Passive immunization against Histomonas meleagridis does not protect turkeys from an experimental infection

Histomonosis or blackhead is a disease of gallinaceous birds, caused by the protozoan Histomonas meleagridis. As recent regulatory action has removed almost all drugs against this disease from the European market, the development of new prophylactics has become crucial. Identification of the protective immune mechanism would facilitate the choice and development of a vaccination strategy to prevent histomonosis. In this study, turkeys were either actively or passively immunized and were then challenged to assess the role of antibody-mediated immunity in the protection form this disease. Active immunization was performed either by experimental infection and treatment or by intramuscular injection with lysed H. meleagridis. Passive immunization was attempted by intraperitoneal administration of pooled, concentrated, neutralizing antisera from immunized donor animals to naive turkeys. A significantly higher IgG response was observed after infection and treatment than after intramuscular injection, which in turn was higher than the responses of placebo and control birds. While active immunization of turkeys by intramuscular injection of dead H. meleagridis antigens appeared not to be protective against histomonosis, immunization by infection and treatment did induce protection. However, no significant level of protection could be observed in the passively immunized birds. These results suggest that serum antibodies to H. meleagridis may not be a key component in the protection against this parasite. It is, however, possible that the concentration of antibodies at the mucosal site is insufficient. Therefore, further investigation on mucosal immune responses is necessary

Host intestinal biomarker identification in a gut leakage model in broilers

International audienceAbstractIntestinal health problems are a major issue in the poultry industry. Quantifiable easy-to-measure biomarkers for intestinal health would be of great value to monitor subclinical intestinal entities that cause performance problems and to evaluate control methods for intestinal health. The aim of the study was to identify host protein biomarkers for intestinal inflammation and intestinal barrier damage. Proteomic analysis was conducted on ileal and colonic content samples of broilers under an experimental gut damage and inflammation model. Effects of the challenge treatment resulted in a worse gut condition based on macroscopic gut appearance (p < 0.0001). Also microscopic changes such as shortening of the villi and increased crypt depth (p < 0.0001) as well as higher infiltration of T-lymphocytes (p < 0.0001) were seen in the duodenal tissue of challenged animals. Several candidate proteins associated with inflammation, serum leakage and/or tissue damage were identified with an increased abundance in intestinal content of challenged animals (p < 0.05). Conversely, brush border enzymes were less abundant in intestinal content of challenged animals (p < 0.05). These candidate biomarkers have potential to be used in the field for detection of gut barrier failure in broilers

Elevated faecal ovotransferrin concentrations are indicative for intestinal barrier failure in broiler chickens

Intestinal health is critically important for the welfare and performance of poultry. Enteric diseases that cause gut barrier failure result in high economic losses. Up till now there is no reliable faecal marker to measure gut barrier failure under field conditions. Therefore, the aim of the present study was to identify a faecal protein marker for diminished intestinal barrier function due to enteric diseases in broilers. To assess this, experimental necrotic enteritis and coccidiosis in broilers were used as models for gut barrier failure. Ovotransferrin was identified as a marker for gut barrier failure using a proteomics approach on samples from chickens with necrotic enteritis. These results were confirmed via ELISA on samples derived from both necrotic enteritis and coccidiosis trials, where faecal ovotransferrin levels were significantly correlated with the severity of gut barrier failure caused by either coccidiosis or necrotic enteritis. This indicates that faecal ovotransferrin quantification may represent a valuable tool to measure gut barrier failure caused by enteric pathogens

Broiler signals : a practical guide to broiler focused management/ Maarten de Gussem (et al)

120 hal.: ill, tab.; 26 cm

Broiler signals : a practical guide to broiler focused management/ Maarten de Gussem (et al)

120 hal.: ill, tab.; 26 cm

Passive immunization against Histomonas meleagridis does not protect turkeys from an experimental infection

