The response of pigs experimentally infected with trypanosoma brucei to isometamidium chloride therapy and the relation to nutrition

Summary

Growing pigs were placed on feeds with high (Group A), medium (B) and low (C) dietary energy and were infected with a virulent stock of T. brucei. Eight weeks later, the infected pigs were treated with isometamidium chloride at 1mg/kg live weight and all pigs were subsequently placed on a high energy diet to investigate their response to therapy.

Clearance of T. brucei from blood was completed 72h after treatment. There was no evidence of relapsed infection up to eight weeks after treatment. Red blood cell parameters returned to normal four to six weeks after treatment with responses being fastest in Group A, B and C had gained about two‐thirds of the live weight gains of their non‐infected pair‐fed controls.

It appears that the retarded weight gain as a result of the infection persisted after therapy since drug‐treated pigs did not gain as much weight as their non‐infected controls.     

Three groups of Babesia canis distinguished and a proposal for nomenclature

Summary

Two stocks of large Babesiae from dogs originating in France, transmitted by Dermacentor reticulatus, two from North Africa, having Rhipicephalus sanguineus as vector, and one from South Africa, transmitted by Haemaphysalis leachi, were compared in cross‐immunity tests in dogs and in the indirect fluorescent antibody test (IFAT).

The French and North African stocks did not immunise against the South African one, while the North African stocks did not protect against a French one. The South African stock partially protected against a French one.

The three groups could be clearly distinguished in the IFAT These differences have practical implications for existing and future vaccines against canine babesiosis and for the serological diagnosis of atypical and chronic cases.

It is proposed to use a trinomial system of nomenclature for these groups: Babesia canis canis (Piana and Galli‐Valerio, 1895), Babesia canis vogeli Reichenow, 1937, and Babesia canis rossi (Nuttall, 1910), having Dermacentor, Rhipicephalus and Haemaphysalis ticks as their vectors respectively.     

Streptococcus suis type 2 infections in pigs in the Netherlands (part two)

Summary

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom.

Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective‐selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%).

A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty‐seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Endoscopic diagnosis and removal of gastric foreign bodies in a caiman (Caiman crocodilus crocodilus)

Summary

An 8‐year‐old caiman (Caiman crocodilus crocodilus) was presented, its history being given as absence of bowel movements and anorexia after ingestion of a rubber toy. Radiologic examination of the abdomen revealed no abnormalities. On gastrocopic examination many radiolucent foreign bodies were detected and removed. Five days after the removal of the foreign bodies from the stomach the caiman was alert and active and showed a normal appetite.     

An immunogold labelling method for the enumeration of canine T‐lymphocytes

Summary

An immunogold procedure using the monoclonal antibody F3–20–7 to canine Thy‐l has been used to label T‐lymphocytes in peripheral blood samples taken from healthy Beagles. By this method, approximately 64% of peripheral blood lymphocytes were identified as T‐lymphocytes.     

Influence of ante‐ and peri‐mortem factors on biochemical and physical characteristics of turkey breast muscle

Summary

The course of post‐mortem breakdown of glycogen and ATP in turkey pectoralis major muscle was markedly influenced by several ante‐ and peri‐mortem variables. Application of a proper stunning procedure was highly effective in preventing peri‐ and post‐mortem muscle stress reactions.

The physiological level of glycogen and ATP was not significantly affected by road transportation covering 260 km. Birds which rested for 24 hrs following transportation had lower glycogen and ATP levels at the moment of slaughter than non‐rested birds.

According to the changes in the rate and extent of post‐mortem biochemical reactions, several meat characteristics such as water‐holding capacity, colour, and tenderness were significantly changed.

Furthermore, the results also indicate that turkey breast muscle is susceptible to a PSE‐like condition as described in pork.     

Incidence,economic effects,and control of Haemophilus pleuropneumoniae infections in pigs

Summary

This thesis synopsis reports the results of investigations on:

– the incidence of clinical and subclinical H. pleuropneumoniae infections on pig farms in North Brabant;

– the economic loss on fattening farms; the effect of husbandry;

– the possibility of eradicating H. pleuropneumoniae on infected breeding farms on the basis of serological testing;

– the possibility of control on fattening farms by means of vaccination.

The principal findings were as follows:

Clinical and subclinical H. pleuropneumoniae infections are widespread on pig farms in North Brabant:

The greatest economic loss was due to mortality and veterinary fees; the daily weight again was not found to be affected.

