biosecurity, and local management. For that, 6 broilers per farm at 14 ± 2 d of age were necropsied and ileum sampled for the ISI methodology evaluation. Biosecurity and management were also evaluated to obtain the influence of those parameters on animal health. SDP-fed birds demonstrated improved feed conversion ratio, reduced mortality, and 1 d less for AS (P < 0.05) vs. control group (P < 0.05) regardless of the type of ventilation. During necropsy, birds fed SDP showed lower coccidiosis and locomotor system lesions as the overall ISI score compared to controls. Histologic intestinal alterations were also lower in SDP-fed broilers (P < 0.05). In conclusion, feeding 1% SDP in the starter period to broilers resulted in improved performance and health under both good and bad management and biosecurity standards independent of the type of ventilation. Overall, there was good agreement between the ISI method and performance improvements observed.

The objective of the present studies was to evaluate muramidase (MUR) supplementation in broilers under Eimeria and/or Clostridium perfringens challenge. For this, 2 experiments were conducted. Experiment 1. A total of 256 one-day old male Cobb 500 chicks were placed in battery cages in a completely randomized design, with 5 treatment groups, 7 replicate cages per treatment and 8 birds per cage. The treatments were: nonchallenged control (NC), challenged control (CC), CC + MUR at 25,000 or 35,000 LSU(F)/kg, and CC + Enramycin at 10 ppm (positive control-PC). Challenge consisted of 15× the recommended dose of coccidiosis vaccine at placement, and Clostridium perfringens (10⁸ CFU/bird) inoculation at 10, 11, and 12 d. Macro and microscopic evaluation, immunohistochemistry, and gene expression were evaluated at 7, 14, 21, and 28 d of age. Experiment 2. A total of 1,120 one-day old male Cobb 500 chicks were placed in floor pens with fresh litter in a completely randomized design, with 4 treatment groups, 8 replicate pens per treatment, and 35 birds per pen. The treatments were: Control, supplementation of MUR at 25,000 or 45,000 LSU(F)/kg, and a positive control (basal diet plus Enramycin). At 10, 11, and 12 d of the experiment all the birds were inoculated by oral gavage with a fresh broth culture of a field isolate Clostridium perfringens (0.5 mL containing 10⁶ CFU/bird). It was observed that in Experiment 1 MUR supplementation reduced the infiltration of macrophages and CD8+ lymphocytes in the liver and ileum of infected birds, downregulated IL-8 and upregulated IL-10 expression. In Experiment 2, MUR linearly improved the growth performance of the birds, increased breast meat yield, and improved absorption capacity. MUR supplementation elicited an anti-inflammatory response in birds undergoing a NE challenge model that may explain the improved growth performance of supplemented birds.