Heat stress negatively affects performance and intestinal integrity of livestock. Our objective was to characterize the effects of diurnal heat stress on nursery-grower pig performance and intestinal integrity. Forty-eight individually penned crossbred gilts (21 ± 2.0 kg BW) were randomly assigned across two environmental treatments (thermal neutral (TN) or diurnal heat stress (HS), n = 24/trt) at the Iowa State University Swine Nutrition Farm. All pigs were allowed ad libitum access to water and a corn-soybean diet that met or exceeded NRC (2012) requirements. After a thermal neutral acclimation period, 24 pigs (HS) were exposed to 3 d of diurnal heat stress with 6 h in HS conditions (38°C; 40–60% humidity) and 18 h in thermal neutral conditions (32°C; 40–60% humidity). The remaining 24 TN pigs were maintained for these 3 d under thermal neutral conditions (28°C; 40–60% humidity). Pig rectal temperature (Tr), respiration rates (RR), BW changes, and feed disappearance were recorded over the environmental treatment. Blood samples were collected at the end of the 3 d environmental treatment and metabolites, endotoxin, cytokines, and acute phase proteins were evaluated. All pigs were sacrificed after the 3 d environmental treatment and ex vivo ileum integrity was assessed in Ussing chambers by measuring transepithelial resistance (TER), FITC-dextran (FD4), and FITC-LPS permeability. As expected, HS pig Tr were increased on average 2°C over the 3 d period (P < 0.05) and RR increased from 50 to 150 breathes per min (TN verses HS, respectively, P < 0.01). Compared to TN, HS pigs had a 30% reduction in ADFI and a 76% reduction in ADG over the 3 d environmental treatment (P < 0.05). Gain to feed was also reduced due to HS compared to TN (0.16 verses 0.55, P = 0.016). Ileum TER was significantly decreased (P = 0.04), FTIC-LPS (P < 0.01) and FD4 (P = 0.015) permeability increased due to HS compared to TN pigs. Serum endotoxin was significantly elevated due to HS (P = 0.031) and there was a reduction in LPS-binding protein (P = 0.06) and tumor necrosis factor α (P = 0.04) in HS compared to TN pigs. Overall, HS reduced blood insulin concentrations by 50% (P = 0.02), but did not affect blood glucose concentrations (P = 0.47). Altogether, short exposure to diurnal heat stress significantly reduced pig performance and intestinal integrity compared to those exposed to thermal neutral conditions.
Development of a competitive exclusion product for chicken meeting the regulatory requirements for registration in the EU R. Plail , V. Klose , M. Mohnl , D. Jolli , A. Klimitsch , G. Schatzmayr, A.P. Loibner , University of Natural Resources and Applied Life Sciences, Interuniversity Department for Agrobiotechnology, A-3430 Tulln, Konrad Lorenzstrasse 20, 2 Biomin GmbH, A-3130 Herzogenburg, Industriestrasse 21. E-mail: regina.plail@boku.ac.at
The control of coccidiosis, an infection of the intestinal tract, is a fundamental concern in poultry farming. In this study an in vitro model was used to simulate the first stage of an infection, the invasion of epithelial cells in the cecum by Eimeria tenella sporozoites. This model was applied to screen various phytogenic samples for their ability to inhibit cell invasion. Fluorescence-labeled sporozoites were co-cultured with Madin-Darby bovine kidney (MDBK) cells in the presence of samples, cell culture medium (negative control) or monensin sodium (positive control). After incubation fluorescent intracellular sporozoites were counted either by microscope or flow cytometer and relative inhibition rates were calculated. Monensin sodium showed a MIC50 of 180 nM. Among the tested phytogenics quinine (1) (MIC50=2.5–19.3µM) and cinchonidine (2) (MIC50=2.7–21.2µM) performed best. Other Cinchona alkaloids showed less effect. A link between molecular configuration and anti-eimerial activity is assumed.
