Malabsorption in the horse associated with alimentary lymphosarcoma.

Three horses suffering from malabsorption were shown to have alimentary lymphosarcoma predominantly affecting the small intestine and the associated lymph nodes. The diffuse cellular infiltration in two of the case produced marked changes in the villous architecture reducing the available mucosal surface area, and, with lowered or barely detectable disaccharidase activities, contributed to the impairment of digestive-absorptive processes. One of the horses maintained a voracious appetite and was not diarrhoeic, but failed to gain weight, indicating differences in the production and utilisation of energy sources absorbed from the small and the large intestines. A large proportion of plasma cells in the infiltrate, and the resulting morphological changes in two of the cases bore a striking resemblance to features of alpha chain disease, an immunodeficiency disease of man, although immunological studies were not conducted on these horses.     

Development and application of an ELISA technique for the detection of antibody to avian encephalomyelitis viruses

A rapid sensitive enzyme-linked immunosorbent assay for the detection of antibody to avian encephalomyelitis viruses (AEVs) in chickens using purified antigen is described. The procedure differed from others which have been described for AEV, in that it involved a negative antigen subtraction step which accounted for the variable adhesiveness of chicken sera to plastic surfaces. The procedure was reproducible (between-assay coefficient of variation 8.95 per cent) and a good correlation was observed with results obtained by neutralisation index tests (r = 0.91, P less than 0.1). The assay detects only AEV-specific antibody and allows monitoring of the spread of AEV in flocks.     

The degradation of (Z)- and (E)-1,3-dichloropropenes and 1,2-dichloropropane in soil

The degradation in soil of the major constituents of a 1,3-dichloropropene-1,2-dich-loropropane nematicide has been studied under laboratory and outdoor conditions. In sealed glass containers, ( Z)- and ( E)-1,3-dichloropene- 2-¹⁴C were converted in soil into the corresponding 3-chloroallyl alcohols and these alcohols were in part strongly bound to the soil. The ( Z)- and ( E)-3-chloroacrylic acids were also found as minor products. More polar products were detected and these released the chloroacrylic acids in 20–30% yield upon hydrolysis. Although the 1,3-dichloropropenes were lost by volatilisation from soil stored in open glass jars outdoors, they also underwent degradation to the same products that were detected in sealed containers. There was evidence of only slight degradation of 1,2-dichloropropane- 2-¹⁴C (4 % or less of the applied radioactivity remained unextracted from a loam soil after 5 months). When soil treated with the 1,2-dichloropropane was stored outdoors in an open glass container, less than 1 % of the original radiolabel remained in the soil after 10 days under these conditions due to volatilisation of the applied material. In a separate experiment potatoes were grown in soil 6 months after treatment with a mixture of both ( Z)- and ( E)-1,3-dichloropropene- 2-¹⁴C and 1,2-dichloropropane- 2-¹⁴C. Although 5 % of the applied radiolabel remained in the soil at potato harvest the potato tubers contained only a very small residue (0.007 mg/kg).     

Effect of avoparcin interaction with anticoccidial compounds on the growth and carcase composition of broilers

The anticoccidial drugs narasin, lasalocid, monensin and salinomycin, with and without avoparcin, were fed to 1280 broiler chickens from 1 to 49 d old. At day 49 significant interactions were detected between avoparcin and the anticoccidial compounds for body weight and food consumption. This indicated that the increases in body weight and food consumption obtained with avoparcin were greater with some anticoccidial compounds (lasalocid and salinomycin for body weights and lasalocid for food consumption) than with others (monensin and narasin for body weights and monensin, narasin and salinomycin for food consumption). Overall there was evidence that avoparcin increased body weight (5.8%), food consumption (2.5%) and efficiency of food utilisation (2.9%). In addition avoparcin produced significant increases in plucked weight and the proportion of visceral fat together with and decreases in the proportions of edible giblets and waste offal.     