The effect of husbandry.

Less mortality occurred: on farms where the animals were not shifted during the fattening period; in compartments where the all‐in all‐out method was systematically used; in compartments with thermostatically controlled warming of the incoming air; in compartments meeting all standards of a good housing climate.

Various sanitation measures on infected breeding farms were not successful.

Only one experimental vaccine afforded good protection, but because of a high percentage of injection abscesses this vaccine was unsuitable for use in practice.     

Investigation into the pathogenesis of Atrophic Rhinitis in pigs

Summary

In two groups of swine herds, herds with and without clinical AR the presence of Atrophic Rhinitis (AR) correlated with the presence of toxinogenic Pasteurella multocida (PM) and not with the Bordetella bronchiseptica (BB) infection.

Six BB‐ and eighteen PM‐strains have been investigated for AR pathogenicity. Broth cultures were injected intradermally in guinea‐pigs (GPST) orintranasally in 3‐week‐old colostrum deprived specific pathogen free (SPF) piglets.

The average atrophy of the ventral conchae (A VC) correlated with the GPST in 4BB‐ and 7 PM‐strains. One BB‐ and 2 PM‐strains were qualified as doubtful, the others as non‐AR pathogenic. With AR pathogenic BB‐ and PM‐strains clinical AR could be induced in 3‐ and 6‐week‐old piglets. AVC lesions (gradation> 1) could be induced with BB in piglets of 6 and with pathogenic PM in 16‐week‐old piglets. Six of seven AR pathogenic PM‐strains resembled Carter‐type D and one resembled type A. No significance was found between AR pathogenicity and somatic serotypes.

Intranasal instillations of cell‐free broth culture filtrates of AR pathogenic PM‐strains also caused AR in piglets. These filtrates also caused lethality in piglets and in mice lethalitytest (MLT) and induced a positive GPST. After heating the pathogenic effects of the filtrates disappeared. The name AR toxin has been introduced for this thermolabile, haemorrhagic dermonecrotic (HDNT) fraction of the AR inducing filtrates. The severity of the AR lesions depended on the amount of the AR toxin intranasally instilled in pigs.

Cross protecting antibodies obtained in rabbits against the AR toxins of two PM strains could be demonstrated by a toxin neutralisation test in the MLT and the GPST.

Broth cultures were injected intradermally in guinea‐pigs (GPST) or intranasally in 3‐week‐old colostrum deprived specific pathogen free (SPF) piglets.     

Return to OESTRUS after first insemination in sow herds (incidence,seasonality, and association with reproductivity and some blood parameters)

Summary

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were:

1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level;

2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics in order to get an impression of the economic importance of reproductive failure.

These objectives were investigated by using the reproduction results of 240 swine breeding herds in the Southern Netherlands in 1987. This information was obtained from CBK plus computerized herd management records. The average incidence rate of return to oestrus after first insemination at a herd level was 16.9 per 100 first inseminations. The occurrence of return to oestrus after first insemination was distinctly higher in the insemination months July and August compared to the rest of the year. An increased incidence, with 10 returns per 100 first inseminations corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 live born piglets/sow/year. A prospective longitudinal study was started in 1988 and 1989 in 37 sow herds. Individual sows were monitored from weaning to first insemination, to the occurrence of return to oestrus, or not, after first insemination, and to farrowing. The investigation focused in particular on the relationship between return to oestrus after first insemination and seroconversion against porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava). During a number of consecutive farm visits, blood samples were taken from sows at weaning and again 6 weeks later. The final data set analysed consisted of 161 animals that did not return to oestrus and 158 animals that did return to oestrus after first insemination. Seroconversion was defined as a 4‐fold increase in titre between the two successive blood samplings: sera were investigated at dilutions of 1:100 to 1:3200 (L. bratislava) and 1:4 to 1:16384 (PPV).

There was no indication of an association between the occurrence of return to oestrus after first insemination and seroconversion against PPV or L. bratislava with the serodiagnostics used in this study. However, it should be noted that L. bratislava infected sows can have a titre below the widely accepted minimum titre of 1:100 used in laboratories, and recently from sows without a titre L. bratislava was isolated. It is suggested that the most appropriate way to assess the influence of infection with L. bratislava on reproductive failure in swine at this moment is to use culture or other methods (e.g. PCR). Litter size and between‐farrowing time of the last farrowing before the study period was not associated with the occurrence of return to oestrus after first insemination in the study period. However, an increased weaning‐to‐first‐in‐semination interval, a high progesterone level at weaning, a low albumin concentration at weaning, and a decrease in albumin concentration between the consecutive samplings and an increase in gamma globulin concentration between the two blood samplings increased the risk of occurrence of a regular return to oestrus after first insemination.

