Trypanosomiasis is a major veterinary problem over much of sub-Saharan Africa and is frequently associated with under-nutrition. There is growing evidence that nutrition can have a profound effect on the pathophysiological features of animal trypanosomiasis. These features include anaemia, pyrexia, body weight changes, reduced feed intake and diminished productivity including reduced draught work output, milk yield and reproductive capacity. Anaemia is a principal characteristic of trypanosomiasis and the rate at which it develops is influenced by both protein and energy intakes. Pyrexia is associated with increased energy demands for maintenance which is ultimately manifested by reductions in voluntary activity levels and productivity. Weight changes in trypanosomiasis are markedly influenced by the levels of protein intake. High intakes allow infected animals to grow at the same rate as uninfected controls providing energy intake is adequate whilst low energy levels can exacerbate the adverse effects of trypanosomiasis on body weight. Reductions in feed intake are less apparent in animals which are provided with high protein diets and where intake is limited by the disease animals will often exhibit preferential selection of higher quality browse. Further studies are required to evaluate the minimum levels of protein and energy supplementation required to ameliorate the adverse effect of trypanosomiasis, the nature and quality of protein supplement to achieve these benefits and the influence these have on digestive physiology.
The epidemiology of ostertagiasis in south west Scotland was studied in groups of cattle grazed through two successive grazing seasons separated by a period of winter housing. Towards the end of the first grazing season (September) the numbers of infective larvae (L3) on the pasture had increased to high levels (up to 24,000 L3 per kg) which resulted in high faecal egg counts, worm burdens, plasma pepsinogen levels and the occurrence of clinical ostertagiasis in the calves. By late spring (May) at the onset of the second grazing season, there was an almost complete mortality of the overwintered L3 on the pasture followed by the appearance of moderately high numbers of a new population of L3 in September (up to 9000 L3 per kg). The latter increase in the numbers of L3 was reflected by negligible faecal egg counts, low worm burdens and a moderate elevation of plasma pepsinogens in the second year animals. It therefore seems that although young cattle acquire a good immunity to Ostertagia ostertagi after one season at grass the small infections established in the early part of the second season are capable of contaminating the pasture to levels which could be dangerous for susceptible stock. An allergic reaction in the abomasal mucosa could be the basis of the elevated pepsinogens present in the second year animals.
In this study, we have compared two different doses of clonidine (bolus of 25 micrograms and infusion of 19 micrograms h-1; bolus of 50 micrograms and infusion of 37 micrograms h-1, both added to 0.03% bupivacaine) with a control group of 0.03% bupivacaine alone. The study was performed in a randomized, double-blind manner, and a total of 45 patients were studied. Both clonidine regimens resulted in marked local anaesthetic sparing, with no change in the quality of analgesia. There was no difference in the severity of lower limb motor weakness and no difference in maternal sedation, although only a small number of patients were studied. No adverse maternal haemodynamic effects were observed. The newborn infants were not sedated on delivery. The number of fetal cardiotocographic traces judged to be of concern was higher in both clonidine groups. However, this just failed to reach statistical significance (P = 0.055).
Two groups of nine in-calf beef cows were given daily for the last 16 weeks of pregnancy and the first 6 weeks of lactation 1-35 increasing to 3-15 kg molassed sugarbeet pulp dry matter containing added urea together with oat straw ad libitum. Additionally, one group of cows received supplementary dicalcium phosphate which increased their total phosphorus intake from about 12 to 28 g P/day.
An experiment was conducted to examine, under laboratory conditions, the pathophysiology of chronic ovine haemonchosis. In the present study, groups of Merino and Scottish Blackface lambs were maintained on a low plane of nutrition and infected with 50 Haemonchus contortus larvae/kg live weight. The parasitized lambs along with respective breed controls were examined over a 27-week period. In addition to the body weight, haematological and parasitological parameters, erythrokinetic, metabolic, digestibility and nitrogen balance studies were conducted in the early stages of the infection. The results demonstrated that a low level of infection with H. contortus in lambs on a poor plane of nutrition caused the development of a normochromic normocytic anaemia which was associated with a modest but significant increase in abomasal blood loss and slightly elevated erythropoiesis in both breeds relative to the controls. The level of anaemia, hypoproteinaemia and pathophysiological changes were more marked in the Merino lambs and they also had higher faecal egg counts than the Blackface lambs.
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