The jejunal cellular responses in chickens infected with a single dose of Ascaridia galli eggs.

This histopathological study was carried out in order to investigate the cellular response in the jejunum to Ascaridia galli during the first 7 weeks of infection. Fourty-two ISA Brown chickens (7 weeks old) were infected orally with 500 embryonated A. galli eggs each while 28 chickens were left as uninfected controls. Six infected and four control chickens were necropsied at each time point 3, 7, 10, 14, 21, 28 and 42 days post-infection (dpi). Samples for histopathology were taken from three sites of the jejunoileum. Significantly higher eosinophil counts were seen in infected chickens compared to uninfected at 3, 7, 10, 14 and 28 dpi (P < 0.01). In both groups, the initial number of mast cells was high, but this high level of mast cells remained for a longer period in the infected group compared to the control group. Significantly higher counts were thus found in the infected group at 21 (P < 0.001), 28 (P < 0.01) and 42 dpi (P < 0.05). A. galli infection induced changes in the mucosal thickness as reduced villi length at 7, 10, 14, 21 and 28 dpi and in the degree of general cellular infiltration in the lamina propria of the mucosal layer. No adult worms were seen during the experiment; therefore, A. galli larvae have elicited a moderate cellular response in the lamina propria, mainly consisting of eosinophils in the early phase and later of mast cells.

Temporal changes and risk factors for foot-pad dermatitis in Danish broilers.

Foot-pad dermatitis is a major welfare concern of broilers caused by ammonia irritation from the bedding material. In Denmark, an action plan to control the condition was implemented in 2002 with monitoring through a foot scoring system at slaughter and with predefined limits that trigger sanctions. The objective of the present study was to study time trends and to identify predisposing factors on the flock lesion scores. The analysis was carried out on a database created by merging abattoir lesion data with antemortem evaluation data, and the flock productivity database managed by the farmers' association. The database had a record for each flock and variables containing information on both flock foot-pad scores and a range of management factors. We observed a dramatic decline in flock lesion scores between the years 2002 and 2005 followed by a minimal decline hereafter. Mean flock lesion scores differed between abattoirs, and subsequent analysis was performed in a mixed effect model where abattoir was considered a random effect. The analysis showed that flock lesion scores increased when the litter quality was evaluated as poor during the on-site antemortem evaluation. Other significant risk factors were winter season as opposed to summer, low daily weight gain, straw as bedding material in contrast to wood shavings and sphagnum peat, and high age at slaughter. Stocking density was only weakly associated with flock lesion scores.

Molecular and parasitological tools for the study of Ascaridia galli population dynamics in chickens.

Experiments were first conducted to compare and evaluate different methods of Ascaridia galli larval recovery from the chicken intestine. The number of larvae recovered from the intestinal wall of chickens infected with 1000 embryonated A. galli eggs and killed 15 days post infection (p.i.) by three methods (ethylenediamine tetraacetic acid [EDTA], pepsin digestion and scraping) were compared. The EDTA and pepsin digestion were found to be the most efficient methods with no significant difference (P > 0.05) in the number of recovered larvae between the two. Subsequently, three different A. galli cohorts were established using the polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) technique. A 533-bp long region of the cytochrome c oxidase subunit 1 gene of the mitochondrial DNA was targeted and 22 A. galli females were allocated to three different haplotypes. The four females with the highest embryonation rate from each haplotype group (total 12 females) were selected and used to inoculate each of 12 chickens with a dose of 1000 embryonated eggs. The chickens were killed 15 days p.i. and A. galli larvae were recovered from the small intestinal wall by the EDTA method and by sieving the lumen content on a 90 microm sieve. DNA of 40 larvae from each of the three different haplotypes was extracted using a worm lysis buffer, and PCR-RFLP analysis of these larvae revealed the same haplotype as that of their maternal parent. The identification of distinguishable cohorts may be a powerful tool in population studies of parasite turnover within the animal host.