The degradation of the herbicide benzoylprop-ethyl following its application to wheat

The herbicide benzoylprop-ethyl [SUFFIX,^a ethyl (±)-2-(N-benzoyl-N-3,4-di-chloroanilino) propionate] has been applied in a radiolabelled form to spring wheat and winter wheat growing both indoors and outdoors. During the application the compound also fell onto the soil. The plants and corresponding soils were examined at harvest at 71-98 days from treatment. Conversion of the herbicide occurred in plants and soil predominantly by a hydrolytic reaction to form benzoylprop^b followed in plants by its conjugation with sugars. Small amounts of N-benzoyl-3,4-dichloroaniline and benzoic acid were also detected in plants. There was no evidence for the presence of 3,4-dichloroaniline in the crops or soils nor was there evidence for 3,4,3′,4′-tetra-chloroazobenzene which has been implicated as a degradation product of some 3,4-dichloroaniline herbicides in soils. Residues on plants were greatest in the straw and consisted mainly of benzoylprop-ethyl and benzoylprop in free and conjugated forms. There was no evidence for appreciable movement of the compound within the plant from the treated foliage. Residues were particularly low in the grain and were not detected in the crop grown outdoors (limit of detectability 0.01 mg/kg). Residues in the soils were mainly in the 0-7.5 cm layer and there was no evidence for leaching below 15 cm.     

Distinguishing high and low anopheline-producing rice fields using remote sensing and GIS technologies

Worldwide, 140 million ha are devoted to rice cultivation, mostly in developing countries of the tropics and subtropics where malaria still constitutes a serious human health problem. Because rice fields are flood-irrigated on a semi-permanent basis during each growing season, they provide an ideal breeding habitat for a number of potential mosquito vectors of malaria. One of these vectors, Anopheles freeborni, is distributed throughout nearly 240 000 ha of irrigated rice in northern and central California, and may serve as a model for the study of rice field mosquito population dynamics using spectral and spatial information. Analysis of field data revealed that rice fields with rapid early season vegetation canopy development, located near livestock pastures (i.e. bloodmeal sources), had greater mosquito larval populations than fields with more slowly developing vegetation canopies located further from pastures. Remote sensing reflectance measurements of early season rice canopy development and geographic information system (GIS) measurements of distance to livestock pasture were combined to distinguish between high and low mosquito-producing rice fields. These distinctions were made with 90% accuracy nearly 2 months before anopheline larval populations peaked.     

Tetracycline resistance determinants in streptococcal species isolated from the bovine mammary gland.

Seventy-one streptococci isolated from dairy cows with clinical mastitis were tested for tetracycline resistance. Twenty-one (30%) isolates were tetracycline resistant (Tcr), and eight hybridized with the Tet O, one hybridized with the Tet L, and one hybridized with both the Tet L and Tet K determinants. The remaining Tcr isolates did not hybridize with any of the 5 Gram-positive Tet determinants tested. The Tet O determinants were plasmid-mediated, and four selected strains transferred the Tet O determinant at frequencies of 10(-6) to 10(-8). Strains which did not hybridize with known probes were tested for resistance to minocycline. All of the Streptococcus dysgalactiae had low minimum inhibitory concentrations (MICs) for minocycline, while the S. agalactiae and the one S. uberis showed high MICs to minocycline. This suggests that at least two different uncharacterized Tet determinants exist in these isolates, one conferring high resistance to both tetracycline and minocycline and one conferring only tetracycline resistance.     

The significance of the gastrointestinal parasites of Asian buffalo in Sri Lanka

Buffalo aged 3–15 months on institutional farms and in the villages of an irrigation project were monitored for gastrointestinal nematodes by faecal egg counts over two years. Apart from treatment for Toxocara vitulorum at 10–16 days of age, no anthelmintics were used. Half of the strongylid egg counts were zero and 90% were less than 500 epg of faeces on the institutional farms, and 67% were zero and 97% less than 500 epg in the villages. No problems arose during four years without anthelmintics on the institutional farms and during two years in the villages. Autopsies demonstrated that the eggs which were present were produced by mixed infections of small numbers of Haemonchus spp., Mecistocirrus digitatus, Trichostrongylus spp., Bunostomum phlebotomum and Cooperia spp. High egg counts of Strongyloides papillosus occurred in calves up to six months old, but were not pathogenic.