Non-intrusive tracking of commercial broiler chickens in situ at different stocking densities

Unlike several other farm animal species, the broiler chicken remains unprotected by species-specific legislation. The densities at which broilers should be kept is a highly contentious issue-some studies have demonstrated increased welfare problems at higher densities, whilst a few others have, contrary to expectations, suggested that broilers may actually find crowds of other birds attractive. A tracking method was developed and used to provide an insight into the social preferences of commercial broiler chickens in situ-inside commercial, closed-system broiler houses. The aim was to simultaneously assess the relative impact of global measures of density, such as target and actual stocking densities and local measures of the social environment on the behaviour and route taken to feed by focal birds. Birds were tracked inside 20 commercial broiler houses across the UK. Results from this study show that stocking density per se seems to have little direct effect on the individual behaviours of focal broiler chickens. However, there may still be an indirect effect of stocking density on broiler behaviour, mediated through the local social environment. (C) 2007 Elsevier B.V. All rights reserved.

Clustering and synchrony in laying hens: The effect of environmental resources on social dynamics

Laying hens generally choose to aggregate, but the extent to which the environments in which we house them impact on social group dynamics is not known. In this paper the effect of pen environment on spatial clustering is considered. Twelve groups of four laying hens were studied under three environmental conditions: wire floor (W), shavings (Sh) and perches, peat, nestbox and shavings (PPN). Groups experienced each environment twice, for five weeks each time, in a systematic order that varied from group to group. Video recordings were made one day per week for 30 weeks. To determine level of clustering, we recorded positional data from a randomly selected 20-min excerpt per video (a total of 20 min x 360 videos analysed). On screen, pens were divided into six equal areas. In addition, PPN pens were divided into an additional four (sub) areas, to account for the use of perches (one area per half perch). Every 5 s, we recorded the location of each bird and calculated location use over time, feeding synchrony and cluster scores for each environment. Feeding synchrony and cluster scores were compared against unweighted and weighted (according to observed proportional location use) Poisson distributions to distinguish between resource and social attraction.

Disruption of egg formation by Fasciola hepatica following treatment in vivo with triclabendazole in the sheep host

Eight indoor-reared cross-bred sheep with no prior exposure to Fasciola hepatica were infected by oral gavage with 200 metacercarial cysts of the triclabendazole (TCBZ)-susceptible Cullompton isolate of F. hepatica. Twelve weeks after infection, sheep were treated with 10 mg/kg triclabendazole. Two sheep were euthanised per time period; at 48 h, 72 h and 96 h post-treatment (pt). Two untreated control sheep were euthanised at 96 h pt. Flukes were recovered from the liver and, if present, from the gall bladder of the sheep. They were processed for whole mount analysis, histology and transmission electron microscopy of the female reproductive system; specifically, the uterus, vitelline follicles. Mehlis' gland and ovary.

Verification of McCabe's Delta L Law for Growth of Lysozyme Crystals by Hanging Drop Method

Lysozyme is a naturally occurring enzyme in egg white and has high commercial importance due to its antimicrobial properties. The main objective of this work was to study the growth rate of lysozyme crystals isolated from egg for the first 72 hours and verify the results with McCabe’s constant crystal growth theory. Hanging drop crystallization method was used to form high purity lysozyme crystals from the embryonic stage. To this end, this work differs from an earlier work of Forsythe et al., who used seed crystals in the size range of 10 µm - 40 µm for face growth measurements at different pH values. The maximum crystal size recorded in the present work was 392.86 µm, which is within the typical size range of 50 µm - 500 µm for which constant crystal growth is expected to hold according to McCabe’s ?L law. Electron micrographs (SEM) revealed the structure and dimensions of the crystals while SDS-Page was used to measure the purity of the crystals. The SEM results showed that that lysozyme growth rate was linear and agreed with McCabe’s constant growth theory, producing a growth rate of 1.77 x 10-3 µm .s-1

Development of an egg hatch assay for the diagnosis of triclabendazole resistance in Fasciola hepatica: proof of concept.

The aim of this study was to develop an Egg Hatch Assay (EHA) test for the detection of triclabendazole (TCBZ) resistance in Fasciola hepatica. A number of fluke isolates were used, of differing sensitivity to TCBZ. Eggs were exposed to solutions of triclabendazole sulphoxide (TCBZ.SO) for 14 days, then triggered to hatch. Egg development was divided into 6 distinct and easily identifiable stages: dead, empty, unembryonated, cell division, eye spot and hatched. The number of eggs reaching those stages was recorded. Initially, the discriminating dose (1% hatch) was determined for the Cullompton isolate, used as TCBZ-susceptible (TCBZ-S) standard. Once this concentration had been resolved, the response of different isolates to this concentration was examined. The hatch rate of the Fairhurst isolate was not significantly different from that of the Cullompton isolate, confirming its TCBZ-S status. The Patagonia isolate has not been exposed to TCBZ in the field and should be TCBZ-S: the results of the EHA supported this. The egg hatch response of the Oberon and Dutch isolates differed significantly from that of the Cullompton isolate; the former isolates are regarded as TCBZ-resistant (TCBZ-R) and the results confirmed this. Another isolate, the Leon isolate, was originally described as being TCBZ-R, but has since been shown to be TCBZ-S. There was no difference in its response to TCBZ.SO in the EHA from the Cullompton (and Fairhurst and Patagonia) isolate(s), further indicating its TCBZ-S status. The impact of TCBZ.SO treatment on the component stages of egg development was determined and revealed differences between the isolates. In conclusion, the results of the study have shown that it is possible to discriminate between TCBZ-S and TCBZ-R isolates of F. hepatica on the basis of the response of their eggs to an EHA and the test could be used to evaluate the TCBZ sensitivity of unknown field isolates

Investigation of the causes for the occurrence of residues of the anticoccidial feed additive nicarbazin in commercial poultry

Investigations were undertaken to identify causes for the occurrence of high levels of the zootechnical feed additive nicarbazin in broiler liver at slaughter. The first investigation on 32 commercial broiler flocks involved sampling and analysis for nicarbazin ( as dinitrocarbanilide, DNC) in liver from birds during a 3-10-day period after withdrawal of nicarbazin from their feed and before commercial slaughter. DNC residues in liver samples of broilers scheduled as being withdrawn from nicarbazin for >= 6 days ranged from 20 to > 1600 mu g kg(-1) ( the specified withdrawal period for nicarbazin is 5 days and the Joint Expert Committee on Food Additives (JECFA)maximum residue limit (MRL) is 200 mu g kg(-1) liver). Further on-farm investigations on 12 of these flocks, selected on the basis of the feeding system in use and the levels of DNC residues determined in liver, identified issues in feed management contributing to elevated residues in broiler liver. A significant correlation (0.81, p