Monensin, Eimeria tenella infection, and effects on the bacterial populations in the ceca of gnotobiotic chickens

Coccidia-Microbiota Interactions and Their Effects on the Host

As a common parasitic disease in animals, coccidiosis substantially affects the health of the host, even in the absence of clinical symptoms and intestinal tract colonization. Gut microbiota is an important part of organisms and is closely related to the parasite and host. Parasitic infections often have adverse effects on the host, and their pathogenic effects are related to the parasite species, parasitic site and host-parasite interactions. Coccidia-microbiota-host interactions represent a complex network in which changes in one link may affect the other two factors. Furthermore, coccidia-microbiota interactions are not well understood and require further research. Here, we discuss the mechanisms by which coccidia interact directly or indirectly with the gut microbiota and the effects on the host. Understanding the mechanisms underlying coccidia-microbiota-host interactions is important to identify new probiotic strategies for the prevention and control of coccidiosis.

Interactions Between Parasites and the Bacterial Microbiota of Chickens

Except for the important role coccidia have as predisposing factors of necrotic enteritis, the role parasites play in the dynamics of a healthy microbiota of chickens is not well explored. This review describes the interactions of relevant intestinal parasites of chickens with bacteria. Infection with Eimeria spp. favor the growth of Clostridium perfringens and suppress the growth of many other bacteria by increasing viscosity and passage time of the ingesta, and by causing lesions to the intestinal mucosa that improve the availability of nutrients for C. perfringens. Conversely, there are indications that bacteria influence the course of disease after infections with Eimeria spp. Not much is known about intestinal cryptosporidiosis in chickens, but results in mice show that the intestinal microbiota induces some resistance against infection with Cryptosporidium parvum and that the innate immune response triggered by infections with cryptosporidia might have an effect on other intestinal microbes. Histomonas meleagridis depend on bacteria in vitro, and in vivo it will cause lesions in chickens only in the presence of bacteria. Blastocystis spp. are very common in chickens, but there is no information about interactions with bacteria. In humans, there is evidence of the correlation of the detection of Blastocystis and changes in the intestinal microbiota. There are indications of interactions between Ascaridia galli and various bacteria in chickens and Ascaridia spp. of mammals are known to produce various types of antimicrobial molecules. However, often the underlying mechanisms of these interactions between parasites and bacteria remain unknown and only correlations but not causation can be established.

Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity

Coccidiosis and necrotic enteritis (NE) are globally common, sometimes intercurrent, diseases of poultry. The risk of NE, due to the Gram-positive bacterium Clostridium perfringens, has increased in recent years because of the voluntary or legally required withdrawal of the use of certain in-feed antibiotic growth promoters with anticlostridial activity. In-feed ionophorous anticoccidial drugs incidentally also possess anticlostridial activity. Such ionophores, although not banned, are usually precluded when live anticoccidial vaccines are used, potentially increasing yet further the risk of NE. This review provides information for the design of rational, integrated management strategies for the prevention and control of coccidiosis and NE in chickens by maintaining gut integrity. Because of differences in local availability of feed ingredients and national legislations regarding antibiotic growth promoters and anticoccidial vaccine licensing, no universal strategy is applicable. The diseases and their interactions are described under the headings of forms of disease, diagnosis, sources of infection, pathophysiological effects, predisposing factors, and control methods. Elements of gut integrity, which influences host predisposition and clinical responses to disease, include physical development, immune competence, gut enzyme activity, mucin production, gut flora and epithelial damage. Experimental studies of coccidiosis and NE are compared, and where possible reconciled, with field observations. Gaps in knowledge and necessary further experiments are identified. Insights are provided regarding interactions between coccidiosis, NE, and the use of live anticoccidial vaccines. Recent changes in NE prevalence in commercial flocks, and their possible causes, are discussed. The necessarily wide range of topics reviewed emphasizes the enormous complexity of this disease combination, and indicates the importance of a multidisciplinary approach in order to reduce its harmful impact on the world's poultry industry.

Effects of dietary protein source and level on intestinal populations of Clostridium perfringens in broiler chickens

Two experiments were conducted to examine the effect of the level of dietary crude protein and protein source on intestinal populations of Clostridium perfringens in broilers. In experiment 1, 6 groups of 12 birds were fed diets containing 230,315 or 400 g/kg crude protein with soy protein concentrate (SPC) or low-temperature-dried fishmeal as the major protein sources in a 2 x 3 factorial arrangement of treatments. A significant interaction between protein source and level was observed where the number of C. perfringens present in the ileum and cecum increased as the level of crude protein in the diets increased from 230 to 400 g/kg in the birds fed fishmeal-based diets (P < 0.05) but not in the birds fed SPC-based diets. In experiment 2, the dietary treatments used were arranged in a 2 x 2 factorial arrangement with 2 levels of crude protein (230 and 400 g/kg) and 2 protein sources (SPC or fishmeal). The main effects of protein source and protein level significantly (P < 0.05) affected numbers of C. perfringens without interaction. Amino acid analysis of the diets showed that the glycine and methionine contents of the fishmeal diets were elevated compared with the SPC diets. This suggests that the level of crude protein, protein source, and amino acid content of diets affect the growth of C. perfringens in the lower intestinal tract of the broiler chicken and might be predisposing factors to outbreaks of clinical necrotic enteritis.

