J van Eck

Dropped egg production, soft shelled and shell‐less eggs associated with appearance of precipitins to adenovirus in flocks of laying fowls

Two outbreaks of dropped egg production and production of soft shelled and shell-less eggs are described. The outbreaks were selected from a larger number of flocks with similar problems in the field. The drop in egg production was closely correlated with the appearance of precipitins to adenovirus in the laying birds. Birds were also infected with Mycoplasma synoviae. A number of other infectious causes of production problems could be excluded in these outbreaks. In particular infectious bronchitis was not a factor and, in contrast to experiences following infections with this virus, production recovered nearly completely within 6 to 10 weeks. The observations suggest that in the field infections with adenovirus may cause production problems as serious as those caused by infectious bronchitis virus.

Vibrational-state-selected ion--molecule reaction cross sections at thermal energies

A method designed to measure relative ion—molecule reaction rates at thermal collision energies for selected reactant ion vibrational states is described. Relative reaction rates are determined for the three endothermic reactions: H2+ (υ)(He,H)HeH+, H2+ (υ)(Ne,H)NeH+, D2+(υ)(Ne, D)NeD+, and for the two exothermic reactions H2+ (υ)(H2, H)H3+, D2+(υ)(D2, D)D3+, whereby data are evaluated for υ = 0–8 for H2+ and for υ = 0–12 in the case of D2+. The results are analyzed in terms of a modified statistical model designed for reactions that go through a collision complex. It is found that all data can be satisfactorily described within this model.

Infectious stunting and leg weakness in broilers: I. Pathology and biochemical changes in blood plasma.

A syndrome of stunting and leg weakness could be reproduced experimentally by inoculation of 1-day-old broilers with homogenised intestines from affected birds. Inoculated birds kept in isolators showed highly impaired growth until 3 weeks p.i. Birds produced mucoid yellowish coloured droppings and at post mortem thin liquid intestinal contents were found. Biochemical examination of blood plasma showed low plasma carotenoid concentrations and an increased alkaline phosphatase (ALP) activity, mainly caused by one isoenzyme, which was most likely of intestinal origin. These findings implicate infectious causal agents with the intestines as the site of primary involvement. Bone abnormalities consisted of rickets-like changes at the age of 3 weeks, whereas a distinct dyschondroplasia was seen at 4 weeks. The syndrome could also be transmitted to uninoculated birds kept in contact with birds inoculated at 1 day of age. Birds inoculated at 7 days of age also showed greatly impaired growth but developed no macroscopical bone disorders. Inoculation at 14 days of age did not result in impaired growth or bone abnormalities. Following inoculation with REO virus, isolated from a field case, no bone abnormalities occurred. However, a shortlived impaired growth, diarrhoea, increased plasma ALP activity and decreased carotenoid concentration were observed. The rapid spread of the disease and the role of REO virus are discussed.

Ability of Massachusetts-type infectious bronchitis virus to increase colibacillosis susceptibility incommercial broilers: A comparison between vaccine and virulent field virus

The abilities of Massachusetts-type vaccine virus and virulent infectious bronchitis (IB) field virus to increase colibacillosis susceptibility were compared. In four experiments, 29-day-old female commercial broilers housed in isolators, were infected intratracheally and oculonasally with IB vaccine strains (HI20 and H52) or virulent IB field strains (D387 and M41) (4.8 or 6.8 log10 median embryo infective dose, per broiler). Five days later, Escherichia coli 506 strain was given intratracheally (5.6 to 8.8 log10 colony forming units/broiler). The incidence of nasal discharge at 3 and 5 days after IB virus infection was used to assess the clinical effect of the IB infection, while mortality, body weight uniformity and E. coli lesions at 7 days following E. coli inoculation were used as parameters for colibacillosis. Nasal discharge was observed in 61/117 (5%), 26/119 (22%), 35/119 (29%) and 115/120 (96%) of broilers infected with H120, H52, D387 and M41 virus, respectively. Apart from H52 and D387, differences between IBV strains were significant. IB vaccine and virulent IB viruses did not generally differ significantly in their ability to induce colibacillosis susceptibility. Mean colibacillosis lesion scores of H52-infected birds even significantly exceeded those of birds infected with the other IB viruses. The ability of H120 virus to induce colibacillosis susceptibility tended to be the weakest. The practical consequences of these findings are discussed.

An Ulster 2C strain‐derived Newcastle disease vaccine: Vaccinal reaction in comparison with other lentogenic Newcastle disease vaccines

Vaccinal reaction and seroresponse induced by an Ulster 2C strain derived Newcastle disease (ND) vaccine (ND) (PoulvacR NDW Broiler) were compared with those due to three other lentogenic ND vaccines (NDP, LZ58 and Clone 30) used in broilers in the Netherlands. Comparisons were made in SPF-WL hens and commercial broilers with maternally derived antibodies, using a fully standardized model. The criteria used were body weight gain and mortality rate following vaccine aerosol exposure and susceptibility to experimentally induced Colibacillosis. The NDW vaccine was the mildest, followed by Clone 30-, LZ58- and NDP vaccine. Although the seroresponse of SPF-WL hens exposed to NDW vaccine was significantly less than that induced by the other vaccines, the response was still substantial. Seroresponse to NDP-, LZ58- and Clone 30 vaccine did not differ significantly mutually. In broilers, serores-ponses to NDW- and Clone 30-vaccine were similar.

