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Title: Studies on the nutritional and toxic properties of bracken (Pteridium aquilinum)
Author: bin Idrus, Ahmad Zaharudin
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1974
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1. A preliminary experiment to study the effect of thiamin deficiency on the absorption of proline in rats using the everted gut-sac technique was carried out. The absorption of proline in small intestines of thiamin deficient rats was found to be greater than in control rats, although it was lower than that found in pair-fed control rats. It was suggested that the effect might have been due to increased permeability of the intestinal membrane and possibly resulted more from passive transfer rather than from active transport. 2. Groups of sheep were fed young and mature bracken with and without protein supplementation. The blood biochemical parameters, nutrient content of some tissues, blood cell counts showed that sheep given a protein supplement did not show significant difference in their nutritional status and blood cell counts, viz. decreased in leucocytes and thrombocytes, from unsupplemented sheep. A marked elevation of SGOT levels was obtained in experiments 1 and 2, which was believed to be due to a combined effect of malnutrition and the bracken toxin. The leucocyte counts recovered after the sheep were withdrawn from the bracken diets and placed on a higher plane of nutrition. A low leucocyte count among sheep pair-fed to those consuming bracken also provided an indication that malnutrition may aggravate the toxicity of bracken fed to animals. The estimation of transketolase activity in blood and the TPP effect following the in vitro addition of thiamin pyrophosphate was used as a measure of thiamin status of bracken fed sheep. The validity of these procedures when applied to blood of bracken fed undernourished sheep appeared to be somewhat limited especially when it was apparent that damage to the liver had occurred: the TPP effect appeared to be the more useful of the two measurements. Thiamin level in blood was measured and seemed to reflect the sheep's status of that nutrient. 3. The introduction of a methanolic extract of bracken into the rumen of sheep appeared to produce a depressive effect on the voluntary intake of hay. This finding suggested that the methanol soluble toxic constituents of bracken promoted a low intake of fodder by sheep and that this may apply to bracken consumption under field conditions in addition to the effect of low palatability on bracken intake. The removal of toxic constituents of bracken with methanol was found to improve the amount consumed by two sheep, thus supporting the suggestion that the toxic constituent(s) depressed intake. However, the toxic constituent(s) appeared not to produce abnormal conditions in the rumen as shown by the absence of adverse effects on the composition of rumen liquor as shown by normal pH, ammoniacal nitrogen content and the quantity and pattern of volatile fatty acids production. 4. Bracken which was collected in July 1973 from Elrick Hill, Aberdeenshire when dried and fed at 50% of a diet to rats proved to be highly toxic: a high mortality occurred in 5 days. When phenothiazine was added to a non-bracken diet and fed to rats it was found to stimulate an increased level of BP hydroxylase activity in liver. However, the provision of phenothiazine and thiamin to rats fed a 50% bracken containing diet, failed to prevent the acute poisoning. The inclusion of 20% bracken in a diet appeared to depress the level of BP hydroxylase activity in liver. 5. When two groups of sheep were fed a diet containing 20% bracken and 80% barley, with and without the inclusion of phenothiazine, no protective effect was obtained in that a similar depression in counts of blood leucocytes and thrombocytes occurred in both groups in spite of the finding that BP hydroxylase activity in the liver of the sheep was increased by the phenothiazine treatment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available