Blood content of broiler chicken carcases prepared by different slaughter methods

Two trials using broiler chickens were undertaken to determine if variations in commercial slaughter techniques affected either the appearance or the residual blood content of the carcases produced. In the first trial groups of broilers were either stunned (55, 80 or 105 volts), electrocuted (240 volts) or anaesthetised and the subsequent bleed-out volumes after one, two, three and four minutes exsanguination were measured. The method of slaughter made no difference to the amount of blood lost after venesection. Haemoglobin content of the pectoral muscle was used to measure residual blood and was uniformly low in all groups (0.7 to 0.16 mg haemoglobin/g of muscle). In the second trial groups of chickens were either stunned and bled out, electrocuted, electrocuted and bled out, decapitated or halal killed before processing. The edible portions of the carcases were minced and the average haemoglobin content for each group was 0.19, 0.36, 0.22, 0.17 and 0.17 mg/g of soft tissue. The appearance of chickens that were stunned and bled out was the same as that of chickens that were electrocuted and bled out. The authors conclude that killing chickens by electrocution before exsanguination does not adversely affect the carcase appearance. Furthermore, electrocution ensures that broiler chickens are humanely slaughtered.     

Trial design to estimate the effect of vaccination on tuberculosis incidence in badgers

The principal wildlife reservoir of Mycobacterium bovis in Ireland is the European badger. Studies in the Republic of Ireland (RoI) have shown that badgers culled in association with cattle herd tuberculosis breakdowns (focal culling) have a higher prevalence of infection than the badger population at large. This observation is one rationale for the medium term national strategy of focal badger culling. A vaccination strategy for the control of bovine tuberculosis (bTB) in badgers is a preferred long-term option. The Bacillus Calmette-Guérin (BCG) vaccine has been shown to decrease disease severity in captive badgers under controlled conditions. As the vaccine has been tested in a controlled environment with precise information on infection pressure, it cannot be assumed a priori that the effects of vaccination are similar in the wild, where other environmental and/or ecological factors prevail. For this reason we have designed a vaccine field trial to assess the impact of vaccination on the incidence of TB infection in a wild badger population. The selected study area for the vaccine trial (approximately 755 square kilometers) is divided into three zones each of which has similar characteristics in terms of size, number of main badger setts, cattle herds, cattle and land classification type. Three vaccination levels (100%, 50% and 0%) will be allocated to the three zones in a way that a gradient of vaccination coverage North to South is achieved. The middle zone (zone B) will be vaccinated at a 50% coverage but zone A and C will be randomly allocated with 100% or 0% vaccination coverage. Vaccination within zone B will be done randomly at individual badger level. The objective of this paper is to describe the design of a field tuberculosis vaccination trial for badgers, the epidemiological methods that were used to design the trial and the subsequent data analysis. The analysis will enable us to quantify the magnitude of the observed vaccination effect on M. bovis transmission in badgers under field conditions and to improve our knowledge of the biological effects of vaccination on susceptibility and infectiousness.     

Initial results from long-term field studies at three sites on the effects of heavy metal-amended liquid sludges on soil microbial activity

In a long‐term study of the effects on soil fertility and microbial activity of heavy metals contained in sewage sludges, metal‐amended liquid sludges each with elevated Zn, Cu or Cd concentrations were applied over a 3‐year period (1995–1997) to three sites in England. The experiments were sited adjacent to experimental plots receiving metal‐rich sludge cakes enabling comparisons to be made between the effects of heavy metal additions in metal‐amended liquid sludges and sludge cakes. The liquid sludge additions were regarded as ‘worst case’ treatments in terms of likely metal availability, akin to a long‐term situation following sewage sludge additions where organic matter levels had declined and stabilised. The aim was to establish individual Zn (50–425 mg kg^?1), Cu (15–195 mg kg^?1) and Cd (0.3–4.0 mg kg^?1) metal dose–response treatments at each site, but with significantly smaller levels of organic matter addition than the corresponding sludge cake experiments. There were no differences (P > 0.05) in soil respiration rates, biomass carbon concentrations or most probable numbers of clover Rhizobium between the treatments at any of the sites at the end of the liquid sludge application programme. Soil heavy metal extractability differed between the metal‐amended liquid sludge and metal‐rich sludge cake treatments; Zn and Cd extractabilities were higher from the liquid sludge additions, whereas Cu extractability was higher from the sludge cake application. These differences in metal extractability in the treated soil samples reflected the contrasting NH₄NO₃ extractable metal contents of the metal‐amended liquid sludges and sludge cakes that were originally applied.     

Molecular markers for improving control of soil-borne pathogen <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> in sugar beet

Fusarium spp. cause severe damage in many agricultural crops, including sugar beet, with Fusarium oxysporum historically being considered as the most damaging of all species. Sugar beet needs to be protected from this class of soil-borne pathogens in order to ensure an optimal sugar yield in the field. Genetic control of the disease is crucial in managing these pathogens. Identification of single nucleotide polymorphism (SNP) markers linked to resistance can be a powerful tool for the introgression of valuable genes needed to develop Fusarium-resistant varieties. A candidate gene approach was carried out to identify SNP markers linked to putative Fusarium resistance sources in sugar beet. Five resistant analogue genes (RGAs) were screened by means of high resolution melting (HRM) analysis in a set of sugar beet lines, considered as resistant and susceptible to Fusarium oxysporum. HRM polymorphisms were observed in 80% of amplicons. Two HRM polymorphisms were significantly associated with Fusarium resistance (P < 0.05). The amplicons that showed association were sequenced and two SNPs were identified. The association was further validated on 96 susceptible and 96 resistant plants using competitive allele-specific PCR (KASPar) technology. The selected SNPs could be used for marker-assisted breeding of Fusarium resistance in sugar beet.     

Naturally occurring trypanosomiasis (Chagas' disease) in dogs.

Nine fatal cases of canine American trypanosomiasis (Chagas' disease) were encountered from November, 1972, through November, 1975. Of the 9 cases, 7 occurred in dogs from 5 central Texas counties, and all but one case was diagnosed during the months of September, October, or November. The source of infection was discovered in only one case--that being a doghouse heavily infested with Triatoma lectularius occulta. Each of 6 bugs collected had infective forms of the protozoan, Trypanosoma cruzi. Trypanosomiasis usually is not considered in the differential clinical diagnosis of cardiac dysfunction in man or other mammals in the United States. An antemortem diagnosis was made in only 1 of the 9 dogs, with diagnosis in the remaining dogs being made at necropsy. The predominant microscopic lesion in all dogs was necrotizing granulomatous myocarditis associated with the amastigotes of T cruzi.