Detection of quinolones in commercial eggs obtained from farms in the Espaíllat Province in the Dominican Republic.

Previously, we reported the use of quinolones in broiler chickens resulted in residues in retail poultry meat obtained from nine districts in the Santiago Province of the Dominican Republic. Residues in poultry products are a concern due to consumer allergies and the potential to develop antibiotic-resistant bacteria. Given the use of quinolones in poultry production and our previous findings in poultry meat, the objective of this study was to evaluate the presence of quinolone residues in eggs. Samples were collected from 48 different farms located in three of the four municipalities (Moca, Cayetano Germosén, and Jamao) of the Espaíllat Province. Each farm was sampled three times between July and September for a total of 144 samples. Samples were evaluated qualitatively and quantitatively for quinolone residues using the Equinox test. Operation systems (cage or floor), seasonality, and location were considered along with egg-producer sizes that were defined as small scale, <30,000 eggs per day; medium scale, 30,000 to 60,000 eggs per day; or large scale, >60,000 eggs per day. From small-, medium-, and large-scale producers, 69, 50, and 40% of samples were positive for quinolone residues, respectively. A greater number of samples were positive (61%) in floor-laying hen producers compared with those using cages (40%). In the Jamao municipality, 67% of the samples were positive compared with Moca and Cayetano Germosén, where 56 and 25% of samples were positive, respectively. Sampling time had an effect on percent positives: samples collected in July, August, and September were 71, 19, and 63% positive, respectively. Overall, 51% of the samples obtained from eggs produced in the province of Espaíllat were positive for quinolone residues at levels higher than the maximum limits for edible tissue established by the regulatory agencies, including the European Union and U.S. Department of Agriculture. The results obtained from this research confirmed the presence of quinolone residue in eggs, which may present a health risk to some consumers.

Upregulation of oxidative burst and degranulation in chicken heterophils stimulated with probiotic bacteria.

The immune system of neonatal chicks is functionally immature during the first week of life. Researchers have previously demonstrated that the avian humoral response can be increased with probiotics. Although the humoral response provides the chick with an effective mechanism to combat pathogens, sufficient antibody titers are not attained until 7 to 10 d postinfection. However, the innate immune system (i.e., heterophils) can respond much more quickly to pathogens. The objective of this study was to determine whether probiotic bacteria can also upregulate heterophil function. Heterophils were isolated from the peripheral blood of neonatal chickens by using a discontinuous density gradient. Oxidative burst and degranulation are bactericidal mechanisms used by heterophils to kill pathogens and were used in this study as indicators of heterophil function. We found that each of the 10 "generally recognized as safe" probiotic isolates (designated G1 to G11) tested in vitro were capable of increasing (P < 0.05) heterophil oxidative burst and degranulation when compared with unstimulated controls. Bacillus subtilis (G3), Lactococcus lactis lactis (G6), and Lactobacillus acidophilus (G8) isolates were determined to elicit the greatest heterophil response in vitro and were subsequently fed to chicks. Phosphate-buffered saline or 1 of these 3 probiotic isolates (approximately 2.5 x 10(8) cfu/chick; 50 chicks/treatment) resuspended in PBS was administered by oral gavage on the day of hatch. Heterophils were isolated from chicks from each of these 4 treatment groups 24 h posttreatment. Significant increases in heterophil degranulation and oxidative burst were observed with the G3-, G6-, and G8-treated chicks when compared with heterophils isolated from birds with no probiotic treatment. These data suggest that probiotic bacteria can significantly improve heterophil oxidative burst and degranulation in broilers. To our knowledge, this is the first study demonstrating a relationship between probiotics and avian heterophil function.

Effect of oral administration of bismuth compounds on Campylobacter colonization in broilers.

Bismuth compounds have been used since the 18th century to treat gastrointestinal ailments in man. Colloidal bismuth subcitrate (De-Nol) is currently used in combination with antibiotics to reduce enteric Helicobacter pylori colonization as a treatment of stomach ulcers. We investigated whether bismuth citrate or its parent compound, colloidal bismuth subcitrate, would reduce colonization of the closely related foodborne pathogen, Campylobacter jejuni in chickens. In 2 studies, birds were either fed 0, 50, or 200 ppm bismuth citrate or bismuth subcitrate (De-Nol) for 10 or 21 d and were orally challenged with 7 combined strains of C. jejuni (n = 6 birds/treatment). For both treatment groups, cecal Campylobacter colonization was reduced when birds were fed 200 ppm for 10 d but not 21 d. For the 50 ppm treatment group, only birds dosed with bismuth citrate for 21 d demonstrated any reduction in cecal Campylobacter concentrations when compared with controls. These data suggest that bismuth citrate and colloidal bismuth subcitrate may reduce cecal colonization by Campylobacter in broilers, but these effects are inconsistent.

Hypobaric hypoxia in ascites resistant and susceptible broiler genetic lines influences gut morphology.

Genetic selection based on rapid growth rates, improved feed conversion, and increased body weights has led to a predisposition to ascites in broiler populations. Sire-family selection was applied to a commercial elite line to produce divergent lines of ascites-resistant (RES) and ascites-susceptible (SUS) broilers by the 8th generation. One objective of this research was to determine the effects of hypobaric hypoxia on gut morphology in these genetic lines. In two separate trials, pedigree broiler chickens were randomly assigned to cages in a hypobaric chamber (simulated 2,900 m above sea level) or a matching local altitude chamber (390 m above sea level). Ascites incidence was characterized by heart enlargement and fluid accumulation in the abdominal cavity. At the end of the study on d 42, all surviving birds were killed and evaluated for the presence of ascites and 2-cm sections from the duodenum and lower ileum were collected from 5 chickens per line, per altitude for each trial for morphometric analysis. At a high altitude, ascites incidence was lower in the RES line (20.9 and 3.7%) than in the SUS line (86.4 and 66.9%, Trials 1 and 2, respectively). No ascites was observed at a local altitude. Under hypoxic conditions, duodenum villus surface area was higher (P < 0.05) in the RES line (181.3 +/- 16.8 and 219 +/- 10.9 microm) compared with the SUS line (130.1 +/- 10.5 and 134.3 +/- 9.3 microm; Trials 1 and 2, respectively). No differences in ileum villus morphology were observed for any of the parameters measured. The reduced surface area in the duodenum of birds selected for ascites susceptibility suggests reduced enteric function and may provide clues as to why these birds have increased incidence of ascites.