An evaluation of K-shell fluorescence yields; observation of outer-shell effects

A new treatment of series of K-shell fluorescence yields omega , traces systematic differences between those series which have overlapping ranges of atomic numbers Z. From 257 experimental values, which have been corrected for the observed systematic differences, accurate average omega values are obtained for 62 elements (3<or=Z<or=98). The resulting accuracy is about four times better than the accuracy of the empirical omega values previously recommended in the literature. Unknown fluorescence yields may be found by interpolation in a (modified) empirical diagram of omega (Z). Local systematic deviations (of a few per cent) from a three-parameter relation for omega (Z) appear to depend on the outer-shell configuration of the elements concerned.

A new method for the measurement of vibrational-state-selected ion-molecule reactions at thermal energies

Abstract A photoelectron-secondary-ion-coincidence method is described that allows us to determine the relative vibrational-energy-dependent cross sections for reactions of molecular ions with neutral atoms or molecules at thermal energies. Results for reactions of H 2 + (ν) in vibrational states ν = 0–8 with H 2 (H 3 + ), Ne(NeH + ) and He(He + ) are reported.

Vaccination of broiler chickens with dispersed dry powder vaccines as an alternative for liquid spray and aerosol vaccination.

Vaccination of chickens with dispersable dry powder vaccines was compared with commercial liquid vaccines. A Clone 30 Newcastle disease vaccine virus was spray dried with mannitol or with a mixture of trehalose, polyvinylpyrrolidone and bovine serum albumin. A coarse (+/-30 microm) and fine (+/-7 microm) powder were produced with both formulations. A commercial reconstituted Clone 30 vaccine was applied as coarse liquid spray (+/-222 microm) or fine liquid aerosol (+/-24 microm). Reduction of virus concentration in the air after dispersion/nebulization was monitored by air sampling and was explained by sedimentation of coarse particles/droplets and evaporation of fine droplets. The vaccine formulations induced high haemagglutination inhibition antibody titres in the serum of 4-week-old broilers (2(7) at 4 weeks post-vaccination). The good serum antibody response with the fine liquid aerosol despite extensive inactivation of virus due to evaporation of droplets, suggested that powder formulations (without inactivation due to evaporation) might allow a significant reduction of vaccine dose, thereby offering new options for fine aerosol vaccination with low-titre vaccines.

State‐selected ion‐molecule reactions: Charge transfer and atomic rearrangement processes in thermal energy collisions of H2+(X;v)+N2 and of N2+(X,A;v) + H2

Using the photo‐electron‐product‐ion‐coincidence method (PEPICO) we have measured state‐selective cross sections for the following processes: (A) N+2(X,A;v)+H2→N2H++H, (B) H+2(X;v)+N2→N2H++H, (C) N+2(X,A;v)+H2→H+2+N2, and (D) H2+(X;v)+N2→N2++H2. The measurements were performed at thermal velocities (Ec.m.≊40 meV). We have found that the charge transfer processes (C) and (D) have cross sections that are at least an order of magnitude smaller than the cross sections for the rearrangement processes (A) and (B). The cross section for reaction (A) with N2+(A;v) as reactant is found to be (50.2±2.4)% of the cross section for the same reaction with N2+(X;v) as reactant. The cross section for reaction (B) is found to be independent of the internal energy of the reactant ion. The measured variation of the cross sections as a function of the internal energy of the reacting ion is compared with calculations based on a RRKM type statistical model and an electronic correlation diagram of the (N2–H2)+ system. Excellent...

An Ulster 2C strain-derived Newcastle disease vaccine: efficacy and excretion in maternally immune chickens.

Efficacy and excretion of an Ulster strain-derived Newcastle disease (ND) vaccine (Poulvac NDW Broiler) were examined in maternally immune chickens. The vaccine was effective in broilers following coarse spray or aerosol (Atomist) application at one to 10 days of age. Immunity did not differ significantly from immunity following vaccination with a La Sota type vaccine. Also, combined spray application of NDW- and infectious bronchitis (IB) (Poulvac IB primer) vaccine at 1-day-old, resulted in sufficient protection against challenge with both virulent ND and IB virus. In layers the vaccine was less immunogenic, requiring large doses to induce sufficient protection in chickens with maternal antibodies. In layers this may make the vaccine economically non-viable. Atomist vaccination using economically justified doses, was effective after maternal antibodies had waned. Clinical signs of vaccinal reaction were not observed in layers. In broilers respiratory signs of vaccinal reaction were absent after spray-application and were very slight following Atomist administration. Body weight gain was temporarily depressed, but significantly less than following vaccination with a La Sota type vaccine. Following vaccination, vaccine virus could be recovered from cloacal content and trachea up to 15 and 8 days respectively.