Histomonosis or blackhead is a disease of gallinaceous birds, caused by the protozoan Histomonas meleagridis. As recent regulatory action has removed almost all drugs against this disease from the European market, the development of new prophylactics has become crucial. Identification of the protective immune mechanism would facilitate the choice and development of a vaccination strategy to prevent histomonosis. In this study, turkeys were either actively or passively immunized and were then challenged to assess the role of antibody-mediated immunity in the protection form this disease. Active immunization was performed either by experimental infection and treatment or by intramuscular injection with lysed H. meleagridis. Passive immunization was attempted by intraperitoneal administration of pooled, concentrated, neutralizing antisera from immunized donor animals to naive turkeys. A significantly higher IgG response was observed after infection and treatment than after intramuscular injection, which in turn was higher than the responses of placebo and control birds. While active immunization of turkeys by intramuscular injection of dead H. meleagridis antigens appeared not to be protective against histomonosis, immunization by infection and treatment did induce protection. However, no significant level of protection could be observed in the passively immunized birds. These results suggest that serum antibodies to H. meleagridis may not be a key component in the protection against this parasite. It is, however, possible that the concentration of antibodies at the mucosal site is insufficient. Therefore, further investigation on mucosal immune responses is necessary.status: publishe

Incidence and associated risk factors of necrotic enteritis in Belgian layer pullet flocks

Necrotic enteritis (NE) caused byClostridium perfringensis commonly reported in broilers. Recently, increased NE prevalence in layer breeds was reported in the Indian subcontinent. NE is also frequently observed by veterinary practitioners in Europe, mainly during the pullet rearing phase. In this study, data from layer pullet flocks in Belgium over a 5-year period (2013-2017) were used to assess the incidence of NE and identify potential risk factors for NE in layer pullets. NE was observed in 26% of the layer pullet flocks receiving veterinary intervention. This accounts for an overall estimated NE incidence of 12.3% in Belgian layer pullet flocks. Occurrence of NE was significantly associated with coccidiosis, with flocks being diagnosed with coccidiosis being two-fold more likely to develop NE. Additionally, birds kept in aviary houses were less prone to NE than flocks reared in floor systems or enriched cages. At necropsy, necrotic lesions in the small intestine were comparable to NE in broilers. A single strain ofC. perfringenswas isolated from the necrotic lesions of three different birds from the same flock; however, no NetB could be detected

The effect of commonly used anticoccidials and antibiotics in a subclinical necrotic enteritis model

Necrotic enteritis poses an important health risk to broilers. The ionophore anticoccidials lasalocid, salinomycin, maduramicin, narasin and a combination of narasin and nicarbazin were tested in feed for their prophylactic effect on the incidence of necrotic enteritis in a subclinical experimental infection model that uses coccidia as a predisposing factor. In addition, drinking water medication with the antibiotics amoxicillin, tylosin and lincomycin was evaluated as curative treatment in the same experimental model. The minimal inhibitory concentrations (MICs) of all antibiotics and anticoccidials were determined in vitro against 51 Clostridium perfringens strains isolated from broilers. The strains examined appeared uniformly susceptible to lasalocid, maduramicin, narasin, salinomycin, amoxicillin and tylosin, whereas an extended frequency distribution range of MICs for lincomycin was seen, indicating acquired resistance in 36 isolates in the higher range of MICs. Nicarbazin did not inhibit the in vitro growth of the C. perfringens strains even at a concentration of 128 µg/ml. Supplementation of the diet from day 1 onwards with lasalocid, salinomycin, narasin or maduramicin led to a reduction in birds with necrotic enteritis lesions as compared with the non-medicated infected control group. A combination product of narasin and nicarbazin had no significant protective effect. Treatment with amoxicillin, lincomycin and tylosin completely stopped the development of necrotic lesions

Using a neural network based vocalization detector for broiler welfare monitoring

The poultry industry in Flanders, Belgium, is characterized by highly efficient production systems. To assure sustainable food production, where broiler quality of life is key, data collection systems and (automated) interpretation of broiler health and welfare are of capital importance. This paper describes the realization and deployment of an acoustic detector for broiler vocalizations, as part of a larger set of behavior and welfare monitoring tools developed within the ICON-WISH project. The vocalization detector is based on a convolutional neural network. For training, a labelled library with vocalizations is built (>2k samples), based on a large set of broiler audio recordings covering the full broiler life-span. Four different types of vocalizations (pleasure notes, distress calls, short peeps and warbles) are identified in function of broiler age to account for spectral changes. Based on this library, the neural network achieves a balanced accuracy of 87.9%. To indicate its potential, the detector is applied in a real-life medium scale housing, in which several groups of broilers are exposed to different environmental conditions (heat stress a.o.). The occurrence and type of vocalizations is analyzed, and the potential to identify broiler stress is investigated