Mark A. Dekich

Comparison of a Complement Resistance Test, a Chicken Embryo Lethality Test, and the Chicken Lethality Test for Determining Virulence of Avian Escherichia coli

Results with four pathogenic avian Escherichia coli isolates and one avirulent isolate in a complement resistance test, a chicken lethality test, and a chicken embryo lethality test were compared. Results of the complement resistance test with these isolates were highly correlated to results of the chicken lethality test of virulence. The chicken embryo test yielded results that were of a medium positive correlation with the chicken lethality results. The results of the complement resistance and chicken embryo lethality tests were highly correlated.

Multisystemic Adenovirus Infection in Broiler Chicks with Hypoglycemia and Spiking Mortality

The search for a solitary cause of spiking mortality (so-called spiking mortality syndrome [SMS]) among broiler chicks has been thwarted by the fact that many agents will cause similar mortality histograms. Recently, severe hypoglycemia has been said to be a characteristic finding in chicks that die with SMS. In the present case study, we report adenovirus inclusions in the pancreas, small intestines, and liver of chicks with hypoglycemia and spiking mortality. We attributed the hypoglycemia and mortality to hepatic insufficiency.

Characteristics of Conjugative R-Plasmids from Pathogenic Avian Escherichia coli

Three of four virulent avian Escherichia coli isolates transferred a single large molecular-weight R-plasmid to two recipient E. coli strains. Antibiotic resistances transferred included streptomycin (two isolates) and streptomycin-tetracycline-sulfa (one isolate). Production of colicin and siderophores, complement resistance, and embryo lethality present in the virulent isolates were not transferred to recipient organisms. From the results, it appears that the R-plasmids of these virulent avian E. coli are not associated with virulence.

Quantitation of Intestinal D-Xylose Absorption in Normal Broilers and in Broilers with Pale-Bird Syndrome

A micromethod was used in order to quantitate intestinal D-xylose absorption in young and extremely small birds. This test was performed in broilers collected from two farms from which birds were extremely uneven in body size and were passing poorly digested or undigested feed. A similar syndrome had been seen on all grow-outs during the 6 months before this investigation. Broilers were also collected and tested from three farms where no clinical signs of disease were seen. D-Xylose absorption peaks and curves for normal broilers closely resembled those observed in normal humans. Mean plasma D-xylose concentrations for virus-infected broilers and for broilers with pale-bird syndrome were consistently lower than concentrations for normal broilers (P = 0.009). Reoviruses, small coronavirus-like particles, small round virus particles, and abundant bacterial flagellar fragments were seen in fecal samples from broilers with pale-bird syndrome. Production performance was lowest on farms showing clinical signs of this syndrome.

Fringed membranous particles and viruses in faeces from healthy turkey poults and from poults with putative poult enteritis complex/spiking mortality.

The purpose of the present study was to use clinical epidemiologic tools to define the relationship between production performance data, virus particles, and intestinal fringed membranous particles (FMPs) in healthy turkey poults and in poults that were experiencing an outbreak of poult enteritis complex (PEC) and spiking mortality syndrome (SMS). Small and large intestines from flocks of healthy poults and poults with PEC/SMS were collected, processed, and examined for viruses. Production performance parameters were collected and analyzed. Hocks of turkeys with PEC/SMS in the present study had low survival expectancy (livability) and poor growth compared to their healthy turkey counterparts. The only significant association between sickness and intestinal virus was the presence of coronavirus.

Clinical application of a light microscopic scoring method to make decisions regarding the pharmacotherapy of an Eimeria maxima abatement programme.

The purpose of the present study was to use an Eimeria maxima light microscopic lesion scoring (MLS) system to measure magnitudes of E. maxima infection in sections of broiler chick intestine, and to help make decisions regarding the efficacy of an E. maxima abatement programme. Chicks with whole-body pallor, elevated feed conversion ratios (10 points higher than normal) and reduced body sizes (0.1 kg smaller than normal) had light microscopic lesions caused by E. maxima infections. These intestine segments had high Eimeria maxima MLSs. High scores, coupled with the fact that there was no microscopic evidence for the presence of gastrointestinal pathogens other than E. maxima, allowed us to conclude that E. maxima was the cause of the signs observed. When changes in the pharmacotherapy of the coccidiosis abatement programme were made (substitution of one ionophore coccidiostat for another ionophore coccidiostat), the MLSs were significantly (P < 0.01) reduced, and chicks returned to their normal colour (yellow) and normal target body size (2.091 kg) on a normal feed conversion ratio (2.06). It was decided that the MLS is suitable for use in health programmes that depend upon detection of E. maxima in broilers.