An increased weaning‐to‐first insemination interval, an increase in leucocyte and gamma globulin concentrations and a reduction in alpha_1,2 globulin concentration between the consecutive samplings increased the risk of occurrence of an irregular return to oestrus after first insemination.     

Production and quality norms of certain grass species for fodder flow planning: Pretoria area

Abstract

Four subtropical (Cenchrus. Digitaria, Anthephora and Sorghum) and two temperate grass species (Festuca. Agrotricum) were grown in a replicated field experiment at three levels of N application, with adequate P and K. Species were mown at 4‐, 6‐ and 8‐weekly intervals. DM production data for 6‐ and 8‐weekly and 4‐ and 6‐weekly intervals are presented for subtropicals and temperates, respectively.

The object was to determine the seasonal accumulative DM production curves, productivity spread and quality, for use in fodder flow planning.

The subtropical grasses produced 2 to 3 times as much DM as the temperate grasses : CGR 745—1237 versus 345—440 kg/ha/wk under supplementary irrigation. The subtropicals produced ca 2^{h times as much under irrigation than under rainfed conditions.

Festuca and Agrotricum, Digitaria. Athephora and Sorghum, Cenchrus, gave peak CGR's after 9, 15, 16 and 18 weeks after end of August, respectively. Irrigation resulted in peak CGR being reached earlier in the growing season than under rainfed conditions and in subtropicals maintaining a high CGR for 1½ — 2½ months longer.

Various implications of the results for pasture management, and the fact that quality and DM yield generally are antagonistic in subtropical grasses, were discussed.     

comparison of an indirect haemagglutination assay and an Elisa for diagnosing Fasciola hepatica in experimentally and naturally infected sheep

Summary

An enzyme‐linked immunosorbent assay (ELISA) with somatic (S) or excretory‐secretory antigens (ES) was compared with an indirect haemagglutination assay (IHA) for ability to detect antibodies against Fasciola hepatica in sheep. The specificity of both assays was determined by testing sera collected from sheep experimentally or naturally mono‐infected with Fasciola hepatica, Haemonchus contortus, Ostertagia circumcincta, Cooperia curticei, Taenia ovis, Eimeria spp., Trichostrongylus vitrinus, Trichostrongylus colubriformis or Nematodirus battus respectively. With S or ES antigens the specificity of the ELISA was 98% or 95% respectively, whereas the specificity of the IHA was 86%. Antibodies directed against Fasciola hepatica were detected by the ELISA with S or ES antigens from 2 weeks after infection until the end of the experiment, whereas the IHA detected antibodies from week 3. We conclude that the ELISA with S antigens compares favourably with the IHA and can be used for the serodiagnosis of ovine fasciolosis in the Netherlands.     

Infections of Edwardsiella tarda among Brook Trout in Quebec

Abstract

Acute bacterial septicemia is commonly diagnosed in brook trout Salvelinus fontinalis of Quebec, Canada. The agents most commonly isolated include Aeromonas salmonicida (furunculosis), Aeromonas hydrophila (motile aeromonad septicemia), and Pseudomonas species. Septicemia in brook trout caused by the gram-negative bacterium Edwardsiella tarda was diagnosed for the first time in the province of Quebec from two different fish farms producing stock for fee fishing establishments. Affected fish displayed nonspecific lesions associated with bacterial septicemia including hemorrhages on the gills and viscera and exophthalmia. Stress-associated immunosuppression due to an increase in summer water temperatures and lack of precipitation were considered as primary causes of these disease outbreaks.     

Editorial

Summary

The possession of common antigens by three trematode parasites which commonly occur together in ruminants in the tropics, Fasciola gigantica, Dicrocoelium hospes and Schistosoma bovis was studied in relation to the reliability of serodiagnosis of infection with these helminths. The crude antigenic extracts of the three trematodes were subjected to Sephacryl S‐300 column chromatography and F. gigantica was fractionated into six peaks, S. bovis into nine peaks and D. hospes into seven peaks. Common antigens were found in these three trematodes in both the crude whole worm antigenic extracts and in the semi‐purified fractions obtained by Sephacryl S‐300 column chromatography.

