Serogroups of Campylobacter fetus and Campylobacter jejuni isolated in cases of ovine abortion

Of 38 aborted ovine fetuses from 23 sheep flocks 29 C. fetus subsp. fetus and 22 C. jejuni were isolated and examined biochemically and serologically for heat-stable antigens. Serologic examinations were carried out by passive haemagglutination test. In case of C. fetus subsp. fetus strains alkaline antigen extraction was used. Antisera to two serogroups of C. fetus and to Penner serotype reference strains 1 to 60 were produced in rabbits. Abortion was caused in 18 (78.3%) flocks by C. fetus subsp. fetus and in 5 (21.7%) flocks by C. jejuni. Six C. fetus subsp. fetus strains grew well at both 43 and 25 degrees C. With one exception all C. fetus subsp. fetus were resistant, whereas all 29 C. fetus subsp. venerealis strains were sensitive to 30 micrograms/ml cefoxitin and cefamandole. These two cephalosporins can be used to differentiate the two subspecies of C. fetus. Passive haemagglutination test using alkaline antigen extraction is a proper method for the examination of heat-stable antigens of both C. fetus subspecies. Out of 24 C. fetus subsp. fetus strains 13 belonged to serogroup A(01), and 11 to serogroup B(02). C. jejuni strains examined belonged to Penner serogroup 1 (6 strains), to serogroup 5 (4 strains) and to serogroup 8 (4 strains).     

Effects of dietary protein concentration and corticosterone injections on energy and nitrogen balances and fat deposition in broiler chicks

Reducing dietary protein concentration in isocaloric diets consistently decreased nitrogen and energy excretion, and increased dry matter (DM), non-protein DM (NPDM), energy retention and fatness. There were significant correlations, negative between dietary energy-to-protein (E:P) ratio and nitrogen excretion and positive between the E:P ratio and the retention of DM, NPDM and energy. Nitrogen excretion was correlated with energy excretion, and NPDM retention with energy retention. Corticosterone injections increased fatness despite significantly increasing nitrogen and energy excretion. A positive relationship was observed in corticosterone-treated birds between nitrogen excretion on the one hand and the retention of DM and NPDM on the other. Increased food intake because of a low dietary protein concentration was not evident when a sorghum-based diet was used. Moreover, corticosterone injections increased neither the food intake nor the fatness of chicks fed this diet. Decreasing the protein concentration in diets containing identical metabolisable energy (ME) levels slightly, but significantly increased apparent ME values in three out of four experiments. Corticosterone injection did not affect this variable.     

Control of Rhizoctonia solani fruit rot of tomatoes by Trichoderma harzianum Rifai

Application of Trichoderma harzianum, to soil or by coating tomato fruits, reduced Rhizoctonia solani fruit rot by up to 43% and 85%, respectively, under laboratory conditions. When mixed with naturally infested soil, Trichoderma reduced R. solani inoculum potential by 86% in field trials. It also significantly reduced fruit rot by 27–51%.     

Spongy degeneration of white matter in the central nervous system of silver foxes (Vulpes vulpes)

A disorder of central nervous white matter in Norwegian-bred silver foxes is described from the case histories of 21 clinically affected foxes. The main presenting sign of this disorder was caudal limb ataxia, which appeared between 2 1/2 and 4 months of age and progressed over the next 4-8 weeks. Only four affected foxes were allowed to live beyond this period, but they showed moderate to marked improvement. Light microscopic examination of specimens from 16 affected foxes necropsied between 3 1/2 and 6 1/2 months of age revealed lesions that were restricted to the white matter of brain and spinal cord. The lesions were characterized by a symmetrical spongy change with vacuoles of varying sizes and included significant myelin deficiency. There was a relative preservation of axons and nerve cells and no significant inflammation or vascular reaction. An astrocytic hypertrophy was usually associated with the spongy change. Ultrastructural examination of central nervous tissue from two, perfusion-fixed, 6-month-old foxes showed intramyelin vacuoles resulting from splitting of the myelin lamellae at the intraperiod line and was interpreted as indicating myelin edema. Expanded extracellular spaces and watery astrocytic processes also contributed to the vacuolar appearance. Astrocytic processes in affected areas were hypertrophic and contained abundant filaments. Although the 16 silver foxes had severe clinical signs, their lesions had features in common with the juvenile form of Canavan's disease in children and a spongy degeneration reported in Labrador Retrievers; however, the clinical course in the foxes was not uniformly progressive.     

Sudden death in training and racing Thoroughbred horses

We reviewed case records, necropsy reports, and histologic sections from 25 Thoroughbred racehorses that died suddenly at 3 Chicago racetracks. These were young horses ranging in age from 2 to 5 years. There were more females (n = 16) than males (n = 9), and the incidence of death increased slightly in the spring and summer. Twenty-one of the 25 horses died while racing or training. Only 8 of the 25 horses (32%) had lesions sufficient to account for the death. In 6 of those 8 cases, death was caused by massive thoracic or abdominal hemorrhage. The site or nature of the vascular defect in these cases could not be determined. One horse died of severe preexisting pulmonary disease, and one died of encephalitis and cardiac papillary muscle fibrosis. The cause of death was undetermined in 17 horses (68%). Nearly all horses had pulmonary edema, congestion, and/or hemorrhage. We postulate that these unexplained deaths were a result of exercise-induced acute cardiovascular failure.     

Effects of different land use types on infiltration capacity in a catchment in the highlands of Ethiopia

Infiltration capacity is an important variable for understanding and predicting a range of soil processes. This study investigated for different slope positions the effects of forest conversion to cultivation and grazing on soil infiltration capacity. Infiltration capacity was measured in the field in each land use type using a double‐ring infiltrometer. A total of 108 soil samples (3 slope positions × 3 land use types × 4 soil profiles × 3 soil depths) were collected to determine the variables that affect infiltration capacity viz. particle size distribution, organic carbon content, dry bulk density and soil moisture content. The results showed that in the cultivated and grazed land compared with forest, infiltration capacity and soil moisture content were 70 and 45% smaller respectively, and dry bulk density was 13–20% larger. Changes in soil structure caused by surface soil compaction because of tillage and animal trampling coupled with a smaller soil organic carbon content, are likely to be the principal factors causing the decline in infiltration capacity and soil moisture content after conversion of forest to cultivation and grazing.