Pathology of experimentally-induced, acute toxoplasmosis in macropods

SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.     

Effect of incorporation of serum from dogs with renal impairment on canine erythroid bone marrow cultures

Serum from dogs with surgically induced renal impairment was incorporated into the medium for erythroid bone marrow cultures. A significant correlation was found between serum activities of erythropoietin and numbers of erythroid colony-forming units grown in culture. Serum creatinine concentrations had no correlation, and serum parathyroid hormone activities had a negative correlation with numbers of erythroid colony-forming units that was below the level of significance. Purified 1-84 parathyroid hormone added to bone marrow cultures was found to be stimulatory to erythroid colony-forming unit growth in higher concentrations, but decreased the number of burst-forming units. Unmeasured substances in the canine serum appeared to have a greater effect on the canine erythroid bone marrow cultures than did creatinine or parathyroid hormone values.     

The effects of aggregating sub-grid land surface variation on large-scale estimates of net primary production

The use of large grid cell databases (1/2° to 5°) to drive nonlinear ecosystem process models may create an incompatibility of scales which can often lead to biased outputs. Global simulations of net primary production (NPP) often assume that bias due to averaging of sub-grid variations in climate, topography, soils, and vegetation is minimal, yet the magnitude and behavior of this bias on estimates of NPP are largely unknown. The effects of averaging sub-grid land surface variations on NPP estimates were evaluated by simulating a 1° × 1° land surface area as represented by four successive levels of landscape complexity, ranging from a single computation to 8,456 computations of NPP for the study area. Averaging sub-grid cell landscape variations typical of the northern US Rocky Mountains can result in overestimates of NPP as large as 30 %. Aggregating climate within the 1° cell contributed up to 50 % of the bias to NPP estimates, while aggregating topography, soils, and vegetation was of secondary importance. Careful partitioning of complex landscapes can efficiently reduce the magnitude of this overestimation.     

Effects of feeding different concentration and forms of zinc on the performance and tissue mineral status of broiler chicks

1. Two studies were conducted to investigate the effect of feeding different concentration and forms of zinc (Zn) on the performance and tibia Zn status of broiler chicks.

2. In Experiment 1, chicks fed on the control or the diet supplemented with 12?mg of Zn as sulphate had lower feed intake, weight gain and tibia Zn content than other treatment groups. Chicks given 12 and 24?mg of organic Zn in starter and grower phases, respectively, had the same performance and tibia Zn content as those fed 40?mg of Zn as sulphate and the same performance but higher tibia Zn content than those given 12?mg of Zn as organic over the 42?d.

3. In Experiment 2, chicks given 24?mg organic Zn had greater weight gain than chicks fed on the other treatment diets in the starter period. Chicks fed on the control diet had lower tibia Zn content than chicks fed other treatment diets. Chicks given 80?mg Zn as sulphate had higher tibia Zn content than chicks fed the other treatment diets except those given 40?mg of Zn as sulphate.

4. The results from these trials indicate that feeding lower concentration of Zn as organic form may better promote the growth performance of broiler chicks.     

The Role of Estrogens in the Pathogenesis of Canine Hip Dysplasia. Metabolism of Exogenous Estrogens

Abstract— —Urinary estradiol-17β was measured by gas chromatography in each of 22 normal or dysplastic dogs that had received intramuscular injections of estradiol. Measurable quantities of estradiol-17β were not found in urine from these dogs prior to administration of the exogenous hormone. The level of urinary estradiol-17β was lower in normal dogs than in dysplastic dogs after injection of the hormone. Larger quantities of the hormone occurred in the urine of older dogs of dysplastic lineage after estradiol-17 β injection. These results indicate dogs with hereditary hip dysplasia have a lower than normal capacity to metabolize biologically-active estradiol. Résumé— —L'estradiol-17β urinaire a été mésuré par gas-chromatographie dans chaque des 22 chiens normaux ou dysplastiques qui ont roçu des injections intramusculaires d'estradiol. Des quantités mesurables d'estradiol-17β n'ont pas été trouvées dans Purine de ces chiens avant 1'administration de hormone exogéne. Le niveau d'estradiol-17β urinaire était plus bas chez les chiens normaux que chez les chiens dysplastiques, après l'injection de l'hormone. Des quantités plus grandes de hormone ont ete trouvées dans l'urine des chiens plus âgés du groupe dysplastique, après l'injection d'estradiol— 17β. Les résultats indiquent que les chiens avec dysplasie héréditaire de la hanche ont une capacité moindre que la mornale de métaboliser l'estradiol biologiquement active. Zusammenfassung— —Oestradiol-17β im Urin wurde mittels Gas-Chromotagraphie in 22 normalen odcr dysplastischen Hunden gemessen, die intramuskulaere Injektionen von Oestradiol erhalten hatten. Messbare Mengen von Oestradiol-17β wurden im Urin dieser Hundc vor der Verabreichung des exogenen Hormons nicht gefunden. Der Oestradiol-17β-Spiegel im Urin war in normalen Hunden niedriger als in dysplastischen Hunden nach der Hormon-Injektion. Groessere Hormonmengen kamen im Urin von aelteren Hunden von dysplastischer Abstammung nach Oestradiol-17β-Injektion vor. Diese Resultate zeigen, dass Hunde mit hereditaerer Hueften-Dysplasie eine niedriger als normale Faehigkeit haben, biologisch aktives Oestradiol zu metabolisieren.     

Long‐term Effects of Pyrethrin and Cyfluthrin,a Type II Synthetic Pyrethroid,Insecticide Applications on Bull Reproductive Parameters

The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks.