Development of an enzyme-linked immunosorbent assay for the detection and measurement of the trypanocidal drug isometamidium chloride in cattle

An enzyme-linked immunosorbent assay (ELISA) was developed to measure accurately levels of the trypanocidal drug isometamidium in the serum of treated cattle. The assay requires only 5 microliters of test serum, is sensitive to a level of 0.5 pg ml-1 and is highly specific. Cross reactivity does not occur with the two other widely used trypanocidal drugs diminazene aceturate and homidium bromide. Serum drug levels are detectable for up to six months in cattle after a single dose of 1 mg kg-1 intramuscularly, the maximum period under field conditions for which effective prophylaxis can be maintained against tsetse challenge. Application of the assay will aid the rationalisation of treatment campaigns and assist in assessing the occurrence of drug-resistant trypanosome populations.     

Pathophysiology of ovine trypanosomiasis: ferrokinetics and erythrocyte survival studies.

The haematological changes, erythrokinetics and ferrokinetics of sheep were investigated after infection with Trypanosoma congolense. Following the detection of parasites in blood, the infected sheep developed macrocytic hypochromic anaemia. Studies with 51Cr-red cells, 125I-albumin and 59Fe as ferric citrate 11 weeks after infection revealed that infected sheep had significantly lower mean circulating red cell volumes but higher plasma and blood volumes than control sheep. The infected sheep also had enhanced erythropoietic activity as judged by significantly higher plasma iron turnover rates, faster disappearance of radio-labelled iron and higher iron incorporation rates than control sheep. The rate of disappearance of 51Cr-labelled red cells was greater in infected than in control sheep. It was concluded that the anaemia observed at this stage of infection was due to an increased rate of removal of red cells from the circulation coupled with haemodilution, with no evidence of dyshaemopoiesis.     

Sodium deficiency of grazing cattle in Papua New Guinea

Summary Sodium deficiency was suspected from low saliva sodium concentrations in cattle at various sites in the lowlands of Papua New Guinea. In an experiment at Erap, Morobe Province crossbred and pedigree Brahman heifers supplemented with copper, cobalt and/or common salt showed no response to copper or cobalt supplementation. There was a significant growth response (P<0·01) to salt supplementation over a 16 week period confirming sodium deficiency in these animals. The response in the crossbreds was twice that in the purebreds. Supplemented crossbred animals grew 0·78 kg/day over the 16 week experimental period.

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Resumen Se sospechó deficiencia de sodio al encontrar valores bajos de este elemento, en la saliva de bovinos que pastoreaban sitios bajos en Pápua. En un experimento en Erap, Provincia de Morobe, novillos Brahman puros y cruzados suplementados con cobre, cobalto y/o sal comun, no mostraron respuesta al cobre o al cobalto. Hubo respuesta significative (P<0·01) a la suplementación con sal en un período de 16 semanas, confirmando así la deficiencia de sodio en estos animales, con major respuesta en los cruces que en los Brahman puros. Los primeros aumentaron 0·78 kg/dia durante el período experimental de 16 semanas.

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Résumé Une carence en sodium a été suspectée en raison de faibles concentrations en sodium dans la salive de bovins paissant à divers endroits dans les plaines de Papouasie Nouvelle Guinée. Dans une expérience conduite à Erap, Province de Morobe, des génisses métissées et de pédigré Brahman recevant un complément de cuivre, cobalt et/ou de sel ordinaire n’ont pas réagi à la complémentation en cuivre ou cobalt. La complémentation en sel a entrainé une réponse de croissance significative (P<0,01) sur une période de 16 semaines, confirmant par là la carence en sodium chez ces animaux, avec une réponse deux fois plus importante chez les métisses que les animaux de race pure. Les animaux métissés recevant un complément ont eu un gain de poids de 0,78 kg par jour pendant la période expérimentale de 16 semaines.

     

Observations on the T wave of the equine electrocardiogram.

The paper describes changes observed in the T wave and T vectorcardiogram in horse after various periods of exercise. Using radiotelemetry and a bipole lead all horses showed negative T waves immediately after exercise. In some of them this was followed by a markedly positive T deflection. Possible reasons for these changes are briefly discussed.     

Influence of dietary protein on the pathophysiology of haemonchosis in lambs given continuous infections

Mixed-sex groups of three-month-old Finn Dorset and Dorset Horn lambs were given complete diets containing either high or low protein. A trickle infection with Haemonchus contortus of 200 larvae, given three times a week, began one month later for a 17 week period. Erythrokinetic, metabolic, digestibility and balance studies were conducted with the male lambs during weeks 12 to 14 of the infection. Clinical signs of haemonchosis became evident only in the low protein diet group. The infection was characterised by severe macrocytic anaemia, hypoproteinaemia, hypoalbuminaemia, reduced survival, high egg counts and a significantly greater worm burden. In the high protein diet group many lambs developed resistance to further infection in contrast to the low protein group in which no resistance developed. Live-weight gain was not affected by infection in the high protein diet group but decreased in the lambs given the low protein diet compared with uninfected controls. However, infection did not appear adversely to affect the digestive efficiency, nitrogen retention or iron absorption in either dietary group although loss of appetite occurred in the low protein group. Examination of a sample joint from the carcases showed infection was associated with a marked reduction in muscle mass in lambs given the low protein diet relative to the control animals.