Bracken (Pteridium aquilinum); the effect of steaming on the nutritive value of bracken hay.

نویسندگان

  • D R WILLIAMS
  • R A EVANS
چکیده

The bracken fern (Pteridium aquilinum) has been known for a long time to be poisonous to cattle (Penberthy, 1893) and horses (Muller, 1897) under farm conditions. Field cases of bracken poisoning in sheep are almost unknown; the more selective feeding habits of sheep may be responsible for their apparent immunity. Bracken poisoning has been experimentally produced in cattle (Almond, I 894), horses (Hadwen & Bruce, 1933), sheep (Moon & Raafat, 1951) and in rats (Weswig, Freed & Haag, 1946). The signs of bracken poisoning in simple-stomached animals, such as the horse and rat, are fundamentally different from those observed in ruminants. In the horse (Evans, Evans & Roberts, 1951) and the rat (Weswig et al. 1946; Evans & Evans, 1949) the signs are typical of thiamine deficiency and timely therapy with the vitamin produces complete recovery. It is now known that the bracken fern, in common with other pteridophytes, contains a thiaminase which converts thiamine into products which cannot replace the intact vitamin in mammalian nutrition (Evans, Jones & Evans, 1950). Bracken thiaminase is thermolabile (Evans & Jones, 1952) and steaming bracken for I h renders it harmless to rats (Evans et al. 1950) although bracken dried in a revolving-drum grass drier still contains thiaminase actively toxic to rats (Evans, Evans, Thomas, Watkins & Chamberlain, 1958). Bracken poisoning of cattle is characterized by haemorrhage and pyrexia with a severe leucopenia and thrombocytopenia due to depression of bone-marrow activity. The tissues of the affected animals are not deficient in thiamine. Thiamine therapy or even treatment with all known members of the vitamin-B group failed to cure the condition (Naftalin & Cushnie, 1954; Evans, Evans & Hughes, 1954a,b; Evans, Thomas, Evans & Edwards, 1958). The factor responsible for ruminant bracken poisoning has been proved to be different from thiaminase (Evans, Evans et al. 1958). Neither the steaming of fresh green bracken (Naftalin & Cushnie, 1954) nor the drying of fresh green bracken in a revolving-drum grass dryer (Evans, Evans et al. 1958) destroyed its toxicity to cattle. However, the steaming of bracken hay has been shown to lower its toxicity below a threshold level (Evans et al. 1954a, b) .

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Tumor induction in germ-free rats fed bracken (Pteridium aquilinum).

This study indicated that there was no significant difference in the incidence of intestinal tumors between germ-free and conventional rats fed a diet containing bracken, suggesting that gut microflora did not play a definite role in bracken tumorigenesis. However, bracken induced exclusively sarcoma but no adenocarcinoma in germ-free rats, whereas it induced predominantly adenocarcinoma in con...

متن کامل

Global chloroplast phylogeny and biogeography of bracken (Pteridium; Dennstaedtiaceae).

Bracken ferns (genus Pteridium) represent an ancient species complex with a natural worldwide distribution. Pteridium has historically been treated as comprising a single species, but recent treatments have recognized several related species. Phenotypic plasticity, geographically structured morphological variation, and geographically biased sampling have all contributed to taxonomic confusion i...

متن کامل

Centre for Evidence-based Conservation Systematic Review No. 3: Effectiveness of Current Methods for the Control of Bracken (pteridium Aquilinum )

Background Control of bracken (Pteridium aquilinum) is a global problem for livestock-based extensive agriculture, conservation, recreation, game management and forestry. Bracken is controlled primarily by application of asulam or by cutting. The success of bracken control may be dependent upon ecological variables (such as habitat type and latitude) and methodological variables (such as number...

متن کامل

Effectiveness of Current Methods for the Control of Bracken (pteridium Aquilinum)

Background Control of bracken (Pteridium aquilinum) is a global problem for livestock-based extensive agriculture, conservation, recreation, game management and forestry. Bracken is controlled primarily by application of asulam or by cutting. The success of bracken control may be dependent upon ecological variables (such as habitat type and latitude) and methodological variables (such as number...

متن کامل

Recent Advances in Bracken Fern Toxin Research

Bracken fern, commonly found in hilly regions contains toxic substances. It is reported to cause alimentary carcinoma and haematuria in both animals and human beings. Present paper deals with the recent advances in bracken fern toxins research in animals. Keyword: Bracken fern, Pteridium aquilinum Kuhn, Toxin, Carcinogens, Animal, Human, Haematuria, Recent advances. IPC code; Int. cl.⎯ AO1N25/0...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • The British journal of nutrition

دوره 13 2  شماره 

صفحات  -

تاریخ انتشار 1959