Lipopolysaccharides (LPS), also termed endotoxins, are the major component of the outer membrane of Gram-negative bacteria. In general, endotoxins in the intestine are considered harmless in healthy animals. However, different stressors, such as heat stress, can lead to a compromised gut barrier, resulting in endotoxin translocation. Chickens are considered to be less sensitive to the effects of LPS compared with other species, for example, humans, pigs, or calves, probably because of the lack of the functional-specific TRAM-TRIF signalling pathway (MyD88-independent). Therefore, six LPS preparations (three different strains with two different preparation methods each) were compared in murine macrophages and characterized according to their MyD88-dependent pathway activation. All tested LPS preparations induced a strong inflammatory response after 4 and 24 h on a murine macrophage cell line. However, there was a similar strong response in the gene expression profile as well as production of nitrite oxide and TNF-alpha from LPS of different strains and preparation methods. On the basis of the results of the in vitro study, one LPS preparation was chosen for the subsequent in vivo study with broilers to assess the effect of an oral LPS bolus (E. coli O55:B5 phenol extracted; 2 mg/kg b.w.) during heat stress conditions (10 h, 36 °C). The most pronounced effects were seen in broilers receiving the oral LPS bolus during heat stress conditions. The endotoxin activity in the intestine as well as the serum concentration of the 3-OH C14 (part of LPS) were increased. In addition, an increased expression of genes related to inflammation and stress response (e.g., IL-6, IL-1beta, HSP70) was observed, whereas the expression of genes associated with gut health (e.g., MUC2, FABP2) was decreased. To conclude, an increase of intestinal LPS combined with heat stress can pose a risk to animal health.
Deoxynivalenol (DON), produced by the plant pathogens Fusarium graminearum and Fusarium culmorum, is one of the most common mycotoxins, contaminating cereal and cereal-derived products. Although worldwide contamination of food and feed poses health threats to humans and animals, pigs are particularly susceptible to this mycotoxin. DON derivatives, such as deepoxy-deoxynivalenol (DOM-1), are produced by bacterial transformation of certain intestinal bacteria, which are naturally occurring or applied as feed additives. Intestinal epithelial cells are the initial barrier against these food- and feed-borne toxins. The present study confirms DON-induced activation of MAPK p44/42 and inhibition of p44/42 by MAPK-inhibitor U0126 monoethanolate. Influence of DON and DOM-1 on transepithelial electrical resistance (TEER), viability and expression of seven tight junction proteins (TJ), as well as the potential of U0126 to counteract DON-induced effects, was assessed. While DOM-1 showed no effect, DON significantly reduced TEER of differentiated IPEC-J2 and decreased expression of claudin-1 and -3, while leaving claudin-4; ZO-1, -2, and -3 and occludin unaffected. Inhibition of p44/42 counteracted DON-induced TEER decrease and restored claudin-3, but not claudin-1 expression. Therefore, effects of DON on TEER and claudin-3 are at least partially p44/42 mediated, while effects on viability and claudin-1 are likely mediated via alternative pathways.
Occurrence of mycotoxins is ubiquitous. Even with the use of prevention techniques, it is virtually impossible to avoid their presence in agricultural commodities. The toxicity of these fungal metabolites brings serious risks upon humans and animals. Mycotoxicoses are animal or human diseases caused by mycotoxin ingestion, inhalation or skin-contact. In animals, these range from immunosuppression and performance effects to hepatotoxic, nephrotoxic, neurotoxic, dermal, carcinogenic, reproductive, teratogenic and gastro-intestinal effects depending on animal-, environmental- and toxin-related factors. A suitable mycotoxin risk management should take the different chemical structures of mycotoxins into consideration as a successful strategy for one mycotoxin, may fail in the elimination of another. Biotransformation and biodegradation are mycotoxin-specific methods which rely in microorganisms and enzymes' capacity of metabolization or degradation of mycotoxins into less or non-toxic metabolites prior to their resorption in the gastro-intestinal tract. Some microorganisms have shown biotransformation capacity both in vitro and in vivo, representing effective mycotoxin risk management tools in animal feed.