In-vitro antimicrobial susceptibility of Clostridium perfringens from commercial turkey and broiler chicken origin

The minimum inhibitory concentrations (MIC) of eight antibiotics and two anticoccidial agents were determined for Clostridium perfringens strains isolated from 26 commercial broiler farms and 22 commercial turkey farms. Isolates were obtained from the intestines of birds on the farm or as the processing plant using standard culture and identification techniques. The microbroth dilution test was used to determine the MIC for each compound. Most isolates from chickens had MICs in the range of 2-16 mg/L for tilmicosin, tylosin and virginiamycin, whereas the MICs for avilamycin, avoparcin, monensin, narasin and penicillin were < or = 1 mg/L. Most strains from chickens had high MICs (> or = 64 mg/L) and appeared to be resistant to bacitracin and lincomycin. Most turkey isolates had MICs in the range of 2-16 mg/L for bacitracin, tilmicosin, tylosin and virginiamycin, with strains exhibiting MICs < or = 1 mg/L for avilamycin, avoparcin, monensin, narasin and penicillin. Several turkey isolates had MICs > or = 64 mg/L to lincomycin. No attempt was made to associate farm usage of a particular antibiotic to the antibiograms.

Effect of dietary fat, fiber, and monensin on cecal activity in turkeys

Two experiments were conducted to determine the physical, chemical, and microbial properties of turkey cecal droppings and relate them to intake of common dietary components, namely fat, fiber, and the anticoccidial, monensin. Experiment 1 involved collection and analysis of physical and chemical properties of cecal and regular droppings from commercial turkey flocks. Experiment 2 tested the effect of dietary fat, fiber, and monensin on growth performance and cecal activity in male turkeys. Compared to regular excreta, cecal droppings analyzed in Experiment 1 were higher in viscosity and fat content, and lower in dry matter, nitrogen, and fiber content (P < 0.05). High dietary fiber and fat significantly (P < 0.05) improved growth performance in Experiment 2. Prolonged feeding of monensin significantly (P < 0.05) reduced cecal evacuation. Results of chemical composition showed that higher dietary fat and fiber significantly (P < 0.01) reduced the fat percentage of cecal contents, whereas prolonged feeding of monensin increased the fat in both cecal contents and droppings. There was no significant effect of any of the treatments on pH, viscosity, and microbial counts of cecal contents. There is the need to identify and characterize the compound responsible for the high viscosity of cecal droppings.

Sensitivity of Escherichia coli O157:H7 strain 932 to selected anticoccidial drugs in broiler chicks

The ability of selected anticoccidial drugs to inhibit the colonization of day-old male broiler chicks (Cornish Rocks) by Escherichia coli O157:H7, strain 932 was examined. Chicks were challenged with 1.8 x 10(9) E. coli O157:H7 on Day 1, and fed diets supplemented with three selected anticoccidial drugs; monensin, nicarbazin, or robenidine. The cecal and colon fecal contents of the chicks were removed on Day 7, 14, and 21 postinoculation and examined for the concentration of E. coli O157: H7 per gram of contents. Monensin effectively reduced cecal and colon colonization of the chicks by E. coli O157:H7. By Day 7, there were significant reductions in the bacterial population of the cecal contents of chicks receiving the monensin-medicated feed, and by Day 21 no E. coli O157:H7 was recovered from the cecal and colon contents. The bacterial counts in the colon contents of the nicarbazin- and robenidine-medicated and unmedicated chicks were significantly higher than the monensin-treated chicks. Bacterial populations in the colon contents were high only when there were high bacterial concentrations in the cecal contents.

Factors affecting the incidence of necrotic enteritis, caecal carriage of Clostridium perfringens and bird performance in broiler chicks

Two trials were conducted to study the effects of a competitive exclusion (CE) product BROILACT and the anticoccidial narasin on the incidence of necrotic enteritis (NE), the numbers of Clostridium perfringens (CP) in the caeca of broiler chicks and the performance of the birds. In trial 1 the effects of type of protein and partial replacement of a narasin containing diet with whole wheat were also studied. All groups of chicks were studied up to the point of slaughter at 43 days of age and after evisceration in a processing plant to determine slaughter yield. In trial 1, statistically significant results included the following: CE-treatment reduced total mortality, and incidence of NE, on diet containing animal but not vegetable protein. Caecal carriage of CP was also reduced, while slaughter yield increased. Narasin reduced caecal carriage of CP and increased both growth rate and slaughter yield in both trials. Whole wheat replacement improved feed conversion but reduced bird growth rate. In trial 2, both CE-treatment and narasin influenced feed intake, CE-treatment significantly only at days 22 and 44. Narasin improved feed conversion until 5 weeks of age and CE-treatment did so until 22 days of age. In both trials, there was also an interaction effect indicating that CE-treatment increased slaughter yield for birds that were not fed narasin.

The effect of feeding diets containing avoparcin and monensin on the occurrence of Salmonella in caecum and liver in experimentally infected chickens

In two experiments (Experiments A and B) chickens experimentally infected with S. infantis at 7 days of age and fed diets containing both avoparcin (10 ppm) and monensin (90 ppm) showed a higher frequency of Salmonella-positive livers and higher caecal counts of Salmonella 1 and 2 weeks after challenge than similarly infected chickens fed only avoparcin (10 ppm). The results may indicate a synergistic action between the two drugs on the ability of chickens to withstand Salmonella infections.