The implications of this finding and the limitation it imposes on the usefulness of serodiagnostic tests in routine use as regards their specificity are discussed in relation to previous studies.     

Amyloodiniosis in Cultured Hybrid Striped Bass (Morone saxatilis × M. chrysops) in North Carolina

Abstract

An outbreak of amyloodiniosis in pondcultured hybrid striped bass × white bass (female Morone saxatilis × male M. chrysops) is the northernmost documented outbreak caused by an endemic source in fish of the western Atlantic. Dinospores produced by this isolate of Amyloodinium ocellatum were anteroposteriorly flattened, as contrasted with the gymnodinoid dinospores of the A. ocellatum-type species, suggesting that more than one strain or species of A. ocellatum may exist.     

The importance of the ecological view of agriculture

Abstract

Marked populations of Themeda triandra and Sporobolus fimbriatus tillers were sequentially harvested at fortnightly intervals both under irrigation and under unamended moisture conditions. Sampling covered a period from tiller initiation through to senescence after flowering.

Tiller masses and green leaf areas were used to derive absolute growth rates, relative growth rates, net assimilation rates and leaf area ratios respectively. Growth rates of Themeda triandra were higher, or were maintained at high levels for longer than those of Sporobolus fimbriatus. Moisture stress resulted in considerably depressed growth rates. Photosynthetic efficiency of spring emerging tillers was potentially greatest in midsummer, but this seasonal influence was masked by moisture stress on non‐irrigated treatments.     

DNA typing of Mycobacterium bovis strains from the Castlepoint area of the Wairarapa

Aim. To investigate isolates of Mycobacterium bovis from the Castlepoint area of the Wairarapa using three different methods of DNA typing.

Methods. Isolates of M. bovis, obtained from animals in the Castlepoint area between 1982–l998, were characterised by restriction endonuclease analysis. An isolate representing each restriction type was characterised by two newer DNA typing methods based on the polymorphic GC-rich repetitive sequence (PGRS) and spoligotyping.

Results. Over 300 isolates were distinguished into 26 restriction types.The 24 available restriction types were differentiated into 11 PGRS types and 7 spoligotypes. The three most common restriction types had the same PGRS type and the same spoligotype.

Conclusions. The relatively large number of restriction types found, indicated that restriction endonuclease analysis was well suited for detailed epidemiological studies at Castlepoint. Spoligotyping was less discriminatory than PGRS typing but both methods could be used to group isolates with different restriction types.     

Epidemiology: Culture of bovine bone marrow progenitor cells in vitro

Summary

In vitro methylcellulose cultures of bovine bone marrow progenitor cells were developed. An existing technique described for bovine species was compared to a method for human tissue and further adapted during subsequent experiments. Bovine bone marrow samples were collected at the slaughterhouse, and mononuclear cells were separated by gradient centrifugation (1.077 g/ml specific density and 400g). The use of 3% bovine leucocyte‐conditioned medium, produced by stimulation of blood lymphocytes with 4 pg/ml concanavalin A and harvested on day 4 of culture, gave better results than the use of supernatant of the human bladder carcinoma 5637, which is widely used in human bone marrow cultures. However, bovine leucocyte‐conditioned medium was not added to erythroid cultures because inhibitory effects were observed. Erythroid colonies were stimulated with erythropoietin, and hemin was added to enable microscopic identification. Reduced oxygen tension was necessary to induce growth of erythroid colonies. This was not necessary for myeloid cultures. In conclusion, the results of this study show that the growth of myeloid and erythroid colonies in methylcellulose‐based medium requires different culture conditions, which are different from the culture conditions for human cells.     

Research note: Level of nitrogen fertilization and the dry matter yield of Digitaria eriantha cv. Irene in the Transvaal middleveld

Abstract

N fertilizer was applied as a single dressing in spring at 0, 20, 40, 80, 160 and 320 kg N ha^‐1 a^‐1 to an established Digitaria eriantha pasture, previously used as a hay crop. The only significant increase in dry matter (DM) yield was obtained with 80 kg ha^‐1 a^‐1. The DM production per unit of nitrogen (N) applied also reached a maximum with 80 kg N ha^‐1 a^‐1. The distribution of rainfall also influenced DM yield.